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Help please got code 88

625fireman said:
the reason I asked about the stepper motor is that the rpm never changes or does the motor sound any different during the entire process while time set or tdco learn.

Its wierd while doing the time set it is 0 in the first box, the center box has NEVER gone below 5.8 and has gone as high as 13.4 but it always goes to set at 8.5 +,- 1.0.

Again no matter where the pump is physicaly on the truck the times set and the TDCO numbers ahve not changes since the first time I ran it.

However listening to the engine it does not sound the same when I move the pump so I know I am changing the timeming but I have no clue where it is at.
Click to expand...

GMTDScanTech doesnt up the idle rpm or anything when doing the timing. Neither does CarCode on OBDII trucks. The only time youll really get bucking is when its too retarded.

The -2.02 is the biggest tell here, it means youre too far to the drivers side. And you collected even more info to show you just how much because its sitting at base timing of 5.8+ degrees, which means its too advanced by 2+ degrees, and you need to go a healthy amount to the passenger side. Anything over 4 degrees and it will ALWAYS show -2.02, thats just the limits of the scanner, it just means its out of tolerance. Thats why it isn't changing at all.

The 8.5 degrees that it always ends up on is just the PCM commanded timing during operation that the stepper motor brings it up to at idle. You cannot change that desired value during operation without reflashing the PROM.

I think you got it figured out now.
 
orrum said:
Errr so how do u set ur TDCO in a mech, DB2? Matter of fact how do u set the IP period?
Click to expand...
No TDCO on mechanical pumps.

Set timing with special tools that can detect the pulsation of the fuel line, or putting an optical sensor inside the glow plug hole to see the start of combustion while using the timing light on the balancer.

But most people do it by feel and sound.
 
buddy said:
GMTDScanTech doesnt up the idle rpm or anything when doing the timing. Neither does CarCode on OBDII trucks. The only time youll really get bucking is when its too retarded.

The -2.02 is the biggest tell here, it means youre too far to the drivers side. And you collected even more info to show you just how much because its sitting at base timing of 5.8+ degrees, which means its too advanced by 2+ degrees, and you need to go a healthy amount to the passenger side. Anything over 4 degrees and it will ALWAYS show -2.02, thats just the limits of the scanner, it just means its out of tolerance. Thats why it isn't changing at all.

The 8.5 degrees that it always ends up on is just the PCM commanded timing during operation that the stepper motor brings it up to at idle. You cannot change that desired value during operation without reflashing the PROM.

I think you got it figured out now.
Click to expand...

Thanks buddy Iill post my final finding/settings.

I owe you one.
 
buddy said:
No TDCO on mechanical pumps.

Set timing with special tools that can detect the pulsation of the fuel line, or putting an optical sensor inside the glow plug hole to see the start of combustion while using the timing light on the balancer.

But most people do it by feel and sound.
Click to expand...

Good luck finding those tools. I've been looking for awhile...
 
Alright I got it. Once I cranked the pump to pass side the time set to set at +3.5 then i got the TDCO offset to +1.85. So then it was a SLOW process to get her back down.

And low and behold I got the elusive -1.94. and yes as stated before it is a dieselgasm when that little number pops up. The neighbors definatly heard the yee haw outta me!!!!!!!!!!!!!!!!!!!!!

Thanks to all who had any all input on my headache YOU guys and gal are the best!!!!!!!!!
 
orrum said:
So Ace how is ur seat of the pants timing???? Can u do it? Any chance a newbie could get it done?
Click to expand...

Truck should sound a little marlbly upon acceleration. Hard to describe, just know what it should sound like but FWIW pretty much almost every DB2 I have done I ended up with the mark on the IP about a matchbook covers thickness to the drivers side from the case mark. Hell, with a IP swap I just start there now. I have yet to see one run good with the marks lined up. if the engine is tioo quiet and smooth and hard starting it's retarded(like me) If it's really noisy/knocking then too far advanced. Kent Moore made a special timing light that could pickup the pulse on the # inj line and you timed it just like a gasser off the Harmonic Balancer to spec. In fact as I later learned with my 93 GM put an adapter on the #1 line on the later DB2. Supposedly the Snap ON MT480 can also do this but good luck fining that as well. Kent Moore currently makes a "Tach N Time" But I have yet to get a straight answer from anyone selling them if they work on DB2s...I wonder if Ford ever made a tool as well. I would think the same procedure would work on a Ford 6.9/7.3 IDI bu I always timed them by ear as well.
 
625fireman said:
Alright I got it. Once I cranked the pump to pass side the time set to set at +3.5 then i got the TDCO offset to +1.85. So then it was a SLOW process to get her back down.

And low and behold I got the elusive -1.94. and yes as stated before it is a dieselgasm when that little number pops up. The neighbors definatly heard the yee haw outta me!!!!!!!!!!!!!!!!!!!!!

Thanks to all who had any all input on my headache YOU guys and gal are the best!!!!!!!!!
Click to expand...

That's good I still don't know how to do it. You should do a write STEP by Step for the complete idiot. In fact a youtube would be even better...:D
 
Acesneights1 said:
That's good I still don't know how to do it. You should do a write STEP by Step for the complete idiot. In fact a youtube would be even better...:D
Click to expand...

Thats an idea for the write up. As for the youtube youall dont want see or hear me on your comp.
 
Nice Joe......Feels good, That DieselOrgasm!

Glad your back to where you should be......Any change in performance, that you feel, at the magic -1.94?
 
Chief915 said:
Thanks for the mental pic....... :eek: :nonod:
Click to expand...

Really..............well atleast he didnt say RuPaul.


As for a change in perf or seat of the pants driving..................not a big change. It definatly starts easier, and seems to be a little peppier but it does have 112,000 on her and she weighs almost 5k so I know she aint gonna get up and chase down a duramax,,,,,,,,,, well at least not yet :hihi:
 
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