new thread, still drivability issues.
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new thread, still drivability issues.
To recap:
just bought the 1994 F150 5.0 MAF, auto, It had very little power so i did a compression test, it had 0 pressure in cylinder 5...so i pulled the heads.
Cylinder 5's valve was stuck. Had the heads machined/valve job.
Replaced components that were worn/suspected worn:
plugs, wires, fuel filter, cap, rotor, coil, air filter, new gaskets, o2 sensor and replaced cats with single higher flow cat.
I wanted to test the MAP/BAP, but it turns otu the 94's (auto/maf/5.0) didn't have them. I found this odd.
Truck was running eye-wateringly rich, no power and backfiring through the intake. Cleaned the MAF, didn't seem to have a change, unplugged the MAF, drove about the same, so replaced the MAF. I THINK that the richness problem is gone now. KOER test reveals that the HEGO sensor is reporting a LEAN condition. Again, i THINK i have the mixture problems resolved and just need to let the computer relearn the sensors/fuel/whatnot
Now i still have the backfires. It sounds like jiffy pop under accelleration and it's like it has a yugo motor trying to move the truck.
The last 3 things that i think it could be would be
1) TFI (long shot, but easy to test) In my experience they usually work or do not, no symptoms of a bad one until it won't start.
2) PCM (at one point early in my diagnosis the PCM was reporting 6 cyl instead of 8. Now that it's running/idling okay, it reports the engine correctly every time.
3) Timing chain. This is currently my #1 suspicion I am thinking it might have jumped a gear and is opening the valves at the wrong time causing the backfires.
I may just dive into that this evening or tomorrow and see what that yeilds.
I also broke the knock sensor when rebuilding things. Turns out that you can't find those ANYWHERE. I'm running without that for now, but not sure what impact that might have on the truck.
just bought the 1994 F150 5.0 MAF, auto, It had very little power so i did a compression test, it had 0 pressure in cylinder 5...so i pulled the heads.
Cylinder 5's valve was stuck. Had the heads machined/valve job.
Replaced components that were worn/suspected worn:
plugs, wires, fuel filter, cap, rotor, coil, air filter, new gaskets, o2 sensor and replaced cats with single higher flow cat.
I wanted to test the MAP/BAP, but it turns otu the 94's (auto/maf/5.0) didn't have them. I found this odd.
Truck was running eye-wateringly rich, no power and backfiring through the intake. Cleaned the MAF, didn't seem to have a change, unplugged the MAF, drove about the same, so replaced the MAF. I THINK that the richness problem is gone now. KOER test reveals that the HEGO sensor is reporting a LEAN condition. Again, i THINK i have the mixture problems resolved and just need to let the computer relearn the sensors/fuel/whatnot
Now i still have the backfires. It sounds like jiffy pop under accelleration and it's like it has a yugo motor trying to move the truck.
The last 3 things that i think it could be would be
1) TFI (long shot, but easy to test) In my experience they usually work or do not, no symptoms of a bad one until it won't start.
2) PCM (at one point early in my diagnosis the PCM was reporting 6 cyl instead of 8. Now that it's running/idling okay, it reports the engine correctly every time.
3) Timing chain. This is currently my #1 suspicion I am thinking it might have jumped a gear and is opening the valves at the wrong time causing the backfires.
I may just dive into that this evening or tomorrow and see what that yeilds.
I also broke the knock sensor when rebuilding things. Turns out that you can't find those ANYWHERE. I'm running without that for now, but not sure what impact that might have on the truck.