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Another compression waveform
Posted to Technical Discussion Forum on 10/13/2010 35 Replies

Hello Group.

I have this 2000 blazer that has misfires on number 3 cylinder. The ignition waveform looks like this .[2000 Chevrolet Blazer LS, Ignition Waveform]. Here is the comnpression waveform of number 3 along with the number 3 2ndaRY. [2000 Chevrolet Blazer LS, Engine/Propulsion Waveform]. The compression pressure is low at idle which is 28 psi. Here is a more detailed view of the same number 3 cylinder.[2000 Chevrolet Blazer LS, Engine/Propulsion Waveform]. This is from the number 5 cylinder and is known good. [2000 Chevrolet Blazer LS, Engine/Propulsion Waveform]. The compression is above 90 psi at idle.

The low compression cylinder is low but I dont see in the waveform a problem in the exhaust valve or intake valve opening or closing. Does anyone see a problem with the valves here? If there is not a problem of valve sealing then whats the cause of the low compression? Thanks for your comments.

Mark from Ontario

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car Vehicle Data

2000 Chevrolet Blazer LS 4.3L

Engine4.3 L
Trans4-speed Automatic (Electronic)