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symptoms of a failing/bad power transistor?

highrpm666

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Feb 19, 2014
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124
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Morrison, Co
Im having a hot start issue with 677. Whenever I drive further than say 10 miles or so and get it nice and warm I have an issue with what seems like a bad misfire and cel when trying to restart. I haven't had a chance to read the flash code/s yet, it seems to only happen when I'm away from my tools of course. If I immediately restart its ok, but if I wait more than 10 minutes or so this issue rears its head. I have figured out that if I open my hood and let it cool off for 2hrs or so I doesn't happen at all.

So im curious if anyone can relate this to a failing power transistor? I havent found many threads at all with a similar issue after google searching. I did find enough information to point me in the direction of the power transistor though. I know I need to pull the code, I'm unfamiliar on how this is done on the galant also.

So could this be my issue and what are some symptoms of failure for this part?

And what the simplest way to get my flash codes? I read somewhere that I need a test light or buzzer setup, is this correct?
 

prove_it

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Jul 3, 2008
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4,201
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Sioux Falls, SD
Will it crank for a while then start after sitting a while? Could be an electronic, could also be the fuel system bleeding off fuel pressure.
 

highrpm666

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124
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Morrison, Co
It starts right up, normal cranking time etc. It just misfires and illuminates the cel after a few seconds and it does not go away unless I let the car cool off.
 

MellowVR4

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Milwaukee, Wi
Failing crank sensor?
 

mitsuturbo

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Near Seattle, Washington
It seems like i suggest this WAY too often, but in this case I've got to relate a personal experience. My very first GVR4 had a problem similar to this. It would start and run fine when cold. After it warmed up, and i eventually shut it off... it would NOT want to restart. When it did restart, it would stumble, run like sh*t, or even flat out just die after tripping some CEL codes. When i pulled the ECU i found it to be leaking capacitors.

Have you checked this yet?
 

prove_it

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Good call, also you really should pull the code. That will at least give something to start with.
 

highrpm666

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Feb 19, 2014
Messages
124
Location
Morrison, Co
Quoting highrpm666:


And what the simplest way to get my flash codes? I read somewhere that I need a test light or buzzer setup, is this correct?



I will pull the ecu tomorrow if I get a chance to check my caps. I think its already been re capped but I will know for sure once inspected.

One thing about this issue. I can drive it all day long without any problems as long as I dont shut it off, it only happens when I re start after driving for a while. It never happens while driving, it runs like a raped ape all the time until I fire her back up without letting it cool for a few hours.

It feels like weak spark or low fuel pressure or the ignition timing is off a bit.
 

BluFalcon

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Jan 20, 2002
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Wichita, KS
Just to chime in, but here's another one for check the ECU. When I picked up my car and drove it back to Texas from Colorado, it exhibited the same symptoms the OP and Anthony described. Threw a CEL every once in awhile, cut out occasionally, and sounded like it was missing. Put up with it for awhile, and figured I'd figure it out once I got some time to mess with it. until it left me stranded while I was getting groceries.

Tried a new Ignition Power Transistor, Coil Pack, CAS and other things. The ECU didn't look like it was leaking, but I decided to try it anyway, and the problem cleared up.
 

MellowVR4

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Milwaukee, Wi
Quoting highrpm666:
Quoting highrpm666:


And what the simplest way to get my flash codes? I read somewhere that I need a test light or buzzer setup, is this correct?



I will pull the ecu tomorrow if I get a chance to check my caps. I think its already been re capped but I will know for sure once inspected.

One thing about this issue. I can drive it all day long without any problems as long as I dont shut it off, it only happens when I re start after driving for a while. It never happens while driving, it runs like a raped ape all the time until I fire her back up without letting it cool for a few hours.


Maybe a failing coolant temp sensor. /ubbthreads/images/graemlins/dunno.gif

It feels like weak spark or low fuel pressure or the ignition timing is off a bit.

 

highrpm666

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Joined
Feb 19, 2014
Messages
124
Location
Morrison, Co

highrpm666

Well-known member
Joined
Feb 19, 2014
Messages
124
Location
Morrison, Co
So I took the car on a spirited drive through the hills today before I tear the ecu out to send off and had another symptom I havent really mentioned before pop up again..

Under a load in 3rd or 4th gear it bucked and misfired for a brief second until I let out of it. This is happening at about 4500rpms and it just seems to fall flat on its face for a brief moment. No cel. If I let out for a second and get back into throttle it doesn't happen again. Very very intermittent. It only happens about 1 out of 20 times I load it hard and get into boost. It feels like an arcing plug wire or something along those lines. Plugs and wires are brand spanking new. Ive put 400 miles on it since getting it buttoned up and this has happened 5-6 times. Twice today.

Anyway the ecu is headed out to ecmlink this week for capping and socketing and whatever repairs to the board are needed. In the meantime I'm going to de loom the injector harness/cas harness etc and see what repairs are needed before I throw any other parts at her.

I'm praying that the ecu alone is the culprit of all these symptoms and I dont have to remake my entire engine harness from scratch.

Ill post some pics of the opened ecu later on today.
 
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highrpm666

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Joined
Feb 19, 2014
Messages
124
Location
Morrison, Co
I found quite the surprise when I opened the ecu...





looks like a recap and socket job was done already but, they installed jumper wires etc and they forgot to clean up properly. Solder job looks good but I can see corrosion setting in already in one spot from the old leakage, nothing serious though. And who knows whats jumped across the back of the board but, I can obviously see the broken traces. /ubbthreads/images/graemlins/banghead.gif

Anyone local want to test the ecu in a different car for me to see if it exhibits any issues?
 
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