High ipr duty cycle and engine missing
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From: Cato Arkansas
High ipr duty cycle and engine missing
I'm stumped. My 95 has a t500 pump 160/30 injectors and I've been chasing a miss. It will idle at 12% duty cycle around 600 icp psi. When your driving the truck empty and cruising with slight throttle the engine misses and the duty cycle will go up to 30-35% and it will hold 2600-2800 icp psi. If you floor it the duty cycle goes to 42% and it holds 2800 psi. The truck has throws a p0263 p0266 p0269 codes.
I have put new uvch harness with gaskets on it. The icp doesn't have oil in it. The ipr I've cleaned and it was new like 3 years ago. I have not done a compression test but blow by doesn't seem horrible. I've checked the wiring harness and fixed all the questionable spots. No fuel in oil or oil in fuel or coolant. Any ideas?
I have put new uvch harness with gaskets on it. The icp doesn't have oil in it. The ipr I've cleaned and it was new like 3 years ago. I have not done a compression test but blow by doesn't seem horrible. I've checked the wiring harness and fixed all the questionable spots. No fuel in oil or oil in fuel or coolant. Any ideas?
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From: Cato Arkansas
It idles good and misses at part throttle empty or loaded when your in it hard it's not as noticeable. I've already stated it's not mixing fluids.
Could the coil on the ipr have a issue causing it to stick when a "x" voltage is applied? Or could the high pressure oil be leaking from internal injector part?
Could the coil on the ipr have a issue causing it to stick when a "x" voltage is applied? Or could the high pressure oil be leaking from internal injector part?
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From: Cato Arkansas
I think I've been misunderstood. There is no oil in the fuel or fuel filter. The truck has electric fuel but I've checked before I've started this thread. I'll put new o rings on it was just curious if the injector or hpop could bleed oil internally causing a high duty cycle?
lost
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From: Worland, WY
Is this a new problem? Does it always miss the same way and is it repeatable?
Have you tried a buzz test and CCT or have you already and is that where the codes for cylinders 1,2,3 are coming from?
42% duty cycle at WOT isn't high. Making sure I understand what you said, at part throttle cruising, when it starts missing the DC jumps and ICP jumps up? If I understood, that would be normal behavior with a miss as the computer is trying to compensate for the non-firing cylinders.
Have you tried a buzz test and CCT or have you already and is that where the codes for cylinders 1,2,3 are coming from?
42% duty cycle at WOT isn't high. Making sure I understand what you said, at part throttle cruising, when it starts missing the DC jumps and ICP jumps up? If I understood, that would be normal behavior with a miss as the computer is trying to compensate for the non-firing cylinders.
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From: Cato Arkansas
No it's not a new problem I was using the 42% duty cycle as a reference that the pump wasn't worn out. Yes it is repeatable always misses under a slight cruising load. No idea why it fails contibution tests I've ohmed the harness replaced uhvc gaskets and harness. Tried different cam sensors. Unplugged icp and no difference. Problem seems to be getting worse.
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Build or borrow an injector break out box, shut the injectors off one at a time when you get it to miss, and see which cylinder it is.
Swap that injector with the one next to it, run and re-test, shutting off injectors again. If the miss follows the injector, then you know it's an injector.
My guess is either a bad solenoid (which you can easily swap around also to see if that is the problem), or worn Poppet that just isn't happy at a certain pressure. I'd put money on one of these 2 being the cause.
Swap that injector with the one next to it, run and re-test, shutting off injectors again. If the miss follows the injector, then you know it's an injector.
My guess is either a bad solenoid (which you can easily swap around also to see if that is the problem), or worn Poppet that just isn't happy at a certain pressure. I'd put money on one of these 2 being the cause.
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