Smeg

Hi,

I tried re-starting the car after a 10 minute shopping spree, and all I got from the car was backfires in the intake, and pinging (knocking), like the timing was shot. I had just driven for 20 mins, and everything was fine. Its very difficult after starting the engine to keep it running, it seems to run if you put your foot down, roughly, and it still pings, and when you take your foot off it backfires splutters and dies. I have searched this forum and all I can deduce is that it MAY be the ingnition module, or it MAY be the AIC.

Has anyone had a problem like this (Duh!) and what did you do to solve it?

TIA.

Smeg.
United Kingdom.

BTW, 89 GTA, 5.7 TPI. Stock. (I think).

Smeg

Anyone???

Vader

Smeg,

Yes, I've had this problem. In my case it was a timing chain.

Check the base ignition timing. That should be your first clue to the problem.

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Later,
Vader
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JOHN/88IROCZ

YOU MAY WANT TO CHECK THE TROUBLE CODES ALSO

tpi_roc

A very VERY lean condition is also possible.

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Smeg

Well, I did check to see if there were any SES codes, only a 12 so thats OK. I dont think it actually IS the timing, well its certainly not mechanical, unlikely to be electrical unless the dizzy slipped round (It didnt).

My conclusion at the moment is that its either Vacuum leakage (Is the vacuum responsible for the advance???) (remember it runs fairly well if you rev the engine high) or its the ignition module.

Any more ideas???

TIA
smeg.

Smeg

Well its been 2 weeks, and I still havent got my car fixed.

The timing chain has been replaced (it was worn but not broken), and so has the pickup coil and ignition module.

Now, the car starts and runs fine for about 30 minutes, then the original problem restarts, ie. backfiring into the intake etc. It seems like it gets worse the warmer the engine gets.

Does anyone have any more ideas???

Please help.

Smeg.

akema

I had similar problems with my -89 Camaro RS after it was not used about 4 months. I think problem was related to water in fuel because after i added new fuel to tank and drove around 30 minutes, everything was ok.
Same thing happened couple of times this summer when fuel level in tank was really low, so i think there must be still some water in my fuel tank. Hope this helps...

Smeg

Well guys, the problem has been found... The MAF. The MAF was tried on another working GTA, and it developed the same problem.
I cant believe that the ECU didnt post a code, and also im shocked that no-one on here knew what it was either...

Grim Reaper

That is probably why no one mentioned it, because a faulty MAF will throw a code.

However, as for no one "getting it", that is to be expected when you don't have Scan Tool information. To have "suggested" the MAF without a code would have been "guessing". You might as well have changed ALL sensors then, because ANY OF THEM can cause the same problem if they are "flakey".

With a scan tool, you MAY be able to see a flakey sensor if it is giving readings outside it's normal operating range. But flakey sensors are tricky and require a knowledge of their normal operating range and their current operating range. The ECM only throws a code when the sensor gives REALLY erroneous readings based on some preset values.

Often these preset values are very broad and will allow "less than perfect" sensor to still go undetected by the ECM. Only a sharp person with a scan tool can see if those readings seem a "little off". And even then, it is a bit of guess, but an educated one.

Smeg

Thanks, that was quite interesting. I think I will certainly look into an i/f of some sort for the laptop and start taking some readings, so that if/when similar problems arise in the future, I will have some "normal" data, ie - a starting point for diagnosis. Cheers.