Hey guys new to the site....just recently picked up a 99 3.0L 4 door 4x4 ranger, love the truck. Got it about a week ago, when I test drove it everything was fine. Picked it up the next day and the CEL came on, and the code went out for a mis fire on Cyl. #6...so I called the dealer and he said to bring it to his mechanic...mechanic changes the wire and plug, no mis-fire for about 10 miles, and then the CEL comes on again...same problem...so back to the shop...mechanic says maybe its the injector, so he puts a cleaner in the fuel system...solves the problem for about 40 miles, and now the light is back on once again...Brought it to my friends dads shop today, did a compression test and my friends dad said Cyl. 4 has 100 psi, cyl. 5 has 70 psi, and cyl 6 has 40psi.......so I called the dealer, and relayed the info. of course he denys it and says its the injector and to bring it back to his mechanic...which I do. His mechanic says its gota be the injector and to bring it in this thursday......Dont know who to believe, it idles rough under load, such as when in drive or reverse, but clears up once you hit the gas. Truck drives great, although there is a slight thunk when you go from a dead stop and start off....got the truck for 4500, its the xlt model, with 106k on it. Absolutly love the truck, dont want to have to return it to the dealer, just want the problem fixed...any ideas? any advice or help is greatly apreciated!

thanks!

James

 

I had a similar problem with my '07, the dealer ended up putting new heads on it.

 

In the Haynes manual, their compression chart doesn't even go below 100 psi. This makes me think it's a multi cylinder issue not just one. Sounds like it's not a fuel issue, it's possible you may have a bad head gasket or your heads are bad.

 

Had the same problem on my '99 @ 160,000. Had a bend valve, and a burnt one. Let to getting new heads as well. Also...mine does the same "thunk" thing when I take off....let me know if you figure out what causes that.