420A Pretty sure my ECM is dead...

[Dalton63841]

I have a 1995 Talon 420A 5 speed. (Yea, I know, should've gotten a 4G63) I've searchedon multiple forums and google and frankly I'm tearing my hair out because symptoms are weird, but I think it's a dead ECM.

So last night, I drove to the store, and she drove like a brand new car, as usual... Then when I got back into the car to leave, I was stuck in a "crank but no start" situation... When I turned the key on, the tach went crazy jumping around, and a few random dash lights blinked. After a while I was able to get it started by padding the gas pedal and limping it home, doing my best to keep the RPM's up or she would die. Today, I checked out electrical connections, cleared off corrosion, and reset the ECU by leaving the battery terminals off for about 30 minutes. After that she drove great for about 20 minutes, but then the CEL came on, and she died. Now, any time the key is in the switch, the tach jumps all over the place, but the CEL does not come on with the key(my clue about the ECM), and she won't start.

Sorry it's a bit wordy, but I want to be thorough, as anything might be the clue to the answer.

EDIT: Just remembered another small thing, but should the ECU be getting VERY hot? Not engine hot, but surprisingly hot.

 

[wolf alchemy]

Well your not getting any attention so I could help though I'm not the best. To my knowledge. No. The ecu should not be hot. My suggestion would be to remove it and check the caps.

 

[wolf alchemy]

Should you feel anything is odd post a picture of the ecu.

 

[luv2rallye]

ECU should not be getting hot. I agree pull it and look inside.
You also can determine the CEL code by doing the key dance: http://www.2gnt.com/index.php?d=PCM Error Codes

 

[Dalton63841]

My ECM is the one where the insides are encased in the silicone type material, so I can't really check anything out. I did the key dance. I did notice that after sitting all night, my CEL comes on with the key now.

In any case I'm not sure what the key dance is reading... The light stays on for a few seconds, off, flashes 3 times, off, then flashes 5 and 5. The closest on the list I can see is 13, for a dead MAP sensor, if I assume that the first few seconds of staying on counts as a 1. I don't think the MAP sensor would account for my odd symptoms though...

 

[wolf alchemy]

Well still. Even if incased in silicone. If you can open it and look at the silicone. It might hold a answer. Especially if it's getting hot.

 

[wolf alchemy]

Not sure if you mean sealed, or everything is coated.

 

[Dalton63841]

Not sure if you mean sealed, or everything is coated.

This evening(109 heat index right now) I will go ahead and pull the ECU to take a look. I already replaced it once about a year ago, and when I opened that one up, it just looks like a brick of dark colored silicone inside.

 

[wolf alchemy]

I'd die in that heat......good luck solider. Post results and hopefully we'll be able to figure this out or someone will come along with more information on this subject.

 

[Dalton63841]

I'd die in that heat......good luck solider. Post results and hopefully we'll be able to figure this out or someone will come along with more information on this subject.

Yea you're telling me! I just recently finished an oil and trans fluid change on this thing.(BTW ATF +4 in a stick felt weird!)

I went ahead and pulled my ECU to check it out. It's under the hood and held in by 3 bolts, so it only took a minute. Here is what I was talking about. Nothing to see or do inside there...

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

 

[wolf alchemy]

Is the bottom left wet, or softer than the rest?

 

[wolf alchemy]

I also see rust, so provided the rust didn't get through the silicone that could be ruled out I guess.

 

[Dalton63841]

Is the bottom left wet, or softer than the rest?

No it's all pretty much identical all the way through.

Okay, It should be noted that today it also started up and ran again, so it seems somewhat intermittent... If it were the ECU, I don't think I'd be getting any starts.

What is the likelihood of the crankshaft sensor? The symptoms seem reminiscent of it, but would it cause the erratic tachometer? If I understand, the tach signal comes from that sensor, but usually it just makes the tach do nothing.

 

[wolf alchemy]

No idea there.

