Hey guys, the neighbor's kid has a new to him truck, 4.2 v6 + 6speed. It's been giving them a little trouble after it gets warm (he says better when it's colder out).
He's changed:
Upper Intake gaskets
lower Intake gaskets,
plugs + wires,
coil pack
It's throwing this code:
Is this indicative to anything in particular to anyone? He's running short on spare change so I'm trying to help out some, I'm running around getting ready for this weekend (and fixing my Granny's van [again] because she found a curb) so I figured I'd ping the collective and then do some research on Monday if it isn't obvious to the smart folks on here.
Thanks guys!
ddavidv
UltimaDork
5/31/24 6:55 a.m.
Misfire codes can be triggered by a dozen things. Try swapping injectors and coils (if they are individual) and see if the code moves. I don't know a lot about the 4.2 other than it's based on the Essex 3.8. Those were known for coil problems. The intake gaskets were a good guess on the 4.2 though; probably the first thing I'd have tried.
Unfortunately I think a compression test is needed here as it's burnt a valve.
Unplug the EGR valve and see if the misfire goes away. These were really bad for some of the six individual EGR nozzles clogging, causing a misfire when the valve would open and send all the exhaust gases to one or two cylinders. EGR valve only opens at full operating temperature, and under light to medium throttle.
Easy to rod the passages out while the upper is off.
There are a bunch of other gaskets and hoses that like to cause leaks... 4.2s were a major reason why I loved having a smoke machine.
ddavidv
UltimaDork
6/1/24 6:26 a.m.
It's funny; the 4.2 has been referred to as one of the most reliable engines ever. Personally, I doubt it comes close to the venerable 300 six.
Ooof, just catching up - this news is worse than I had personally hoped for, but I appreciate the input!
Let me take what we have here and see if I can put hands on the truck itself....
We used to do intake gaskets on the 4.2 all the time and cleaning the EGR ports was paramount to get rid of the codes and driveability concerns.
