# hesitation upon acceleration when hot..



## B14U97 (May 25, 2012)

97 sentra 5spd GA motor 150xxx 

When the engine is cold it runs great, upon shifting into any gear there is no hesitation whatsoever. As soon as it gets to operating temp it starts hesitating upon acceleration, but if you power through it, it gains rpm like normal. Iv been chasing this bs for months now trying to figure out what is causing the issue. I have adjusted idle then timed. Everything else is GRAVY based on basic inspection and diagnosis. I have access to consult II and have ran the vehicle while looking over the data presented and dont see anything out of the ordinary. Iv also ran specific diags just for the hell of it to see if anything fails. I also have the fsm and access to alldata and ASSIST which is nissan specific (for those of you in the dark).

My conclusion to the issue is it has to be a component that only works properly when operating temp is reached and system moves from open to closed loop. Not to mention I am a novice mechanic who doesnt know everything so thats why I am here with my observations and opinions. I would like to know from those of you who actually understand and maybe can shed some light on a component that might be the cause of this issue.

my ideas start with o2 sensors, coolant temp sensor in thermostat housing, anything else? Please throw your 2 cents. Help is much appreciated.

god damn these riddles


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## B14U97 (May 25, 2012)

btw no dtcs are stored for any components including o2s and coolant temp


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## rogoman (Dec 16, 2004)

After the engine is fully warmed up, check the following:
- Coolant temp sensor electrical resistance. Should be around 0.23 - 0.26 K Ohms.
- Check the fuel pressure. With vacuum hose connected to the fuel pressure regulator: 34 psi; with vacuum hose disconnected from the fuel pressure regulator: 43 psi
- Check intake system vacuum level. The reading at idle should be 18 - 20 InHg; at 3,000 RPM, it should be around 21 InHg


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## smj999smj (Jan 1, 2006)

Any signs of oil on the inside, bottom-side of the distributor cap?


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## B14U97 (May 25, 2012)

rogoman said:


> After the engine is fully warmed up, check the following:
> - Coolant temp sensor electrical resistance. Should be around 0.23 - 0.26 K Ohms.
> - Check the fuel pressure. With vacuum hose connected to the fuel pressure regulator: 34 psi; with vacuum hose disconnected from the fuel pressure regulator: 43 psi
> - Check intake system vacuum level. The reading at idle should be 18 - 20 InHg; at 3,000 RPM, it should be around 21 InHg


Thanks for the leads gotta get my hands on a fuel pressure gauge and ill post my findings.

@ SMJ :changed my rotor and cap a couple months back with nissan parts and didnt see anything when i was in there but ill check again.


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## B14U97 (May 25, 2012)

-no oil in distributor
- using consult 2 got temp to 195 fans kick on at 195 everytime knocks it back to 183.
resistance reads 0.24 at 192 so coolant temp sensor checks out.
- spent time repairing multiple vacumm lines and havent been able to test gross vacumm because of cannister vacumm lines in rear being so fd up. (is there anyway to test engine vacumm without using the rear vacumm set up like capping off vacumm from gas tank or something?)

fuel pressure havent tested because gauge is busted gotta get another one. 

*injection pulse* is staying at *3.2* on consult when at operating temp.

02 sensors are reading correct voltage from 0.1 to 0.4 front and rear according to consult.

any ideas from what info is here?? got weird feeling about the injection pulse just sayin.

ALSO.. forgot to add when running few things on consult i saw the the catalytic converter was saying incomplete which i was not sure what that meant. Completely clogged motor should show more signs of air out being stopped. so any ideas there?


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## smj999smj (Jan 1, 2006)

The catalytic converter being "incomplete" means it hasn't passed the SRT, or "System Readiness Test." There are several areas tested in the SRT, including the O2 sensor heaters, EGR system, EVAP emissions system, and catalytic converters. Many states that test for emissions use this information via the OBD II port rather than checking tailpipe emissions with an exhaust analyzer. If any of the SRT tests are "incomplete," they will not pass the vehicle until it is "complete." They do this to prevent someone who has an issue that sets the check engine light from using a code reader to erase the codes out of the system and trying to pass state inspection before the codes reset.


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## B14U97 (May 25, 2012)

i see. any ideas regarding the original post information like injection pulse for example being different than anyone else?


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## B14U97 (May 25, 2012)

ok so i tried setting the timing 2 different times before today and never was able to get the ecu into timing mode so i was fighting the ecu the whole time when i was trying to set it up and it was running really bad.

JGD posted this and this is a good bit of information for the 95-99 b14 procedure



jdg said:


> http://www.nissanforums.com/ga16de-1-6l-engine/118530-definitive-guide-how-adjust-timing.html
> The first post of the above thread is NOT what you want to be following. It's for a B13 (earlier years) I think. There's a few steps missing in there somewhere needed for the '95-'99 GA16DE's.
> 
> Start engine, let it run until it's warmed up completely.
> ...



:thumbup: GOOD STUFF, this procedure worked great after i got the ecu into timing mode the car was shaking and when i looked at what the rpm was it was at 400-430 from me adjusting the incorrect way before. So put the idle where it is supposed to be set it at 8 btdc and readjusted idle once more before finishing. Road tested it around the dealership a little bit and it feels really smooth and it was at operating temp. Before this adjustment at operating temp was where i was having my most noticable issue. Im going to get it out on the main road tonight after i leave and ill really run it through its paces to see if it fixed my issue. Hopefully iv found the info i need to help people having this same issue.

btw when i had it up on the lift i did a little inspection and right were the mid pipe meets up with the muffler underneath near the middle there is a (smile looking) crack under where the pipe is welded into the muffler, cv's are trash, trans seal on driver side is leaking a very small amount, and i also see a little oil wet above the oil filter up by the oil pressure sensor. needs new engine mounts and trans mount, struts all the way around and strut bearings, lower control arms and tie rod ends.... uhhh fml.


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## CannibalCorpse (Oct 2, 2006)

Below is the link to an old thread regarding accelleration misfires on a warm engine. I ended up replacing the ignition coil inside the distributor after months of fiddling.

http://www.nissanforums.com/b14-95-99-chassis/133233-stumbles-missfires-acceleration.html


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## B14U97 (May 25, 2012)

good stuff and yea the timing adjustment only made it feel better for a short lived experience. The only way to get an ign coil from nissan is to buy the whole distributor assembly which is 304.29 for employee price to 430.00 list and 579 retail. lol wow. guess its better to grab one from junkyard car with low miles. Also the two wires that come out of the distributor on the radiator side that go to what looks like a little capacitor or something have been spliced into at one point in the cars life, possibly these wires being open to elements have something to do with the issue??

good thing we got it narrowed down to an ign coil. guess i know what im looking for now.


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