Engine Knock - '98 Corolla Ve

[Canadian]

My 1998 Corolla VE developed engine knock. I took it to the dealer and the mechanics did throttle body cleaning, fuel injector cleaning etc. They did the diagnostic tests but could not find any fault.

When the engine knocks all four plugs miss firing then continue as usual. The car never stalled. The knock happens when idling or when the brake pedal is pressed (like stopping at a red light) and when I start rolling from a complete stop. It does not happen at high speed.

The mechanics are as confused as myself. High octane gas and "Octane boost" additive helps to minimize the knock but does not eliminate it. It has been almost 8 months and went to 2 Toyota dealers who did the test without success. One mechanic told me probable cause is bad gas and ask me to burn it away by driving but after 6 months I still have the engine knock.

Any ideas/suggestions?

Thanks

[hb2u]

Had a Honda Civic that did that too. Turned out to be the vacuum pump for the brake system. It leaked and when you pushed the brake pedal, it pulled cold air into the vacuum system and caused the car to stall unless the engine was revved up.

The new vacuum pump for the brake system worked for that car.

I suggest that you check the integrity of the vacuum system.

Good luck.