Tired of this intermittent idle issue.
 

Shot a video of this idle issue I've been dealing with for months now. Not sure where to start. Well, already did with 6 new Hitachi ignition coils. With $300 already down the drain I figured I'd throw a video up and see what the forum thinks.

Thank you all in advance!

Regarding the hard starting after shut down, does it only do that when the car is warmed up? If so, could it possibly be related to a leaking fuel pressure regulator or maybe a bad coolant temp sensor?

only 300??? i've got 3,000.00 into my 95 and still counting!! codes?? i did coils too and trust me, that's just the start. your mileage is close to mine, scan and see what you come up with. i got a code for an iacv twice and it took me 2 times to realize that that was the culprit. i put 2 aftermarket ones on her and she only likes oem iacv's apparently.

Look into the condition of the fuel injector(s) and the adjustment of the TPS.

Also, instead of flicking the accelerator to to 7K RPM to break it out of it's stupor, how do things act if you very slowly and smoothly increase the engine speed?

And for the record ... having spent $300 on brand new OEM coils is not money down the drain. That was a wise move in my opinion.

Sometimes the problem is gone @ cold start-up and sometimes it's still there. I did check the lines coming off the pressure regulator and all seems well. As far as the coolant temp sensor I have no clue. Not sure how to test it either.

Slowing down at a stop sign I'll see the idle drop and feel the vehicle shake. As soon as I apply some gas and get going it drives fine. As long as the rpm's are above 750 the issue seems to disappear.

Yes $300 is not bad compared to the OEM coils. But it's still $300 I spent on a part that was working.

So you guys are thinking:

Fuel pressure regulator
Coolant temp sensor
Injectors (where should I pick these up from)?
TPS (How do you test or calibrate this one)?

Would this have anything to do with the EGR system? I had cleaned out the EGR guide tube and tested the sensor summer of 2018.

When my injectors leaked, it had hard starts when warm with 17-18 city mpg. When my Egr is clogged with no leaking injectors, it gets 16 or less city mpg. But it can also be cracks in your air intake system that causes idle issues, so I'd look for cracks.

Typically an EGR issue that results in drive-ability problems is going to generate a DTC ... but, weirder things have happened.

Another item that I didn't read has been looked at this the MAF.

Does the idle/deceleration symptom seem to be at all related to engine temp ... i.e does it only show itself when the car if cold or when it's at operating temp. or does it even matter?

Here's a link to the FSM for the '99 model year. TPS stuff is in section EC:

http://www.boredmder.com/FSMs/Nissan/Maxima/1999/

If yours isn't a '99, here's a link to parent directory:

http://www.boredmder.com/FSMs/Nissan/Maxima/

The vehicle fires right up when it's cold. The idle issue shows itself right away. And sometimes it does not. But when the idle is an issue at operating temps and I shut the vehicle off it's a pain in the *** to fire back up unless I give it gas or let it sit and cool down.


I'd like to start with the small easily accessible parts and leave the big jobs for the end. Like the injectors. Especially the rears. But not sure what to start with.

This vehicle has been good to me for yrs. I'd like to fix it and keep going. Out of all the cars I've owned this ones my fav. Gone from a brand new 07 Maxima to an 01 and now the 95.

If you want to start small look at the connections on your MAF and clean it. Also clean/spray your throttle position sensors with electric parts cleaner.

Could also try cleaning the cam position sensor since it's easy to get to and has been known to get oiled up to cause intermittent starting issues. Should be up top on the timing chain cover area, i think. If anything, it's a good preventative issue even if it doesn't solve your issue.

The idle air control valve is responsible for idle management. They need cleaning eventually.

I think that's what your problem is.

What is your year model?

You're exhaust almost has the same rhythm my car had when I was experiencing fuel problems. Check your injectors...I'm thinking its fuel related, check throttle body, the boot and etc. I've noticed a lot of 4th gens recently are starting to experience fuel problems due to age.

Do something to clean out the fuel lines because when you revved and the problem went away, that's a sign it's either fuel/air related..something is not flowing smoothly.

coolant temp sensor just make sure its still plugged in, many years back i bought a Nissan for cheap because the owner couldnt figure out why it fired up fine cold but flooded warm, coolant temp sensor connector broke off. however after idling for a few seconds, the flooding cleared up with the coolant temp sensor unplugged

otherwise, Ohm test the injectors. if you do end up buying some, get new and not reman. EGR can cause idling issues if its plugged or the valve is acting up, but as said check IACV before anything else.

i've replaced mine twice in the past year, and after replacing the cat yesterday i got a code for it, again. someone told me to get an oem one cause the inter motor ones keep failing.is there a reason why??? i still have some smoke at start up and it goes away, but under load the car bucks and eventually stalls. plus, the idle sucks at start up, not horrible, just a little choppy. could the iacv be clogged, i know my plugs are black again, but i didn't have time to clean them.

How to test your IACV.


If you have a good IACV, then I would read you plugs after a misfire episode to identify a plug that may be getting too much fuel.

I had a myriad of hard to start issues from flooding caused by leaking injector o-rings with cracked pintle caps. I bought an injector kit from eBay for $34 that contained new screens, o-rings, and pintle caps and refurbished my own. That was well over 5 years ago.

