# lopey idle with hesitations



## IWantRWD (Feb 2, 2006)

So let me start off by saying that I have recently bought a decently clean ('specially for a michigan car) NX2k. And it has been starting to through me for a loop.

First: The lopey idle. It happened after installing a new speedo cable. This isn't my first Nissan or my first rodeo so i know just removing the cluster wont effect the idle as bad as it has. It idles as though it has 280s and set for 700 rpm idle. Also the smell of unburnt fuel can occasionally be smelt.

Second: The hesitations. Light throttle, high gear low speed (read cruising in 3rd at 25mph) its got hesitation, sluggishness, and just seems down on power. Now, if i get into it, it feels like it pulls fine..but then again, ive only been driving this car 1 week.

So, having a CA swapped S13 and other modded rides, i went though the basics. Did a tune up, plugs, wires, cap, rotor, fuel filter. But i did all of this AFTER this started. Checked MAF voltage. The ground was alittle high at .015 no matter where i put the ground. But i tried to reground it a couple of times, and no such luck, gotta do the big 3 soon.

Here is also what i found. I can unplug the FPR vacuum. no change in idle. If i pinch off the return line, i get a much smoother idle, but i also get a raw fuel smell.

So, im stumped. I cant quite wrap my head around it. Im getting code 12 and 33. But i just replaced the o2 sensor and checked out the maf and the voltages at idle are 1.4, .015, 14.5. So maf checks out voltage wise, reset the ecu, codes came back. Idle didnt improve.

Oh, so i think i forgot this. 92 NX..sr20, half an exhaust cone filter and half assed removed emissions. 165000 miles 5 speed


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## jdg (Aug 27, 2009)

IWantRWD said:


> #1-It idles as though it has 280s and set for 700 rpm idle. Also the smell of unburnt fuel can occasionally be smelt.
> 
> #2-......Light throttle, high gear low speed (read cruising in 3rd at 25mph) its got hesitation, sluggishness, and just seems down on power. Now, if i get into it, it feels like it pulls fine..
> 
> ...


#1 - I was going to say a vacuum leak overall, but that doesn't really jive with point #1. Then again, the unburnt fuel smell could be from the fuel tank itself, like the filler cap or something.

#2 - Sound like a vacuum leak there, or maybe a sticky EGR valve?

#3 - .015 volts or ohm resistance? Either or...heck, that could be just the resistance of the leads, or maybe some induced voltage in the leads themselves.

#4 - That's kinda neat eh? Initially I'd say it's running lean, like a vacuum leak 'cause when you unplug the FPR, it's wanting more fuel, and when you plug the return line it gives it more fuel.

#5 - That's no good overall right there...doesn't really help in troubleshooting things at all.

What's your base timing set at? Any pinging? I might try bumping it up 2 or 4 degrees and see how it feels, even though GENERALLY, a more advanced timing will simulate or help to correct for a slightly rich mixture, it may or may not help here.


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## IWantRWD (Feb 2, 2006)

See, that's where I got stuck. I also think it sounds a lot like a vacuum leak. But I checked and rechecked and double checked, no vacuum lines are disconnected or in bad enough shape to cause this type of problem.

The EGR is not the culprit. I can move the EGR diaphram while the car is idling and it effects the idle.

The MAF number is voltage. .009 is what i was shooting for. Ive had some problems arise from my CA swap because of improper voltage going through the ground on the maf.

The FPR thing is whats leading me to believe it is the fuel pressure regulator. Normal idle fuel pressure should be around 33psi IIRC, and when i unplug the regulator it should hit 45psi. So, if there was a vacuum leak that should "take care" of the lean condition, and make it bog and run worse due to being over fueled. Now when i pinch off the return line it should increase the fuel pressure in the rail, which would in turn do what unplugging the vacuum would do. That's the part that gets me, is unplugging the vacuum and pinching the return line should do the same thing.

I haven't yet checked base timing, although i need to. A friend of mine has my timing light. To be honest i'd have to brush up on setting the base timing on a nissan because i've been in the DSM game for so long I forgot. My assumption is that it would be right around 15btc. But you know what assuming does.

Ill check timing and do a compression test this weekend just to be on the safe side of things. And maybe a intake leak test just to make sure i didn't blow an intake manifold gasket or anything.


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## LvR. (May 26, 2010)

This all sounds like funky injector/injectors to me.

