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Won't idle, changed tps & iacv, checked ecu


Razzmatazz
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So I have exhausted every search function on every pathfinder forum and here we are. 

Any ideas? 

'02 3.5 pathy with 295,xxx on it

Was driving through town one day when it just died at a red light. Only way to keep it going was feathering the gas on startup and left foot braking to get home, if I let off the gas it died. 

Did some research, figured it was the IACV. Ordered one of those.

I then put a zip tie over the throttle stop screw, just to use as a spacer to keep the throttle open a bit so that it would idle without me being in the drivers seat. Got one whiff of a weird smell I hadn't had before (no smoke from the steering column/ecu area) and shut it off. Replaced the IACV with a hitachi OEM unit, pulled the ecu apart to check if that IC17 chip had been fried by the failed iacv, or if there were any other signs of damage. Nothing, and i mean nothing, looks mint. 

Changed the TPS next to another OEM Hitachi unit, made sure to install it with exactly the same orientation as the original (it was a hitachi and looked factory). 

Truck still won't idle. Starts up but immediately falls on its face and dies without throttle. Sounds great with some throttle though, real smooth and steady. 

If I unplug the MAF while its running it dies so that leads me to believe that's working. When I plug in my scantool to the obd2 I don't get any codes either. 

 

I can't do the idle relearn procedure OR the Tps relearn if the truck won't stay running without the throttle open. 

Also really havent been able to come up with a good tps adjustment how-to/diagnostic. If anyone has one that would be the next thing I'd like to check more thoroughly. 

 

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The symptoms (minus the smell) sound just like when the idle control valve on my '93 stuck closed. I like your zip tie bodge, I'll have to remember that one.

 

The smell's not a good sign. Blown electrical components don't always fail in visually obvious ways, so I wouldn't assume the computer's good. Work out which wire going to the IACV is supposed to be switched by the ECU, then check for power there with a voltmeter to see if it's doing it. You might have to cycle the key or try to start the engine before the computer powers it up.

 

Download the service manual here if you haven't yet. That should have the wiring diagram for the IACV and the TPS info you're after as well. If your scanner does live data, you can check the TPS with that too, just watch the throttle position as you slowly press and release the pedal and see if the numbers agree with where your foot is. If it jumps all over the place or has dead spots, the sensor is junk.

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