[Diesel Novice]

Well, today I finally got a chance to hook my laptop up to my 95 gmc vin f. These are some of the results. Keep in mind that the truck runns like crap snoking and such when COLD, once it warms up its ok.

Results:
Coolant temp after warming up 195.7*F
Intake air temp 76.8*F
Injector pulse width 1.69mm
Crank pulse and cam pulse sensor 0
Idle fule rate Fluctuating rapidly between 5.44 and 7.19
Barametric pressure 13.93
Fuel pump timing 31.5* at idle, as RPMs increase so does the timing
Desired timing 9*
Actual timing 9.1*
TDCO -2.02


I am thinking I don't understand the timing on the fuel pump being 31.5*


Any help is greatly appreciated!

Craig

 

[gmctd]

Any DTC's?

I'm not even understanding that "fuel pump timing = 31.5deg at idle" thing

1.69ms injector pw is way on the low side - should be around 1.84ms - seems like there ought to be a DTC 35 for pw short

Des\Act at around 9deg is acceptable as long as they're within 1/2deg or so, but you're the third post where initial TDCO value is -2.02deg.

The varying idle and high TDCO value sounds like a bad case of the 'BUMP', where someone did the Optic Sensor adjustment, and thought - if a little is good, a whole bunch is better.

The varying idle, coupled with the low Inj pw, could be fuel supply problems - checked your lift pump operation and fuel filter?

I've borrowed a Celeron laptop with a 10gig HD which has only 269meg of free space and 128m memory, so I'm attempting to clean it out for GMTDScan-tech installation, here shortly - this thing is as slow as a Pc-AT\8088

 

[Diesel Novice]

In the GMTD program it has a selection to monitor injection pump timing, that is what the 31.5* is when I am ideling. As the RPM's increase the number increases also, (the way I am thinking is like a vacuum advance on a gas engine would work) when the rpm's increase the number goes up w/ them at 2000 rpm it is around 36.0*

Fuel lift pump is new, fuel filter is good

I don't knolw what the "bump" means or even what the optic sensor is.

There aren't any codes now, there was one, it was #2 cylinder balance problem. That could be from when I did the individual injector test, or from replacing them and when it first started. I do have a problem when it is cold that it smokes and chugs until it warms up. Turning off the #7 injector gets it to reproduce that same situation while warming up.

 

[Diesel Novice]

does anybody that has used the GMTD scan tech program, have any comments on these #'s?

 

[gmctd]

The OPS controls the lift pump - no power, no fuel.

Again, the symptoms indicate fuel supply problems - low fuel rate, low inj pw, erratic idle.

Or, the PO over'bumped' the Optic Sensor - the IP is dumping more fuel than PCM is demanding.

Do the diagnostic checklist in FAQ's, post the results on the lift pump test.

 

[autoxsteve]

I suspect your injection pump needs to be adjusted.

Also, I noticed you've got a few miles on the engine. When did you replace the fuel injectors?

If you haven't replaced them since new, I'd strongly encourage you to do so. They are probably worn if their original.

Regarding the TDCO of -2.02, I had that too. I have GMTDScan Tech as well.

I did a TDC time set and a TDC learn when my truck had no codes showing. After that time, I started throwing DTC88.

I finally got the code to go away by adjusting the injector pump towards the pass side of the truck, and got tdco to -0.18 deg.

Once I did that, my codes have disappeared.

 

[gmctd]

If PCM wsn't logging a DTC for high TDCO BEFORE you connected the scanner, there was no reason to adjust the Inj Pump - you created the DTC WHEN you adjusted the pump.

Somethin' ain't kosher, there, IMO - this bears lookin' into, as the gynecologist said.

 

[Diesel Novice]

I did replace my Injectors about........0 miles ago, I just ran it since they were replaced, but didn't drive it.

GMCTD- this does have an aftermarket chip in it, but even w/ the factory chip it still does the same thing.

 

[Diesel Novice]

1.Lift pump test - New, when opening drain valve on filter I get fuel underpressure
2.Service Engine Light - off
3.Model year 95
3a. Odometer reading 198,000miles
3b. Miles on major engine components if been replaced NEW injectors, New Fast heat glows, New glow relay, New crank and bearings at 100,000 miles
4.Do you have any engine codes? No.
5.If you do have engine codes -
6.Air Filter condition NEW stock paper
7.Fuel filter condition (freshly changed )
8.Condition of Battery terminal connections (cleaned and tightened)
8A.Known condition and age of the batteries. 3 years
8B.Are batteries of differing age or are they a matched set? matched
9.Upon cold start, does the radiator hose get hard quickly? no- even when hot after driving it doesn't get hard
10.Upon cold start, do you have excessive white smoke? Yes
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? didn't try it
13.During hard acceleration, do you have excessive black smoke? no
14.Do you have any unusual exhaust smoke issues? when starting smokes whitish blueish for 10 minutes if left to idle, clears up after 200 yards if driven right away (when smoking you can't even see the truck)
15.Turbo check out - pass
16.Do you have an EGR on the engine? F engine
17.Indicate if you know if it’s a K3500.
18.Indicate fuel that you are using: #2 Diesel,
19.Are you using any fuel additives? Marvel mystery oil 1 pint at fill up
20.Please indicate geographic region you are in: Eastern Pennsylvania
21.Do you have any service history available that might pertain to the problem you are having?Just bought the truck in september
22.Please indicate any modifications to the vehicle that might help us diagnose better.3" exhaust turbo back, no cat or muffler, BD EPROM CHIP
23.Upon unscrewing the fuel cap, do you have a large vacuum formed in the tank? no
24.Location of PMD/FSD? on the pump
25.Are ALL glow plugs in proper working order as per this thread?Replaced in oct06 w/ fast heats

 

[autoxsteve]

If PCM wsn't logging a DTC for high TDCO BEFORE you connected the scanner, there was no reason to adjust the Inj Pump - you created the DTC WHEN you adjusted the pump.

I believe you may not understand what I did (sorry to lead this thread astry). I did not adjust the IP before the fault code. The Fault occurred after I did a timing set and TDC Learn (via GMTDScan Tech), which created the same results (for measured timing and offset) as before I set them (when I ran them they did not change the results).

Odd, no?

 

[gmctd]

Yes, it is odd, and no, you didn't confuse the issue - adjusting the IP is part of the timing procedure.

Your truck had no failure symptom until you scanned and initiated the timing procedure.

I've got a cable coming, and will have more info, shortly.

I would suggest scanning your vehicle, then posting the data for confirmation prior to making any adjustments.

As the proctologist said, we'll get to the bottom of this.