Pinching off the return line imo should not do the same as the FPR vacuum removal - the FPR can at worst cause around 45psi rail pressure while a return line pinch-off may/will cause a way higher pressure ................... and if the motor runs off a simultaneous injection loop at idle, its easy to see how pinching the return line will cause a funky injector position to experience "improved" fuel arrival and as a result improved idle quality at your nose's expense


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## jdg (Aug 27, 2009)

IWantRWD said:


> The EGR is not the culprit. I can move the EGR diaphram while the car is idling and it effects the idle.


But is the EGR solenoid opening/closing to allow the EGR to do the job?



> The MAF number is voltage. .009 is what i was shooting for. Ive had some problems arise from my CA swap because of improper voltage going through the ground on the maf.


I've never back-probed mine, just hooked it up to an OBD scanner and read the raw values coming off of it. If I remember right, I'd get something like 230 g/sec at idle. For reference only. I could be wrong...



> The FPR thing is whats leading me to believe it is the fuel pressure regulator. Normal idle fuel pressure should be around 33psi IIRC, and when i unplug the regulator it should hit 45psi. So, if there was a vacuum leak that should "take care" of the lean condition, and make it bog and run worse due to being over fueled. Now when i pinch off the return line it should increase the fuel pressure in the rail, which would in turn do what unplugging the vacuum would do. That's the part that gets me, is unplugging the vacuum and pinching the return line should do the same thing.


Have you put a fuel pressure gauge on the rails? Does the fuel pressure raise up, or are you just guessing that it's NOT raising up? If the diaphragm was shot in the FPR, it probably explains the "vacuum leak" symptoms as being a lean fuel mix that the ECU can't compensate enough for. Maybe try putting a little bit of pressure INTO the FPR and see what happens. Maybe just put your mouth on the line and suck and blow into the hose and see if the idle moves around because of the alternating rich/lean fuel mix (my ex-wife might be able to wreck the FPR diaphragm for you, but that's another story entirely!)...I don't know if a person could actually make enough difference, but it's worth a try. You could disconnect the front O2 sensor (once the engine is good and warmed up) and force the ECU into 'open-loop' and prevent the ECU from trying to compensate for the rich/lean fuel mix while you do this. Might work, might not...just a theory off the top of my head.

Again, might want to try and find an OBD scanner that gives you numbers, not just trouble codes, specifically he MAF, Long Term, and Short Term fuel trim values, which should be any decent OBD2 scanner.



> I haven't yet checked base timing, although i need to. A friend of mine has my timing light. To be honest i'd have to brush up on setting the base timing on a nissan because i've been in the DSM game for so long I forgot. My assumption is that it would be right around 15btc. But you know what assuming does.


I don't have my book either. I want to say 10BTDC, maybe 8. At any rate, if it don't knock, bump it up 'till it does, then dial it back a bit! Let the knock sensor take care of the rest eh?!

I think I smell what you're cooking and I think the FPR is a good next step.

And as far as the 'simultaneous' injection at idle, I know the later models ('95-up) are exclusively sequential fire in all modes (except start) until you get really high into the RPM's and loads...so sayeth the almighty FSM anyways. Who knows what they've done to the flash over the years though... The earlier models may very well be 'batch' injection at lower revs/loads.


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## LvR. (May 26, 2010)

Well - the Sentras and Maximas (I own one of each) here up to 95 all had both sequential and simultaneous injection as a ECU feature (FSM ala eg EF+EC215), so it may or may not apply in IWantRWD's case


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## IWantRWD (Feb 2, 2006)

Back on the EGR thing. Effectivally as the EGR is sitting right now, there is no vacuum to move to diaphram, and on the underside of the diaphram at the intake manifold, there is vacuum. So the intake vacuum should hold the egr diaphram closed, making it, theoretically like having an EGR blockoff. And im going to be honest. I dont care what the service manual says, putting exhaust gas back into the intake does not do anything but increase intake temps and lower the A/Fr going into the combustion chamber.

I just got my timing light back and bought a fuel pressure gauge so I will be installing the gauge and checking basing timing today and will report my findings. I still suspect the FPR but i'll see what my pressure gauge shows me. I am definatly running way rich since im only seeing 17ish mpg with the awesome b13 4speed trans. haha

SER.net is saying 15btdc to 17btdc. The 8 to 10btdc is dsm..haha Im going to check and check and backprobe and backprobe again. To report my findings. Thanks for the ideas ill check back in later


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## jdg (Aug 27, 2009)

IWantRWD said:


> And im going to be honest. I dont care what the service manual says, putting exhaust gas back into the intake does not do anything but increase intake temps and lower the A/Fr going into the combustion chamber.


