I cant seem to get a straight answer.

Im having some issues with my car, I originally thought I had an exhaust leak..but now Im thinking otherwise. It sounds like an exhaust leak..but only happnes on acceleration and deacceleration..at constant throttle it doesnt happen.
Also when I blip the throttle off idle, it makes a quick clank/knocking noise.

Some have told me that it sounds like dentonation...but can detonation happen on de-acceleration?

 

Detonation can occur on decelleration. However, it is highly unlikely that your car would be detonating if you blip the throttle with no load on the motor.

To know for sure, put in some (unleaded) race gas, and see if it goes away.

Its probably something else. Have you checked the timing?

Steve

 

Unfortunately I dont have access to race gas at the moment

Timing and everything should all be fine..I havnt changed anything...it just started one day, the exhaust leak noise. The weird thoing is though, if I just rev the engine...it doesnt seem to sound like I have an exhaust leak..only seems to appear while accelerating and deaccelerating. The plugs look fine also...
Im going to jack up the car tonight and try to listen a little better.

 

Normally (stock computer) the ECU cuts the fuel injection off during lift throttle, right?

 

only until a predetermined RPM level

 

I think that is 1500 rpm....
No fuel = no detonation.


[Modified by EuroITR1689, 5:02 PM 2/13/2002]

 

It seems more likely that it's a backfire if it's on deceleration.....

 

So then youre saying detonation CANT happen on de-acceleration right?

 

If there is no fuel then there is no detonation. You can't detonate air with some electrical sparks. But I don't know if your ECU shuts off the fuel injection at zero throttle.
And maybe you heard some detonation at deceleration but at part throttle. It could also be fuel detonating in your exhaust.