4g61t.org

Hello,

I am new here but have been searching the archives. I have been driving a 1.5L auto Colt GL for 4 years and am experiencing issues I can't solve.

Car has been running fine but recently started to have problems around town to the point where the car completely died and CE light appeared. It only happens occassionally but the event occurs quickly...first, no gas pedal response no matter how much I push the pedal, then engine stumbles/then stalls with CE light flicker. This happened a couple of times, but started up each time after I coasted to side of road and restarted. I didn't really smell anything and was always looking for signs of what may cause it but saw nothing.

Here is what I have done or have had done recently...plugs, wires, distributor, fuel filter, fuel pressure check, air filter and just recently a rebuilt ECU from ECM TO-GO (thanks to this forum!). Well, I thought the rebuilt ECU w/new caps would solve my issues but the car just did the same thing again over the weekend.

Any ideas are greatly appreciated. I love this car, it is clean and only has 88,000 miles so I'd like to keep it running.

Thank you.

Have you read the error codes stored in the ECU after a failure? Your Colt is probably not new enough for the OBDII readers to be of use, but there IS a way to read the codes - check a service manual or go down to a local auto store - they may read the values for you.

At 88K miles one of the sensors that feeds the ECU or one of the controls fed by the ECU may be faulty. The ECU error codes will point you in the right direction.

_________________
Phil Hutchinson
1986 G15B, 1986 G32B, 1988 G32B

There are instructions out there on the web on how to read error codes using an LED or a buzzer. I remember posting a how-to several times. Just do a search, I'm sure you'll find it.

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Got rabies?

I found the instructions and purchased an analog tester. No codes. However, I previously re-hooked up a rebuilt ECM and reconnected the battery (lost any codes) so I took the car for a long ride. The symptom appeared only periodically again and a little less drastic. When it happened, the throttle was not responsive when I would floor the gas to try to get it to act up. The car would bog down for an instant while I was pressing the throttle and not respond with any speed increase but no CEL and did not stall out. It acted like the car was running fine but then didn't know what to do when I began to floor the gas. Then, when I lifted, the car stuttered for a second (probably flooded from extra gas in the cylinders) and then drove fine. I got home and still no codes. My guess is a failing TPS but no codes yet.

Any thoughts? Also, if it is a TPS, are the ones at AutoZone, NAPA, etc. all the same?

Thank you for your help.

You can test the tps with your analog meter. There are three leads, one is a ground, one is constant 5 volt reference, and the other reads 0-5 volts depending on position.
I had to hack a old tps switch to make a pig-tail to get leads into. With power on, hook your leads to the ground and variable lead. Slowly move the throttle through the range and look for a smooth needle sweep. Any spikes or dips could indicate bad spots in the switch. You can also test for resistance in the same manner with the switch off the car. I dont remember the exact resistances but just look for dips and spikes.

_________________
http://members.cardomain.com/socrateez
04' Olds Alero
91' Colt GL hatchback
4g15 12valve 5spd.
4g37 TB, MAF & Injectors. 4g37 ECU
Ported & polished & custom CAI w/K&N filter
5* Cam retard, 7*Ignition advance
2-1/4" catback w/flowmaster muffler
89 GT brake and suspension swap
Lots of little s#@t

I tested the TPS plug end earlier today and the volt readings are good (around .5 with slight sweeps up with throttle input). That would say that the plug is good but can you test the TPS unit itself mounted on the TB? Do these often go bad after years/miles? I'm guessing that it might be the TPS at this point but am now sure enough to spend the $$ for a new one. Also, the problem is intermittent.

Thanks again.

i recently changed mine because i was getting a bad flat spot on acceleration. Turned out to be a bad spot in the tps. The resistance would go high on that one spot. The ECU thought it was back at idle position and momentarily cut fuel. Or so i surmise. Anyone else?

_________________
http://members.cardomain.com/socrateez
04' Olds Alero
91' Colt GL hatchback
4g15 12valve 5spd.
4g37 TB, MAF & Injectors. 4g37 ECU
Ported & polished & custom CAI w/K&N filter
5* Cam retard, 7*Ignition advance
2-1/4" catback w/flowmaster muffler
89 GT brake and suspension swap
Lots of little s#@t

see if this will help you out at all.
even though its says 1.8 its the same set up of 1.5 for testing the dist. housing.






when testing transistor do not use more than the 1.5 volts its says to use. damage to the transistor can occur.

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94 Mirage Project underway...

Socrateez - that sounds exactly what I am dealing with (flat spot where car cuts fuel momentarily on acceleration). I didn't notice a spike in resistance at any point but I didn't really spend a lot of time analyzing every RPM range. Sounds like it's worth it to spend the $$ on a new TPS. Is replacement as straight forward as it looks? Suggested preferences on where to buy?

91_LaserRS - thank you. I will spend some time closely looking at the diagrams. I recently had the distributor replaced but will take a closer look to see if it was done correctly.


This site is great. Thank you all for your help. I'll respond later in the week to let you know how it turns out.

sorry the pics are so big. not sure how that happen

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94 Mirage Project underway...

Heres another possibiltiy. When some of the caps in these ECU's fry, occasionally something else will get a little weird in the ECU.
My old boss used to send Mitsu ecu's to a friend who would repair them. Every once in awhile someone would return one that still would have problems. There have been a few people on the board that have had bad rebuilt ecu's.

_________________
http://members.cardomain.com/socrateez
04' Olds Alero
91' Colt GL hatchback
4g15 12valve 5spd.
4g37 TB, MAF & Injectors. 4g37 ECU
Ported & polished & custom CAI w/K&N filter
5* Cam retard, 7*Ignition advance
2-1/4" catback w/flowmaster muffler
89 GT brake and suspension swap
Lots of little s#@t

I went for a ride last night and car acted up to the point that CEL appeared (almost didn't make it home). Anyhow, I parked it, pulled codes and sure enough, it finally exhibited a code! #14...what's #14???...(to the manual)...#14 is TPS! ...aha! Now the car has validated my theory. New TPS going in this weekend.

I'm feeling relieved!

To add to the collective wisdom of this site: Failing TPS was intermittent with occassional throttle stumble over a period of a few weeks while gradually getting worse. Pushing the gas pedal had no effect as the car hesitated for a moment at speed and wanted to stall. As the TPS continued to fail, conditions worsened. Last night, the car came to a stop on the side of the road. I had to restart the car 3 times to go two blocks.

im a newb member to 461t, thanx 4 all the info .bought 89 dodge colt for 550$ last year ran good except for a slight accelaration stumble. i have all the same symptoms as 92gldaily. i just want to be sure, tps = throttle position sensor ? also some opinions on where to get a replacement ecu for cheap.

Dred - yes, TPS = throttle position sensor. I'm installing my new one this weekend.

From what I understand (still a bit of a newb), ECM/ECU's can usually be rebuilt for a lot less $$ than buying new. I recently had mine rebuilt at ECM TO-GO/Houston. My CAPS weren't yet fried. Do a search...lots of info on this site about that subject. If you still need a new ECM, I've seen them while searching for new TPS at autozone.com, and I think NAPA for around $300-$400 but do a search first.

uber thanx daily.ill reseach the ecm rebuild, local napa can order 1 for 279$.please post with results on your tps install,like to know how it works out.all the info is greatly appreiated.ill check the resistance this weekend,figure i should go ahead and test air flow sensor,injector coil,isc servo motor while im at it. cant hurt to put in a new fuel filter, at a 100$ will be the most expensive i ever bought.get parts this week do the install next weekend.