Then, you are the only one...
Exhaust gas recirculation - Wikipedia, the free encyclopedia



> I just got my timing light back and bought a fuel pressure gauge so I will be installing the gauge and checking basing timing today and will report my findings. I still suspect the FPR but i'll see what my pressure gauge shows me. I am definatly running way rich since im only seeing 17ish mpg with the awesome b13 4speed trans. haha
> 
> SER.net is saying 15btdc to 17btdc. The 8 to 10btdc is dsm..haha Im going to check and check and backprobe and backprobe again. To report my findings. Thanks for the ideas ill check back in later


If 15-17 doesn't ping, then I'd say go for it.
I agree though about the FPR being out in the weeds...


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## IWantRWD (Feb 2, 2006)

okay so just did some tests and diagnostics.

TPS is reading the proper voltage.

Fuel pressure is at 36psi at idle and raises to about 44 when vacuum is removed and holds fuel pressure after shutoff

o2 sensor is getting the proper voltage even though I'm getting a code for it, and unplugging the sensor does nothing to change the idle at all.

When i squeeze the pcv hose, nothing happens. Well, the hose cracks, but thats it.

Timing is at around 15btdc as it should be.

unplugging the injectors and plug wires one at a time does change the idle. But number 4 fuel injector doesn't change the idle as much as the rest.

Im now getting o2 and knock sensor codes. but i cant quite grasp the concept of turning the ecu to o2 monitoring mode. Even though ive read the FSM about 10 times and tried to do it like my s13 was setup.

ECU reported no self faults.

There is one thing that gets me and since i hate the highport intake setup so much it frustrates me even more. There is a definate air hissing sound coming from the intake, but since its such a cluster-f--- under there i cant find out where its coming from. All vacuum lines are pluged. The only vacuum lines i have are to the evap canister, brake booster, and FPR.

I did a simple leak check of the intake with soapy water and the injector seals are not leaking and didn't see bubbling on the head side of the intake. Now i guess i just have to find some air to do the good ole' boost leak tester.


That wiki article still doesn't convince me that the EGR system is useful.


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## jdg (Aug 27, 2009)

EGR - yes, I agree it's not useful as far as power goes, but maybe that's where we differ in thought. I think it's a great idea and works well for dropping off NOx emissions and keeping low load knocking/pinging out of there.

TPS - good
FPR - looks like it's actually working right. Guess that ain't it...
O2 sensor - might be getting the right voltages, but might not be responding quick enough, i.e. might be lazy (not doing it's switching quick enough for the ECU)
I wouldn't think squeezing the PCV hose would do anything unless it's bleeding vacuum everywhere, but you'd be able to find that straight away.
Maybe #4 injector is jacked up, maybe not. If you had an injector tester you might be able to tell. Who knows.
O2 and knock sensor codes - I can see how lean mix's could cause both of those. Too bad it's not OBD2 compliant. You could look at the short term and long term trims to see what the ECU is doing.

How about spraying some carb cleaner around the intake and seeing if the idle goes nuts if/when it hits a possible vacuum leak?


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## LvR. (May 26, 2010)

> There is a definate air hissing sound coming from the intake, but since its such a cluster-f--- under there i cant find out where its coming from. All vacuum lines are pluged. The only vacuum lines i have are to the evap canister, brake booster, and FPR.
> 
> I did a simple leak check of the intake with soapy water and the injector seals are not leaking and didn't see bubbling on the head side of the intake. Now i guess i just have to find some air to do the good ole' boost leak


IMO you are wasting your time if you know for a fact that you have unwanted hissing and leaking in the intake ................. soapy water is not going to blow bubbles because you are tracing a vacuum leak - iow the soapy bubbles is formed inside the leak location. Get your self a can of lighter fluid (butane etc) and spray THAT onto all the joints/seals around the hissing manifold - if you spray the leak idle will change immediately and revs will go up. If you cannot locate it this way, then its time to remove the intake.

I said earlier it sounds like injector/s and you now reported "unplugging the injectors and plug wires one at a time does change the idle. But number 4 fuel injector doesn't change the idle as much as the rest." ......................... Me? - if you cannot physically see any funky characteristic on that injector, I would swap #4 and #2 injectors around and do the same experiment - easy enough to see if the injector's influence on idle is as a result of the injector or the actual cylinder's mechanical characteristics/state.


