Truck is a 1990 454 auto, one ton crew cab that is stock. OK, so I've had a check engine light forever (code 42,) I never paid it much never mind because the truck ran ok, not good, but ok. I did a tune-up on it and O2 sensor when I got it (maybe 10 thousand miles ago.) If I floored it to jump on the freeway and get up to speed on a short on ramp it would miss, pop through the intake and generally be low on power. I threw a coil on it for giggles and ****s to see if that would fix it; it didn't. And with it being little more than a winter comuter, i could live with this. Well, with putting the bed on it I'm taking more pride in the truck and I want it to run (and work) like it should. I want to get this thing straightened out.
Recently the truck developed a bad hesitation when taking off, say from a light, it feels like the motor cuts out, then catches, then cuts out, then catches. This came to light around the same time I cut the muffler off due to it having a hole on the top directing the exhaust at the floor, heating the floor and damn near starting a fire. I have since replaced the muffler and the truck now only hesitates like this on occasion.
Poking around under the hood the other day I was spraying around some brake cleaner looking for vacuum leaks around the TB base, I couldn't get the idle to change. I capped the vacuum port where the vacuum line going to the vacuum ball because those lines were shot and colapsing. Pulling the line off had no effect on the idle. After capping the port and letting it idle for a few minutes, pulling the cap off caused an increase in the idle rpm. Plastic lines and rubber boots for the vacuum lines feeding the MAP, and EGR look and feel good from what I can inspect of them without taking them off. After doing this the truck developed a single cylinder missfire at idle and light to moderate load. I checked the plug wires at the distributor and at the plug, and hit them with a spray bottle. None of this exposed any faults.
Last night working to diag the CEL and code 42 I began doing the test as outlined in my factory service manual. In that test it has you ohm the ground circuit for the ESC module at the ECM, and tells the resistance should be less than 1000 Ohms. And if not it condemns module, the circuit or the connection. My test found 900 Ohms resistance. I pulled off the module and the white paste was still pasty with no green fluff or corrosion under the cap, the distributor is an aftermarket unit of unknown age and make; but shows no signs of age or defect.
This is where I had to stop last night. Saturday I want to tear into it more. I would like to Ohm out the EST wire from the ECM to the connector. Should I be content with my 900 Ohms of resistance? It is under the spec of 1000, but not my much. Should I throw a module at it for piece of mind? Any brand preference? Should I just keep going with the test? help!
Recently the truck developed a bad hesitation when taking off, say from a light, it feels like the motor cuts out, then catches, then cuts out, then catches. This came to light around the same time I cut the muffler off due to it having a hole on the top directing the exhaust at the floor, heating the floor and damn near starting a fire. I have since replaced the muffler and the truck now only hesitates like this on occasion.
Poking around under the hood the other day I was spraying around some brake cleaner looking for vacuum leaks around the TB base, I couldn't get the idle to change. I capped the vacuum port where the vacuum line going to the vacuum ball because those lines were shot and colapsing. Pulling the line off had no effect on the idle. After capping the port and letting it idle for a few minutes, pulling the cap off caused an increase in the idle rpm. Plastic lines and rubber boots for the vacuum lines feeding the MAP, and EGR look and feel good from what I can inspect of them without taking them off. After doing this the truck developed a single cylinder missfire at idle and light to moderate load. I checked the plug wires at the distributor and at the plug, and hit them with a spray bottle. None of this exposed any faults.
Last night working to diag the CEL and code 42 I began doing the test as outlined in my factory service manual. In that test it has you ohm the ground circuit for the ESC module at the ECM, and tells the resistance should be less than 1000 Ohms. And if not it condemns module, the circuit or the connection. My test found 900 Ohms resistance. I pulled off the module and the white paste was still pasty with no green fluff or corrosion under the cap, the distributor is an aftermarket unit of unknown age and make; but shows no signs of age or defect.
This is where I had to stop last night. Saturday I want to tear into it more. I would like to Ohm out the EST wire from the ECM to the connector. Should I be content with my 900 Ohms of resistance? It is under the spec of 1000, but not my much. Should I throw a module at it for piece of mind? Any brand preference? Should I just keep going with the test? help!
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