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Discussion Starter · #1 ·
The truck starts and runs fine. Power seems adequate. There is a little more noticeable "knock" when it shuts down than I used to remember (but then that could be my memory). The problem I’m having manifests itself in two basic modes.

The first is when starting off, sometimes the engine seems to slightly accelerate on it’s own, and when the pedal is released to control this the truck jerks back & forth a few times trying to find a point of "equilibrium". Once you get underway and generally when the truck is traveling on level ground, accelerating, under a load or at lower speeds everything seems "normal".

The second is if the truck is traveling at a higher speed and you begin to decelerate or coast (such as starting down a hill or letting up ever so slightly on the pedal), that same "jerking" is apparent, and depending on the reaction of the driver either continues to "oscillate" or cease (releasing or increasing APP significantly or putting the engine under load seems to stop the jerking - minor APP adjustments seem to perpetuate it longer). If you are paying attention and correct quickly, usually you can limit the "jerk" to a single "off" if you continue to decelerate - or an "off/on" if you continue to accelerate. The problem is more noticeable when using the cruise control (as it tries to subtly maintain speed).

The truck has never stalled nor failed to start (except when there was air in the line a few times). First problem seems to have been present ever since I purchase the truck used (@ 156K). The second problem started last spring after I had ran about 5000 miles on WVO. Got me thinking the hot WVO might have damaged the PMD or OS. The problem is livable, but a PITA nuisance. Doesn’t seem to be getting worse, after another 3000 miles on WVO & diesel (shorter trips).

Although I’ve taken quite a bit of time to search, read, and sort through lots of threads, I don’t feel I really I have a good handle on the cause of problem. None of the threads I found seemed to be exactly like my problem. One solution suggested was an optic sensor adjustment. Not having performed an OS/IP replacement, I’m a little cautious about tackling these without feeling pretty certain what the problem is and knowing exactly what I’m up against (tools, proper testing/replacement procedure & calibration - I only have a Chilton manual which has proven to be wrought with occasional errors and omissions).

So I’m hoping the collective experience of forum members can provide some good advice and help speed up things by pointing me in the right direction for diagnosis & remedy. Thanks.

DIAGNOSTIC CHECKLIST
1. Does the engine crank, or 'turn over'? YES
1a. Does the engine start and run? YES
1b. Do you have a Wait To Start Light YES & the amount of time (seconds) lit. ~5-15 seconds (depending on engine temp)
1c. Ambient Condition (temperature outside) 40 F (or less)
1d. Engine Cranking speed (if you have an accurate tachometer). Rapid
1e. Are you experiencing stalling? NO
1f. If Stalling, describe (upon startup only, down the road, hit a bump etc)
1g. If Stalling, do you notice loss of dash or instruments?
-note if experiencing stalling,you must indicate PMD location in #24.
1.1 Lift pump test - describe results Initial test - NO fuel coming from the T-valve, engine died from sucking air. Inserted volt meter on positive lead to fuel pump (at disconnect plug below wiper motor) - pump receiving 2-4 volts. Connected jumper to battery - pump now receiving 14.5v. Re-primed fuel filter, started truck, fuel now coming from the T-valve. Replaced OPS and added relay control per schematic from HowieE. Pump working great now.
2. Service Engine Light while running?- on/off/intermittent Normally OFF, in the past was intermittently ON when pulling a load uphill at speed and/or with AC on and engine under load. Have not noticed SES on since OPS replacement.
2a. Service Engine light does glow during start/cranking YES/bulb check OK
3. Model year 1994 - 1GCGK29F9RExxxxxx (VIN)
3a. Odometer reading (indicate if in miles or km) 213,200 miles
3b. Miles on major engine components if been replaced (example Injection pump)
New vac pump,OPS @ 127,494 miles (Dec 1999)
New IP DS4-5288 , 8-NA56x rebuilt injectors @ 138,863 miles (Jul 2000)
New lift pump @ 140,136 (Aug 2000)
New lift pump, fuel tank & sock cleaned @ 196,400 (Aug 2005)
New OPS & relay, starter solenoid (Dec 2007)
(other repairs presumed not pertinent to this problem not listed - ie: water pump,harmonic balancer, belt, starter solenoid, transmission, etc.)

