I recently replaced the the intake manifold gaskets on my 99 f250 with a 5.4. I had a bad coolant leak and I thought it was the tube from the back of the water pump. It seemed ok but my gaskets were horrible. I replaced both and stopped my coolant leak but after reassembling it has a bad miss and virtually no power. It does have a miss while idling also. I did not replace the coils and spark plugs just because of money. The taxman came calling. I have replaced numerous coils in the past but the miss seemed different. I torqued the intake down to 22ft/lbs. I did notice on reassembly the #8 fuel injector connector did not want to reach, and I assumed I had tangled it. I ended up spinning the injector toward the firewall so it would reach. I am at a loss as to what is wrong. Could more than one of the coils be bad? Oh also I replaced the throttle position sensor. Still running like crap and is really not driveable. i would appreciate any and all suggestions.

Thanks....... 1st time posting I hope I have it in the right place.

 

Based on your post, you most likely have something plugged in wrong. You can verify that with a wiring diagram, or look at another truck with the same engine. I would start by checking the injector that would not reach. You likely got the wires switched with another one. If that doesn't work, you need someone with a good scanner to look for codes and read live data to see what is going on.

 

Thanks David. I thought about that but that is the only injector that plugs in off the wiring harness coming around the back of the motor. All of the others feed off of the top of the head gasket, and it is the only one left. I have no check engine light and the only code i got was a throttle position sensor. A guy i took it too says all of the coils and plugs need to be changed but I don't think the coils and plugs are the problem. could be contributory but not the actual problem.

 

It's also hard to find a 99 f250 to look at. All of the newer ones are setup different.

 

You should not take it back to the person who said that all of the coils and plugs need to be changed. That person is not competent to work on your truck.

If you are POSITIVE that ALL of the injectors are plugged in correctly, then check to be sure that ALL of the cops are plugged in correctly.

The next step would be to get a scanner to read live data and look at fuel trim, misfire data, etc. That is the only way to quickly pin down the problem. Guessing is not smart and can be really expensive.

 

hi. My name is jeff. I have a 99' f250 that seems to have the same issue you had. Do you recall what you did to resolve the issue? From what I ha e gathered MAF or O2 sensor. Any help would be awesome!