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## IWantRWD (Feb 2, 2006)

to be honest i did not think about swapping injectors because of frustration. Thanks for reminding me. The injector did change the idle quality, just not as dramatic as the other 3. So I would say it's an underlying problem and not the main problem. Even though it needs to get fixed as soon as i can make it happen.

I know the soapy water wouldn't scream results, but i've had luck before and i currently dont have any brake clean handy.

I'm gonna pick up some "idle inducer" tomarrow at work and ill report back.

As for the hissing sound, like i said i was out of the nissan game for awhile but both of my KA's had minor hissing sounds even though the intake was sealed. So i wasn't sure if it was a common thing or not, which is why i posted.


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## jdg (Aug 27, 2009)

I'd suggest letting it warm up, let the idle steady out as much as it's going to get, then unplug the IACV (and AAC if you've got one) when you spray the "idle inducer" fluid around in there. Try to keep the computer out of the loop as much as possible. Ya, sure you'll likely get a code for it that you'll have to reset, but I think it would help to pinpoint any vacuum leaks.


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## IWantRWD (Feb 2, 2006)

So, I'm a little more frustrated and I'm losing patience at this point.

So i tore down the intake manifold over the weekend. Pulled out the upper and lower intake, checked the AAC. Removed the AAC. Cleaned the IAC, and made an EGR delete plate for the top part of the intake manifold. I also noticed corrosion on the injector grommets, so i took care of that. Pretty much cleaned, removed, regasketed everything on the intake manifold. Removed the evap canister and removed the coolant lines from the TB.

STILL getting lope uncontrolable idle and it SEEMS down on power. I say SEEMs because i've never ridden in a fully functioning SR powered car.

So lets go down the list of what i've diagnosed.

MAF, voltages checked out to be good.
Fuel pressure. 36-38psi at idle and 44ish with no vacuum
Cleaned and sealed the intake up.
Removed faulty AAC valve

The car no longer smells like gas and doesn't sound AS BAD..but still horrible at idle.

Here is more information:
only code im getting is 34. I left the battery unplugged for 3 days to reset.
Plugs are gapped around .040 and they are ngk coppers
emissions are almost completely removed

i dont know, like i said im losing patience and getting more and more frustrated. New lead though is the knock sensor, since thats the code im getting and would explain why i cant set an idle and why it feels like my little egg is slow.

p.s...i HATE sr intakes..but i hate them less now because its simplfied.


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## LvR. (May 26, 2010)

On the KS - remove the plug from the KS and on the ECU side of the lead, fit a 470 KOhm resistor in the terminals - this bypasses the KS and effectively prevents the ECU from interacting and reacting to the KS.

Does this improve matters at all? (or change the situation in any way then)


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## jdg (Aug 27, 2009)

Is the timing mark steady when it's "idling" (even though it's lope-ing)?
How about the timing chains and/or tensioners? Have you ever replaced them?
Pop the distributor cap and rock the crank back and forth...see if the distributor rotor follows without slop. I'm wondering if the timing isn't bouncing all over the place or something.


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## LvR. (May 26, 2010)

How about taking a simple video with either a mobile phone or video camera to show the engine's idle and to allow us to hear what is you are talking about?


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## Jr71vette (Dec 13, 2003)

dude...i had the same code on my 92 Se-R...it is for the knock sensor..it's a bit pricey, but i would replace it because my car was doing the same thing. after you replace it, disconnect the battery for about 30-40 minutes to really discharge the computer, and drive it. you should notice a huge difference, also replace no 4 injector, if there was no change and it still ran like crap disconnected, theres your culprit...hope this helps...check e-bay for the sensor, advance has it for about 130..trust me, i know...lol


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## IWantRWD (Feb 2, 2006)

So i bought a knock sensor, havn't installed it yet.

BUT!..i did take videos. Apparently my phone takes mp4 videos..which is cool. Here are the links
video-2010-12-01-18-48-03.mp4 video by nissantouge87 - Photobucket

video-2010-12-01-18-42-40.mp4 video by nissantouge87 - Photobucket

so, i wanna know what you guys think is going on from these videos. There just from my cell phone so nothing special.

ALSO!!..i went to my friendly neighborhood nissan dealer and talked to the tech. We went through the diagnostic charts and then he took a look at my vehicle. He said it is an interested problem. Hooked it up to Consult-2 and everything checked out..no active codes. One thing he thought was weird but he chocked it up to using consult-2 on a consult-1 vehicle was he could not change the idle or timing. But all the voltage stats and everything were normal. He also gave me 2 new sr20 oil filters and told me to change my oil since low or broke down oil COULD bleed down the lifters.

