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Discussion Starter · #1 ·
Cars a 1990 AWD that we've owned since new. Stock with a newer motor as of 2 years back. It was out driving the other day and after running warmed up for a bit it cut out. I ran my TMO logger on the car and found no error codes or problems.

Thinking about all the issues these older ECUs have with leaky caps I swapped out the computer in the car with another 90 unit that I have here (we have a bunch of DSMs). Sure enough after the car was fully warmed up it cut out again just as it did before.

The car will RUN FINE when its cold or when started after its been off for a while. Once it gets up to a normal temperature and all it will cut out and will NOT restart. Tow it home or let it sit and it will fire back up fine later on.

I swapped the computer with another perfect unit, nope nothing at all

I was thinking ignition like coilpack or ignitor but why would it be fine and run perfect one second and not the next? Injector resistor? (but ive never seen these go out and again why work 1 second and not the next)...

Is there a small computer chip/box by the ECU just for the MPI controls? I am not all that familiar with these being a problem but I am stabbing in the dark trying to figure this out.

The only other out there idea is a problem with the coolant temp sensor but that should pull a CEL and may just not run right.

Any ideas would be helpful. Thanks!
 

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Discussion Starter · #3 ·
Yes I agree, Ive only seen coolant temp sensors being a problem with cold starts in the past.

The fuel pump relay, is this a part that could act up only after running for some time/heated up? I may swap it out but I have yet to see one be a problem with all the DSMs ive had.

Thanks for your input!
 

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Its the main relay, starter relay, or fuel pump relay. What happens to these relays are when they get old, the sotter inside gets old. When the relay is cold the sotter contracts and is together. When the relay heats up the sotter expands leave "dead zones" where the cracks are. I've had so many hondas come in with this same problem, its ALWAYS the main relay. I take it apart, resotter all the joints, and put them back and there as good as new.
 

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Discussion Starter · #5 ·
Thank you! Funny you mention that... I have a main relay here on the shelf that I bought for an older accord I had cuz they act up a lot.

I know where the one relay is by the ECU, where are the other 2 relays? The car is old, its a 90 with 250-275k on it so that could very very well be the problem. And it sounds JUST like the problem the honda I had was having...cant believe I forgot about it and all tho.

Thanks for your help!
 

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Hotimportcrx said:
Its the main relay, starter relay, or fuel pump relay. What happens to these relays are when they get old, the sotter inside gets old. When the relay is cold the sotter contracts and is together. When the relay heats up the sotter expands leave "dead zones" where the cracks are. I've had so many hondas come in with this same problem, its ALWAYS the main relay. I take it apart, resotter all the joints, and put them back and there as good as new.
I am glad that you know that a Mitsubishi/Chrysler product has the same exact problem as a Honda. Also you might want to look into rule #7, solder is pretty easy to spell, just sound it out, hell there isn't even a t in the word. IF you want to know the truth, I've only had to replace one of these relay's in many many cars, and it was because someone did a hack job on the wiring.
 

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Sorry, i type a mile a minute while im at work and sometimes misspell things. Anyways, it has nothing to do with the engine bay at all. When the relay is being used the solder heats up, creates this little dead zones, and well you turn the car off, the solder cools and contracts back to its original size with no dead zones. Then the relay works like new. Anyone who has a minor backround in electronics should know that. Btw, who said anything about the engine bay? The problem is a relay 100 percent guarenteed.
 

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I have ALOT of electronics background, and more background with these cars than you can even imagine. The solder points would heat up instantly if this were the case, it doesn't take 5 minutes for that to happen. And if they were heating up that high, chances are that it would just melt the solder. There are MANY other reasons as to why this could happen.
 

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Im not doubting your intelligence. You sound like a smart guy, i'm just saying based on my personal expierences and knowledge i'd go with the relay.
 

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The guy says that it happens when the car reaches normal operating temp's. How does this have anything to do with a relay under the dash? The relay has no coolant going thru it, there is no heat from the engine compartment. The relay will reach it's max temp within seconds of it being actuated.
 

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It has nothing to do with heat from the engine compartment. By the time the car fully warms up, is about the same time it take for solder to expand. After he shuts it off, it wont start. He lets it cool down, it contracted already, its starts. I've seen this a million times.
 

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Discussion Starter · #14 ·
I am going to swap out the relay with one from one of the other talons. Honestly this is soo common on the older accords (like one I had) I cant even believe I forgot about it.

Again it runs great, flawless actually... drive it or let it sit for 15 min and it cuts off. WONT start or even sound like its trying to (like no fuel or no spark at all). Let it sit for a while and it cranks up, turns on like it should, perfectly.

The relay your talking about, do you mean the one by the ECU for the pump? or is there one under the steering wheel dash area like my honda was? I am not familiar with there being multiple ones and I have to locate my manual... I am by no means new to these cars, had this one since 90 just never had to deal with a relay issue before.

Thanks!
 

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Discussion Starter · #15 ·
I am going to end the debate altogether... I swapped out the main relay for the fuel and it did nothing. I toyed with the logger and found the pump still worked after the car was cutting out.

I then found it was getting no spark, swapped out the coil pack, nothing...
The igniter did the trick used the one from my other car on it and it kept running even after the other original one in the car cut out.

I didn't consider the igniter since it ran great and then only cut out when it got warmed up. From the many cars I've had and seen its usually been a situation where they either work or don't work, not that they work until a specific point and then cut out. Plus I didn't have a spare available at the time so once I had the other car around I just spent some time late last night trying a few components to see what would do it.

I appreciate your guys insight and ideas, I am just glad at this point to have the car running! Thanks again
 

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Hotimportcrx said:
i guarentee when the car wont start, you cant hear the fuel pump prime when the key is switched to 2.
EHHHHHHHH, once again, i will tell you that you are wrong about this, the fuel pump doesn't prime anyways when you turn the key, only when cranking.
 
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