Cylinders missing

[ryanw87]

I have a 95 XLT with only 98k.. cylinders are misfiring, was told it could possibly be a blown head gasket and/or cracked cylinder head, however im not getting the usual symptoms of those two problems. im assuming its an injector problem or a computer problem, more sure its a computer problem because every diagnostic tester i try connecting to the OBDII is not able to connect to the ecm. therefor, i am not able to get any readings necessary to diagnose anything. intake manifold gasket was replaced after i did a pressure test, replaced the coil pack and plug wires for the hell of it. it honestly drives OK, but occasionally when i really give it gas i can hear the cylinders knocking. the engine temp is perfect the entire time, im not losing any antifreeze. this seems to be a problem nobody is able to fix. ive been told the 95 was the cross year between OBDI and OBDII.. will i need a special adapter to get a reader to connect, or should i try replacing the computer?

 

[MrShorty]

a computer problem because every diagnostic tester i try connecting to the OBDII is not able to connect to the ecm.

That's because the OBDII connector under the dash is not functional on '95's. Don't ask me why they put it there if it wasn't intended to work.

'95 was the last year for OBDI/EEC-IV. The diagnostic connector for your '95 is under the hood on the driver's side. It has a very different connector, so you'll either need some kind of adapter (assuming your diagnostic tester is capable of talking to an EEC-IV computer), a different code reader, or a paper clip. The sticky threads in the EEC-IV forum describe the test protocol for the paper clip method. Even if you use a more expensive reader, the test protocol is the same, so it is still useful to know how the self-tests are performed. You'll also see how to get the computer to perform a cylinder balance test to determine which cylinder is misfiring.

 

[ryanw87]

Thank you very much. I got my hands on a snap-on tester, which was the first to tell me I needed a special Ford adapter to connect to that tester plug under the hood, which of course I didn't have. The fun part is finding someone that does, apparently not too many techs have them anymore. I will refer to that forum though, thanks again!