I changed the spark plug, cap-rotor and adjust the timing to 8* and i fill my car with 87 octane fuel. Is it normal that my car have detonation most all of the time when hard acceleration??? I seen that the pinging increase when the heat is around 220 deg.

What is the cause of the problem??? I project to use tko cleaner for the plenum.

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trans-am 91 3.08 posi 5.0 lb9 5 speed stock

 

sounds like you have built up carbon. also did you try 92-93 gas

 

Yes, without success! The tko cleaner is it good to remove carbon?

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trans-am 91 3.08 posi 5.0 lb9 5 speed stock

 

up

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trans-am 91 3.08 posi 5.0 lb9 5 speed stock

 

You advanced the timing, are running the stock temperature fan switches and thermostat and are using 87 octane fuel. You will get detonation with full throttle application. Run 92 octane fuel or put the timing back to 6 degrees. Even with stock timing, you might still have detonation with 87 octane fuel. 87 octane fuel has a low resistance to detonation, you should be using a higher grade of fuel.

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1988 Formula 5L/5sp 3.45 gears, SLP cold air kit, MAS gutted, TPIS air foil, TPIS AFPR, MAC headers, Mac under drive pulleys, MAC cat back, Relocated MAT.
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I agree, retard the timing a little, use 92 octane fuel and put in a lower temperature fan switch and thermostat. That should clear up the problem, and if not you may need some GM top engine cleaner.

 

Is it very bad for the engine the pinging???

Its a very lite pinging almost time.


Thanks for reply

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trans-am 91 3.08 posi 5.0 lb9 5 speed stock

 

Yes. If it's bad enough you can seriously damage the engine. Just barely noticeable autoignition every now and then shouldn't hurt anything, but it doesn't help anything either and I would get it fixed ASAP if you notice it at all. I'm wondering if your knock sensor is working too. Just my $0.02.

 

Yes, detonation/ping is bad. Pre-ignition detonation happens when during the compression stroke, the air/fuel mixture ignites before the spark and before the compression stroke is complete. This happens when the cyclinder top is excessively hot. When this happens, it causes the cyclinder to have to complete the compression stroke against the explosion of the air/fuel mixture, causing a great amount of stress on the piston, rods, bearings.
If not corrected, it can lead to a burned piston, and loose rod bearings.
The main cause of this, too much timing.
Other causes, too hot of a spark plug, plugs gapped incorrectly, not enough fuel (lean), or not good quality of fuel.
*
Reduce timing to the recommended 6 degrees, and use better gas, or keep your foot out of it


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Rob
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Thanks a lot guys
How can i check my knock sensor??? I dont have any engine code. Is it possible that the knock sensor is bad if i dont have any engine code???

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trans-am 91 3.08 posi 5.0 lb9 5 speed stock

[This message has been edited by stallone (edited March 11, 2001).]

[This message has been edited by stallone (edited March 11, 2001).]

 

Need to hook a scan tool up to it to tell if the knock sensor is working. I take it that you are hearing the ping on accelleration?
You can still hear the ping if it is serve enough even if the knock sensor is doing its job, but that means it is usually severe.
Once detonation starts, it is more difficult for the ECM to get rid of it. In other words, you may have the timing adv 2 degrees, but when detonation starts, the eCM can't just retard 2 degrees, it must retard say 6-10 degrees to get rid of it once it begins, or let off the gas is the other way.
*
Gotta have a scan tool to tell if the sensor is working or not, some of the newer ECMs will set a code sometimes.

 

I had the same problem with my 87 5spd 305 tpi trans am.After replacing the cap rotor, plugs n wires, knock sensor,tps,egr and its switch with new GM parts and installed a 6al the msd coil and pick up it still pinged.
After all that i reset the timing to 6deg.and discovered that somebody switched two of the wires in the weatherpack conector going to the tps,causing it to read only .8 volts at wot.The thing is,every one of the components i replaced was toast.