99 7.3 idel problems - Ford Powerstroke Diesel Forum
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post #1 of 35 Old 07-28-2009, 07:12 PM Thread Starter
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99 7.3 idle problems

hey everyone this is my fist post on powerstroke, and im having some problems with my 99 7.3 the problem im having is a rough idle and my truck does this power surge while driving. when im cruzing at low rmps and have the throttle about 1/4, it will start jerking and speeding up and down as if im feathering the pedal. as far as the idle goes, it allways does it no matter the temp or how long its been drivin.

ive have had a loacal deisel mecanic run some tests on it and hes come up with nothing. so far ive had him change the wireing harnesses that are under the valve covers for the injectors, he took out all the injectors and replaced all the o rings. ive had ford change out the cps under the recall 2 months ago. he did the contribution test like 20 differnet times and so far no injector is showing its faulty. there are no codes stored in the computer and no engine light ever comes on.

my truck has around 130k on it, its got a 4" stright pipe smoke stacks with and aftermarket donwpipe. k&n filter, banks intercooler, banks biger tourbo housing and wastegate controler, and a banks chip. ive also put the high oil preashure cross over line and the fuel regulator bypass kit from diselinnnovations. i have snowperformance water meth injection that i use for towing. the truck runs real good once you get past that certain rmp, gots plenty of power, and runs real smoth in higher rpms. i tow a 10K pound weekend warrior with no problem. its just that idle thats been realy irriatating me. i tried a search on this subject but didnt find anyone having that same probmlem, so if anyone has any sugg on what to try or change, i would shure appricate it.

jeremy

Last edited by diebog; 07-28-2009 at 07:17 PM. Reason: typo
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post #2 of 35 Old 07-29-2009, 06:11 AM Thread Starter
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anyone have a sugg?
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post #3 of 35 Old 07-29-2009, 06:34 AM
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Have you tried pulling out your chip and see if it still does it?
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post #4 of 35 Old 07-29-2009, 06:36 AM
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im thinking chip also....
post #5 of 35 Old 07-29-2009, 04:55 PM
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Yeah take the chip out and check it. If it's still doing it my next choice would be to observe ICP (Injection Control Pressure) in psi. and IPR duty cycle in % when it is skipping/jerking and see if it is erratic or pretty steady. I've had IPR valves start going out and can cause an erratic high pressure oil problem. Also a common trick is putting a 5k ohm resistor in the oil temp sensor circuit to fool the PCM into thinking the oil is warm enough to run the cylinder contribution test and this can sometimes pinpoint weak injectors.
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post #6 of 35 Old 07-29-2009, 09:46 PM Thread Starter
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yeah ive tried taking the chip out and it doesnt change anything. i also have a superchip tuner that ive tried and have same results. so how do i go about observing the icp in psi? the regulator bypass kit i put on has a fuel preshure guage, do i use this? and what about an IPR duty cycle? my mechanic also tried the contribution test after the truck was well warmed up. is this the same as the 5k resitor?

thanks for all your help
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post #7 of 35 Old 07-29-2009, 09:51 PM
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I have very similar issues with no codes, no leaks and no clue where else to look but here's a

early 99 7.3 supercab xlt s/b auto 4x4
08 Tailgate
Isspro gauges (boost,pyro,trans temp)
Ford AIS
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post #8 of 35 Old 07-30-2009, 03:02 PM
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The resistor fools the PCM so you can run the contribution test BEFORE the engine warms up. I've had some weak injectors that only show up when the engine is cold. The ICP and IPR can be monitored through a scanner with data capabilities that can read engine data. Also have you checked fuel pressure?
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post #9 of 35 Old 07-30-2009, 03:07 PM
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Quote:
Originally Posted by diebog View Post
hey everyone this is my fist post on powerstroke, and im having some problems with my 99 7.3 the problem im having is a rough idle and my truck does this power surge while driving. when im cruzing at low rmps and have the throttle about 1/4, it will start jerking and speeding up and down as if im feathering the pedal. as far as the idle goes, it allways does it no matter the temp or how long its been drivin.

ive have had a loacal deisel mecanic run some tests on it and hes come up with nothing. so far ive had him change the wireing harnesses that are under the valve covers for the injectors, he took out all the injectors and replaced all the o rings. ive had ford change out the cps under the recall 2 months ago. he did the contribution test like 20 differnet times and so far no injector is showing its faulty. there are no codes stored in the computer and no engine light ever comes on.

my truck has around 130k on it, its got a 4" stright pipe smoke stacks with and aftermarket donwpipe. k&n filter, banks intercooler, banks biger tourbo housing and wastegate controler, and a banks chip. ive also put the high oil preashure cross over line and the fuel regulator bypass kit from diselinnnovations. i have snowperformance water meth injection that i use for towing. the truck runs real good once you get past that certain rmp, gots plenty of power, and runs real smoth in higher rpms. i tow a 10K pound weekend warrior with no problem. its just that idle thats been realy irriatating me. i tried a search on this subject but didnt find anyone having that same probmlem, so if anyone has any sugg on what to try or change, i would shure appricate it.

jeremy
Same thing happened to me today- idles rough, but seems to smooth out at high RPM. My mechanic hooked it up to the scanner and went though each injector. Found out #7 was weak. You could actually hear the difference.

2000 Ford F-450 - 6 Speed - CC - Dually - 4x4 - DIY intake & filter - 5" downpipe - DP F-5 - LUK clutch - Wicked Wheel
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post #10 of 35 Old 07-30-2009, 05:37 PM Thread Starter
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Quote:
Originally Posted by ajpu1983 View Post
The resistor fools the PCM so you can run the contribution test BEFORE the engine warms up. I've had some weak injectors that only show up when the engine is cold. The ICP and IPR can be monitored through a scanner with data capabilities that can read engine data. Also have you checked fuel pressure?
well i can adjust the fuel pressure, i currently have it set at 62. what should it be at? i set it at 52 with the key on and not running. is there a correct way to set it?
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