Crazy miss at light power settings
1. Describe the problem you are having in detail:
Bought this rig a year ago. It always drove fine, cruise worked, etc. But it wouldn't high-idle with the pedal--any contact and it would rev to 3600 in about four seconds. Added a high-idle switch; would do OK at 1100, but fish at1400and 1600, though it would maintain theselected speed, spastically. No throttle or engine "service" light.
About a month ago, after a cold start (near instantaeous, even with only seven good glows), it would havetrouble idlingsteadily. Once it warmed up (needle off the peg), it would stop fishing and run "normally." Now, when cold it fishesviolently. It'sOK whiledriving,but atlight load (say less than about 15% power) it will fish.
Swapped all three of my good (black) PMDs. No change. Replaced with new gray PMD and new extension harness. No change. New liftpump.No change. New fuelfilter (bowlwas sterile clean). No change. Removed optical sensor filter. No change. Disconnectoptical sensor. Runs differently, but still fishes. Pulled coveroffIP.Clean in there, but nervousaboutpulling optical sensor out. Last-chance screen/filter in IP is clean, not a speck of anything.
Gah, what now!!!
2. Year of truck/engine. 1996s. OBDII, electric pedal. 3. Odometer reading (indicate miles). 191k 4. Indicate the model number on the Injection pump (starts DS4 or DB2......). ds4 5. Indicate if you know if it’s a 2500HD 6. Do you have an EGR on the engine? (An F or an S engine code 8th VIN digit) no egr 7. Air Filter condition (visual check). clean 8. Fuel filter condition (freshly changed, mileage since changed). just changed, bowl was sterile 9. Location of PMD/FSD? (ex. on pump/remote over intake, behind bumper). new gray, between nostrils behind license 9a. If remote mounted, describe wiring harness (homemade or purchased from which vendor). OE, came with gray one 9b. Indicatethelocation and condition of the FSD/IP grounding wire. clean, center screw on left side of OS cover 10. Outside Temperature (C or F). _____ ° various15-75dF
11. Service Engine Light while running?- none 11a. Service Engine light doesglowduring start/cranking/bulb check: Yes 12.Have you scanned for engine codes? Yes 12a. List exact results on engine codes. none
13. Condition of Battery terminals (removed, cleaned and tightened). clean, brass bolts 14. Known condition and age of Batteries. one 12 months old, other one is tired; "matched" interstates 14a. Are batteries a matched setof sameage? 15. Condition of Major Grounds (removed, cleaned and tightened) unknown
20. Are you experiencing Stalling? no 20a. Describetheevent (upon startup only, down the road, hit a bump, etc...) always, worse when engine is cold 20b. Do you notice loss of dash or instruments? no 21. Check turbo inlet and air filter for obstructions. intake elbow removed from manifold, no change 23. Lift pump test - Describe results. brand new 1993 delphi, 7 psi always
24. Upon cold start, does the radiator hose get hard quickly? No 25. Upon cold start, do you have excessive white smoke? No 26. Do you have excessive cranking time beforetheenginestarts? No, less than one second
29. During hard acceleration, do you have excessive black smoke? No 30. Do you have any unusual exhaust smoke issues? no 31. Turbo check out - Pass/Fail 32. Indicatefuel that you are using: typically Bio-Diesel but no change on #2 Diesel 3. Are you using any fuel additives? If so, please list. B100 "additive" 34. Upon unscrewing fuel cap, do you have a large vacuum formed in the tank? No, no change with cap off 35. Do you have any service history available that might pertain to the problem you are having? no 36. Please indicate any modifications to the vehicle that might help us diagnose better. 3" exhaust and Heath tune and turbomaster.
Here's an idlevideo.itsalmostlikea governor return spring is broken or something.warm, in drive, it will idle fine.
http://s912.photobucket.com/albums/a...=VIDEO0175.mp4
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Originally Posted by Robyn
