rough running / won't rev, no codes
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rough running / won't rev, no codes
My truck is a 93 150 with a 4.9L 5 spd, I purchased it recently and when I got it the CEL was on with 17 codes, for all the sensors and the code for the PCM internal voltage failure. I opened the computer and found the capacitors had leaked badly and ruined the board. I ordered a new computer from autocomputerexchange.net that is programmed with the VIN and accurate mileage, and all the released updates to the programming.
After installing it this afternoon I started the truck up and it's running kinda rough, the idle seems pretty low and it won't rev without starting to buck and miss. I pulled the codes and there's nothing helpful, 522 on demand, 111 continuous
I'm wondering if anyone has had any similar problems or ideas of where to possibly start looking at what the most likely cause is? The truck ran before with the bad PCM, it just ran poorly and would cut out from time to time.
I'll have to dive into checking the sensors, fuel pressure, vacuum, spark etc tomorrow, just want to see if there's anything I haven't thought of to check.
Also, while waiting for the PCM to arrive I replaced the valve cover gasket, upper intake gasket, throttle body gasket, pcv valve and grommets, all the bad or cracking vacuum lines and checked all the lines to hold vacuum. Replaced plugs and wires and fuel filter also.
After installing it this afternoon I started the truck up and it's running kinda rough, the idle seems pretty low and it won't rev without starting to buck and miss. I pulled the codes and there's nothing helpful, 522 on demand, 111 continuous
I'm wondering if anyone has had any similar problems or ideas of where to possibly start looking at what the most likely cause is? The truck ran before with the bad PCM, it just ran poorly and would cut out from time to time.
I'll have to dive into checking the sensors, fuel pressure, vacuum, spark etc tomorrow, just want to see if there's anything I haven't thought of to check.
Also, while waiting for the PCM to arrive I replaced the valve cover gasket, upper intake gasket, throttle body gasket, pcv valve and grommets, all the bad or cracking vacuum lines and checked all the lines to hold vacuum. Replaced plugs and wires and fuel filter also.
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Hey guys a brief update, I got to do some quick checks today of the main systems.
The vacuum gauge was reading right around 10"Hg and was fluctuating very fast back and forth. The truck is still running VERY rough and will not rev at all, when given any throttle it chugs and bucks really bad. I sprayed starting fluid into one of the vacuum ports and it didn't improve the idle at all and maybe got a bit rougher.
Unplug vacuum to EGR no change, uplug vacuum to fpr no change, unplug iac valve no change and no stall, unplug vacuum to map no change, unplug the connector to map and the truck stalls.
I also checked every fuse in both boxes and they are all good, also checked the power diode and it is good. BUT while checking the three relays in the engine box I became confused. I'm not sure which relays are which exactly except I think the one closest to the fender is the fuel pump relay. While checking that one I found 3v on pin 87, 12v on 85, 12v on 30 and 0v on 86. This just doesn't seem right...why do I have 3v on 87? Isn't that the switched pump side, how could it have voltage on it with the relay removed?
All checks were KOEO
If anyone has some good wiring diagrams of the engine fuse box, fuel system wiring and a decent pcm wiring diagram I would greatly appreciate it.
The vacuum gauge was reading right around 10"Hg and was fluctuating very fast back and forth. The truck is still running VERY rough and will not rev at all, when given any throttle it chugs and bucks really bad. I sprayed starting fluid into one of the vacuum ports and it didn't improve the idle at all and maybe got a bit rougher.
Unplug vacuum to EGR no change, uplug vacuum to fpr no change, unplug iac valve no change and no stall, unplug vacuum to map no change, unplug the connector to map and the truck stalls.
I also checked every fuse in both boxes and they are all good, also checked the power diode and it is good. BUT while checking the three relays in the engine box I became confused. I'm not sure which relays are which exactly except I think the one closest to the fender is the fuel pump relay. While checking that one I found 3v on pin 87, 12v on 85, 12v on 30 and 0v on 86. This just doesn't seem right...why do I have 3v on 87? Isn't that the switched pump side, how could it have voltage on it with the relay removed?
All checks were KOEO
If anyone has some good wiring diagrams of the engine fuse box, fuel system wiring and a decent pcm wiring diagram I would greatly appreciate it.
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Today I started doing some more checking and found some things that I'm not quite sure where to look. After buying a new fuel pressure gauge I hooked it up and when I cycle the key on and the off after it primes the fuel pressure is already back to 0psi by the time I can run around to check the gauge
Then I tried starting the truck and it fired right up and ran great with the fuel pressure gauge on it, would rev up just fine and had a constant 50psi, then after a few minutes it started to idle down lower and starting missing and wanting to buck and jerk again when I tried to rev it and the pressure went up to 60psi I assume because the rough idle was producing less vacuum.
Here's the part that has me confused, I tried pulling the spout jumper out and the truck almost immediately went back to running good and I could rev it again and it stopped missing badly just has a little bit of a rough run to it, but for this age that seemed almost normal.
My questions are, what could cause ALL my fuel rail pressure to bleed immediately after priming and after shutting off the engine?
And why would taking computer control away from my timing somehow make this whole situation better?
Then I tried starting the truck and it fired right up and ran great with the fuel pressure gauge on it, would rev up just fine and had a constant 50psi, then after a few minutes it started to idle down lower and starting missing and wanting to buck and jerk again when I tried to rev it and the pressure went up to 60psi I assume because the rough idle was producing less vacuum.
Here's the part that has me confused, I tried pulling the spout jumper out and the truck almost immediately went back to running good and I could rev it again and it stopped missing badly just has a little bit of a rough run to it, but for this age that seemed almost normal.
My questions are, what could cause ALL my fuel rail pressure to bleed immediately after priming and after shutting off the engine?
And why would taking computer control away from my timing somehow make this whole situation better?
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After reading around in a few other threads I'm thinking I may have 2 separate issues which in combo are causing my rough running and hard to rev issue.
First, I think my injectors may be leaking, either that or the fpr. Does anyone know what the factory lb/hr rating for the 4.9l injectors is?
Second, ford TSB 95-15-11 for the wires near the PCM rubbing through and causing rough running issues that can be related to spout and ignition control.
Any thoughts?
First, I think my injectors may be leaking, either that or the fpr. Does anyone know what the factory lb/hr rating for the 4.9l injectors is?
Second, ford TSB 95-15-11 for the wires near the PCM rubbing through and causing rough running issues that can be related to spout and ignition control.
Any thoughts?
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