*Power Transistor Questions*

[Merciless]

I have a couple questions about the Power Transistor in a 1G turbo.

1.- Is the transistor actually sending power to the coils, or is it just a noise reduction device?

2.- Is there a way to remove it without taking the back piece of the timing cover off? It looks like one of the screws is behind the back plate of the timing cover, and that's a major pain in the ass for just a transistor replacement.

 

[RiceKiller_TSi]

Hey, what makes you think there's a problem with the power transistor? I'm currently troubleshooting some power issues myself.

 

[set3422]

I have a couple questions about the Power Transistor in a 1G turbo.

1.- Is the transistor actually sending power to the coils, or is it just a noise reduction device?

First part of the answer, no. It sends GRND or NO GRND signal to the coil pack to determine which coil to fire. The coil pack gets 12V power from MPI Ignition switch. 2nd part of the answer, yes and no. 90-91 5 pins power transistor does what wrote in 1st part of the answer. The tach noise filter is located near the TB cable bracket and filters the noise with signal coming from the coil pack. 91.5-99 power transistor has tach noise filter built in and filter in coming noise from the power transistor.

2.- Is there a way to remove it without taking the back piece of the timing cover off? It looks like one of the screws is behind the back plate of the timing cover, and that's a major pain in the ass for just a transistor replacement.

Need to remove the coil pack to get to a better angle on removing the PT, but still can be done with CP intact (PITA).

 

[Merciless]

Hey, what makes you think there's a problem with the power transistor? I'm currently troubleshooting some power issues myself.

Sorry for the extremely late reply.

I was getting multiple misfire on all four cyls over and over, and was working on tracking down the cause of the problem. The car was dumping fuel and the car ran richer than I've ever seen anything run before, fouling plugs instantly. The motor itself was fine, compression was perfect all across. The ECU was fine, and it turned out the ignition was straight, too.
I checked resistance on every piece of the ignition system individually, and everything was in spec.
My next step would've been to check the injectors. But I flipped out before I got that far and gave up. Actually, I was forced to scrap the project for financial reasons, and I'm now parting the car out.

 

[RiceKiller_TSi]

Oh, ok. I'm having totally different issues here. Thanks.