History:

It started detonating about a year ago but I didnt realize what it was until about 6 monthes ago. You could only hear it if you didnt have the radio on. It also only did it when pulling off and with me driving it(I pull off alot faster) it wouldnt do it.

Well, I made a switch to premium and it went away. It went away and came back about a month later. I then checked the timing and it was set at 5* base timing, so I set it back to 0* and it went away again.

Then three weeks ago it started doing it again. I then changed the fuel filter(I dont know if its ever been done) and checked the timing and it was still good. Then I water injected it and didnt get any carbon deposits.

After all this it was still doing it, so I pulled codes and got a code 42. Which is a fault in ESC. Well th diagnostic chart tells me to clear codes and idle the car until the code sets again. Well it wont. Detonation is completly gone. I then washed the engine off because I had a little extra time and when I cut the car back on I had Lean O2 sensor code so I was like ****. I figure it was just because I got it wet because I let it dry and cleared codes and it didnt do it again. I talked to a GM tech today and he told me that if a code 42 is set that the ESC is "turned off" until the codes are claered. So you know I'm happy as **** now.

Well my girlfriend came over and said that it was doing it again. it is back to doing it when pulling off. I checked codes and it didnt set 43 again. WHAT THE ****!!!!????!!!!????. I'm thinking it might be the knock sensor because I couldnt get it to detect my fake knocking. But this would set a code right? They dont just go to sleep and never wake up do they??? Sorry this was so long!

 

You may want to check your manuals again on the base timing. I beleave its supposed to be like 8*, personally, mine runs better at 10*. Also, are you setting the timing with that little wire disconnected? Just checking. Try resetting the timing to 8-10* and see what happens, at least its free to try.

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Rob
'86 TA 305 TPI
Gutted MAF, Ported Plenum
TB Bypass, Home made Cold Air Intake,
Edelbrock T.E.S.

 

Maybe it could be an over stretched timing chain? How can I check this? It is supposed to be set at 0* and I did it with the wire disconnected(this is via the emmisions label and Chilton's).

[This message has been edited by LottaBallsCamaro (edited June 07, 2001).]

 

How many miles, what kind of engine?

 

0*? I'm not too familiar w/tpi engines, as i've never owned one , but when you reconnect the wire, does it change the timing back to 8* or so? I've neverheard of a car that runs BEST at 0.. maby for emmisions, but it will run much better being retarded a bit. chiltons knows alot(a helluva lot more than me), but they may not have the best answer for this

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• 83 Z28-- not a pretty site to look at, 200k miles and im sure it was treated like a rental car every day of its sad life(before i got it).. sold, thank the lord
• 74 Z28-- 383/400, green on black. pretty clean. FOR SALE!!!

 

hey guys the base timing is set at 6*,the factory didn't set it.the dealerships were supposed to set it but some of them didn't

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1987 Trans AM GTA
305 5SPD
Hypertech airfoil
gutted maf
kn filter
High Flow Cat,
3"Walker pipe
Dynomax Super turbo Muffler
TB Coolant bypass

"Three of the scariest letters you will ever see GTA"
Take a good look you won't see em for long

 

Its an LO3 with 150,000mi., and it is supposed to be set at 0*, sorry if I misled any of you. By the way, it is the only engine that they tell you to do that to.

[This message has been edited by LottaBallsCamaro (edited June 08, 2001).]

[This message has been edited by LottaBallsCamaro (edited June 08, 2001).]

 

First: yes, with over 150k, change that timing chain.

Second: I am looking through my chilton book now, you must have either a '90 vin E, or a '91/'92 vin F. Just double checkin, what year and vin do you have.

 

Its a VIN E. I put it on the scanner and the 02 sensor seems to be lazy. The knock sensor is also working. At idle, it read 8 IHG from the MAP. Is this low?? It seems to be, which would point to a vacuum leak.

 

Also, its a 1991