Stalling Problem HELP!

[InfinJ30T95]

i have a 1995 Infiniti J30T... im having a problem with it stalling when sitting at a stoplight.. I do not have a engine light come on, i would like to fix this car so any help would be great

[driverdriver]

If you keep revving the engine at a stoplight will it not stall out?

I would hedge a bet that either one of your fuel sending unit or fuel pump is close to toast (or both are close to toast).

You have to remove the backseat to access them.

[InfinJ30T95]

If you keep revving the engine at a stoplight will it not stall out?

I would hedge a bet that either one of your fuel sending unit or fuel pump is close to toast (or both are close to toast).

You have to remove the backseat to access them.

yes i have to keep one foot on the brake and the other on the gas and it will stay running, but then some days the car does just fine and never stalls out

[yodawill2000]

I agreeWhen you start it up do you hear a buzzing sound from the trunk ?

[InfinJ30T95]

I agreeWhen you start it up do you hear a buzzing sound from the trunk ?

well not really the pump has all ways been really quiet.

[GerryO]

Start wth the simple stuff.

- Clean the MAF and electrical connections leading to it- Clean the Throttle Bodies- Clean the IAA/AAC valves/assembly

General:Erratic idle is one of the most common problems with our cars. This is caused by the number of engine components that are affecting it, such as: IAA (Idle Air Adjusting unit), Air Regulator, Throttle Bodies, Injectors, CAS, fuel delivery, vacuum piping...This article will cover the three components mentioned first.

IAA-unit:This unit consists mainly of two valves: FICD and AAC. The FICD valve compensates for RPM drop when AC compressor is activated. The symptoms of the FICD failing are idle drop and vibrations when switching on the air conditioner.

The AAC (Auxiliary Air Control) valve: Is controlled by the ECU (PWM-control) to set the idle speed to a pre-programmed level. The ECU switches the AAC on and off very fast and thereby is able obtain a gradual opening of the valve. The AAC opening ratio can be observed on a Techtom MDM-100. If the valve is completely closed at idle it could mean that the idle screw is not adjusted correctly (too much air enters through it) or there is a vacuum leak (could be dirty TB's not closing all the way).

Very often is the IAA unit (pic 1.) diagnosed faulty and replaced. Since it costs ~$200 it's worth to take the time and fix it yourself. Just as long as the solenoids are electrically intact there's not much that can go wrong with this unit.First off, check the solenoid resistance (don't forget to clean the connectors too).FICD => ~22 OhmAAC => ~10 OhmYou can also check the solenoid operation by applying 12V from the battery to its connectors (you should hear a click). If the resistance is far off then you really need a new IAA-unit, if not then read on...

Remove the IAA from the plenum. It's attached to it with 4 screws. There is also a gasket between the IAA and the plenum. I reused the old one since it wasn't broken.



Disassemble the solenoids as in picture 2. Check if the spring inside them is not broken.Now clean the solenoids and the IAA-unit casing with WD-40 or Brake Cleaner or similar.Reassemble and it's as good as new.



Air Regulator:The purpose of the air regulator is to raise the idle during engine warm-up by letting additional air to enter the intake.The symptoms of the air regulator going bad is either low unstable idle during warm up or constantly high idle.The regulator consists of a bimetal-activated shutter that closes after ~5 min of engine operation and cuts off the airflow.Note: It's normal that the shutter is only partially open at room temperature.

Check the resistance between the pins in the connector. It should be ~75 Ohm. If not good then replace the whole regulator.

Another problem could be that the regulator is clogged, causing the shutter to stick. The air regulator is located on the rear of the plenum and is attached to it with 2 screws. There are 4 screws keeping the housing together. Remove them and clean the regulator internals (pic 3).



And maybe check the engine timing, for vacuum leaks and TPS output voltage too.

[InfinJ30T95]

and to add, my idle is real low and i have to keep my A/C on to keep the idle at normal rpm

[GerryO]

The full article can be found here:

http://home.swipnet.se/e-solutions/IdleTech.html

[yodawill2000]

Golden GerryO !!!

I was gonna try to explain it and you come in like a teacher !!

You are a asset to this forum bud.Nice job.

[GerryO]

Just passing along what I find that others have summarized so well or that I'm learning the hard way. You and driverdriver are this forum's mainstays, now that gr8scott and naladude have really moved on.

[GerryO]

and to add, my idle is real low and i have to keep my A/C on to keep the idle at normal rpm

So it sounds like your FICD valve is working properly, along with the Air Regulator unit that would help keep the idle speed higher until the engine is fully warmed up. I just opened up a spare IAA unit and based on what I saw, the Idle Adjustment Screw and the area around it inside the IAA might be very dirty/clogged, but don't forget those other inexpensive and good to do things.

[InfinJ30T95]

also to add, the car surges while driving sometimes too

[GerryO]

also to add, the car surges while driving sometimes too

One at a time and in order:1) listen for and address any vacuum leaks2) if necessary replace the air filter, and clean the MAF and its' electrical connectors3) clean the throttle bodies4) check, and if necessary adjust the TPS output voltage, unplugging it for a moment with the engine running to clear previously stored values in the ECM 5) check, and if necessary adjust the engine timing6) adjust the idle speed, using the adjustment screw on the IAAC unit7) if necessary, test and clean IAAC/AAC unit component parts

[InfinJ30T95]

One at a time and in order:1) listen for and address any vacuum leaks2) if necessary replace the air filter, and clean the MAF and its' electrical connectors3) clean the throttle bodies4) check, and if necessary adjust the TPS output voltage, unplugging it for a moment with the engine running to clear previously stored values in the ECM 5) check, and if necessary adjust the engine timing6) adjust the idle speed, using the adjustment screw on the IAAC unit7) if necessary, test and clean IAAC/AAC unit component parts

and where is the IAAC/ACC unit?

[driverdriver]

J30 Field Service Manual Location:

http://www.nicoclub.com/FSM/J30/

I think its on page EC-15 and EC-20

[GerryO]

also to add, the car surges while driving sometimes too

Fuel filter or fuel pressure regulator?