# 91 Nissan sentra only starts with pedal to floor



## Capeaney (Mar 21, 2011)

Got a 91 Nissan sentra with a 1.6L I've been working on for a friend of mine. When I got ahold of it cranks but no start. 3/4 tank of fuel, battery good. Since then fuel pump and filter changed with no difference made. Checked spark then changed cap rotor Plugs wires and ohmed coil and it is within spec. Cleaned iac with carb cleaner and car started idleing by itself but soon died. Also replaced coolant temp sensor. Seems to only run on one cylinder because you can pull all spark plug wires with car running and none make a difference except#2 and car will die no matter what rpm motor is running. Car will not idle or run without throttle being pressed atleast 1/2 way Down. Very hard to start when engine cold. I'm out of ideas and first car I've had this many problems getting to idle. Please help


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## jdg (Aug 27, 2009)

Check the MAP sensor, particularly the vacuum line and/or fittings leading to it. If the vacuum line is broken, the ECU will think it's being floored all the time, and basically flooding out the engine. But...if you actually hold the pedal to the floor, it IS being floored all the time (or close to it) and the ECU and the engine will match up, and the engine will run.
Past that...check the codes in the computer?


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## Capeaney (Mar 21, 2011)

No codes on the computer. Just won't start. Gonna check the map tomorrow. This thing is really giving me a headache. Gonna check fuel pressure too while I'm at it just to make sure I don't have a bad fuel pump. Thanks for the advice. Will Post further progress


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## LvR. (May 26, 2010)

Compression pressures for all cylinders?


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## Capeaney (Mar 21, 2011)

Car runs great once fuel is introduced doubting compression issue, but not gonna rule that out yet... Anything is possible. Honestly suprised the car even ran when I got it after seeing the condition of plugs cap and rotor. Factory everything as far as I can tell. Even fuel filter was original as far as I can tell. Don't think much manufacture scheduled maintenance has been done. Has 202xxx miles too so probably gonna be more after getting this issue solved


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## jdg (Aug 27, 2009)

Ever changed the upper chain tensioner or checked it out?
Does it kinda sound a bit like a diesel when it's idling?


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## Capeaney (Mar 21, 2011)

Kinda does when at low rpm. Doubt any of that has ever been replaced. Probably will need that too. Chugs real hard and shakes car horribly. But I figured that was from misfiring issue


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## Capeaney (Mar 21, 2011)

Does the map sensor bolt onto egr bracket


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## Capeaney (Mar 21, 2011)

Can't find anything about the map sensor for a 91 sentra, or how to test it. Anybody know how to test and where it's located?


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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.


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## jdg (Aug 27, 2009)

Have you changed out the upper timing chain tensioner yet? 'cause I'm almost positive I can hear the results of a worn tensioner...that kind of clattering at idle that almost makes it sound like a diesel. If the timing chain isn't EXACTLY where it's supposed to be when it's supposed to be there (i.e. chain riding on a shot tensioner causing it to slop around a bit), it could quite possibly cause a bit of a skipping during a fairly good throttle blip.


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## chrismariscal (Jan 10, 2011)

Oh yes i'm sorry i forgot to mention that. Yes i did change my tensioner back in January, and my car ran perfectly after that, and i haven't messed with it since..


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## jdg (Aug 27, 2009)

Damn...thought I had something there...but I listened to it again this morning and I still think I hear that tell-tale rattle of the upper chain.
Ya didn't forget to pull the pin out of the tensioner when ya put it in did ya? ...just checkin'...


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## chrismariscal (Jan 10, 2011)

oh its all good jdgrotte.. a great guess. 
and you're talking about the pin, that once you remove it, the it adds the tension or releases the tension? 
yes i removed it.


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## jdg (Aug 27, 2009)

Then you might be into an upper chain or maybe lower chain or swapping out the whole works.
Pop the distributor cap, rock the crank back and forth by hand and see how much play you have in the crank before the distributor rotor starts to turn. That should be a fair indication of how much 'slop' you've got in there.
Other than that, I think I'd start looking for vacuum leaks or air that's getting into the intake manifold other than the air going thru the mass air sensor.