We see so many issues caused by leaking rubber injector o-rings that is becoming one of those standard maintenance items like radiator and vacuum hoses. They just deteriorate over time.

Pictures:

https://i286.photobucket.com/albums/...psdba69046.jpg

Injectors with leaking o-rings and broken pintle caps.

http://i286.photobucket.com/albums/l...pscp7iddyr.jpg

Injectors that would have soon caused problems.

http://i286.photobucket.com/albums/l...psi0kojavo.jpg

Injectors that I refurbished.

https://i286.photobucket.com/albums/...psmd85h4qe.jpg

Other pictures

http://i286.photobucket.com/albums/l...psmgpsfhtm.jpg

Cap insulators.

http://i286.photobucket.com/albums/l...psragiprnd.jpg

Link to a thread on replacing injectors.

https://maxima.org/forums/test-posts...ment-tips.html

Link to a thread on how to refurbish your own injectors.

NOTE - Depending on your comfort level with tackling engine projects at home and time the car can be take out of service, this may not be for you. Its easier to send your injectors our for refresh service and test, than to refurbish your own. I just want to do myself to see if could be done.

https://maxima.org/forums/test-posts...struction.html

IF YOU DECIDE TO REPLACE YOUR INJECTORS, BE SURE TO OIL THE O-RINGS BEFORE INSTALLATION. We read about people who do not oil their new injectors and pinch the o-rings on installation.

1995 Nissan Maxima SE (Federal)

My IACV has some carbon buildup but the shaft does move back n forth like in the video. Does this mean the problem is elsewhere?

Also every single vacuum hose has been replaced summer of 2018. I don't think there is a vacuum leak. If there was the idle would always act up. Not come n go right?

I'd like to check everything else and save the injectors for last. Only bc I'd have to pull the plenum off again and the vehicle would be down for awhile.

Plugged in the Nissan-14 Conzult and ran some live data during poor idle and good idle conditions. Here's what I got. Hope someone knows how to read this bc I don't understand any of it.


https://cimg8.ibsrv.net/gimg/maxima....1b2314fd8a.jpg
Nissan-14 Conzult ECU Talk Data

Have we checked for vacuum leaks? Tried seafoam in the intake and gas, or some other injector cleaner in the fuel?

basic easy stuff, then I'd say pull another iacv from a junkyard (hopefully oem)
​​​​​

Vacuum leak test complete. Haven't tried any seafoam or injector cleaner yet. Whats the proper/best way to get those done?

look it up on you tube.

part of the bottle goes in the gas.

part goes down a vaccuum hose such as the brake booster.

You would have a better chance of success if you disassemble your iacv, then thoroughly clean it with carb spray.

While we are on the subject of sprays and cleaning things. Buy some CRC Throttle body spray. Clean the inside of your tb and especially the edges of the throttle. Might as well also buy a bottle of CRC maf spray. Clean your maf with it. You will use these sprays again someday .

Won't I experience more idle issues after cleaning these parts? How will the vehicle relearn proper airflow?

I'll give these all a shot but also worried I may make things worse.

sea foam the engine first, then do the throttle body wipe out, then do your maf carefully not to spray the sensor in the middle, just wipe out the tube around it. you'll have to run the car around the block while the sea foam is cleaning the intake and internals anyway. it'll smoke like crazy while it's working, you'll know when it's done when the smoke stops and the engine smooths out a bit. check your idle when that's all done, might have to adjust it a little.

The ecu will adjust to the new conditions soon enough.

I have personally done all these things on my own car.

Sorry but this is just wrong.

The point of cleaning the MAF is to clean the sensor wire.

Care should be taken not to "touch" the wire but cleaning the wire with an appropriate spray applied solvent/cleaner is what cleaning the MAF is all about.

From watching the video a couple of times and hearing the situation, it appears to me the issue is from engine running way too rich. The engine appears to be cold when this too rich condition is occurring. I believe:

1) When the engine is misfiring and you stop the engine, you are required to hold the accelerator in WOT position to get it to restart. This is clearing a flooding condition. Way too much fuel is being dumped into the cylinders and causes it to flood out.

2) When you rev the engine up to 7,000 RPM, it clears up. At high RPM the engine is burning off the excess fuel.

Does the problem return if you let the engine idle for a while after revving it to 7,000 RPM?

I would remove and read your spark plugs during a misfiring episode to check for a wet plug or plug that appears to be receiving way too much fuel.

Possible contributors to a rich condition on cold engine are:

1) Leaking Fuel Pressure Regulator.

2) Leaking Injectors

which is what i meant, don't touch the sensor. :russ: and the sea foam works, but i never put it in my oil, just my gas. and user1, you've been a member for a few months and have had a few derogatory remarks that i've noticed. maybe just stfu and learn some **** first before you yap.

Perhaps it might be, for you, for a little while.

That attitude does get in the way of receiving the kind of advice you might need some day, when you need it most.

Old Man Murphy and his friend Instant Kharma might pay you a visit at an inconvenient time.
They usually do, as a team.