3c. Indicate the model number on the Injection pump (starts DS4 or DB2......) DS4-5288
4. Have you scanned for engine codes? (varies by pre/post 96) yes/no previously- NO, prior to this thread- YES
5. List exact results on engine codes: Codes never checked prior to disconnecting battery power for starter solenoid repair (didn’t know how) - upon reconnect downloaded codes (from info on the DP forum) - endless repeat of 13 (with NO preceding 12) - reset diagnostics then only 12 - have run the truck since with problem symptoms showing, but NO codes other than 12.
6. Air Filter condition (visual check) GOOD - K&N last service Dec 2006, inspected recently - very good, 50% still ‘red’ from last refresh (both sides)
7. Fuel filter condition (freshly changed/condition unknown/mileage since changed) Fuel filters changed frequently - last two times Dec 2006, Sept 2007
8. Condition of Battery terminal connections (removed YES, cleaned YES and tightened YES)
8a. Known condition and age of the batteries. New Batteries Jan 2003
8b. Are batteries of differing age or are they a matched set? Matched set
8c. Condition of Major Grounds. (same drill as batt - removed, cleaned, retightened) Cleaned & tightened neg batt grounds, added 10ga copper supplement to braided firewall to engine ground (cleaned engine side- couldn't access firewall ground.
9. Upon cold start, does the radiator hose get hard quickly? Yes/no Unknown, but engine warms up nicely & does not overheat.
10. Upon cold start, do you have excessive white smoke? NO
11. Do you have excessive cranking time before the engine starts? NO
12. Have you used the block heater, and does this effect engine starting? Not at 40 degrees - helps cranking speed at considerably lower temps.
13. During hard acceleration, do you have excessive black smoke? Yes/no Have noticed this in the past primarily going uphill, pulling a trailer, pedal down to the floor - other wise NO, including hard acceleration on level ground.
14. Do you have any unusual exhaust smoke issues? None observed.
15. Turbo check out - pass/fail Unknown
16. Do you have an EGR on the engine? (An F or an S engine code 8th VIN digit) YES (F code)
17. Indicate if you know if it’s a 1500, 2500, 2500HD, 3500, 3500HD. 2500
18. Indicate fuel that you are using: Bio-diesel, #2 Diesel, #1Diesel, SVO/WVO, other #1 Diesel, then home-brew Bio-diesel for 1 year, then DIY WVO conversion (#1 diesel startup/shutdown/short trips) since Nov 2006 (8K miles)
18a. If running a VO (Veggie Oil fuel) setup, indicate details of your conversion (homemade, or packaged system) 70 gal. alum.aux.tank in bed; lift pump (same as stock) for VO at aux tank (a relay switches between the lift pumps); 3/8" alum VO fuel tube inside ¾" heater hose to engine compartment; separate VO filter in engine compartment (same as stock but with added heating element); to fuel switch (VO / diesel); to pre-heater (DIY - 75-120watts); to IP; return line to fuel switch (recirculate to IP / return to diesel tank); panel switches to control fuel switches and heaters via relays; temp guage monitors IP input, VO tank, and VO filter temps; electrical system fused and off/on with ignition sw.
19. Are you using any fuel additives? If so, please list. With VO - NO; with diesel occasionally Power Service Cetane Boost (mostly cold weather).
20. Please indicate geographic region you are in: (example: Texas or Canada) Idaho - late spring through fall; Mexico - winter
21. Do you have any service history available that might pertain to the problem you are having? Don’t think so, but had to replace some leaking return lines from bio-diesel softening. Also have had two bouts of transmission problems (think that is finally solved).
22. Please indicate any modifications to the vehicle that might help us diagnose better. None other than those mentioned elsewhere.
23. Upon unscrewing the fuel cap, do you have a large vacuum formed in the tank? yes/no NO
24. Location of PMD/FSD? On the pump/remoted over intake/remoted out of engine bay (please specify placement specifically) PMD was still intact until recently - wasn’t aware of remote mounting issue at time of VO conversion - recently remote mount FSD using film pad on HD alum finned heat sink to driver’s side near air intake aft of washer reservoir.
24a. If remote mounted, describe wiring harness (homemade or purchased from a vendor?) DIY 62" harness extension - used old FS>PMD harness with existing female plug on one end, spliced, soldered & insulated inline using 12 ga.flex copper wire inside flexconduit - made a male plug for other end using other (gray) connector from harness (casing form fits female with some dremmel work), J-B welded the pins to fit female - connected in similar fashion (used existing 4 pins & added 2 modified paper-clip pins) -(works & looks good)
24b. Indicate the location and condition of the FSD/IP grounding wire. Before research here, spliced in 8" to try & mount FSD to intake manifold & ground wire to IP; after research removed splice (I think the wire is 1/8" longer now) and attached to IP (changed mounting screw to pass side, cleaned connection)
25. Are ALL glow plugs in proper working order as per this thread? Unknown, but engine starts great.
 

