Rough idle and missing throughout rpm . . help!!

[Quickhorse]

shim mod is a plastic clip that goes on the UVC harnes to keep it from sliding down and becoming disconnected.

I wonder how common it is for a harness to go bad? and if I can get just one side?

[melmount]

yes, i am pretty sure you can get one side. I think they are like 100 bucks but i could be wrong
they fail. Its not very day but i read a lot on it here. Of course theres a lot of trucks out there running great and people dont come here to post that.

[slickwilly_185]

Yea you can get just one side and its only 50 dollars if you go through and international dealer. thats were i got mine at. i would put both the harness for the injectors and valve cover gasket that way you know its good.

[Quickhorse]

I bought a UVC harness for the drivers side but before putting it on we ohm tested from the driver module all the way to each injector plug. ohm tested between valve cover gasket/etc. All checked out. Swapped another IDM in also. Also, I put a new CPS (black one this time BWD) just to be sure the gray one from Ford Recall didn't go bad. No luck. Still missing on take off/low idle/and rough all through rpm range. Getting full boost from turbo and nothing but a KAM error (PO603).

On a side not . . . been looking at a new 2500HD w/6.2L super crew. I am going to pull the drivers-side head and oil pan to replace whatever is wrong but if someone is interested in buying a strong well built truck let me know. I have way too many new parts in this thing and plow is like new also. Just think I need something new now.

[96F350KID]

Have you tested between the IDM plug and each connector on each injectors?? This is something not alot of people do. They just check between the wiring harness under the valve cover to the plug on the outside. It sounds almost like your getting air or lack of fuel to # 8. Have you had the pressure checked on the HPOP?? Also how is the soot in you EBPS tube?? Mine was clouged solid and had to buy a new sensor and tube. Made the truck run like crap at idle but plenty of power at 2000+. It caused the PCM to think the truck was warm all the time ( no back pressure leaded it to belive the EBPV was inop) and the ECT said it was cold and then warm. This caused a limp mode situation and failed all 8 injectors with a contrubution test. Next thing is take a infered temp gauge and probe each exhaust port and see if the temps are the same. For example in you case cly 1-7 are at 400 degrees and cly 8 is a 200 this means its cold and there is too much fuel. if its greater then the rest its lean meaning not enough check fuel psi in the head at the back. There are fuel plugs in the front and rear of the head you can stick a diesel gauge there. Good Luck!!

[Quickhorse]

Originally Posted by 96F350KID

Have you tested between the IDM plug and each connector on each injectors?? This is something not alot of people do. They just check between the wiring harness under the valve cover to the plug on the outside. It sounds almost like your getting air or lack of fuel to # 8. Have you had the pressure checked on the HPOP?? Also how is the soot in you EBPS tube?? Mine was clouged solid and had to buy a new sensor and tube. Made the truck run like crap at idle but plenty of power at 2000+. It caused the PCM to think the truck was warm all the time ( no back pressure leaded it to belive the EBPV was inop) and the ECT said it was cold and then warm. This caused a limp mode situation and failed all 8 injectors with a contrubution test. Next thing is take a infered temp gauge and probe each exhaust port and see if the temps are the same. For example in you case cly 1-7 are at 400 degrees and cly 8 is a 200 this means its cold and there is too much fuel. if its greater then the rest its lean meaning not enough check fuel psi in the head at the back. There are fuel plugs in the front and rear of the head you can stick a diesel gauge there. Good Luck!!

Hey thanks alot for the post. Very good info. I have taken off the EBPV tube and cleaned but the sensor I did not mess with. Only things I haven't done yet is check oil pressure, fuel pressure and swap out pcm. Using a digital pyrometer gauge on each port I never thought to do. Good idea. I will have a local shop with gauges/fittings/etc check fuel and oil for me. I have replaced the ICP sensor, CPS, and done alot of other things and didn't want to waist my money on a EBP sensor if I didn't need to. I unplugged it and it didn't change anything while running. Maybe it is bad. EBPV tube is new as of 4 years ago so I just cleaned it out and put it back on. I took each harness and ohm tested separately and then went from IDM all the way to each injector on both sides just to be sure it wasn't a wire problem. Is there a way to put a diode on the EBPV sensor plug to serve as a fooler like the Map sensor and the 10k mods we have done??? Or do I need to buy a new sensor? POS!

