Fixture

Hello all,

I have been lurking around reading all the posts about misfires and I am still having the issue. The truck has a hard time starting and once it starts it has a very lumpy bad idle and once it warms a little, it will stall. I have cleaned the TB and the IAC.
Here is a video of the engine. Cant hear too good, but you can see the car mirror shaking from the misfire.
Video:

I have codes:
P0500 - Vehicle speed sensor A circuit
P1281 - Engine is cold to long (LOL)
P0172 - System too rich bank 1
P0175 - System too rich bank 2

I have replaced:
Coolant temp sensor
Cam sensor
Injectors
Sparkplugs
Coils
MAP sensor
Downstream 02 sensors Bank 2
Thermostat


On hand to replace.
Crank sensor
Downstream 02 sensors Bank 1


I have heard that the valves could lose some kind of retaining clip or something to that affect. I assume I would need to remove the valve cover to verify that. Anyone have a picture of what I would be looking for?
Was also thinking a major vacuum leak somewhere. Some of the time there is no codes, other times there are codes.

Thanks for any and all help.

Jonathan
AKA - Fixture

Fixture

I have had quite a time finding the bad idle/misfire. The truck still feels like its running on 5 cylinders. I had a P0202 code that I fixed with a new injector connector and the fuel injector was not seated properly in the head. I still have no codes and the truck idles, again, like its running on 5 cylinders. I have to keep my food on the gas to keep it idling or it will die. It takes a couple time to restart the engine once it has stalled.

Going to get a compression tester and check #2 cylinder. Been reading about valve seats and springs breaking on they cylinder.

Any other ideas on what to check?

Caish

Start with Fuel pressure.
I fought a fuel pump issue wanting to deny the issue could be that, I didn't want to drop the tank again.
Pull schrader valve use a paper clip to jump the relay, with hose attacked to the port on the fuel rail.
let it run into a bucket, how much volume do you have?
Next attach a pressure gauge, 49 psi?
Shut it off, watch the pressure drop, is it instant? Bad return valve common on the WJ.
Anyway many issues come from low fuel volume,
Long Crank,
Won't pull out any RPM under load,
Pops back fires, comes from the lean condition of not enough fuel.
Vapor Locks......

Fixture

Thanks Caish. I just ordered a fuel pressure tester as well. Will check it out and report back my findings.

Fixture

Did a compression test and cylinder #2 has zero compression. The others are around 150.

Any good write-ups for removing the passenger side head?

ZJMAX

The 4.7 has rocker arms that ride directly on the lifters. It is super common for a rocker arm to slide out of place due to a sticky lifter. I would pull the valve cover first and see if a rocker arm is off it's pivot. If so you can try replacing the lifter and putting the rocker arm back. I bought a 01 super cheap that had this issue and fixed it and drove it for a few years before selling it. Oil changed are super important on these engines and I always add 1/4 quart of ATF to the oil with every oil change as it has a higher detergent ratio and is thinner to keep the lifters cleaner.

Max

Fixture

Thanks ZJMAX, will check that out once I get the valve cover off. would love for it to be that. I ended up getting the head, so if its needed I got it.

Will report back my findings.

Fixture

I pulled the valve cover off and the #2 rocker had popped off. I pulled the head and sure enough, the #2 valve seat dropped. I have a couple more parts to get the truck going, accidently broke the breather/pcv valve.

Thanks all for the assistance on this.

dropped valve seat #2