I am new to this board. Just recently purchased a Picoscope. I have a 1988 Ford Ranger 2.9 that has a skip on cylinders 1 and 4. Other shops have replaced the usual things...plugs, wires, even the distributor. I have performed a compression check [OK], removed valve covers to inspect valve components [all OK] and I have tried to perform a cylinder pressure test with the Pico {cylinders 1 and 4 are a little lower that the others]. We removed the cylinder heads and they were rebuilt...no help.
Is there anyone who can help me [or point me] in the right direction? I tried a new computer, new distributor, smoked the engine checking for vacuum leaks, and replaced the two injectors on the affected cylinders. I can get a good clean firing pulse on the two cylinders that are skipping also. I removed the fuel rail and manually pulsed the injectors...fuel flows easily from injectors. I had a local instructor look at it and he was baffled. I have ran out of options.
Because 1 and 4 are beside one another in the firing order, I lean toward ignition but I have tried it all. Any help would be greatly appreciated, Mike
Mike, one month ago you posted this same truck problem. You are being like the horse that is dying of thirst and we have led you to a nice fresh water pond - but you will not drink ! where are some pressure waveforms ? what was the valve lash clearance set to ? How are the cam lobes on these two cylinders ? If you don't post some info the guys on here cant be more then parts changers, much like the people that have spent big money on this truck already.