must be something other than the ecu

hey everyone, i recently posted a new topic called ecu problem on the board where i received some great input
back. I purchased a non eprom ecu out of a 92 talon and it linked up perfectly! it doesnt even run lean at idle like was expected too! so thanks again turned out great, but my original problem from the start is still happening so as it turns out the ecu was not the problem. The car runs next to perfect for 15 min then starts to die engine bogs out and sometimes pops loosing all of its power! At that time only the dash more towards the ecu below the glove department comes a loud on off click. I have owned the car for two months, again its a 91 gvr4 747/2000 totally stock and the sad part is i have not drove the car one day that it hasnt left me sit due to this problem /ubbthreads/images/graemlins/banghead.gif any input will be much appreciated again!

 

[broke down]

i haven't read your old thread, but have you looked into the injector relay? Gold box looking thingy down by the ecu.

 

[talon]

The clicking sound you are hearing is most likely the main relay.

The relay it self can be bad, and start to fail once it gets hot. That relay controls the MPI and fuel pump.

 

[broke down]

^^^that's what I meant to say, thanks for correcting me. /ubbthreads/images/graemlins/smile.gif

 

[1941Galant]

Nick, I have one or two of those relays laying around here if you want to throw one in, it should only take a few minutes at most to do.

 

[BoostedAWD91]

we just checked the relay and it was fine, replaced the MAF thinking that was the problem and still doing it. It seems like its a short to the ECU somewhere that its shutting power on and off to the MPI relay. While your driving the car, the rpm needle goes crazy and jumps all over the place.
here is a picture of the ECU harness wiring after i removed some of the tape, not sure if its supposed to be like this or not. anyone know?

 

Yes, several of the wires do tie together and then split right at the ECU. Ones the O2 I believe and I can't remember off the top of my head what the other is. I wouldn't suspect the wiring as your issue does sound like its related to heat soak. I'd bet on the MFI relay fouling once it warms up. If you checked it before it was warm, it may not show any signs of problems. Only other thing then the relay, is the coil pack. Seen them do similar things where they heat soak and start fouling up, but since your relay (or something in that area) is clicking, I'd put my money on it.

 

[1941Galant]

^^They borrowed a relay from me and put it in the car. Would it be possible for a bad CAS to cause this?

 

[BoostedAWD91]

we already tested and tried another MPI relay and thats not the problem. The biggest thing that stumps me and why the rpm gauge is going crazy. the car can be idling fine and the rpm gauge goes crazy and it does it while your driving the car.
what all exactly gives the rpm gauge the signal? it has to be something that is part of the rpm circuit for the gauge cluster to make it do that

 

[GVR4ZUM]

Datalogger might help. Whoa Chris when I responded I didn't see yours..

 

[BoostedAWD91]

i hooked my logger up to his car and i really didnt see anything

 

[Yao]

there is a short somewhere in the ecu harness. Do you have IDLE controller in the car?

 

[BoostedAWD91]

his car is completly stock, nothing has been touched or modded. it idles fine
but once it gets warm it starts doing it.

 

[Hertz]

Those splices don't look "completely stock".

 

[Yao]

What I am getting at is not "fine idle". It's that fact that Idle motor have known to burn out ecu and that if it has and the ecu replaced, the RELAY would still see the short in the harness somewhere, there for cause the clicking and short out in the system, ask me how I know

 

[BoostedAWD91]

from what i noticed, it idles fine. ive heard it surge alittle bit im almost positive the iac is not messed up.

where does the rpm signal come from?

 

[SleepinGVR4]

There is no way to see (by looking at it) if the IAC is doing its job or frying your ecu. I would just unplug it to be on the safe side. And if he really wants one, get one of these. DSMISC

 

[toybreaker]

Almost sounds like a ground issue. /ubbthreads/images/graemlins/dunno.gif

Are the grounds by the ecu and up on the firewall clean and tight?

Battery well grounded?

[edit] Could also be the filter/ignition capacitor on the intake manifold or it's wiring. The black and white wire that leads to it get's cruchy and develops bare spots. Shorting that against the intake *may* do something like you're describing. Another place to look for a problem that would cause the tach to hop is in the coil/ignition transistor wiring harness, the harness at the cas, or the cas itself

 

[BoostedAWD91]

im gonna swap one of my CAS into his car in the morning and see if that helps. If it still does it then its gotta be a wiring issue somewhere

 

chris and i are going to try one more thing in the morning, if we cant solve the problem ive decided to put the car in the shop. unfortunately i dont have the time to waste or the know how to solve this problem myself. although, all of the new friends ive met have been a huge help and if have not solved the problem, at the very least helped me sort out all the things its not, which in this case is a huge deal. this is my only car and have missed out on alot of work due to it and need the problem solved with a quickness, or im afraid i will not be a gvr4 owner in the future. everyones input has been very appreciated more than you know! after tomorrow i will find the most related to the problem mechanic in the area and turn the car over to him hopefully not resulting in a huge bill and nothing accomplished. i will make sure to let everyone know the outcome of this electrical nightmare, maybe to help someone with the same problem in the future. thanks again NICK