2002 QX4 New IACV Wont start & idle on its own.

[s13srcoupe69]

Hello. About the Car...
2002 Infiniti QX4 with 200,xxx Miles
3.5L 4x4

No CEL/SES
Vehicle was idling up and down, Idle high.
I was told the IACV was cleaned in this vehicle and that it had screw up his idle more.

I replace his IACV and that fixed the erratic idling and everything.
I smell fuel in the exhaust on start ups.

Now when i start the car, it will start but not stay running. This is when the car is cold (not been driving for some time). It doesnt start and run rough and die, I turn the key, vroom and dead. RPMs go up to what its supposed to on cold start and dies right after. This all happens with in a second of turning the key. I can start the car and get it to idle but when i have to start it, i hold my foot on the gas a hair and once it starts, i can slowly remove my foot off the gas and it will hold idle. Low idle, around 500 RPMs.

When the car is all warmed up, it will idle fine. When i start it when its warm, It starts and almost dies, down to 150rpms maybe, and then will idle right back up to 750.

I have tried the Idle air volume relearn. I have found two procedures with that.
1. is the key on and stop the gas peddle 5 times....so on all with in this time. I get to the step where the SES light is flashing. They say it is supposed to go solid and then you release your foot and it learns it. I get it where it is flashing but never goes solid?
2. The other way is get the car all warmed up and the unplug the brown throttle clip and plug it back in.

None of this has helped. I have also acess to a verus pro. Thanks and good day!

[atraudes]

Sounds like the ECU may be fried. A bad IACV has been well known to take it out if the problem isn't addressed quickly enough. This thread has all of the info on it. You should also take a look at the TPS. A bad unit can cause erratic or unusual idle.

[EdBwoy]

I was going to suggest an idle air relearn, but it seems you already attempted that. Are you using a stopwatch? Timing is very crucial.

I can't recall if I had to do any other procedure than what the manual calls for when I did that for my 2002 qx4. From the manual EC pg 69:

DESCRIPTION
“Idle Air Volume Learning” is an operation to learn the idle air volume
that keeps each engine within the specific range. It must be
performed under any of the following conditions:
-Each time IACV-AAC valve, throttle body or ECM is replaced.
-Idle speed or ignition timing is out of specification.

PRE-CONDITIONING
Before performing “Idle Air Volume Learning”, make sure that all of
the following conditions are satisfied.
Learning will be cancelled if any of the following conditions are
missed for even a moment.
-Battery voltage: More than 12.9V (At idle)
-Engine coolant temperature: 70 - 99°C (158 - 210°F)
-PNP switch: ON
-Electric load switch: OFF
(Air conditioner, headlamp, rear window defogger) I turn the radio and dome lights off as well, just for good measure
On vehicles equipped with daytime light systems, if the parking
brake is applied before the engine is started the headlamp
will not illuminate.
-Cooling fan motor: Not operating
-Steering wheel: Neutral (Straight-ahead position)
-Vehicle speed: Stopped
-Transmission: Warmed-up
...
For A/T models without CONSULT-II, drive vehicle for 10 minutes.

OPERATION PROCEDURE
1. Turn ignition switch “ON” and wait at least 1 second.
2. Turn ignition switch “OFF” and wait at least 10 seconds.
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic “PRE-CONDITIONING”
(previously mentioned) are in good order.
5. Turn ignition switch “OFF” and wait at least 10 seconds.
6. Start the engine and let it idle for at least 30 seconds.
7. Disconnect throttle position sensor harness connector (brown),
then reconnect it within 5 seconds.
8. Wait 20 seconds.
9. Make sure that idle speed is within specifications. If not, the
result will be incomplete. In this case, find the cause of the
incident by referring to the NOTE below.
10. Rev up the engine two or three times. Make sure that idle
speed and ignition timing are within specifications.

ITEM SPECIFICATION
Idle speed 750±50 rpm (in “P” or “N” position)
Ignition timing 15°±5° BTDC (in “P” or “N” position

[s13srcoupe69]

Thanks for the responses.

Ed, I have tried that a few times with a stop watch as well. I will try it again later today once i have got the car warmed up.

atraudes, I check the TPS a sec ago on the scan tool. It did a clean sweep from .5v to 5v i wanna say.

The car will idle. It is not an erratic idle either. It just wont start and idle on its own. I have to touch the gas every time i start it.

I also check the idle with the ignition timing and it was correct
TEM SPECIFICATION
Idle speed 750±50 rpm (in “P” or “N” position)
Ignition timing 15°±5° BTDC (in “P” or “N” position

Still no luck. Gonna check for vacuum leaks next although i have done that once before.

[atraudes]

You're probably on the right track by checking vacuum then. If the throttle body has any carbon buildup, give it a good cleaning too, though I'm guessing that was done already if the IACV was cleaned.

[s13srcoupe69]

Thanks atraudes.
I will check the vacuum soon and will post results.

[s13srcoupe69]

No vacuum leaks

[EdBwoy]

Is your floor mat out of the way of the throttle pedal?

[atraudes]

Curious, what's the ignition advance when it's idling?

At this point, I'd get ahold of a fuel pressure gauge and see what the fuel pressure is after shutoff, when you start and it dies, and what it is when you're idling. I'm sort of wondering if the fuel pump is on its way out.

[s13srcoupe69]

atraudes, I just set the idle again warm. It is idling fine at 750 give or take 30. The Timing is 15 BTDC. It is correct. I just hooked up the scan tool, i thought the fuel pump might not be priming, so i activated the fuel pump relay via the scan tool, I herd it pumping, i then started the car and no changes. I messed around with that for a sec. I am going to hook a fuel pressure gauge up to it next. I also unplugged the MAF and it stalled....I thought it would keep running but not rev over 2500 rpms or something like that. The maf g's per sec was around 4 at idle. I cant find what its supposed to be.

[s13srcoupe69]

I unplugged the 3 wire grey plug on the Throttle body and no change, idling or starting. If i unplug the 3 wire brown plug, slight idle change.

[s13srcoupe69]

I was measuring resistance in the brown plug, pin 5 and 6. The middle pin and bottom pin (from what ive read). I am reading a high resistance. Bad TPS?

[s13srcoupe69]

Also could it be the idle switch? The plug/sensor attached to the TPS

[Buzzman]

Sounds like the ECU may be fried. A bad IACV has been well known to take it out if the problem isn't addressed quickly enough. This thread has all of the info on it. You should also take a look at the TPS. A bad unit can cause erratic or unusual idle.

If the ECU is fried, you should get a code with the SES light on. Usually it's a P0500 code.

From my experience with this IACV business, the idle relearn procedure sucks.
After I replaced my IACV and had the ECM repaired, I tried and tried to do the relearn as per the manual. No luck.
I finally just went to the dealership where a tech hooked up his OBD machine and did the relearn in about 2 minutes. No charge. In and out in 5 minutes.
Has been running fine ever since.

[s13srcoupe69]

I ordered a TPS.....
I called inifiniti and they said what i expected....."well its gonna take at least an hour". yea they want that diagnostic hour.....130 bucks here too....