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jamesm
12-31-2011, 00:03
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

phantom309
12-31-2011, 00:48
try running it without the noise filter harness,.?
http://www.ssdieselsupply.com/images/products/fullsize/62--20041226175457.jpg

it plugs into the ip on one end and wiring harness of the truck on the other,. just unplug it and plug the truck wiring harness straight into the IP,.
my best guess,. my next guess is your IP going bad,. there' a simple test for that (which said already doesn't seem to want to work) bring the rpm up up to 2000 rpm and see if it will hold it steady,.if it won't it probably is the IP

Just MY 2C

nick
NWEOI
YRMV
PDCC

DmaxMaverick
12-31-2011, 01:03
.........or an air leak.

Robyn
12-31-2011, 08:37
As Maverick mentioned AIR

install a clear plastic line on the fuel return nipple at the top of the Injector pump, run the thing to purge the line. (be sure to put a LOOP in the line)

If no air bubbles then thats not an issue, if you see a stream of bubbles, find out where the leak is and fix it.

If no air then the possibilities get darker.

The 96 does not have a filter harness, that stopped with the OBD1 stuff.

The run away with light throttle points real hard at an injection pump thats heading out the door.

You should be able to rev the engine very steady from idle to high RPM without surging or runaway.

Check the air thing first.

The PMD's will not cause the symptom you describe..

How many miles on the pump ???


Let us know

Missy

jamesm
01-01-2012, 18:43
As Maverick mentioned AIR

install a clear plastic line on the fuel return nipple at the top of the Injector pump, run the thing to purge the line. (be sure to put a LOOP in the line)

If no air bubbles then thats not an issue, if you see a stream of bubbles, find out where the leak is and fix it.

If no air then the possibilities get darker.

The 96 does not have a filter harness, that stopped with the OBD1 stuff.

The run away with light throttle points real hard at an injection pump thats heading out the door.

You should be able to rev the engine very steady from idle to high RPM without surging or runaway.

Check the air thing first.

The PMD's will not cause the symptom you describe..

How many miles on the pump ???


Let us know

Missy

No bubbles.

I removed the OS filter. No change.

Cleaned the grounds on the right rear intake manifold (near AC receiver/dryer). No change.

Warmed it up to 190 dF coolant temp (on OBDII scanner), and it runs "almost" normal. Idles lumpy in neutral, idles fine in gear. Still will rev to the moon with 1 mm pedal in neutral. Still no codes.

JohnC
01-01-2012, 20:04
the electronic pumps do not lend themselves to steady no load speeds, especially right above idle. However, if you have a sticky fuel solenoid, the situation will be exacerbated.

If you can get your hands on a scanner, you can use the cylinder balance function to figure out if it is one or several cylinders rather than a system wide issue.

Bad injectors sometimes show up much more prominently at low loads and seem fine under heavier throttle.

jamesm
01-03-2012, 21:13
the electronic pumps do not lend themselves to steady no load speeds, especially right above idle. However, if you have a sticky fuel solenoid, the situation will be exacerbated.

If you can get your hands on a scanner, you can use the cylinder balance function to figure out if it is one or several cylinders rather than a system wide issue.

Bad injectors sometimes show up much more prominently at low loads and seem fine under heavier throttle.

Engine/fuel warmed up enough today to act normally at neutral/idle. Mac scanner showed one historic code 1216 for solenoid time, and also allowed cylinder balance test. Each of eight showed pretty uniform droop/lope, followed by about two seconds of re-adjustment after turning injector back on.

Incidentally, scanner showed TDCO of -1, and fuel delivery of 1.25 mm^3 at idle/neutral, and ~4 mm^3 at idle/drive.

phantom309
01-04-2012, 09:30
Incidentally, scanner showed TDCO of -1, and fuel delivery of 1.25 mm^3 at idle/neutral, and ~4 mm^3 at idle/drive.

you have your own scanner,.??

awesome,.. wish i did,.

i did the optical 'bump' on this 5068 pump i have and it makes the throttle real twitchy,.if you let off quick while moving it around in the yard at very slow / low rpm etc,. it droops then catches it quick , touch the throttle lightly and it over responds then drops back quick,. very similar to an old 2 stroke detroit, with too wide a governor gap,.it,s also not happy about keeping a steady no load rpm above idle either,. but is rock steady with the fast idle switch on, (obd1 so only 1 setting)
Can you drive it and scan inreal time? data log so to speak?
I was also wondering about yourr throttle pedal,. but usually if it,s getting bad, the high idle switch will still keep the motor at steady rpm,.

Nick

jamesm
01-04-2012, 17:04
you have your own scanner,.??

awesome,.. wish i did,.

i did the optical 'bump' on this 5068 pump i have and it makes the throttle real twitchy,.if you let off quick while moving it around in the yard at very slow / low rpm etc,. it droops then catches it quick , touch the throttle lightly and it over responds then drops back quick,. very similar to an old 2 stroke detroit, with too wide a governor gap,.it,s also not happy about keeping a steady no load rpm above idle either,. but is rock steady with the fast idle switch on, (obd1 so only 1 setting)
Can you drive it and scan inreal time? data log so to speak?
I was also wondering about yourr throttle pedal,. but usually if it,s getting bad, the high idle switch will still keep the motor at steady rpm,.

Nick

No scanner. It a pal's co-worker's MAC unit.

Fast-idle--ONCE WARMED UP--is almost normal at 1100 (maybe 10% fishy). 1400 and 1600 are still lumpy, but do average out right around the setpoint.

Pedal showed three voltages on scanner, something about 1, and the other two around 4, as I seem to recall. And no "service throttle" light.