Hey guys, a coworker of mine was telling me that his ranger wouldn't get over 50 mph when warmed up and was chugging (like in traffic). He took it in and the mechanic changed the fuel regulator, fuel filter, and the o2 sensors. Now he said it gets up to freeway speed fine but still chugs and only when its hot. What is it?

Thanks,
Chris

 

If it's running good when cold then it's getting plenty of fuel. (uses more fuel when cold)

After warm up the mixture leans out and the egr opens more and more.

I'd suspect either ignition or egr.

Rich

 

What is the cheapest way to go about diagnosing the problem?

 

He said he thinks the EGR was replaced last year, but doesn't know for sure. He also said that the door chimes when the key isn't even in it, and the lower cover of the steering colum is exposed. I don't think thats what you meant by ignition though....

 

bump...

 

could be a dead plug....mine did the same thing and it was a bad plug.......also might be a bad coil pack...it might get hot and expand causing something to not make contact...

 

did they have coil packs in 94? I thought it was a distributor?

 

have him get new plugs an wires i have same truck an same problem.. turned out to b theplugs being bad.. have him clean the maf sensor too that might help...and yes 94 4.0s do have coil pack

 

FWIW, the 4.0L never had a distributor.