Mechanics

VW T4 SLIGHT MISFIRE

2000 Volkswagen Transporter • 4 cylinder FWD Manual • 94,829 miles

My VW T4, which is 4 cylinder petrol engine 2000cc made in 2000, has got a very slight misfire at idle. We've changed the plugs, wires, rotor and cleaned the distributor cover which seems in a good condition and replaced the coil.

Cylinder pressure compression has done and is fine. Fuel pressure will be checked, we believe it's in spec as we accelerate, we have more power.

Recheck the plugs, which all seem fine, white, not black or wet.

When the engine starts, rpm goes up to about 1400, within a few minutes, it goes down to 750. But you can still here some sound coming out out of tailpipe, like "pong, pong".

No check engine code, no check engine on.

The vacuum is about 17, a very very slight swinging at idle, no at acceleration.

Any suggestion will be appreciated.


Tony
Avatar
Lhlmu
November 19, 2010.



Have you checked for vacuum leaks? Also, have you checked the idle air control valve for the looping idle?