Dead left front piston
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Dead left front piston
Using an infared sensor I find that the left front piston is not producing the temperatures that the 7 others are producing. I also have dificulties starting this truck if it sits longer than 8 hours. Night time temps about 54 degrees right now. The glow plugs have all been changed, the glow plug controller has been changed, the batteries have been changed. I have a new pcm to put in but need to know where to find it and what I have to take apart to replace it. I have been told that it is behind the left front fender and want to know if there is a trick to replacing it.
Fleet Owner
Joined: Jun 2004
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From: Rio Rico, AZ.
What year is your truck? It doesn't matter in this case, but on other things it makes a difference.
The PCM ( assume you are talking about the Engine Control Module ) is located right next to the parking brake pedal. You need to detach the plug for it from under the hood using a 10mm socket to unscrew the center bolt from the ECM. The plug will follow the bolt out and sometimes it needs help or the bolt jams up. It happened to me that way. Then go around to the cockpit and remove it from the truck.
That said, when it starts does it run ok? If so I don't think the ECM is the problem. I am really keying up on the fact that you have low temperature on one cylinder. Diesels REQUIRE good compression to start regardless of working glow plugs or not. If your engine is bad you'll see huge clouds of white smoke coming out the tail pipe on a cold start.
The PCM ( assume you are talking about the Engine Control Module ) is located right next to the parking brake pedal. You need to detach the plug for it from under the hood using a 10mm socket to unscrew the center bolt from the ECM. The plug will follow the bolt out and sometimes it needs help or the bolt jams up. It happened to me that way. Then go around to the cockpit and remove it from the truck.
That said, when it starts does it run ok? If so I don't think the ECM is the problem. I am really keying up on the fact that you have low temperature on one cylinder. Diesels REQUIRE good compression to start regardless of working glow plugs or not. If your engine is bad you'll see huge clouds of white smoke coming out the tail pipe on a cold start.
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From: STEPHENVILLE,TX!!!!!
yeah i would do a compression test on that cylinder. have you had the valve covers off?? could also be a dead injector, harness burned going to that cylinder, bent or broken push tubes. burned valve....pull that valve cover.
Fleet Owner
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From: Rio Rico, AZ.
Originally Posted by barebackjake
yeah i would do a compression test on that cylinder. have you had the valve covers off?? could also be a dead injector, harness burned going to that cylinder, bent or broken push tubes. burned valve....pull that valve cover.
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This is a "96" f250 4X4 extended cab 7.3. The motor was rebuilt about 70,000 miles ago and it now has 171000 miles on it. !st owner severally abused it and I didn't find out until I started having compression problems and a lot of smoke. I do not get smoke when I start the truck and after it is running it smooths out except it is missing on one cylinder. I have a superchip program and thought that it might be a problem and returned to the stock option and the truck ran more poorly. I reinstalled the off road package and it is back to missing on the front cylinder. I am going to pull the valve cover and check the connections. Is there a way to check that injector besides replacing it? My son is my mechanic and he went to VA so pops has to do the work.
I bought the computer control because someone told me they thought that the computer had lost one leg or left front cylinder.
I bought the computer control because someone told me they thought that the computer had lost one leg or left front cylinder.
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From: Bonney Lake, WA
I'd investigate the wiring harness under the valve cover, and the connector that plugs into the valve cover on the outside. I've had bad pins in my connectors, and those could give you the same symptoms.
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From: STEPHENVILLE,TX!!!!!
yeah quick same cyl as mine. if he bent/broke a tube the oil pressure gauge should show nothing at idle cause its loosing the oil through the lifter tube not there to stop it up. im thinkin harness or injector.
after you pull the vc's, check everything as a visual all connections there pushtubes where there supposed to be. valve stems against the rockers....if the visual checks out fire the truck up and see if oil is coming out the little aluminum oil deflector on the injector. if no or little oil then could be electrical or injector. oh yeah any check engine lights?
most likely its not the computer causing this. its normally in the valve cover harness or its the injector itself. i know a diesel injector shop can "pop" test your injector to see if its good. they have a machine they hook up to it and sees how it fires. getting deep into theese injectors troubleshooting can be a whole nother world...
after you pull the vc's, check everything as a visual all connections there pushtubes where there supposed to be. valve stems against the rockers....if the visual checks out fire the truck up and see if oil is coming out the little aluminum oil deflector on the injector. if no or little oil then could be electrical or injector. oh yeah any check engine lights?
most likely its not the computer causing this. its normally in the valve cover harness or its the injector itself. i know a diesel injector shop can "pop" test your injector to see if its good. they have a machine they hook up to it and sees how it fires. getting deep into theese injectors troubleshooting can be a whole nother world...
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Joined: Oct 2004
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From: Dover, Florida
had this happen to me after replacing a water pump (99 250 psd) it turned out to be an injector (more specifically, o-rings for said injector, but the injector looked rough as well -so replaced it, and ALL the o-rings. Seems that in some of the older ones (sadly, mine included) the o-rings had square edges and had a tendency for premature failure. Newer ones have rounded edges and seemingly longer life, and I figured if one set could die, so could they all)
In any case, not the least expensive repair on the book, but certainly not the worst. Truck runs like a top now.
In any case, not the least expensive repair on the book, but certainly not the worst. Truck runs like a top now.
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Pulled valve cover and found that there isn't any oil coming out from under the aluminum cover. Is it electrical or do I need to change the injector? No check engine lights. just had all of the injector rings changed about 10,000 miles ago. Have all of the new type in. The reason I thought it could be the computer is because if I don't start it every 8 hours or so I have to give it wd 40 to start it. Maybe I have 2 problems and this is why I get mixed signals.
Last edited by jeldaz; Apr 4, 2005 at 06:36 PM. Reason: missed spelled word
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From: STEPHENVILLE,TX!!!!!
ok so we know now its injector or associated wiring.....the mechanical is ok...
check the wiring harness plug that goes into the injector make sure the pins are nice and clean and dont look like they have overheated....go back through all the connections at the injector, valve cover, harness plug. with the truck running there should be 115VDC at the connector. REMEMBER 115VDC !!!!! it will take a very very fast sampling digital meter to catch it...
it could be a bad spot in the IDM also, did you buy a IDM or a computer? IDM under hood. injector driver module. i would check the connections first though.
check the wiring harness plug that goes into the injector make sure the pins are nice and clean and dont look like they have overheated....go back through all the connections at the injector, valve cover, harness plug. with the truck running there should be 115VDC at the connector. REMEMBER 115VDC !!!!! it will take a very very fast sampling digital meter to catch it...
it could be a bad spot in the IDM also, did you buy a IDM or a computer? IDM under hood. injector driver module. i would check the connections first though.