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Pulling my hair out

S

Sawsall

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Jacksonville, NC
My buddies 1994 1 ton ramp truck/car hauller with 4L80E auto trans. I replaced the engine with a engine I built. (side note not to brag, but to qualify I know how to build an engine, specifically a 6.5. I've personally built litteraly over a thousand 6.5 engines and run them in on a dyno. I work for the largest user of 6.5 engines in the world. I have been the QA/QC of the engine rebuild shop for the past 5 years... they are all mechanically injected.) This is my first DS-4 pump. All moving parts in the engine are new, new heads, new bosch injectors that I personnaly checked, pop tested and calibrated...

Installed and fired it up... It had a dead cylinder. after some checking, swapped injector from good to bad cylinder (same cyl still dead). compresion test for dead cylinder was great. After discussion with my buddy, decided the pump was bad from his past info. He said he had injectors replaced but still had a weak cyl, turns out the same cyl that is dead.

New pump, fired up and all 8 hitting good and engine smooth... But very rich, eye watering blue smoke rich!!! sluggish throttle responce in park and nuetral, none in gear... A call to the folks in Wilmington where we bought the pump and some research/reading here and other sites, we determined it was timing and needed relearn.

We purchased Engh Motors GMTD Scan Tech and cable and ran it today... I set the TDC and got it within 0.8 and then ran the Learn... ended up TDC offset 1.97...

Now, Fuel smoke is worse, throttle response worse and just barely moves... What am I missing????????????

Plugged the PMD in that was on the truck before the engine swap and the same... So i don't think it is a communication problem between the PCM and pump/PMD??? I went through every sensor on the scan tool and nothing looked out of wack... turned off and on all 8 injectors, the fuel rate is high (fluctuates between 25-28)...

SOMEBODY Point me in the right direction PLEASE... Thanks...
 
Is your TDCO a 1.97 or a -1.97? If it is 1.97, then your timing is quite a bit off. You want it to be around -1.25 to -1.50 for optimal performance and minumal engine rattle. Also did you have the injectors checked? I would NEVER re-use injectors from a bad engine in a new engine without at least having them pop tested.
 
Welcome to TTS

The fuel rate should be between 6-11mm3 thereabouts. I don't know if your rate would cause any problems, less than 6mm3 will cause touchy throttle issues.

The 1.97, is that - or +? IF + move the pump about 1 mm towards the drivers side and redo the learn and TDCOffset.
 
THEFERMANATOR said:
Is your TDCO a 1.97 or a -1.97? If it is 1.97, then your timing is quite a bit off. You want it to be around -1.25 to -1.50 for optimal performance and minumal engine rattle. Also did you have the injectors checked? I would NEVER re-use injectors from a bad engine in a new engine without at least having them pop tested.
Click to expand...

+1.97 New and tested by me Bosch injectors
 
25-28Mm3 of fuel is enough to be pushing you down the road at 60 MPH or better. Mine only runs around 22-25 running 70 on interstate flat gound. Wit hthat fuel rate you either have bad inejctors, your pump is messed up, or a REALLY bad PMD/FSD.
 
NVW said:
Welcome to TTS

The fuel rate should be between 6-11mm3 thereabouts. I don't know if your rate would cause any problems, less than 6mm3 will cause touchy throttle issues.

The 1.97, is that - or +? IF + move the pump about 1 mm towards the drivers side and redo the learn and TDCOffset.
Click to expand...

+... Will the wrong timing affect the fuel rate?
 
Sawsall said:
+1.97 New and tested by me Bosch injectors
Click to expand...
You need to get that back to a negative. You have the pump ring WAY out past it's normal operation range with that offset. I'm trying to remember, but I believe an offset that high has your timing off by about 8-10 degrees at idle.
 
THEFERMANATOR said:
25-28Mm3 of fuel is enough to be pushing you down the road at 60 MPH or better. Mine only runs around 22-25 running 70 on interstate flat gound. Wit hthat fuel rate you either have bad inejctors, your pump is messed up, or a REALLY bad PMD/FSD.
Click to expand...

Right! as posted above I need to be in the - range -1.25-1.5... will the wrong timing affect the fuel rate that much?
 
THEFERMANATOR said:
You need to get that back to a negative. You have the pump ring WAY out past it's normal operation range with that offset. I'm trying to remember, but I believe an offset that high has your timing off by about 8-10 degrees at idle.
Click to expand...

but, at idle, the desired timing and actual timing was with .5 of each other... if I recall correctly it was around 4-5
 
Desired/Actual factory are usually 3.5/3.5, my tune IIRC is 8.5/8.5

+2.02 to -2.02 are the limits before a timing code is set. Most go for a - TDCOfset, -1.94 is about as far as you want, the colder the climate the less - number for less rattle on start.
 
Anything under 0 for TDCO offset can cause issues. Get your timing correct 1st, then go from there. With your TDCO you're already running right at the end of the ramp plate for the pump.
 
When everything else is straightened out you may still have to adjust the optic sensor to get the idle fuel rate in line. There are old threads on how to do it.
 
reset the timing. got the TDC offset to -1.23 throttle responce still sluggish in nuetral. worse in gear. not enough power to get it over a 1 inch lip to get it back in the shop... no codes...

don't know if I'm doing something wrong or something wrong with the truck... FRUSTRATED! to say the least... HELP!
 
I believe I have figured it to be the wrong pump... found the reciept for the pump and called them. My buddy told them it was a 96, but the truck is a 94 which is a one year only pump. the pump he bought is a 5521 and we need a 5068.

would a ecm or chip change work or do I have to change the pump again?
 
A chip swap will work. You want to find one from a 95 is the cheapest route. Factory EEPROMS are all but gone, and the few left are going for big bucks. Have you verified it in fact needs a 5068 pump? Not all 94's came with the 5068, and if GM ever put a pump in it, the EEPROM was changed to work with a 5521 pump. Need to check the broadcast code on the current EEPROM to see if it is a 5068, or a 5521 compatible chip. It sounds like you got the wrong pump in it, but just want to make sure you didn't get a bad pump as this has happend to more than a few.
 
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