Misfire

[swcraig1]

I have a 2000 Ford Ranger 3.0. A few months ago it started having #4 cylinder misfire. I tried replacing all the basic things plugs, wires, coil pack, fuel filter, crankshaft sensor, #4 injector. I took the truck to the garage, they said it had a burnt valve. They found a used head and replaced it. After picking the truck up and driving it about 30 miles cel came back on, showed #4 and #2 misfire. Took truck back to garage, they replaced the other head. After picking truck up about 30 miles cel came on again, #4 misfire. To try and make a long story short, the truck has been in and out of the garage now, more in than out, for about 2 months now. Finally got rid of the #4 misfire only after replacing both used heads with brand new heads. The other day when I picked the truck up for the last time, I was told by the mechanic that he could not figure out what was causing the misfires. He said the last time he drove the truck sitting in the parking lot idling it had a #2 misfire. During driving it, it came up a #5 misfire, and by the time he got back to the shop it came back up a #2 misfire. Luckily since they could not figure out what was wrong with the truck they refunded all my money. Here is a list of everything I know they changed or checked on the truck. They also replaced everything that I had changed before I originally took it to them, plugs, wires, etc.

both complete cylinder heads replaced
cam phaser replaced
cam sensor replaced
Injectors #2 and #4 replaced
coil pack replaced
plugs replaced
plug wires replaced
head gaskets replaced
intake gasket replaced
exhaust gaskets replaced
air filter replaced
fuel filter replaced
all O2 sensors checked
pressure on all cylinders around 145psi
valves water tested
air flow pressure from exhaust
converter temperature good, not overheating
fuel pressure good
fuel rail checked for blockage
timing checked
computer checked
timing on cam syncro checked
cam checked for ware
changed some vacuum hoses

Trying to see if there is anything else I can check myself before I take it to another garage. Any help would be greatly appreciated.

 

[Rearanger]

Luckily since they could not figure out what was wrong with the truck they refunded all my money.Any help would be greatly appreciated.

WOW! Nice of garage to refund your money. They sound like a place to do further business with.

I wonder if you have a defective crank angle sensor, the one taking signals off the crank pulley. That's how misfires are detected, a change in rotational speed is my understanding.

 

[swcraig1]

Thanks for the idea. I replaced the crank sensor before I first took it to the garage. I will check it though to make sure the connector isn't loose. I still have the old one I might put it back on just to see if it makes a difference. Would this actually cause the truck to misfire, or just false codes? You can actually feel the motor misfire sometimes.

 

[Rearanger]

Truck will not run without operational CAS, but if it was not picking up consistent signals it could maybe give a fault signal without actual fault.

No real knowledge here just throwing out an idea since you've seemed to have done everything else.

 

[Stevorocks]

cam phaser replaced
cam sensor replaced

do you mean the synchro? my 3.0 threw up a code for a #3 misfire. went away when i replaced the synchro.

sounds to me like maybe a bad wire or connection. very tedious to track down.