3.6 conversion idle problem/ECU help - Page 4

ssfrancis · 05-30-2015, 03:29 PM

I checked resistance at each pin of the 55-pin plug. The TPS and Hall sensor bits were around 0.2 ohms.
Given what the engine harness looked like. I pulled the entire wiring harness from the engine to the DME, stripped the cloth and inspected ever inch. Nada, zip, zero problems. Not a frayed or nicked wire, no obvious problems at any connector and resistance of everything I checked seemed OK.

I also checked the resistance on the TPS itself. Seems with in spec ~1000-2700 ohms. Reads well in the car and on the bench. I'm getting 5.5 volts at the TPS and the Hall sensor when the key is on.

I cant see a reason to buy a new TPS for 100$ can you?

The odd thing here is that I still can get it to flash out codes, no matter what I do. The light is on and stays on on.
Perhaps the problem really is the ECU??

ischmitz · ischmitz's Garage

Flashing out codes should give you a sequence of flashes.

When you had the diagnosis done did you check what the DME "sees" when you press the accelerator? It should show the value the internal A/D converter reads.

ssfrancis · 06-05-2015, 12:10 PM

I haven't been able to get back to the shop to get the ECU read again, and I cant get the rennlist scantool to work despite a whole days effort (I need a better cable). But I did try another TPS and guess what?....no change

Now I have a new: ISV, TPS, DME relay and engine harness

The are no continuity issues in the whole harness from the engine to the 55pin DME plug.

If I clear the ECU memory and start the car it will idle but hunt a little, staying mostly at 1000 rpm but hunting to 1500rpm. after I let it warm up it stays idling fine. If I turn the key off then immediately restart it idles at 3000rpm.

I have never been so frustrated with a car in my life

ssfrancis · 06-05-2015, 01:43 PM

Took it in for another durametric reading.
No more Hall sensor code (thats good) but TPS still throws a code.

We could not get any live readings from the ECU.... I'm thinking its time for a ECU diagnostic.

shahram · 03:14 PM

What happens when you disconnect the O2 sensor?
Maybe I missed it but did you have the chance to run the egnine with a stock 95 chip?

ssfrancis · 09-25-2016, 08:17 AM

Problem is RESOLVED!!!

After nearly 2 years of intermittent issues that led to barely ever driving the car I found the problem.
One day I was letting it idle and I unbolted the ECU and moved it to the side... then the idle changed. moved it back and it changed again. I cut open the harmed near the ECU and fount that 6 or 7 of the wires had a small nick in them. It looked like some one may have put the screwdriver through the harmed at some point (wasn't me! pic attached)
I prepared the wires and have now put well over 1000 miles with not a single isle issue or code.

Thanks to everyone for all the help!

Jaskas · 10-29-2023, 10:16 PM

I have to come back as reading this topic almost every year. Im facing increased idle issues from time to time. During the last 12 months it has been really bad. Usually occurs only when engine is hot and its running on "normal" ECU-map. I´ve been changing components like crazy.... does not help.

-> Every bloody time the problem is a measly vacuumleak somewhere, eventhough I though that i have not found any. Same **** this time as well.

Now, lets go out and drive.