I posting this on behalf a friend with a 2005 enthusiast model. We've recently installed an Injen intake on his car. The next day, we installed a navigation system and onboard computer system. The computer only taps into the battery.

The car was fine the first few days after the install. Then, after about the third day, the engine suddenly shut off while sitting idle in traffic. The car restarted fine and didnt see problems until another day or two later. Over the past couple of weeks, this worsened.

Today the engine idling is about to stall everytime after it gets warm. When cruising, the engine is fine. Only when idle, it stalls a bit (to about 300 rpm) and almost dies before it revs itself back up to 500rpm.

My initial guesses were leaks in the intake. We've thoroughly searched and could not find any. Next, he tried to reset the ECU by disconnecting the battery for an hour or so. Didn't help. Now I'm wondering if its possibly a degrading MAF sensor?

The engine can idle for about 5 - 7 seconds before it stalls to 300 rpm. Then recovers back to 500 rpm for another 5-7 seconds.

Any thoughts on how I could diagnose this problem please?

Thanks.

 

I just found some more information at this thread:
https://my350z.com/forum/intake-exha...en-intake.html

Sounds like the people there had similar problems. But no solution was ever found...

Any ideas?? Take it to the shop and hook the computer up to it to measure the air/fuel flows??

 

You can increase the idle a little bit with a reflash, turn on the AC (for the same effect), drill a tiny hole in the throttle plate (I wouldn't but it will raise your idle), remove the cold air intake, or get a tune that adds a little more fuel at idle.

If you did a true ECU reset and followed the procedure for idle air learning and throttle position reset, I would think the stock ECU would be able to adapt.

You might want to try clean the MAF sensor (with special MAF cleaner/spray from auto store).

 

It seems I've seen alot of people have idling problems after installing some type of intake system, including myself. I still haven't figured out what my problem is to this date, but really don't care anymore since I rarely drive it...

 

I suppose we'll try to clean the sensor and re-install the stock intake. If the problem persists, then perhaps its related to something else other than the intake. Fortunately, the car has extended warranty so we can take it to Nissan as a last resort.

 

The stock intake will fix this, I'm most certain. How long do you sit at idle before the car dies?

 

It seems to start as the engine warms up and approaches its idle at around 500 rpm. Its about a minute or less before it starts.

 

<< UPDATE >>

So last night we swapped the MAF sensor and the idling issue went away. We were confident it was the MAF sensor until this morning. Fortunately for my friend, he has extended warranty which covers the MAF and was hoping to get it replaced under warranty. But when Nissan looked at it, they did an ECU reset and charged him $140 saying it was out of warrenty coverage. To our surprise, the ECU reset fixed the problem and now the original sensor works.

I'm puzzled at how this worked because the second MAF sensor we used worked and the first didn't. Then after the ECU reset, the first sensor worked. Does the ECU translate sensor readings differently??

 

The ECU learns its idle sounds crazy but its true if the ECU learns certain idle parameters and you change the air flow over the MAF it will have to relearn its idle if he would have continued to drive the car it may have relearned on its own. Chrysler's are the worst for this... replace a battery on a neon and you will be forced to run the car with accelerator pressed for a couple minutes while the ecu learns to idle again. What a pain in the ***

 

thanks for the tip. We'll be keeping an eye on this over the next few days.

 

Hmmmm. I'm wonder if they really did an ECU reset. Maybe they actually did the Idle Air Volume Learning procedure so the ECU "learns" how much airflow is now needed.

 

Hook-up to ECU Diagnostics/Analysis doohickey?? Go safe! Don't guess.

 

I usually only have to do this after the throttle body/plate has been disturbed or the gas pedal has been replaced. These drive by wire systems can be tricky though.

 

The FSM describes it as "Idle Air Volume Learning is an operation to learn the idle air volume that keeps each engine within the specific range." Since the air flow is measured by the MAF, any change or disturbance in it would seem to require a relearn procedure to be performed. I believe that's what nismoz1260 was referring to in post #9.

 

When you disturb the throttle plate manually on many drive by wire applications its seems to throw the tps/actuators out of "whack" for lack of better terms and ruins the engines ability to idle and causes major driveability problems. I only know bc. I opened one manually before to clean carbon build up and it did not idle worth a damn then "reset" the computer and it worked fine. Sometimes you live and learn I guess. Just an fyi if you do ever clean a drive by wire throttle body, do so with key on engine off and get someone else to depress pedal while you clean to avoid this problem.

I was thinking that the two may be related since the engine has no idle air control and if the actuators for the drive by wire were out of calibration it would also require the Idle Air Volume Learning.