Tom. M

So..here's what I posted in the 89harness request... no luck with the rebuild..symptoms still remain:

"Well...although I've got a nice front engine harness...the old issues still seem to be there. Backed out of the garage this am and it started the old..idle up....then down...then up.....but ran ok..till I headed out of the neighborhood...got to the main road and it started running really rough and no amount of throttle could clear it..(Belching black etc)...and then it died....cranked..and it started but I didn't want to take a chance..so back to the house..

Any thoughts?....I've swapped in a different brain and it did the same thing..so I think that rules that out. Temp II was replaced a few years back... Could the temp I cause this kind of issue? Any other thoughts? "

So went and tested the temp II at both the sensor and inside the car at the LH and ezk. Both were within spec.

Moved on to test the MAF per John and Electronik repairs web sites. Tested the resistance of the hot wire.. spec is 3.6 to 4.1 ohms.... mine came in at 4.3 (and 4.2) ohms. Problem?

Tested the idle mixture pot.. spec is between 300 to 600 ohms ..mine came in at 1200 ohms. Problem?

Also the MAF connector is pretty beat up and there are some exposed wires..so will likely replace that.. but wonder if the above readings are a concern.. Will be trying a known good MAF soon so might be moot..but thought I would throw this out there.. looking for any ideas..

thanks,

PorKen

Have you tried another MAF? Checked volts/ohms at ECU plug?

LH 2.3/EZK has no Temp I, MAF CO pot is not used/wired.

Tom. M

a known good MAF will be swapped in soon. The one in the car is a rebuilt unit (maybe 4 years ago)..by Injection Labs.

Will run the Volt check soon...and test at the ECU plug soon too to check if wiring is an issue.

John Speake

The resistance tests are only for gross MAF failure. Tolerances are taken out during calibration.

I suggest you disconnect the MAF to force the car into limp home mode, see if the car will keep running.

Tommy928

Have you checked the coils? Coils could be checked fine with a meter but bad. Both of my coils died within a week time and exibited similar symptoms as your's.

John Speake

It almost sounds as though the MAF has the classic thermal fault if it runs so rich. Try the MAF disconnect trick. It sould run consistantly although not perfectly at idle.

Tom. M

I tried the disconnect before and I seem to recall that it didn't change anything....but that was also when the car was running "OK". Only seems to be a big deal when it's not cold..but not yet warmed up. I will try again and see if I can disconnect it when it starts acting up.

John Speake

If it was OK -ish when cold but running very rich when hot (O2 sensor being used closed loop) then I would suspect the O2 sensor. This doesn't seem to apply in your case...

Tom. M

bumping this to the top...after removing the SMT 6 I had wired in (to help tune the rear turbo when it was on the car)....I reconnected the wires in the brain connector harness (the ones cut to insert the SMT wires)..and tested the car again last weekend. It started up and ran rough..no throttle response...and as it warmed up, the throttle response came back slowly.. at about mid warm up it started to idle better...but then started the idle up to 1200...hold......drop down.... hold......back up.... etc....

When it finally got above 80degrees C....everything was normal. I figured that since it was during the warm up stage where I was having all the issues, that the Temp II could conceivably be causing problems (even though I had tested it before..within spec). I put in the new Temp II today, and decided just to check the old one again (running under hot water to see how the ohms changed). Connected one side and grounded the other end....and it started at around 1900...and dropped as it heated up. Move to the other pole....to check....and the meter just read 1. No change...move the ground around to make sure it was getting ground..no change...so seems the one pole was bad (not sure it was the LH or the EZK signal one)... but will test drive the car this weekend to see if this truly is my problem....

Keeping my fingers crossed....would be nice to have the GT back again...

Tom. M

So...in conclusion...it was the Temp II. Weird thing is that it tested within spec both at the sensor and at the brain connectors. After repairing the harness, trying to run it with the O2 sensor disconnected (to see if that was the prob), swapping in both a different MAF and Brain, and removing the SMT.. It came down to something in the warm up cycle. I had issues with a non-start issue way back when I first got the GT..if the car was shut down before it was fully warmed up, it wouldn't re-start until it cooled. Replace the temp II back then and it cured the problem...

Took it out this am to get some gas, and it fired up and ran great from start to finish. Glad to have the GT amongst the living again...and now on to the next project .

shawscove928s

Tom,
I am so glad you have solved this. Now you can just drive and enjoy. You deserve a road trip..................
Ray