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Discussion Starter #1
Hey guys, I don't think I've posted here in years! Mainly because my car has been garaged for years. I finally got it going again with a new clutch, front end and some other stuff. several years ago I replaced the coil packs with Accel coil packs and one of those died so I am replacing those with the MSD ones. Within 2 weeks of it running again the PTU blew out. This is the second one in 22 years so I did not think much of it. Unfortunately the new PTU I got from Amazon for $22 blew out in 20 minutes. The new one did not come with any thermal compound for the bottom nor did it say it was needed. I've done a lot of reading and the main issue I see is heat or too much current. I have plenty of thermal compound so I'll put some on the new one that will be here today. The coil pack plugs are now the spade connectors that just plug into the back and I have zip ties and electrical tape holding them in. I tested all of them and there is no short to ground so that was not the issue. Several of them were loose though and the tape and zip ties were all that was holding them in place.

I know that poor connection can increase current so I am going to be fixing all the spade connectors so they go in nice and tight. Besides that and the thermal compound, what else should I do?

Is there anything else that could cause the PTU to blow like that?

History of the car in order of work done by me (I do almost everything myself):

ECU was replaced with a chromed ECU.
Wideband O2 sensor kit installed.
Injectors were replaced with VR4 ones that were refurbished, flow tested and guaranteed. I also added the resistors for each injector.
Coil packs were replaced with Accel.
New downpipe and cat from 3SX installed.
ECU was tuned and running awesome for at least a year.
Valve seals were finally replaced and car ran better for at least another year. (probably should have been tuned again after that)

The car got side swiped and ended up in my garage until we could do the body work. Unfortunately that took too long so I bought another car to drive. 3 years later I finally got back to the GT and replaced the front end bushings, ball joints and clutch. When we started the car the CEL came on with no codes. We checked everything and could not find anything loose or unplugged. I flashed the original ROM to the chromed ECU then flashed it with the last known good one. Everything was great. We started tuning the ECU again because it needed it after the valve seal replacement and it was running good again until the PTU blew last week.
 

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Discussion Starter #3
Lol so just a junk part? I’m hesitant to spend $100 on a part though if it’s going to blow out again. I also paid around $35 from a local parts store 5-7 years ago and it lasted a few years. Is there anything I need to check or do before spending that kind of money?
 

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I would ask if he has one 91 stealth RT TT part out!!! 100k miles.
It obviously would be used, but I've bought 2 or 3 used PTU's and never got a bad one....
Name is Patrick. Great guy to work with, buy from him A LOT.

Bob.
 

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There's only one reason your $22 Chinese counterfeit part failed... Do I need to tell you how lucky you were to get 20 minutes...?
lmfao I wanted to say this earlier, but at least you did it for me/rest of us :ROFLMAO:

But yeah... even a good, used OE unit will work way better than that aftermarket one. Even for absolute peace of mind, the price for new is still worth it too.
 

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Discussion Starter #7
Ordered Patrick’s PTU.
I’m still going to fix all the coil wires to make sure they stay in the back really good. Anything else I need to do besides thermal compound?
 

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What is this Thermal compound you are talking about? Ive gonna be replacing my PTU soon and looks pretty simple but just dont know what you mean by Thermal compound....
 

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What is this Thermal compound you are talking about? Ive gonna be replacing my PTU soon and looks pretty simple but just dont know what you mean by Thermal compound....
Any silicone tune-up grease will work just fine. You just put a thin film on the bottom of the PTU where it contacts the metal base. It helps promote heat transfer and helps keep out water and corrosion that could hamper heat transfer.

They actually make thermal compound specifically designed for mounting of electronic components, and if you have access, or can source easily would be a great option. But like I said, in this application a typical dielectric tune-up grease works just fine.
 

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Any silicone tune-up grease will work just fine. You just put a thin film on the bottom of the PTU where it contacts the metal base. It helps promote heat transfer and helps keep out water and corrosion that could hamper heat transfer.

They actually make thermal compound specifically designed for mounting of electronic components, and if you have access, or can source easily would be a great option. But like I said, in this application a typical dielectric tune-up grease works just fine.
Thank God you told me this lol or else i wouldn’t have known that dielectric grease should be put on the bottom metal base the PTU sits on. Thanks 🙏🏽
 

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Discussion Starter #11
I actually don't see it used too often on parts like this. Mostly I see corrosion or rust under the parts because of moisture. and sorry I didn't answer sooner. I actually have a tooth paste sized tube of thermal compound for all my different hobbies lol.
 

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Discussion Starter #12
Also I got the PTU and it works great. The only issue now is after it warms up it has a dead miss. Can't tell if it's one of the coil packs or not though. I did have a injector resistor break but I soldered a new one in and it ran so smooth for quite a while. I'll be digging in deeper tomorrow to see which cylinder is misfiring. Once it cools down it runs smooth again.
 

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Discussion Starter #13
Ok I got it. I had to start from scratch on my ECU tune. Somehow my tune got set back to factory and I had to turn off all the unused things like EGR, secondary O2 sensor and map sensors. Runs pretty smooth now. Now I just need to get the clutch and brakes back to normal. I guess sitting so long made the seals dry because I lost the clutch master cylinder on day one, the drivers front brake caliper went the other day and now I think the clutch slave cylinder has blown out. Such is the life of older cars lol.
 
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