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## chrismariscal (Jan 10, 2011)

jdgrotte said:


> Then you might be into an upper chain or maybe lower chain or swapping out the whole works.
> Pop the distributor cap, rock the crank back and forth by hand and see how much play you have in the crank before the distributor rotor starts to turn. That should be a fair indication of how much 'slop' you've got in there.
> Other than that, I think I'd start looking for vacuum leaks or air that's getting into the intake manifold other than the air going thru the mass air sensor.


Well i hope it's not the chain, but i haven't checked them yet, only because it seemed fine once i parked the car however many weeks ago. 3? 

And i've checked and checked again for leaks but haven't found any. 
Also, i even replaced my Ignition Coil, but that didn't make a difference.. 

SO- Here is my next theory- ever since i replaced my fuel injector, the car has never been the same. Yes i did have to disconnect the Fuel Rail from all the hoses and stuff, took it out, popped it the new injector and reconnected everything. And yes i rechecked everything is back right where it is supposed to go. 
Ever since then my car will turn over, but it will take several tries before it actually catches and stays on- but it wont stay on unless i keep my foot on the gas, and man it sounds like it has the worst MISS ever! It's really frustrating. And then my car sputters and cuts out and dies. 
So is this becuase there is air in my fuel lines? Someone suggested that i bleed my fuel lines. I tried searching youtube and this forum, but i couldn't find anything. eHow gave some very lame, vauge instructions. 

So does anyone know how to bleed the air out of fuel lines? 

If thats even my problem. I hope it is. Like i said it's never been the same since i replaced the injector. 

Or wait- could this also be the sign of a bad distributor? 

Please help. 

I've been having to ride my bike or take the bus everywhere for the past few weeks.. :lame:


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## LvR. (May 26, 2010)

On an EFI motor its basically impossible to have air in the rails or anywhere else for longer than probably 2 seconds - the fuel pressure regulator ensures that.

From your last post I would guess you either have a wrong/funky injector in there or you have damaged the O-rings on the rails and as a result the engine is actually running close to flooded.


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## racerty1 (May 8, 2011)

If you have a vacuum leak you should be able to have someone else turn the car over ad as soon as it acts like it wants to fire spray around the engine bay with starter fluid or carb cleaner. If you have ANY vacuum leaks it will find them. 

Another thing, check your cold start injector if its stuck closed it will have trouble getting idled up. The cold start is kind of like a choke for an EFI car, if its not breathing your cars not getting the gas to start properly.
The cold start was causing a similar problem on my car.
Just my two cents hope it helps.


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## chrismariscal (Jan 10, 2011)

any one have any more details on what or where the cold start injector is? 
is it just one of the injectors? if it is, i have already cleaned them all, and even replaced the one on cylinder # 3, rechecked with a multi and they are all still working.


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## chrismariscal (Jan 10, 2011)

so, now i think its my MAF or IACV. 

I took out my MAF, cleaned it with MAF cleaner, and it did help a lot, but the car still wont idle. 
the car will only start, and, stay on for that matter only if i floor the pedal. 

also, adjusting the idle air screw on the IACV doesn't make any difference, so i think thats what might be wrong..


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## chrismariscal (Jan 10, 2011)

*FIXED FIXED FIXED!!*

Well almost two months later i finally got this punk fixed. :fluffy:

It ended up being a leaky injector, and the guy that sold me the car had just installed a few pump. *TURNS OUT HE INSTALLED A FUEL PUMP FOR ANOTHER NISSAN!* 
So i had to buy a new fuel pump. 

If you are having a similar problem where your nissan won't idle try this: 


Grab a multimeter, and test all your injectors
Buy some MAF cleaner, clean it.
Test all your spark plug wires, no matter how new they are.
Spark plugs properly gapped?
Test your IACV with a multimeter. Clean the spring inside with carb cleaner.
Same carb cleaner, but clean your throttle body.
Lastly, compression test for proper fuel pressure, or a vaccum leak somewhere.

Well i hope this helps everyone. :waving:


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