Possessed ECU?

[Forrest]

Hello all, I'm a long time lurker, first time poster.

I have a 2001 Protegé ES with an odd problem... The ECU seems possessed. I'll list what I've observed.

- The seat belt reminder chime dings for 1-2 seconds every 5 minutes. This happens randomly when the car is sitting in the drive way. Sometimes it goes for hours, sometimes 30 minutes. This is unrelated to weather.

- The CEL comes one randomly. I'll reset it and it'll go for weeks before coming on. Sometimes it flashes. There is no performance problems when this happens. Once the CEL came on and then turned off a minute afterward (is this even possible???).

- 2 of the coils stopped operating once for several miles (right in front of the mechanics place). The mechanic pulled the code and said the coils were bad. When the car was started the coils were fine again (and still are after many months).

The only hint I have is that the battery was hooked up backwards several years ago. The dealer fixed it, but could that've created a fuss in the ECU? Do any of you guys have any ideas what's going on here? I've reset the ECU so many times but it just randomly pops up a CEL still. The car runs great and has no modifications.

EDIT: (10/04/04) The car is a 2000 Protegé 1.8! Long story, sorry about that. :(

[pdhaudio83]

1) it could be your seat belt sensor is shot. my sisters is in her 92 pro and does the same thing
2) if your CEL flashes, that is NOT GOOD. Who did you buy your car from? First thing that comes to my mind is FLOODING damage.
3) if the battery was hooked up backwards, your battery should have had to be replaced. (it should have fucked it up, if not exploded)
4) i've only heard of a bad ECU in domestic cars. However, maybe you did fuck it up with the battery, but then i'd expect it to not even run at ALL!

[Forrest]

1) it could be your seat belt sensor is shot. my sisters is in her 92 pro and does the same thing
Why would the seat belt minder go off when there's no key in the ignition? I don't think the sensor could go past the key/ignition part but I'll check.


2) if your CEL flashes, that is NOT GOOD. Who did you buy your car from? First thing that comes to my mind is FLOODING damage.
Yes it rarely flashes but performance is fine and when reset it doesn't come back until a month later. The car was purchased new from the dealer and, to the best of my knowledge, has never been flooded. I assume you mean in the interior?


3) if the battery was hooked up backwards, your battery should have had to be replaced. (it should have fucked it up, if not exploded)
4) i've only heard of a bad ECU in domestic cars. However, maybe you did fuck it up with the battery, but then i'd expect it to not even run at ALL!
The battery thing was a serious F'up but the battery didn't blow. The car was towed to the dealer and the dealer fixed it. The car operated fine after that (maybe).

I think that if the ECU was screwed up it just wouldn't work at all. What's weird is the seemingly random events that occur with the car. The mechanic just thinks we're crazy when we mention it.

[flat_black]

Replace those coils, most likely; They're probably flaking out with age. Also, instead of resetting the ECU every time you get a CEL, pull it, and find out what it means. Autozone does this for free, and it'll allow you to diagnose the problem. It's there to help you, not to hinder you! =)

[Forrest]

The car is 3 years old and it needs O2, coils, seat belt sensor, etc.? Was 2001 a real shitty year for Protegé's or something? I have a 626 that's 10 years older that's only had a replaced clutch. Maybe I'm in denial but I just can't believe these problems could occur on a 3 year old vehicle. :(

If I fix all the "reported" ECU errors I'm going to be going well over a grand in repairs. I somehow have a problem with this when the car operates fine and the CEL is usually off. Wouldn't a real problem trigger the CEL all the time?

[flat_black]

I bet everything, as far as the engine, is related in one way or another... For example, the coils flaking would make the mixture highly rich, which could cause the spark plugs to foul, then to arc, which causes the coils to work intermittantly, then that fouls the O2 sensor by overheating/excess carbon on the filiments... That would be the most likely situation, I'd think.

[Forrest]

I bet everything, as far as the engine, is related in one way or another... For example, the coils flaking would make the mixture highly rich, which could cause the spark plugs to foul, then to arc, which causes the coils to work intermittantly, then that fouls the O2 sensor by overheating/excess carbon on the filiments... That would be the most likely situation, I'd think.

Ok, maybe we're getting closer then. Thanks for your input flat_black.

The coil incident was a one time event that lasted for maybe 3 miles. This happened 2 months ago. The O2 sensor error (CEL code) has been on/off for the past year. The car was driven a bunch and it's well beyond warranty service... other wise this won't be an issue.

Why would the O2 sensor be bad but only once a month? Maybe it's a connection issue? I've removed most of the strain points in the cable and have inspected the harness. All appears fine. I'll through a tester on to be sure though.

[flat_black]

Testers won't do you any good, unfortunatly... The O2 sensor has to hit really high heat before it even reads anything... I've bench tested O2's with a torch before, which worked, but it's a long way to go. The O2 most likely is flaking out due to milage/age. How many miles does the car have on it? My guess is if the coils gave you problems, even once, they're worth replacing, as they're almost certainly not working properly, IE, not giving full spark, if they've flaked out once on you.

My idea on the O2 sensor becoming intermittant is distance driving... Your precat may just be totally hosed, and the error you're getting could be 'Secondary O2 sensor voltage low'. If that's the case, then the downstream O2 is reading out-of-sync with the upstream one (the one in the manifold portion of the exhaust).

If I were there, I'd offer to take a look at it for you, as it's easier than shooting in the dark, but those are my best guesses. =)

[Forrest]

The car has 78,000 miles on it.

I have another O2 sensor here that I was about ready to return. I'll try to track down a new connector body and install it. I'll also go ahead and order new coils.

I probably won't be able to get to this until the weekend but I'll reply with the results. Thanks guys for the help... I hope you're right. :)

[flat_black]

No problem at all; You'll want to make sure you're replacing the proper O2 sensor, too! There's two of them, one at the pipe right after the big, chunky precat which is right off of the manifold, and one in the manifold itself. One can be seen from under the car, the other from looking in the engine compartment.

[garretts77]

maybe you could try to get another ECU out of a similar car (wrecker) and swap it. If you still have the problems, then it isn't that...

just an idea...

[pdhaudio83]

very weird.

[flat_black]

Get an MP3 ECU if you're gonna get a replacement. ;) A little more zoom, but you'd have to fill up with 93 octane. Hehe.

[Forrest]

UPDATE: I replaced both coils ($27.99 each, including mount). A big thanks to the Rider Mazda (http://www.ridermazda.com) parts department in State College for rush shipping at no cost. The car seems fine so far. No CEL after 1 week and the engine doesn't hesitate or stutter anymore, although this was very very minor to begin with.

A small (or rather large) correction (braindead. The car is a 2000 Protegé 1.8, but it was manufactured about 1000 units after the recall VIN number range.

I still have no answer for the seat belt minder. I haven't heard it in over a month and I park the car under our bedroom window.

Thanks for all the help and suggestions guys. (drive)