Maybe the power transistor to blame?

[tsidrift1]

Here is the deal. I have been fighting this stupid misfire at my idle forever now. It seems like it might be misfiring while driving a bit too. I have replaced the plugs with ngk bpr6's at .028, I have a "new" used coil pack that tested out ok, i replced the fuel filter about a year ago and the wires are new. I am wondering if something is wrong with my power transistor. The car will idle ok right when it is started when cold. Then once the needle gets past the first tick on the guage it will misfire bad at idle. I am really getting annoyed by it. It probably does it every like 10 sec or so. I also got a problem with my idle in general. I will press in the clutch and it will go down to 1kand then go back up to 1400 and sit there till I am stopped and then drop back down to 900-1000 rpms. I would like to fix that too, but right now that is the least of my worries. i wanna know what is causing my idle misfire!

Let me know guys,
Anthony

 

[TurboChrged93]

#1 You have some infamous Idle surge. Adjust your BISS so your idle sits at 750 no accessories on. Did you hack your MAF? Remove the honeycombs? Test your IAC motor? Change settings with a piggyback:AFC etc.

#2 Ignition modules or power transistors are known to go bad once they heatup/reach op temperature

 

[tsidrift1]

I will try and swap out an isc motor and see if that helps my idle a bit. I have tried to adjust many times but it just doesnt seem to adjust it will still idle at 1000 and sometimes like 1300 and sometimes it will drop to 700-800. so you think that the power transistor could be bad then? I have read about them, but it seemed like to me that when they go bad, the car doesnt even start or run. I hope this is the problem, as it will be a quick fix. I will try to get a hold of one and swap it out and let you know.
Thanks,
Anthony

 

[luv2rallye]

Be aware that a coil (or power transistor) can go bad with age and/or temperature but may test ok when not in car or engine not running. If suspect, test with a heat gun or hair dryer.

 

[tsidrift1]

ok, I swapped out my isc motor and it didnt change the idle at all. Could my o2 sensor be causing this. I have never replaced the o2 sensor, I just dont want to go and buy one and it not change nothing

 

[DECODER22]

if you need coil packs let me know i got a bunch of them

 

[Iroc_g]

Well, i had a bad one just last month. My car was idleing poorly, and misssing alot. swapped a new power transister in and immediate fix.

One thing that happened that really made me think of the transistor was that my tach was very jumpy. But ive heard that isn't a must when they go bad.

 

[tsidrift1]

if you need coil packs let me know i got a bunch of them

Do you mean transistor pack? I have a new coil, or a used one that tests good. I also have wondered if it is maybe my cam sensor?

 

[tsidrift1]

I was checking my ignition timing today, and when I had the timing light going it would like skip a flash and then go back to the regular blink, so obviuosly the things is getting a funky spark from somewhere.

 

[DallasN2O]

tsi.. did you ever figure out what was causing the light to blink erradically on the timing light? Was it the power transistor or the coil or both? I have the same problem.

 

[mhuffman]

tsi.. did you ever figure out what was causing the light to blink erradically on the timing light? Was it the power transistor or the coil or both? I have the same problem.

i have a similar problem. my base timing jumped around all over. also, i have terrible misfire about 4500 rpm's. dont know if they are related.

 

[blackjdm90]

I am having exactly the same problems with my car, the surge when i put the clutch in while driving, misfiring at idle, misfiring bad when i hit boost. when i start my car sometimes it feels like it is getting a weak spark and so i pop the hood, wiggle the wires that go into the transistor and my idle changes and all kinds of weird stuff and the more i mess with it i seem to make the car sound better and stronger... it is really getting on my nerves. any suggestions on where to start first? its a 1990 talon tsi awd. thanks

 

[blackjdm90]

Well, i had a bad one just last month. My car was idleing poorly, and misssing alot. swapped a new power transister in and immediate fix.

One thing that happened that really made me think of the transistor was that my tach was very jumpy. But ive heard that isn't a must when they go bad.

would that be the same for a 1990 tsi? i picked up a new transistor from my friends parts car (1992 tsi) but they didn't match up so i couldn't get the problem fixed.

 

[JSM1991]

Hey im hoping some one can help me out here ok so I just totally rebuilt the bottom end of the engine just got it back in and it wont start. So I checked my timing belt everything is lined up perfect then i checked spark and I have a 95 eclipse GST 2.0L Turbo and its weird I have 2 coils and am getting spark from one but not the other so i switched the wires on the back of the coils now the other coil doesnt spark and the one that didnt before does and I get 12.72 volts to the back of the coils at the wires on all 4 with the key on. Oh and the car ran but missed before the rebuild but I had low compression so I rebuilt it. Any help would be great please pm me if you know whats wrong or have an idea thanks