 

[o0GuitarKid0o]

When I had a ecu go out on me I think I had a check engine light for like 10 codes, so I said f#$k it and bought a new one ,

with the old ecu the car had issues starting and when it ran it would not run nicely this is my experience from a 6 bolt 4g63 ecu

It did have a faulty coolent temp sensor and a bad injector but I know for a fact that my cars maf was fine and all the other codes that came up were wrongly coming up,
let's just say a new ecu fixed those issues so it wouldn't hurt to borrow one or get one from a wrecker that allows returns if the ecu turns out to be fine ,

check the ecu connectors and make sure the little prong things are not pushed back to where it will cause no contact on certain pins

 

[Dalton63841]

​

When I had a ecu go out on me I think I had a check engine light for like 10 codes, so I said f#$k it and bought a new one ,

with the old ecu the car had issues starting and when it ran it would not run nicely this is my experience from a 6 bolt 4g63 ecu

It did have a faulty coolent temp sensor and a bad injector but I know for a fact that my cars maf was fine and all the other codes that came up were wrongly coming up,
let's just say a new ecu fixed those issues so it wouldn't hurt to borrow one or get one from a wrecker that allows returns if the ecu turns out to be fine ,

check the ecu connectors and make sure the little prong things are not pushed back to where it will cause no contact on certain pins

I WISH I could get parts that easily. I live in the heart of nothing, USA. All the pins look good. Is the ECU capable of a failure that is temperature dependent? When it was acting up, the ECU was VERY hot, but when I let it cool off completely, I can get it to start and run.

 

[o0GuitarKid0o]

​

I WISH I could get parts that easily. I live in the heart of nothing, USA. All the pins look good. Is the ECU capable of a failure that is temperature dependent? When it was acting up, the ECU was VERY hot, but when I let it cool off completely, I can get it to start and run.

How hot was it? Did it burn you? Since the ecu is in the engine bay I guess it could get a bit hot , any smells? Burnt wires ect..? Did your car over heat?

And I'm not exactly sure it's possible that you melted a soldier joint

On a unrelated note I once fixed a ps3 that had bad soldier joints by useing a heat gun on the motherboard that fixed the issue with a ps3 but yours seems to be the opposite I'd get the multimeter out if I was you id start tracing wires, metal contracts when cold and expands when hot so I'm not really sure what could be causeing your issue , it always starts on cold starts? What happens when you let it run will it start again? I no a crank shaft sensor causes no starts

 

[luv2rallye]

Okay, It should be noted that today it also started up and ran again, so it seems somewhat intermittent... If it were the ECU, I don't think I'd be getting any starts.

What is the likelihood of the crankshaft sensor? The symptoms seem reminiscent of it, but would it cause the erratic tachometer? If I understand, the tach signal comes from that sensor, but usually it just makes the tach do nothing.

It sounds like the ECU (aka Powertrain Control Module on 2g NT) is the #1 suspect to me. Yes, components on the ECU board can have temperature dependent failures.
The tach signal is derived from the CPS, but the ECU (pin 73) drives the tach.
The ECU should not be heating up excessively. If it does, almost anything can happen (including producing false CELs). Try when the engine is cold blowing on the ECU with a hairdryer or heat gun to see if it brings out the failure. Also if you can borrow another ECU try that.

 

[Dalton63841]

The ECU was uncomfortable to keep my calloused hand on more than like 3 seconds. After it's completely cooled off, it will start and die once, and then start and run fine. I wish there was a way to get ahold of a PCM to test, but I will have to order one online IF I can find one at all.

 

[wolf alchemy]

I'm glad someone with more knowledge showed up. I was running out of help. XD

 

[Dalton63841]

I'm glad someone with more knowledge showed up. I was running out of help. XD

There's about a 99% chance she's going back to the shop that replaced the PCM before. I just prefer to fix myself if I can, and any help toward that is appreciated.

EDIT: After having my ECU off the car, I noticed when I put the positive battery terminal back in place that even tightened down completely it will pop off if you wiggle it. I DOUBT I'm this lucky, but I made a shim and got the terminal nice and tight. For the moment, it's running nicely, but my car has been off all day so, can't really say anything at this time.

 

[o0GuitarKid0o]

There's about a 99% chance she's going back to the shop that replaced the PCM before. I just prefer to fix myself if I can, and any help toward that is appreciated.

