A customer brought in a 96 crown vic LX, 4.6 motor in it. It is an odd car, as it only sees about 3000 miles a year for whatever reason. It gottuned up about a year ago, and he comes in today for an oil change and wants us to see why the check engine light is on and fix it. Mind you, Im like a C tech... I do brakes, oil changes, trans service, alignments, struts etc. The guy who would normally handle this had the day off.

So I pull the code and and stream the data and it is showing a cylinder 8 misfire when you give it gas (no load), and it has a HIGH misfire count, yet it runs and drives pretty well.. So I do regular trouble shooting, discover the wire has ALOT of resistence (2x as much as a new one) ... grabed a new one from the back and put it on to see what happens. Nope, no change. Throw the old one on, and discuss it with another guy, and trace it back to the coilpack. I replaced the coil pack, and the engine no longer misses while I rev it set up on the lift, so we roadtest the car assuming it will be fine, and it comes back missing again, BUT, we can not get it to miss while it is up on the lift. WTF? Also, there is no noticeable miss with the engine while it is driving... runs smoothly, plenty of power and nothing else sticks out on the data stream.

So my boss checks and there is a TSB out about throwing false codes, including a cylinder misfire code without driveability problems. Solution is to reflash the computer. Heres the good part... It had already been re programmed by a dealership when the TSB originally came out.

So, What do I do??????? If the computer was reprogrammed once before due to the TSB, then why would it need to be flashed again for the same problem years later? I need help! This is kicking my ***. We can not re program this computer at our shop, so we would have to send it to a ford dealership, which means we would have to pay a decent amount of $ and would rather not be wrong on this one.

Thanks

Jim

 

Since no one else has answered I'll throw out an idea.What about the injector for that cylinder?Try switching it to another cylinder and see if the miss follows.

 

Yeah , I asked another guy and thats what he suggested. It seemed like a bit of a pain at the time, so I just took a screwdriver and listened to the injector... it SOUNDED like it was firing ok, but Im going to switch it liek you said.

Thanks

Jim

 

Bad Injector. Switched it with the one next to it and the misfire followed.

Thanks

Jim

 

Wooohoooo I got one right!!!!![sm=bounceybounce.gif]