Rough Idle, Loss of Power, Stalls Out - PowerStrokeNation : Ford Powerstroke Diesel Forum
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post #1 of 6 (permalink) Old 04-01-2017, 01:27 AM Thread Starter
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Rough Idle, Loss of Power, Stalls Out

I recently purchased a 1995 F250. The truck can take a few cranks to start and requires some throttle input to keep it from dying out. Once it is running it has a very rough idle, it lopes badly. Once again with a little varying throttle input it will eventually settle down and idle smoothly. It will idle fine at this point seemingly forever.

When trying to drive however the truck feels down on power and the first time I drove it around the block it seemed like it lost more power the farther I went and it ultimately stalled when I pulled back into my driveway.

I sent the PCM out to be updated so that I could use a OBDII scanner. After it gets going and the idle settles down the ICP is at around 580 psi (give or take 10 psi at any time) and the IPR is around ~12%. At WOT the ICP is at around 2500 psi and the IPR is at about 34%. So I think that all seems good?

The second time I drove the truck around the block to get the above readings it did not seem to lose power as I went (although I didn't drive that far) but was definitely still down on power and still had the hard starting and idle issues.

I ran a buzz test and injector 1 was very clearly soft. If only the one injector is sounding like that can I assume that the IDM is fine? I removed it just to see if there was water in it (there wasn't) but didn't go any further. Could the UVCH be damaged in a way that only one injector would be effected or is it safe to say there is an issue with the injector itself? Obviously I have to pull the valve cover either way just looking for some more info until I have the time to do it.

Could being down one injector cause all of the issues I am having?

Other info: Truck is an automatic, 240k miles, ICP sensor didn't have any oil in the plug
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post #2 of 6 (permalink) Old 04-01-2017, 01:31 AM Thread Starter
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Re: Rough Idle, Loss of Power, Stalls Out

One more piece of info I thought of was that I have not seen any sort of smoke come from the truck at any time.
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post #3 of 6 (permalink) Old 04-01-2017, 04:41 PM
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Re: Rough Idle, Loss of Power, Stalls Out

Your numbers seem OK. What do they look like when it is loping? Try starting it in neutral and see if the loping on start stops. I would make sure that the oil level is good. I would also check the injector and GP wiring to make sure there are no shorts or opens.

For checking the injector/glowplug wiring: From each valvecover gasket connection's outermost pins (2 per connector) to ground you should get 0.1 to 2 ohms (indicates good plug and wiring). From each valvecover gasket connection's center pin to each immediately adjacent pin, you should get around 3 ohms (indicates good injector solenoid and wiring). You should not get any continuity from any of the outer pins to the 3 inner pins (indicates no shorts between injector and glowplug wiring). You should also get 0 to 1 ohms from each of the external harness connectors outer pins back to the Glowplug Relay's large terminal on the GP side (indicates good wiring from external connections back to the relay).

If the solenoids and wiring check out, you could have a loose injector poppet screw. You have to remove the injector solenoid to check for that. You can run it with the valvecovers off to see which injector is not discharging the same amount of oil as the others out it's discharge spout. The injectors could also just have worn poppets at 240k. New injectors will have an armature plate-to-body clearance of 0.004" and worn injectors will be less than 0.002". Generally, these trucks don't really smoke in stock form. Cheers!

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post #4 of 6 (permalink) Old 04-06-2017, 09:55 AM Thread Starter
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Re: Rough Idle, Loss of Power, Stalls Out

Thanks for the reply, haven't gotten around to testing that all out yet but I definitely will.

What you said about trying to start the truck in neutral (no change) made me think about some other stuff I had read. Then i realized that my o/d light was also flashing. I checked and I was getting a P0708 code (transmission range sensor circuit high) so I replaced the sensor and adjusted it then cleared the code. Unfortunately the code comes right back after about 15 seconds or so, with the truck simply idling in park. That would make me think that that would be some kind of electrical issue? I didn't see any obvious damage when I checked over the harness. Any chance you or anyone else has info about the transmission harness pinouts so that I can test the wiring?

Really want to make sure the transmission doesn't have any serious issues before I spend any time/money on the rest of the issues the truck has.
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post #5 of 6 (permalink) Old 04-06-2017, 08:36 PM
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Re: Rough Idle, Loss of Power, Stalls Out

I'd start out checking the UVCH and plugs. I would also pull the fuel bowl, clean EVERYTHING and rebuild with an O-ring kit from its only 20$. Its probably never been cleaned before, mine was nasty at 120k, i'm pretty sure it had been done before. Also check your intake air. You might have turbo issues and the truck is being starved of air. I would assume you'd have some smoke if air was an issue but who knows. start it with the filter off and see if its spinning. My other truck had 400k on stock injectors before they were upgraded and they were fine.

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post #6 of 6 (permalink) Old 04-08-2017, 01:55 AM Thread Starter
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Re: Rough Idle, Loss of Power, Stalls Out

Thanks I do plan on going through a lot of that stuff if I can get this transmission issue sorted out.
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