[Quickhorse]

Did contribution test today and came up with injectors 5 and 6. Going to replace them tonight. This is good news for me. Finally telling me something. Scan was done by the diesel tech at Ford. I was returning the IDM I borrowed from him to try out and he graciously did a few tests on it then went to the buzz and contribution tests just for giggles and boom! 5 and 6 show up. I am very happy.

[nastea]

You know, Reading this I'm having very similiar symptoms. I guess I'll do a contribution test.

[Quickhorse]

All fixed!!! Ended up injectors 1&8 came up first on contribution test then 5 and 6. Note to anyone having a hesitation problem. Replace injectors that come up on contribution test then run contribution test again. Repeat this process until you get nothing on the contribution test. Ohm testing from the IDM all the way through the harness to each injector plug is a good idea the first time you tear into the valve covers to replace injectors that are bad. This will eliminate any wiring issues. I swapped IDM's, PCM's, put new sensors in all over and did a lot of other things b/c of overthinking the problem. Stick to the basics first then get more detailed if needed. Hope this thread helps someone else having the same problem.

Also, the easiest way I found to replace the injector was this:

-take valve covers off and remove gasket and uvc harness all together
-use allen key and take out the two oil plugs. . . let them drain for 10 minutes before pulling injector(s)
-if you can loosen the 1/4" drive fuel plugs in back of each head to drain the fuel fine mine were too rusted. Do not pull these out if you do get yours loose. Just loosen and tighten back up in 10 minutes before pulling injectors.
-if you couldn't get plugs loose in back of heads don't worry. Just pull injectors after oil plugs have drained for 10 minutes(these need pulled all the way out) and use a turkey baster hooked to a small rubber hose with a foot long or longer piece of plastic vacuum hose attached to end. This fits in the injector hole so that you can suck any fuel and oil off the top of the piston. If you don't get it all out you can pull the glow plugs out of the injectors being replaced and put one bolt in the valve cover while main injector harness is still unplugged crank over engine to get any left over fluids out of the cylinders. Then pull valve covers back off and reinstall uvc harness, glow plugs and finally the valve cover. Be sure you have the injectors and oil plugs in before cranking engine to clear fluid out of cylinders. Only glow plugs should be out when cranking to clear fluids!!!
-once everything is bolted back up be sure to top off the HPOP. Small plug at top of pump case(torx bit).
-After oil has been added it will take a few 10 second intervals of cranking engine over to get engine running again. Take your time so you don't fry the starter or solenoid.
-Let the engine run for a while at idle then take it out for a 20 minute drive on the highway or somewhere where you can turn the o/d off and hold the rpm's over 2k for a while. It may take a day or so to get all the air out of the system and you will notice a longer startup time till all of the air has worked its way out.
-also, easiest way I found to get injectors out is once you have the UVC harness and valve cover gasket out of the way take the bottom 8mm bolt out of injector clevice hold down then just loosen the top 8mm bolt and few revolutions. Use a small pry bar prying under the front side of the injector hold down piece while sliding and holding that piece forward(slotted to clear 8mm bolt in front) pry on the clevice and injector will come right up. In reverse of this you will put injector in sliding clevice over top bolt and tighten the bottom bolt first until it starts getting tight. Then loosen bottom bolt halfway and tighten top bolt all the way. Now you can tighten bottom bolt all the way.

GOOD LUCK!!!

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Last edited by Quickhorse : 11-23-2009 at 11:22 PM.

[melmount]

good write up, I assume when cranking the motor over to clean the cylinders, before glow plug install, both sides even the one not being worked on would have the uvch unplugged? would not want it to run on 4 cylinders? Or try to.