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Discussion Starter #1
I bought a 92 stealth rt/tt and Ive noticed it doesnt seem to start up well if it sits. It lived its life in a hot climate and here it already saw 10º. Its not a daily and it sat for 2 weeks between starts outside. The tach was going crazy, not reading accurately and I think the capacitors that control that are in the ECU? Also it wasnt running on all cylinders for a few seconds. Once it warms up its not bad, that was the first time I saw the Tach do that craziness.

So as per my user name I had a 92 vr4 awhile back. That car was good but had the same weird hesitation in 1st. I sold it at a loss, always thinking it was the ECU but never bought one to try. The new owner put one in and it was cured. This stealth kind of reminded me of that when it was still cold.

The 92 stealth I am wondering if I should just do the new ecu considering the Tach issues and the weird running issues. I got a fast paced clicking noise while its running but I dont know if thats the computer or the solenoids or what. I had the 92 stealth tt and 92 vr4 at the same time and I vaguely remember rapid clicking. I dont want a used ECU because it'll fail again, and the chrome ECU should add value?

Im thinking ill get a Xmas bonus and this would be a good buy. But I dont know if im correct thinking the Tach issues can be caused by the ECU...Then theres also the PTU...too much I dont know about!
 

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1991 VR4
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What is your hesitation to just get the caps replaced? Mine leaked so bad they fried the board and i ended up having to get a used ECU with caps already replaced. That was about 8 years ago and the car has been fine ever since.

If you want the upgraded ECU for the tuning potential, to support future mods, etc, it makes sense. But if you just want a working ECU i am sure a used one with good caps would be much cheaper...

Yes, your issues could be caused by the ECU. The PTU can cause those symptoms as well, but i haven't personally seen it cause the crazy tach, just cause the tach to read wrong when it drops 1 or more coils.
 

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93 NA ATX 3000gt DOHC
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......The tach was going crazy, not reading accurately and I think the capacitors that control that are in the ECU? .......
Not in ECU, in tach itself: see attached quote from 2015 by socrace and link to thread dealing with tach issue.
Just fixed the "lazy" tach on my 94 base, and so resurrecting this post to detail the repair. There were 2 10uf 25v electrolytic caps on the tach board that both needed replacement. You can see them in the above picture of the circuit board, at 12 and 9 o'clock positions.
The caps can be easily replaced without removing the tach needle, just remove the cluster cover and the 3 screws at the rear, and then remove the whole tach unit from the cluster.
https://www.3si.org/threads/tacho-problem-fron-across-the-pond.813650/
 

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Discussion Starter #4
Well the old owner said the capacitors were replaced already. I am considering the new ecu because I just done want to mess with another one of these cars. The car has dr650 turbos too that I'd like to push more boost out of as well (it's currently at 10psi) I have an arc2 not hooked up I could possibly sell. I was just super sore about selling a 92 vr4 with 32k on it for a huge loss because it needed a computer.ccould throw as much parts as you wanted at it but with a bad ecu nothing mattered. I got this car fairly cheap and the cost of the new ecu wouldn't hurt.

Does the ecu for sure control the tach?
 

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Discussion Starter #6 (Edited)
Car doesn't have a lazy tach, it works fine. It just started up the one day blowing a crap ton of smoke (won't lie I beat the crap out of it before it got turned off, then sat for 2 weeks, hasn't smoked since either). It was running extremely rough, 5 or 4 cylinders, tach was jumping from 1600 to 300 but the engine wasnt. The smoke couldve been from it not fireing on all cylinders, not worried yet. Its a 3rd car and a 3rd toy. After a couple seconds it all calmed down and idled fine.

Just trying to decide if its worth it to go with the chrome ECU this time around. It will need tuning sooner or later. I guess once I finally get it titled in my name and new tires and am driving it more I can see how it does.

Btw F this new site on android.
 

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Discussion Starter #7

So there's a video. No idea what that noise was at the very beginning, maybe my car port rattling? Wasn't the car. No smoke or anything this time but you can see the tach randomly going up and down. Lifter tick sounds like hell in that vid lol, it goes away when warm.
 

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The ECU could do it, could be a bad tach as well, could be a wiring issue in the harness, etc.
 

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Have you looked at the capacitors ON THE TACH ITSELF like previously mentioned? The tach on the VR4 is spun by a tiny electric motor, so if you had a leaking but still partially functioning capacitor it would cause a voltage loss and an erratic needle as voltage to the motor varied. Pull your gauge cluster and take a look, you might just save yourself $850 on a Jester ECU. You'll have to pull hard on the trip reset to get it to come off so you can remove the front plastic.
 

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Did you find the issue? that's a really HIGH idle lol. Mine did the same thing and I simply changed out the Idle sensor, for 40 bucks, solved my issue ;-)
 

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Discussion Starter #14
I borrowed a used coil pack to try and everything seemed normal, but I went to start the car saturday and it was cold, ~20º. Once again the top coil pack saw no spark. Usually once the car warmed up or shortly after start up the coil would start working again, this time it doesnt seem to want to work. Im leaning towards PTU, found one for $200 but unsure if I want to take the gamble, or I can send my ECU in to get looked at for about half that. I think this weekend ill take the coil back off and look into the PTU to see if its a loose connection or maybe I need some contact cleaner. Not sure how else to diagnose a bad PTU, but I do remember reading a post recently about on and off symptoms like this before the ptu went bad.
 

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1991 VR4
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Yes, intermittent dropping of a coil can indicate a failing PTU. You can bench test the PTU with a multi meter, i thinkt the instructions are on stealth316. You need to make sure you do this when it is not working though, or else it will test fine. When my PTU was failing, i also got a CEL. The CEL would disappear when it started working again.

Also, 200$ for a PTU? that seems crazy, you can probably get a good used working one on here for cheaper. Also, i know people usually hate on non OEM PTU, but i have been running one from autozone for probably 8 years with no issues.
 

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Discussion Starter #17
Yes, intermittent dropping of a coil can indicate a failing PTU. You can bench test the PTU with a multi meter, i thinkt the instructions are on stealth316. You need to make sure you do this when it is not working though, or else it will test fine. When my PTU was failing, i also got a CEL. The CEL would disappear when it started working again.

Also, 200$ for a PTU? that seems crazy, you can probably get a good used working one on here for cheaper. Also, i know people usually hate on non OEM PTU, but i have been running one from autozone for probably 8 years with no issues.
Yea I get the cel that comes on and goes away. I was going to go OEM, wonder how the quality is on the non oem ones now?
 

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OEM will always be better i think. Like i said, no issues on non-OEM from mine for the past 8 years or so. This was from autozone, not from amazon, which may or may not be better quality?
 

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Discussion Starter #19 (Edited)
It showed up and me in all my glory bought the wrong part. I got one that was 3 pin instead of 9 pin, possibly for a sohc car? I dunno, this pandemic is causing me lots of errors. But I ripped the car apart to inspect it anyways to check it out and found the 3 pin plug is missing a clip, so then I looked into the fuel injectors to see if I could steal a clip (easier to replace one there) and found none of my injectors have clips on them. Doubtful they are the same style clip, anyone know?

I was also going to put some Napa silglyde on the shifter bushings to see if it helped but then saw the snap ring thing and gave up lol. Just wasn't feeling it today.

Another member is looking to see if he has a ptu I can try, it looks like I need some injector clips too.
 

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1993 3000GT VR4
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I may have all those injector clips (same style but smaller than the PTU clip) and the PTU clip. I also have a used non-OEM PTU (worked perfectly when I removed it when installing the Haltech ECU and COP setup).
 
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