Got my oil changed. No change in idle or drivability.


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## IWantRWD (Feb 2, 2006)

And no ive never changed the chain on it. Ive only had it for about 3 weeks now. But i don't hear any of the infamous nissan chain rattle or guide rattle. I also havn't popped off the valve cover to see if any rockers or anything fell off.


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## jdg (Aug 27, 2009)

Jeeze...both of them almost sound like an "over-cammed" engine, like a V8 with a huge cam in it meant for 8000 rpm racing, but that's out of the question obviously.
Failing that...now that I've heard it, it almost sounds like a cam jumped a tooth or two, intake side if I had to guess. Not enough to make it NOT run, but enough to make it run like crap. Sticky valves?
What about the results of the compression check?
This is still a DOHC engine right?


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## IWantRWD (Feb 2, 2006)

that is a good theory and a solid one at that...makes since also since it suddenly showed up. Ill buy a v/c gasket tomarrow and check timing problbly this weekend while i replace the knock sensor. Possibility of bent valves with 1 or 2 teeth off?

it sounds really bad..but when the idle was stable but lopey i LOVED pulling into a gas station or parking deck because so many people would look and the old v8 muscle car guys would double take..haha


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## LvR. (May 26, 2010)

jdgrotte said:


> Jeeze...both of them almost sound like an "over-cammed" engine, like a V8 with a huge cam in it meant for 8000 rpm racing, but that's out of the question obviously.
> Failing that...now that I've heard it, it almost sounds like a cam jumped a tooth or two, intake side if I had to guess. Not enough to make it NOT run, but enough to make it run like crap. Sticky valves?
> What about the results of the compression check?
> This is still a DOHC engine right?


+1 on that all.

Guess a compression test may tell a lot more (all plugs out and open throttle)

Hydraulic VVT on that motor perhaps? ............... and it somehow got stuck in a high rev position? ..................


What gets me is that you say it all started with a speedo cable replacement! - what did you do with the cable - plug it into the AFM?

Pity you bouuught the KS - that bypass I mentioned could have saved you some beer money I am sure


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## jdg (Aug 27, 2009)

Ya...or now that I think about it more...a massive vacuum leak, which if the timing chain jumped one tooth, the intake valves would be closing late, effectively rendering the compression stroke halfway null and void, causing a much lower dynamic filling of the combustion chamber, and the back-pumping of the intake would simulate a vacuum leak...
Or taken the other way around, a vacuum leak could simulate a bunch of the conditions of an intake cam that's closing too late (or in the case of a single cam engine, intake AND exhaust valves closing too late).

Did the 'idle inducer' fluid (i.e. ether, carb cleaner, whatever) ever get sprayed all up and down the intake pieces/parts?

And ya...the VVT stuck in high rev position...that sounds pretty good...or bad depending on how you look at it.


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## IWantRWD (Feb 2, 2006)

Haha..yup..i turned my speedo into an air velocity speedometer. Haha, no just pulled out the intake tube and bumped a couple of vacuum lines and put the cable in.

Idle inducer did not do anything around the head to intake, fuel injectors, lower intake, IAC, and throttle body. I did not unplug the iac though. My thoughts were the iac and ecu are not fast enough to compensate for that sudden of an idle change.

no VVT on this engine. completely stock b13 usdm SR.

I bought the knock sensor because, while it would be worth while to have. I personally can't hear detonation like most people can. I need that knock sensor to interact with the ecu. Just as much as i need the o2 sensor in there.

The vacuum leak theory is a sound one. But with the 4 components on the intake manifold now, it would have to be so severe that me putting a finger near the leak would feel the rushing air.

I hate to say it because I hate that if im right what i would have to do to fix it. Skipped teeth sounds so far like the best thing and would explain everything. Poor drivability, poor gas mileage, intake hissing sound where no vacuum leak is present, low performance. Could even explain how at 165k miles i dont hear any chain noise.

So i guess compression check 2marrow after work and knock sensor soon and ill post the results. Any more ideas that i should check? I thought about pulling the cover off the ecu to see if i have any burn marks. (dsm experience telling me this)


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## jdg (Aug 27, 2009)

I think the IACs are fast enough. Look at how fast it compensates for you turning on headlights and such to keep the idle constant and the voltage up! And for that matter, I'll bet they're working double-overtime trying to maintain that idle. Those stepper motors aren't SLOW like a guy would think. They're zinging right along in there...

