Sup org. Having an issue with my second 4th gen where the idle is correct at a stop at 750RPM but if at a stop too long, it jumps down close to 500RPM and after a few seconds, it will return to normal.

Had two codes before P0170 and P0173 which are fuel trim malfunctions which only appear in the 95 FSM. I replaced the fuel filter and clear the codes and having the same idle issue.

Scanned again for ghost codes and P0173 is there. I did the MAF test that I dug up in an older thread that njmaxseltd suggested but it didn't work. I disconnected the TPS and started the car to see the idle. It was at 550RPM. Left it running and even then, the idle dipped to 400RPM.

All the gaskets and the MAF, IACV and TB have been cleaned but the parts guy at nissan suggested that I clean the IACV again. Do you guys have any ideas? Also, I am using NGK Iridium spark plugs which were replaced recently with gaskets which were all less than a year. Thank you guys for any help.

 

If you disconnected the TPS which disables the IACV and it still dipped, then the IACV is not your problem.

 

Ok this is good news to hear. Also, I forgot to mention that while it was running, I sprayed TB cleaner on all the vacuum hoses and there was no fluctuation in idle. Do you suggest anything else?

 

Could be a bad throttle position sensor(TPS). They tend to go bad with great frequency

 

You might want to replace that. I had roughly the same problem a couple weeks ago since I went back to stock IM, and my stock TPS was toast. Try giving that a try, and for future reference, I would stick to just platinum plugs, which are OEM.


Good luck!

 

If I disconnected the TPS and its still having the same issue, wouldn't it mean that the sensor is good?? Also, the P0173 fuel trim code is what's bugging me. I am pretty sure P0170 is not too far behind either.

 

A vacuum leak should make the idle speed increase.
Do those fuel trim codes point to a lean or rich condition?
If its system to lean, I'd check fuel pressure and injectors.
If its system to rich, I'd check for a misfire do to spark.

 

That's the strange thing about these codes for the 95. The P0170 and P0173 don't point to anything specific. The manual says those codes mean they are running lean or rich.

If it were running in any of these conditions, wouldn't there be a code thrown for the O2 sensor from the respective bank?

 

For those codes, did you specifically go to the FSM or just the Haynes Manual? Cause the Haynes won't give you squat. If you need a link to the FSM, here it is, already in the section with the year of your car. Just go to page 187 or 205, which are for codes 0170 and 0173: http://www.nicoclub.com/FSM/maxima/1995/ec.pdf

Hope this helps man.

 

I am using the FSM and for the 95, it doesn't let you know if its lean or rich. I bought some Chevron Fuel Cleaner this evening and put it in since it was buy 1 and get one free at AZ. If it still occurs, then I will have to start removing plugs.

 

I had the same symptom, decided to rebuilt my fuel injectors and the replaced them and idle issues went away plus more power restored

 

to metallica: did you rebuild the injectors yourself by changing the o-rings, injector filters, pintle caps and insulators or did you send them someplace?

 

Good question - Those codes are set because of the information sent from the o2 sensor to your ECU. They are working correctly, however your ECU cannot adjust the fuel trim to the correct a/f ratio.

I think the suggestion on rebuilding your fuel injectors might be the way to go.

 

I am currently experiencing the same problem with my max. Replaced the IAC and nothing changed. Keep us updated please.

 

I sent them off to deatschwerks. You have to get an extra set of injectors unless you have another car to drive around cause its a one week process to get the injectors back. Very good customer service, $19 per injector, like $10-20 shipping.

 

Ok. I will let the cleaner do its work and report back. I was in the middle of rebuilding a rail with OEM injectors. I already have 4 and missing two and some o-rings. Will get this completed as well.

 

The only time an o2 code is thrown is if the sensor is bad. It merely monitors and sends infor so the ECU can adjsut A/F. However, as NJmaxseltd pointed out if it is unable to adjust it properly because something like the injectors are malfunctioning then that is the root of the rich or lean code. GL

 

Just to update this thread, took the car to the dealership for fuel injector service and they cleared the codes. Noticed that the car shaking got worse and I installed the other fuel rail and problem was solved.

 

yeah mine does this too, when the fans kick on. take your car for a drive and see if it does it when the fans turn on. roll the windows down if you need help hearing them.

I'm pretty sure it's normal to do that when the fans turn on

 

Check the voltage on your tps. It might have to be adjusted.

 

Again, problem was solved. The fuel injectors were done for. Bought a new set of OEM ones and replaced. Njmaxseltd had it down to a science. It was definitely rich because it feels like pickup slowed down a bit since.