Hi everybody,

I have some problem with my Trans Am GTA 5.7 1988.

Car run perfect and the service engine light is off but as soon as the light came on (and it came on completely randomly) the car would go berserk and idle crappy, hesitate, backfire.... It is happening very often without any rules, but I can say that it is very rare when engine is o normal operating temperature. I tried to pull ecm codes, but with no success, SES lamp is always on without flashing. Gas mileage is very poor, about 10mpg in city, terrible

Please help

Thank You all in advance,
best regards,

Nenad!

 

Should hold a code. Take to auto parts house and have them scan car for free.

 

Problem is because I'm from Europe (Serbia) and nobody know anything about old USA cars

There is no flashig code at all, SES light is on all the time when I connect AB terminals on ALDL.

 

that may be normal.. I dont know.

Normal CE light function is key on-engine off CE blinks once then solid on. when car starts it turns off.

It should be holding a code? to clear code disconnect battery terminal for a minute and then reconnect. start car. If CE is on constant it should hold a code.

 

In my case, CE light function is key on-engine off, CE is solid. Sometimes blinks without any order (one blink than solid, and after few seconds again one ore two blinks, sometimes it's non-stop solid, there are no rules).

 

I actually work at an autozone in ga, we can't pull codes on cars that old which sucks because my 88 pontiac lemans is doing someting similar, well we carry for store use are the OBD-2 readers and the cheap ones at that lol, we do sell the obd1 but they won't let me just borrow one... kinda sucks i know

 

http://winaldl.joby.se/aldlscreen.htm

about 1/2 way down is error codes. this website will also instruct you as to how to build aldl cable.

may tell you what issues are now and if ever in future. good to own.

 

This morning I could't start engine at all Engine starts, but for 1-2 seconds, and turn off. There is strong gas/petrol smell and smoke from exhaust. SES light is on all of the time

 

If you cannot pull codes you may need to take ECU and or sensors in for diagnostic test. Any facilities near you that run check that out?

 

No , I'll get one ECM which is OK in another few days to try it and see if it's reason for bad engine work. Anyway, I'll inform you here

 

check your 02 sensors and all your plugs. Also check for Vaccuum leaks as well as your grounds.

 

O2 sensor, all sparks and spark wires are brand new, but I'll check them again. Vacuum leaks and grounds I didn't check, but I will too

 

I just tried new ECM and everything is the same I can't start the engine no more. This is real nightmare...

 

Before you waste more time and money, and end up raging on this site calling your car a POS like so many other forum users have, take it to a mechanic who knows what he is doing.

 

This is almost impossible in my country

 

It's unlikely that your trouble is being caused by the ECM. It sounds more like you're losing spark(strong gas smell from exhaust). Check for spark using a spark tester. If no spark, check for injector pulse using a noid light(this will verify whether the problem is in the crank referrence circuit or in the coil or coil drive circuit). If you have no spark or injector pulse - test the pick up coil, located under the rotor in the distributor(green and white wire to the back of the ignition module), using an ohmmeter. It should test at 800-1000 ohms. If not, replace the pick up coil. The pick up coil is difficult to replace and requires disassembly of the distributor and replacement of a special retainer. It may be easier to find a quality replacement distributor. If the pick up coil tests good, remove the ignition module for testing at your local parts store.

If you have injector pulse and no spark, carefully check wiring between your distributor and ignition coil. The fuel pooling in your exhaust likely means that your injectors are firing while your ignition is not. This would seem to indicate that your ECM is receiving crank referrence pulses from your distributor but that either your ignition coil is bad or it is not being fired by the ignition module. This type of ignition module failure is common, so is ignition coil failure. Also, on this age of car, wiring problems are a fair likelihood.

Check spark using a spark tester, if no spark and all wiring looks good, use a test light to check for power at the large pink wire of the coil connector, with the key on. If you have power there, test the ignition coil using an ohmmeter. Any service manual should have details on testing the coil. I won't try to explain the process here. If the coil tests good, remove the ignition module from the distributor and take it in for testing at your local parts store.

Your ECM may be flashing codes and you don't recognize it. Trouble is, now that you've disconnected power from it, the codes will be gone. You'll have to run it or at least try to start it a few more times to see if the code(s) will set again. If there is a hard failure, it should come right back.

When A&B are connected, the CEL will turn on solid for a few seconds then turn off, then codes will begin to flash. Code 12 is first, telling you that the ECM is diagnostic mode. Code 12 will repeat 3 times. Then any code(s) stored in memory will follow, each one repeating 3 times. Long flashes are tens, short flashes are ones. You may have to repeat the cycle a few times to verify code numbers.

 

Thank You for detail answer Problem is that I couldn't see any code when connect A&B, Check engine lamp turn on solid and stay all the time solid. Anyway, I contact my electrician and he will come to me on saturday to check everything he can. I have GM Service Manual and he will check everything by testing procedure, so I hope he'll solve this problem. I'll print your message too, and check everything as You said.
Thank You again, I'll inform you what will happened.
Best regards!

 

Just to inform you that problem is solved

First problem with engine start was because of bad ignition coil, and after that, I put ECM which user whitedevilTA gave me instead of mine and everything works fine. There are no bad codes, I can read code 12, engine is working perfect