Back to the vacuum leak...what if the gasket was slipped right at the intake ports somewhere? The leak might be so spread out that you can't feel it with a single finger/hand/leg/other-body-part .

And the base timing might be right at 15BTDC, 15BTDC for a cam that has slipped one tooth. Might actually be something like 0BTDC with the slipped tooth. Heck, bump it up to 20 or 25 once and see if it helps a crapload or makes it loads worse. With that much advance, it either won't start or it'll run great. And as long as you don't get crazy on it, won't hurt anything if it IS actually 25BTDC for a little bit.

Good luck... I think ? Maybe ? Sure? Hell I dunno. Almost sounds like a kinda fun (in a sick way) project that I would go over to a friend's house and help him with on a weekend...but, can't do that...so...

Oh and bent valves with one or two teeth off? I don't think so...I think. Even the 'interference' engines have enough slop in them that one or two teeth won't cause a clearance issue. It's when the pistons are moving and the valve ain't that real problems set in.


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## IWantRWD (Feb 2, 2006)

so morning bump before i go to work. Did a compression test to check for rings and late or early valves. 185-180-165-185. Put a drop of oil in number 3 and 195psi. The plugs even though they are about 2 weeks old. Look brown on 1 and 4 and alittle white from being lean on 2 and 3.

So..i don't know what next besides this knock sensor. But as for the gasket questions. The manifold ones were hung on the studs. The TB had a couple of dabs of form-a-gasket to hold it on. The iac i used RTV but carefully spread it on. And the egr plates i just globbed it on and cleaned out the holes.

I also didnt see anything weird in the hoses when i had them all off.

I can usually see a delay from when i turn on accessories to when the idle is bumped up. So i think especially if the vacuum leak as that big, it would affect idle before the iac caught up.


So whats next in this cluster of crap?...knock sensor and ECU are my 2 next steps i think.


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## jdg (Aug 27, 2009)

Compression numbers look pretty good, even with that low-ish #3, I wouldn't think that would hurt anything anyways.
Gaskets - ok, pretty much rules those out (except for that EGR thing, but I don't think that's an issue at the moment).
Knock sensor - I'm you have, but, what happens if you just disconnect it and try running? Same thing?
ECU - kinda spendy but I suppose if you've got a spare hanging around, why not...


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## IWantRWD (Feb 2, 2006)

Yea, the only gaskets i worry about them sealing is the RTV ones, because while it works, I'm just not comfortable right now with anything i do unless i know its 100% perfect.

Knock sensor, i have no idea. i tried to disconnect the harness but it was at a shop i used to work at and my old boss who's a dueche walked in while i was under the car while it was getting an oil change and had some choice words with me. But i can tell you the housing is cracked and it looks like from the crack there's rust building up. So its definately bad. Just cant get back there right now to unplug/replace it.

Another update. After i did the compression test which i was impressed with, considering the cars got 170k on it. I dumped a pint of seafoam in a half full gas tank, sloshed it around and id say about 60% of my hesitation is gone. Idle is still rough as hell but when its at NOT, occasionally it'll lope around 1k and stay there until i hit the gas pedal.

Also, when its warming up..probably around 130degrees or so it rev hops and hunts from like 2k to 2100 for about a minute then drops and tries to die. If i hit the gas again, does the same thing until its at NOT


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## jdg (Aug 27, 2009)

What is *NOT*? Not Open Throttle?
Seafoam - Some people swear BY using that stuff, some people swear AT using that stuff. Personally, I don't know if I'd use it or not, maybe on a beater...
At any rate, if that Seafoam took care of some of your hesitation, maybe you've got an actual problem with your fuel injectors themselves....maybe? Maybe ya gotta pull them out and have them professionally tested and/or cleaned. Or hell, maybe another can or two of Seafoam.
There's a test you can do to the injectors while they're installed, requires a "specialized" tester.
Basically, works like this. You connect the tester to a fuel injector. You turn on the key, bump up the fuel rail pressure to X psi, let's say 30psi, then turn the key off. Hit the button on the tester which blips the injector something like 20 times for 1ms at a time. The fuel rail pressure will drop by X psi, let's say it drops to 10psi. Then turn the key again and bump the fuel rail pressure back up, then you go to the next injector...and the next...and so on.
So, in theory, all 4 injectors, under the same pulsing conditions, should drop the fuel rail pressure the same amount. If one injector drops it too much, it's leaking. One injector barely drops it at all, it's stuck and/or plugged.
Fairly simple check to do, but kinda hard to find those testers, and you can't do it by hand by flipping a switch either (mechanical switch contact bounce, arcing, fingers ain't fast enough, over drive the injector coils and burn them out, etc.).


