6 bolt swap power transistor hot no idle help

[ZombieSix]

perfromed a 6 bolt longblock swap on my 98 gsx. everything is hooked up, everything looks solid. The power transisor keeps getting hot as #### and the car will idle like absolute shit for abotu 20 seconds. withen 20 seconds of the car turning on the car will idle at like 500 rpm, the PT will get hot as #### (burned me hot), and then the car will die. Wiring all looks pretty good. Using a green top cas with a RRE harness, white wire is spliced into the old cas wire. everything looks good. PT is connected to its bracket and bolted to the firewall, it still gets hot as ####. tried another pt, it got hot immediately once car was on (and idling like shit) so i shut it off quickly, i dont want to burn up this one. Need some help. Engine was swapped because old engine spun bearing/began knocking. Stock 6 bolt longblock, good compression.

 

[92AWDHX40]

Idle could be wiring, isc, boost leak, grounds bad, power wire bad, throttle body problems, anything like that, coolant temp sensor.

 

[ZombieSix]

Why then is my PT getting hot as fire? like, my exhaust mani is cool enough to touch, i cant touch the PT. i burned my first one up. The car wouldnt start at all, no spark. Then got the new one, Car turned right up, and did the same shit idle and what not so i turned it off real fast.

 

[92AWDHX40]

Throttle cable stuck, got a video, hard to tell what your problem is generally about.

 

[GDNF2ET]

What would cause the power transistor to get hot to the touch after a 6 bolt swap ?

 

[inthemidst]

Why do you have the white wire spliced into cas.That is the problem.Remove and try again.

 

[MALaCasse]

It is getting hot because it has to much current being drawn through it. What all is on it on the engine side?

 

[GDNF2ET]

Is it wired exactly like this ?

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[slammedndirty]

i am having the same issue currently and have blown 2 ecu's as well. my power transistor will spark when ever it makes any contact to metal.

 

[ZombieSix]

GDNF2ET its wired exactly like that.

THe problem is not the idle, the problem is the car spins up at initial start the PT begins to heat up like a firecracker, the car then begins to only run on two cylinders, and then dies once the PT gets hot enough to litterally burn you. (30 seconds)

Something is making the PT get hot as ####. The PT has voltage to the 1/4 and 2/3 cyl wiht the key on, it also has a good ground. i sanded the firewall and bolted it to it, so it has a good case ground.

 

[MALaCasse]

I'm not sure where the pt gets its power from but make sure that it's not getting to much juice. I'm not at home right now otherwise I would check mine and tell you.

 

[ZombieSix]

sad update. unplugged harness and pulled back to the firewall, inspected everything everything looked good, put harness back, neatly, under fuel rail. saw that 1g coil packs have a little black square thing on them that 2g coil packs do not. hacked 1g bracket kinda to fit my 2g coil packs, put them in car. hoped for the best. everythings plugged in, car looks good wire tuck good, go to start her up. spins up to 1k, i see fuel leaking from #1 injector, guess didnt seat rail properly, shit, car sputters and begins its "half idle" on 1/4 cylinders but 1 aint getting fuel so it just dies. ran a total of 8 seconds. So i grab a rag to get fuel leak cleaned up, soaking it up. then i hear a POOF and look over at Power transistor and its smoking, i guess it fried inside of itself and then shot voltage through the coil pack which ignited the igniters which burned teh fuel giving the motor a little momentum. I never turned the key off because i was cleaning up the fuel. So i fried another power transistor. I then read for voltage on the power transistor with the key in the ON position heres what i got, reading from teh black wire with teh white stripe over
12.2
4.1
12.2
EMPTY
8.8
GROUND .2 OHMS
6.1
12.2
I was wondering if anyone could go to t hier car, put the key in the ON position and read out your Power transistor let me know what you get.

 

['97 Cayenne]

Something to maybe check out. I recently just had a hot power transistor issue. I looked at all my wiring and didn't see anything unusual. Until I thought about he car was idling. I would drive Long enough for the car to warm up then the car would start idlin around 500 rpm and eventually die. Then it would be hard to start unless I hit the gas. Then I would have to feather or hold the gas to keep it running. But once I let the car sit for a while and cool off it would run fine again till warmed up.
Ended up being a broken wire at my odd plug. And one of the red power wires was also stripped back a little bit. I wired in a new plug and haven't had an issue for the past couple days since that.

 

[ZombieSix]

ECU was toast. i guess it went with the motor. new ecu fixed the problem.

but i went through all this bullshit, and only to find the 6 bolt longblock has a blown headgasket and coolant/oil is mixing

 

[beny87]

It's sad to hear about your ECU. I'm trying to figure out a reason why it could be showing this behavior. Firstly, was the power transistor properly sinker? Now coming to fuel injector leak. What might've actually triggered that is kind of a difficult. It might be because of excessive opening and closing of the valve at a much higher rate. ECU isn't something which can be burnt this easily so there has to be a reason for this. When the power transistor was getting hot, it meant that it was supplying excessive current to some mal-functioning component or there was a short in the circuit somewhere.

pcb assemblies