EDIT: After having my ECU off the car, I noticed when I put the positive battery terminal back in place that even tightened down completely it will pop off if you wiggle it. I DOUBT I'm this lucky, but I made a shim and got the terminal nice and tight. For the moment, it's running nicely, but my car has been off all day so, can't really say anything at this time.

I bet your right acually I got stranded at the bank about 2 weeks ago , wanna no what happend? I hit a bump turned my car off came back to a no start. After getting a boost and driveing it home I quickly start to diagnoseing what the heck happend,

First thing I suspected was my battery so I grabed my other battery and boosted it again cause it wouldn't crank it starts then dies after it idles for a bit,

well I end up removeing my command start because my locks were being funny , I checked out my starter relay, took alot of damn relays out to check them because my fans were staying on ,

well then I grab the battery tester and holy crap ! 109 cold cranking amps! My battery was fully charged! So I end up buying a new battery and guess what my battery I brought in to get test got 650 CCA I was like what?? I just tested it at 109! We even load tested it An retested and got 650

Well after 5 hrs of hell I go to tighten the new battery up , and the car wouldn't start! I was like fuk

, wanna no why I got 109 CCA ? My DAMN battery connectors were so shot that you couldn't tighten it any more ! And I tested my battery in car but with the bad connection it was only getting 109 CCA , all in all I wasted 5 hrs to realize my connectors were done. And the reason my car was fine with a boost was because I connected the booster cables to my battery connectors and then ran off my alternator till I got home !
I replaced the connectors and no problems since , I learnt my lesson for over thinking stuff that's for sure

 

[Dalton63841]

I bet your right acually I got stranded at the bank about 2 weeks ago , wanna no what happend? I hit a bump turned my car off came back to a no start. After getting a boost and driveing it home I quickly start to diagnoseing what the heck happend,

First thing I suspected was my battery so I grabed my other battery and boosted it again cause it wouldn't crank it starts then dies after it idles for a bit,

well I end up removeing my command start because my locks were being funny , I checked out my starter relay, took alot of damn relays out to check them because my fans were staying on ,

well then I grab the battery tester and holy crap ! 109 cold cranking amps! My battery was fully charged! So I end up buying a new battery and guess what my battery I brought in to get test got 650 CCA I was like what?? I just tested it at 109! We even load tested it An retested and got 650

Well after 5 hrs of hell I go to tighten the new battery up , and the car wouldn't start! I was like fuk

, wanna no why I got 109 CCA ? My DAMN battery connectors were so shot that you couldn't tighten it any more ! And I tested my battery in car but with the bad connection it was only getting 109 CCA , all in all I wasted 5 hrs to realize my connectors were done. And the reason my car was fine with a boost was because I connected the booster cables to my battery connectors and then ran off my alternator till I got home !
I replaced the connectors and no problems since , I learnt my lesson for over thinking stuff that's for sure

It would be great if that is all it is, but at the same time, for my nerves to be SOOO frayed over something so simple would be very annoying. Just out of curiosity, I did the key dance again. This time all I got was a 12(power cut to ECU within last 50 key turns), which makes since, considering the ECU was removed.

 

[o0GuitarKid0o]

It would be great if that is all it is, but at the same time, for my nerves to be SOOO frayed over something so simple would be very annoying. Just out of curiosity, I did the key dance again. This time all I got was a 12(power cut to ECU within last 50 key turns), which makes since, considering the ECU was removed.

Yeah don't stress , go for a drive till operating temp and keep driveing (in your area just in case) see how long it idles , turn it off let it sit start it let it run, turn it off start it ect if there's already an improvement than your prob lucky ! Go buy some new battery connectors get the right ones tho I got the wrong ones at first

 

[Dalton63841]

Yeah don't stress , go for a drive till operating temp and keep driveing (in your area just in case) see how long it idles , turn it off let it sit start it let it run, turn it off start it ect if there's already an improvement than your prob lucky ! Go buy some new battery connectors get the right ones tho I got the wrong ones at first

So this morning I took it for a small drive, about 10 minutes. It got well up to operating temp, and ran perfectly, but now it did a new thing... When I pulled it back into the drive and brought it to a stop, the car was idling at 2100rpm. I goosed it a little, and then it continued at 2100. After shutting the car off and restarting though, she idles normally again.