Resolved Looking for electrical connector to "power transistor" to run compression test

[juntjoo]

Is one of these black connectors under the blue spark plug wires in the pic supposed to be what I'm supposed to disconnect before doing a compression test?

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my Haynes manual mentions this "electrical connector" attached to the "power transistor" a billion times but without a picture just describes it as being on the driver's side of the intake manifold. Thanks!

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[210carlos]

look for the coil pack connector and disconnect it just find the coil pack dont forget to disconnect the fuel pump relay to

 

[juntjoo]

Huh? Mind you I'm not very familiar with these components and that area is really tight.

Can anyone refer me to some online overview of this electrical system? Also, it's be helpful if they're were any repair manuals more detailed and with higher quality photos than Haynes, so if anyone knows of any share please. Thanks. I'll keep searching in the meantime.

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[9!'clipseDOHC]

Huh? Mind you I'm not very familiar with these components and that area is really tight.

Can anyone refer me to some online overview of this electrical system? Also, it's be helpful if they're were any repair manuals more detailed and with higher quality photos than Haynes, so if anyone knows of any share please. Thanks. I'll keep searching in the meantime.

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To disable spark for a compression test just unplug the coil pack. It looks like this:

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and is mounted on the intake manifold, behind the fuel rail.

The best and most detailed repair manual is the Factory Service Manual (FSM). I found mine on ebay. You can also download an electronic copy for free.

 

[Boostinsideways]

http://www.lilevo.com/mirage/92-93 1G DSM Engine Service Manual .PDF/ENGINE.PDF
http://www.lilevo.com/mirage/92-94 1G Talon Laser Vol 1 Electrical Service Manual .PDF/92-94EL.PDF
http://www.lilevo.com/mirage/92-94 1G Talon Laser Vol 1 EngChasBody Service Manual .PDF/92-94ECB.PDF

Applicable service manuals for your car.

 

[steve]

It's a lot easier to just remove the MPI fuse on the battery when performing a compression test. That disables the ECU so you won't get fuel or spark.

 

[juntjoo]

To disable spark for a compression test just unplug the coil pack. It looks like this:

You must be logged in to view this image or video.

and is mounted on the intake manifold, behind the fuel rail.

The best and most detailed repair manual is the Factory Service Manual (FSM). I found mine on ebay. You can also download an electronic copy for free.

I'm familiar with the coil pack since I replaced my spark plugs, so, will that satisfy the purpose of disconnecting this "power transistor" Haynes keeps mentioning? What about this fuel pump relay that 210Carlos above mentioned? Thanks

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http://www.lilevo.com/mirage/92-93 1G DSM Engine Service Manual .PDF/ENGINE.PDF
http://www.lilevo.com/mirage/92-94 1G Talon Laser Vol 1 Electrical Service Manual .PDF/92-94EL.PDF
http://www.lilevo.com/mirage/92-94 1G Talon Laser Vol 1 EngChasBody Service Manual .PDF/92-94ECB.PDF

Applicable service manuals for your car.

Sweet! Thanks

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It's a lot easier to just remove the MPI fuse on the battery when performing a compression test. That disables the ECU so you won't get fuel or spark.

Really? I was aware of that and disconnected that, but didn't know it would be that simple. Who do I believe in here?? With the simplicity of your solution, you've got to be either right or wrong.

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[steve]

With the simplicity of your solution, you've got to be either right or wrong.

It's what I've done for the 20 years I've owned the car. I'll let others speak to if I'm right or wrong.

 

[9!'clipseDOHC]

Really? I was aware of that and disconnected that, but didn't know it would be that simple. Who do I believe in here?? With the simplicity of your solution, you've got to be either right or wrong.

When it comes to DSM ECU stuff, you listen to Steve. End of story. I've always pulled the MPI fuse for fuel and unplugged the coil for spark. I didn't realize the MPI fuse did both. Good to know! (not that its any trouble to pull the coil plug too).

Here is a good write up on how to do a compression test, I'm no sure if you've seen this or not: http://www.dsmtuners.com/forums/articles-engine-fuel/338152-compression-leak-down-testing.html

 

[steve]

The coil and power transistor will still be powered from the ignition fuse but since the ECU is turned off the ECU will never signal the power transistor to charge the coil or fire it. The starter is independent of the MPI circuit but depends on the ignition switch which is powered from the ignition fuse so you can't pull that one and still crank the engine.

The CAS is power off the MPI circuit so while your cranking the engine you won't get any CAS signals either.

 

[Super Sport]

It's a lot easier to just remove the MPI fuse on the battery when performing a compression test. That disables the ECU so you won't get fuel or spark.

Great to know it disables both.

 

[juntjoo]

When it comes to DSM ECU stuff, you listen to Steve. End of story. I've always pulled the MPI fuse for fuel and unplugged the coil for spark. I didn't realize the MPI fuse did both. Good to know! (not that its any trouble to pull the coil plug too).

Here is a good write up on how to do a compression test, I'm no sure if you've seen this or not: http://www.dsmtuners.com/forums/articles-engine-fuel/338152-compression-leak-down-testing.html

Yes, thanks. This is where I got the idea to pull the coil connector. never officially found it but I think I'm going with Steve's recommendation here. Thanks ya'll.

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