MAJOR idling problem... an ideas?

[classicpitts]

Please help ive put over $5000 into this car's body and engine and still i find new problems. I'm gonna just get straight to the point. My 95Q was been driving terribly, first off it's not changing gears! This took a while to notice cause i am still able to push up to 80mph on the highway, not that i do. but the worst problems occur when i take my foot off the gas. The rpm will drop all the way down to about 1000rpms thats when it jerks. it tries to drop lower but it will continue to bounce up to like 1500-2000 rpm and back down unless i give it some gas. ive been driving in one gear below (3) just to avoid the jerking. what should i do?! HELP!

[gniknave]

You say you spent $5000 on the car... What's the maintenance history like? How many miles do you have on it? Was the transmission replaced? Have you changed the fluid, cleaned the pan and changed the filter? Any "transmission malfunction" indicator? Would I be correct in saying this is an issue with drivability and not necessarily idling?

[elwesso]

do you hear humming form the rear?

[Q45tech]

IAC span Misadjusted? What is the IAC duty cycle as read by Consult at warmed up idle [10-15%] and then in gear [rpm?] for on brake [20%]?

IAC Duty cycle at problem speed?

[gniknave]

IAC span Misadjusted? What is the IAC duty cycle as read by Consult at warmed up idle [10-15%] and then in gear [rpm?] for on brake [20%]?

IAC Duty cycle at problem speed?

go easy on him, he's new.

[maxnix]

go easy on him, he's new.

Yeah, but you got to know. Especially when FSM and TSB are only $20 from Nissan, and this board is free.
Modified by maxnix at 7:49 PM 3/27/2006

[classicpitts]

well it was mostly body work, rear end was smashed so replacing rear bumper, rear windshield, trunk, rear quarter panel and neww paint and polish, alignment etc... was about 3G's. then i did get a complete tune up and maintence tune up this was all at about 95k miles now it has 116k and problems like i said it doesnt stall out feels like it wants to when it jerks and bucks alternator died a few weeks ago but i replaced that hoping the problem would stop but it did.... i'm having problems with that too now my alernator sometimes doesnt kick in until i rev the engine up to about 3000 rpm but im more concerned with help with the transmission

so once again any ideas?

[96Qowner]

Three ideas to look into:

1) It doesn't sound like the problem is a mechanical transmission problem. But these Qs are very particular about the transmission fluid level, so make sure it's exactly correct.

2) Might be a fuel delivery issue. Is your fuel pump humming loudly yet? Yours might be ready for replacement. If so, you might also have a problem with the fuel pump controller (FPCU). Old pumps can fry the controller. Here's a thread about it.

zerothread?id=18148

3) One of the most common issues with early Q45s is the MAF. Start it up and wiggle the connector - see if the idle changes.

zerothread?id=82862

And here's a thread about the IAC that Q45tech suggested as something to check:

zerothread?id=33796
Modified by 96Qowner at 3:04 PM 3/27/2006

[classicpitts]

ok i somewhat understand what u are talking about, however i dont have a manual does any1 have a service manual via email, so as far as the FPCU and the IAC span and duty cycle, well im not to sure where and how to check it but will and able if i can get a lil help on the know hows...nor do i know what the FSM and TSB are... like the that one person said im new take it easy on me, it took me a whole day just to change my alternator and that took work so send all the helpful info u can thanx

[classicpitts]

oh and another important question how much is all this gonna cost if i get it done by like a pep boys or somethin... in the military so i dont have many mechanic connections down here in delaware... and yes i do hear a buzz like hum coming out of the trunk where the gas tank is

[Q45tech]

YOU NEVER ALLOW a generic shop to work on the Q. This is a sure way to get more problems. Find a trained Nissan technican with EXPERIENCE on a Q. They must have a Consult diagnostic computer and a copy of the Factory Service Manual to get passed the basic interview stage!

[maxnix]

oh and another important question how much is all this gonna cost if i get it done by like a pep boys or somethin...

Quite a bit once they F___ it up.

You need to do a lot more reading at this site. The manuals and TSB are available from http://www.nissan-techinfo.com/infiniti/ if it is 1994 or later.

If you have a hobby shop on base with a lift and tools and can read English, you are better off reading the posts on this site and doing it yourself.

[96Qowner]

The buzzing fuel pump is not good at all - you're going to have to replace that very soon, whether it's the current problem or not. It can be done by a noob, but it's a huge pain. To give you an idea about non-Q45 techs and repairs, I had Nissan techs do my pump and they STILL managed to bend the sender float and had to go back and fix it. Here's an extremely detailed, step by step writeup for a fuel pump R&R, from the archives:

zer...age=2

You can fairly easily pull the FPCU and check it for signs of overheating. Do that right away. The FPCU can fail intermittantly after having been overheated by an aging fuel pump. If there are no signs of burnt connector pins or solder joints, then neither the FPCU nor the pump are probably your current problem.

FSM is Factory Service Manual, TSB is Technical Service Bulletin.

Don't be afraid to become familar with this forum's search function. Almost everything imagineable has already been diagnosed and dealt with at some time in the past 4 years of archived threads.

[96Qowner]

Dennis, can you put a little thought into this one? I suspect you're the best one to try to diagnose this. Anything other than the IAC?

[Q45tech]

Plug a Consult in and do all the data reviews and tests.

[classicpitts]

well im back went to Aamco to get a second opinion they immediately said it was the transmission after a test drive no plugs or computer readings fortunately no charge either, is theyre word reliable? i plan on bringin the car to a nissan dealership when i get the time cuz its so far, as far as the hummin in the tank, if it is the fuel pump can changin it solve all my problems and in another uunrelated topic my alternator whistles when rpms up to 3000 lights brighten up also

[maxnix]

well im back went to Aamco to get a second opinion they immediately said it was the transmission after a test drive no plugs or computer readings fortunately no charge either, is they're word reliable?

When you are a hammer, all problems look like nails.

You receive for what you pay. Free is great if you have nothing to lose.

Reliablity isn't the issue; working knowledge of the G50 is.

Get thee to Infiniti Online Mechanic and do some searches on fuel pump and alternator.