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## IWantRWD (Feb 2, 2006)

NOT, normal operating temp.

I was thinking the same thing after the seafoam cleared up some hesitation. I'm gonna ohm test the injectors and probably do a backyard mechanic test and pull the rail out turn the CAS slowly and check the patterns of the injectors and see if i can see leaks or cloggage.

I love seafoam. Some people love marvel mystery oil and some people love small amounts of diesel fuel or ATF. Personal preference really.

injectors would account for the hesitations, idle and the fact that im getting a rough average of 15-17mpg. haha. Well my CA was getting 11mpg when i first got that driving.

Ill check that stuff on saturday and post back, hopefully ill have the new knock sensor in as well ill report back

I really appreciate the help and brainstorming in this thread. One of the reasons i went to be a DSMer is the community is basically just a bunch of friends and family who just trade parts and help get each others cars running. Something i'm glad is happening here.


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## chrismariscal (Jan 10, 2011)

And how does this story end?!?!! 

man. im having similar problems. im going to do the injector test tomorrow and let yall now what happens. 

haha as if anybody cares. oh well.


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## chrismariscal (Jan 10, 2011)

Turns out fuel injector #2 is out! Man i love my multi-meter. 
Will update when i have replaced the stupid injector.


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## chrismariscal (Jan 10, 2011)

Hello All, 
Well my car is having this same exact issue. *My car is practically impossible to start.* Prior to this one of my fuel injectors went out, replaced it with a new one, not much of a change, still doesn't want to start. 
Then, i cleaned my IACV, but in doing so i messed with the minimal air screw, aka idle air screw whatever. However i was able to get my car to start once, and i then followed the FSM to set the idle- "plug in obd1, neutral @ 2000k rpm's for two minutes, then check timing/ adjust and then check rpm's and adjust the screw, now my car idles at 700-800 which is what it is supposed to be. 

Yes i've done a tune up (cap rotor ngk plugs wires), new fuel filter, new fuel pump. 
I actually managed to get it to start once, and it sounds as if it has a slight miss or something. And now it also hesitates, or chugs, like it takes a few seconds once i push the gas pedal (while in neutral) for it to get going, then it sounds and revs like normal.
I took the liberty of uploading a video so you can see whats going on, and maybe you could even help me? Here is a link: 
YouTube - 94 Sentra starting problems


So what do you think? EGR Valve? Map Sensor? Or any other suggestions? 

This is my daily work commuter, but i've been taking the bus since i dont feel like taking any chances messing up this car. 
Oh and no check engine light, and no codes when plugged into the obd1.
THANK YOU so much everyone. 
Especially you jdgrotte. I really appreciate your help and knowledge. I'll take your advice and not breed. 
Oh and thanks also to the Darth Vader guy on here. Sorry i just forgot your name. 
Thanks. 

(Yes sorry i know i posted this twice in two threads)


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## jdg (Aug 27, 2009)

Other thread for more info on the upper chain tensioner.


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## FirstCarNX2k (Dec 21, 2011)

*BUMP*

So any more info on this thread??i am having the exact problem! and im still thinking it could be the cams skipping? i just joined this board but ive been reading it for awhile... i totally agree with you chrismariscal. 
"I really appreciate the help and brainstorming in this thread. One of the reasons i went to be a DSMer is the community is basically just a bunch of friends and family who just trade parts and help get each others cars running. Something i'm glad is happening here."


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## jdg (Aug 27, 2009)

If you had cams skipping, then that's how you'd be getting to work....skipping....'cause you wouldn't have any compression left from the bent valves.
"Lopey idle with hesitations" has sooooooooo many root causes, until you start whittling out possible causes, it's damn near impossible for the rest of us to help you narrow it down to real causes.


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## chrismariscal (Jan 10, 2011)

FirstCarNX2k said:


> So any more info on this thread??i am having the exact problem! and im still thinking it could be the cams skipping? i just joined this board but ive been reading it for awhile... i totally agree with you chrismariscal.
> "I really appreciate the help and brainstorming in this thread. One of the reasons i went to be a DSMer is the community is basically just a bunch of friends and family who just trade parts and help get each others cars running. Something i'm glad is happening here."


