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Code 44 and 45 OBD1 Tahoe is weirding out

TurboTahoe

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Esteemed 6.5 colleagues, I humbly request your brainpower on this one:

0. Describe in detail the problem you are having. Please be as descriptive as possible.
Vehicle in Signature (Tahoe) starts and runs normally, but intermittently throws SES light, and then cuts vacuum to the turbo, causing loss of power. When going down the road, the light will then turn off, and turbo will come back on. Have checked for vacuum at pump - OK. Vacuum at solenoid - OK. Solenoid is only 3 years old. Replaced in June of 2005, at 156K miles. Also, purchased new wire harness for wastegate solenoid at that time, and used solder and shrink wrap (i.e. I think the electrical connection is fine). I think it might be the solenoid (again?) and will likely check to ensure that the electrical signal is getting to the solenoid when SES light is on (Have to wait til it happens again). Are they THAT flakey? Any suggestions welcome. Thanks! Rob. :)

1. Does the engine crank, or 'turn over'? YES
1a. Does the engine start and run? YES
1a1. If the engine does not start - Crack injector line: do you have fuel? Yes/No
1b. Do you have a Wait To Start Light & the amount of time (seconds) lit. YES, normal time of 5-10 seconds.
1c. Ambient Condition (temperature outside indicate F or C) _____ ° 65 degrees F.
1d. Engine Cranking speed (if you have an accurate tachometer). Normal (I don't look at tach when cranking, but it sounds normal)
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.

1h. Check turbo inlet and air filter for obstructions. Cone filters have lost disk and stopped air to turbo. NONE
1.1 Lift pump test - describe results NORMAL.
2. Service Engine Light while running?- on/off/intermittent INTERMITTENT
2a. Service Engine light does glow during start/cranking/bulb check: Yes/No YES
3. Model year 95
3a. Odometer reading (indicate if in miles or km) 176K
3b. Miles on major engine components if been replaced (example Injection pump) IP replaced around 135K, so around 40K on it.
3c. Indicate the model number on the Injection pump (starts DS4 or DB2......)
4. Have you scanned for engine codes? (varies by pre/post 96) yes/no YES
5. List exact results on engine codes: 44 and 45
6. Air Filter condition (visual check) Clean, normal.
7. Fuel filter condition (freshly changed/condition unknown/mileage since changed). Approximately 5K since changed.
8. Condition of Battery terminal connections (removed, cleaned and tightened) Cleaned, replaced with steel bolts, tightened.
8a. Known condition and age of the batteries. 3 years old.
8b. Are batteries of differing age or are they a matched set? Matched, replaced in pairs.
8c. Condition of Major Grounds. (same drill as batt - removed, cleaned, retightened). Appear fine -
9. Upon cold start, does the radiator hose get hard quickly? Yes/no NO
10. Upon cold start, do you have excessive white smoke? Yes/no NO
11. Do you have excessive cranking time before the engine starts? NO, in fact, starts very quickly.
12. Have you used the block heater, and does this effect engine starting?(only try for starting problems) NO
13. During hard acceleration, do you have excessive black smoke? Yes/no NO when SES off, YES when SES ON (i.e. when wastegate vacuum not present.)
14. Do you have any unusual exhaust smoke issues? NO
15. Turbo check out - pass/fail PASS
16. Do you have an EGR on the engine? (An F or an S engine code 8th VIN digit) line to EGR is blocked off, hasn't thrown codes for 3 years.
17. Indicate if you know if it’s a 1500, 2500, 2500HD, 3500, 3500HD. 1500, S code.
18. Indicate fuel that you are using: Bio-diesel, #2 Diesel, #1Diesel, SVO/WVO, other. Mix of Biodiesel and #2.
18a. If running a VO (Veggie Oil fuel) setup, indicate details of your conversion (homemade, or packaged system)
19. Are you using any fuel additives? If so, please list. NONE
20. Please indicate geographic region you are in: (example: Texas or Canada) OREGON
21. Do you have any service history available that might pertain to the problem you are having? NO
22. Please indicate any modifications to the vehicle that might help us diagnose better.
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) Heath Isolater kit!
24a. If remote mounted, describe wiring harness (homemade or purchased from a vendor?)
24b. Indicate the location and condition of the FSD/IP grounding wire. In stock location.
25. Are ALL glow plugs in proper working order as per this thread? YES.
 
I saw you replaced the harness. I can tell ya that sounds like a broken wire in the EGR solenoid harness just like I had. It drove me (more) nuts. Does it stumble like a miss when this happens? If you look at the plans, the solenoids are right on the +voltage line to the PCM so anything weird happens to them, it affects the way the engine runs.
 
I saw you replaced the harness. I can tell ya that sounds like a broken wire in the EGR solenoid harness just like I had. It drove me (more) nuts. Does it stumble like a miss when this happens? If you look at the plans, the solenoids are right on the +voltage line to the PCM so anything weird happens to them, it affects the way the engine runs.

Sorry John,

Didn't see your post.

It doesn't stumble, but it does kill the turbo wastegate - i.e. no vacuum to wastegate, so it kills the turbo. Truck suddenly loses power and rolls black smoke on acceleration. It's either the solenoids or the wiring, I think.

Rob :)
 
Yow. It looks like those solenoids are $40 each from the dealer - total of $80. Is there anyway for me to eliminate them without throwing codes or affecting other system components?
 
You can put a resistor where the were.. let me dig around to find what resistance value I used before the Heath prom got installed. I got out a potentiometer and dialed around until the CEL went out. :ihih:
 
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