1997 4.6L Runs Rough
05-15-2017, 06:13 PM
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1997 4.6L Runs Rough
I have had a terrible time with my 1997 Ford F-150 4.6L 4x4. It feels like it is missing all the time. It shakes at idle, so badly that it rattles the doors. When I step on the gas it revs easily, but when under pressure it feels like it misses severely. Here is what I have done to try to correct the problem:
Replaced fuel pump, replaced fuel filter. Did a fuel pressure test with 35 PSI. Cleaned all the fuel injectors and tested them. Replaced fuel injector O-rings. Replaced all spark plugs and wires. Replaced both coil packs with MSD high performance packs. Replaced the EGR valve. Replaced the intake manifold gaskets, top and bottom. (because of Small vacuum leaks detected with smoke test.) Replaced the IAC valve. Replaced the MASS airflow sensor. Did an exhaust backflow test with the gauge bouncing on 0 PSI. I did a compression test and get 135 PSI on all 8 cylinders within +-2 PSI. Changed the air filter. I took it to two different mechanics for some of these items and did some myself. Neither shop could figure it out. One shop did a de-carbon treatement of the engine. One mechanic thought it was the catalytic convertors because one side is getting very hot, but they tested ok.
I am very frustrated! After $1600 from the mechanics and parts I have put on myself the truck runs exactly or very close as it did before I started all this. Ready to drive it off a cliff, may or may not get out. Please help.
Replaced fuel pump, replaced fuel filter. Did a fuel pressure test with 35 PSI. Cleaned all the fuel injectors and tested them. Replaced fuel injector O-rings. Replaced all spark plugs and wires. Replaced both coil packs with MSD high performance packs. Replaced the EGR valve. Replaced the intake manifold gaskets, top and bottom. (because of Small vacuum leaks detected with smoke test.) Replaced the IAC valve. Replaced the MASS airflow sensor. Did an exhaust backflow test with the gauge bouncing on 0 PSI. I did a compression test and get 135 PSI on all 8 cylinders within +-2 PSI. Changed the air filter. I took it to two different mechanics for some of these items and did some myself. Neither shop could figure it out. One shop did a de-carbon treatement of the engine. One mechanic thought it was the catalytic convertors because one side is getting very hot, but they tested ok.
I am very frustrated! After $1600 from the mechanics and parts I have put on myself the truck runs exactly or very close as it did before I started all this. Ready to drive it off a cliff, may or may not get out. Please help.