Well i no longer have the sentra, but i think i can still help! 

It ended up being the fuel pump- apparently O'reilly's gave me a fuel pump for another car, not the b13. Also, one of the fuel injectors had to be changed because the washers had worn, since the car sat for a few years. 

Have the mechanic do a fuel pressure test, and ensure that your fuel pump is functioning properly. 

What symptoms are you having with your car?


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## chrismariscal (Jan 10, 2011)

So i ended up replacing the 4 washers, and 2 fuel injectors, getting the correct fuel pump, and i was good to go.


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## FirstCarNX2k (Dec 21, 2011)

Thanks for the quick responses.
Well i have the lopey idle, and the hesitation. Ive been trying to get it in base timing mode but it never got in (I know this because the timing marks were jumpy when trying to set the timing). 
Ive had the problems since i got the car. and after i replaced my clutch i decided to figure it out. its been like 5 months now and still cant get it.

Ive replaced all the vacuum lines. ive tried the "famous" EGR block off kits. and i ended up being dumb and using no gasket so i had a huge vacuum leak around the plates. I ended up just putting the EGR system back on till i figure this out (I cleaned the hell out of the EGR and BPT)

So about an hour ago i figured out how to pull a code (yeah im kinda a nube on ECU stuff) but it was code 33. which my FSM says is the oxygen sensor. think that could cause this whole thing? ive replaced the wires with NGK's , same with the rotor, cap, and plugs. the power balance test showed equal drops. but im about to test it again cuz its been about a month before i tested again

Thnks again.


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## FirstCarNX2k (Dec 21, 2011)

Power balance test is the same. (i just went out and did it again)
Oh and sometimes when i turn the key and listen to the fuel pump i can hear a rattle and its like something is loose in the gas tank.. any ideas?


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## jdg (Aug 27, 2009)

The timing marks will jump around a bit even when in "timing mode".
The most effective way I found to figure out if I'm actually *IN* timing mode is to turn on everything...A/C, headlights on bright, blower on high, step on the brakes, open the doors, turn the steering wheel, etc. Load it down at idle. If you're in timing mode, the idle will drop a fair amount and stay there. If you weren't in timing mode, the IAC would compensate and the idle would stay where it normally does.
Figure out for yourself how to get into timing mode (read, then re-read the stickies)...and try again.


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## FirstCarNX2k (Dec 21, 2011)

yeah i understand the procedure completly. but am i right in saying you cant enter timing mode when you have a malfunction.. like code 33 ? (oxygen sensor)


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## jdg (Aug 27, 2009)

Can't remember for sure. I would think that you should be able to enter timing mode no matter what, since that would be one of those things that would help you fix something, but...
What kind of car do you have...exactly?


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## FirstCarNX2k (Dec 21, 2011)

I have a 93 NX2000.. USDM Sr20DE highport. Manuel trans.. and isnt the whole running th engine at 2000 rpms for 2 min to warm the sensor up? id think it would be key haha


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## jdg (Aug 27, 2009)

FirstCarNX2k said:


> I have a 93 NX2000.. USDM Sr20DE highport. Manuel trans.. and isnt the whole running th engine at 2000 rpms for 2 min to warm the sensor up? id think it would be key haha


Yep. I guess I meant up to the point of a major failure in something, doing the stuff for the "normal" entry to the timing mode would (or should) work.
And revving it up isn't the only thing you gotta do. There's a list of things that have to happen in particular order for it to work right.

As far as warming the sensors up, that's not really the purpose since most engines have heated O2 sensors. I've put a scanner on my '98 200SX, and from a bone cold start, like -20F, I've seen the ECU go into closed loop as soon as about 30-35 seconds after start.


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## Exalta (Jan 21, 2003)

Very informative thread! AM currently experiencing the same problems. 

My car has a GA16DE VTC with an automatic tranny

I have been getting the same rough idling, muscle car cam sounds, engine stalling, and rpm divebombing as the others on this thread...

Here's what I've done so far
-replace ignition coil
-replace high tension wires
-replace sparkplugs
-replace fuel filter
-tested fuel pump 38 psi
-cleaned and tested AAC and MAF

What strikes me is when the engine has been running for quite some time (30 mins onwards) the idle divebombing goes away..idle is still jittery but the car doesn't stall as opposed to when it's just started.


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