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Discussion Starter · #3 ·
Are you implying that the OS failure is permanent due to heat or that the OS fails to operate properly in the presence of WVO. If it is due to heat, is there any preventative measure or workaround (such as limiting temp?), or are all drive-by-wire 6.5's doomed to run only on "cool" diesel? If the later is true, which trucks are good to go with WVO?

Are there any threads that talk about exactly how the OS works to affect drive-ability related to the problems I'm having.

Anybody out there have any long term success stories with using heated VO/WVO in drive-by-wire 6.5's?
 

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You have coated the sensor with what I call gunk. Heat is not a problem with the sensor.
 

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Discussion Starter · #5 · (Edited)
I drove the truck today down a long hill using WVO. The jerking began and I then switching to diesel. After about 60 seconds -time to purge the WVO (or might it be thin out - still in re-circulate mode), the jerking gradually subsided and seemed to stop. Then I switched back to WVO and in about the same time the jerking started again. Don't know why I didn't try this earlier. Seems you are correct. I've filtered the WVO down to 5 microns. Is it the opacity of the WVO that causes the OS to fail? In recalling what the inside of the IP looks like, I'm assuming that the OS reads a visual light wave (or is it infrared?) that is broken by the perforated timing disk in the IP. If that is so, how is that wave generated?
 

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I'd check your crank pully and harmonic balancer because of the clunking you describe when you shut it off. I had a clunk like that and it was the crank pully. While your other problem is probably related to the WVO since you can create it or make it go away, I had a shutter/jerking in my truck at 55 MPH and 1500 RPMswhen the TCC was locked up in OD and replacing the crank pully fixed that too.
 

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Discussion Starter · #7 ·
DieselPro - I'm curious to understand exactly how the OS is electrically constructed and what it's principals of operation are - if you know this? If not, who would you recommend I pose this question to?

fonecop1 - I had a SERIOUS knock at shutdown a couple years ago, which WAS a bad harmonic balancer that I replaced (the rubber connecting disc was "rotten"). The current "clunk" is very subtle, but I will take a closer look at the crank pully. Other than having it securely bolted, and finding it not bent, misaligned or otherwise damaged what might I be looking for?
 

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One other way to test to see if the optical sensor is the culpret is unplug it and drive. You will get a check engine light however. If it runs w/out the same issues it is probably the culpret. TD gave me this test to do when I was having problems w/ my IP. Basically the pump is going to run off the PCM instead of the FSD. IT will not be as responsive.

After that I would take some diesel purge or seafoam and pour it into the filter housing w/ a new filter and start it up. That should help clean off the Optical sensor if it is clouded. If you can hook it up to the intake before the LP and run a few cans of it through the fuel system while idling may fix your problem.

MY guess is The WVO you are using is dark. If you run diesel purge or sea foam through when you do your oil changes it will prevent it from happening again.
 

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Discussion Starter · #10 ·
DieselPro - thanks for the link - good info. Does the light emitter dim over time/use? Any way to bench test these devices?

Rodd - Found some seafoam - plan to run some through the fuel filter (on the diesel side of the system) tomorrow to see if that helps. I agree with you on your diagnosis. From what I've learned, how the truck performs on WVO & diesel, and visual inspection of the WVO, I think the WVO is inhibiting light transfer to the sensor and confusing the PCM. If that is the case and the seafoam doesn't clean off the emmitter/sensor then I guess I'll try to filter the WVO down to 1 micron (or change suppliers). If that doesn't work, is it possible to "step up" the light output? Any other options?
 
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