Hi guys I'm new here so make fun of me if you want! What I have is a 94 3/4 ton 6.5TD VIN F. Here's my problem(s): At first I had codes 34 and 88. Which is ITS motor, and TDC offset. Well my dumb ass went and had the Injector pump done, put reman injectors in it, an FSD cooler, 4" Exhaust, and a new FSD. Now I took it to the dealer on Monday and had them re-learn the TDC offset, but when I picked up my truck code 88 was back, so today I put a new PCM in and had the TDC offset relearned, now this thing runs so poorly I wanna kill it. The pump timing is at what the pcm requests, what I'm wondering is: do you have to set the pump timing, then the TDC or vice versa. Also after the new PCM, now I have trans code 85, high ratio error. I had 0 trans codes before, just the 88 after I installed the pump. I also hear a knocking noise in the cab like a stuck injector, but can't hear it outside the truck. Here is another problem you may know about, I put a timing chain in it when I first bought it, the old chain was VERY VERY loose, so I put a new chain and gears in and it was still 1/2 or so loose. I just need some help!!!!! I'm hoping someone out there can talk the talk with me, I've tried to ask people but they just laugh, so here I am.


Thanks a million for ANY help JamesEdited by: quantum mechanic

Hello Superpro82,


I'm sure we can help you make some sense of it.


Sorry about that edit, just wanted to see my name on your post.

The knocking noise you hear is probably the heater core pipe touching an injector line. (Probably about 8 or 10" from the thermostat housing)

whatnot YOU ARE GOD ON THAT NOISE!!!! I went out and moved the pipe and no noise, but it still runs bad lol Thanks!

Did you clear the codes after you got it back? I just remembered that mine had a codee 88 in it after I had the TDC set. I think they ran it too far and set the code then backed it up.

yeah, I reset the code, but the guy setting the TDC this time, I have no idea where its at, he didnt know much about these.

Will the TDC offset being off make it run this bad if it is off? And also, do you set the timing first or after the TDC?

Can you describe what kinda "bad" you are talking about? Black smoke, no power . . .


How's simple maint. items like air filter, fuel filter, etc. I'm only ASSUMING that the lift pump works great after IPump change out, is it?

all new, no power, white smokes, lift pump does work, but I'm kind of thinking you should hear it until pressure builds then no noise? Mine makes continuous noise.. like its not pumping fuel?

SP,


White smoke might indicate timing retarded. The stepper arm on the passenger side of the pump may help you set timing if you loosen the three 15mm bolts and push it to drivers side with the truck idleing. Constant pumping of the lift pump says that you're not building pressure and possibly leaking fuel/pressure after the liftpump. Do you ever smell diesel or see it in the pump valley. Edited by: quantum mechanic

I have the timing now at like 9 degrees according to my snap on scanner. I do not smell or see the fuel, but I will look at the fuel filter tomorrow, what my question is, does the TDC need to be set before or after you time the truck, I do not know where the TDC offset is as of now, my scanner just says 0.0 for the TDC offset. I also believe that this is all in the timing/possible air in fuel now that whatnot helped me correct the knocking noise, so like I say, I'll check the fuel filter tomorrow. also, could it be possible to be not returning enough fuel?

I think that might be the problem.


The scanner should show a TDC between -0.5 and -1.9 (1.94 if it has that many digits)


I would go back to where you had the timing set and make them fix it at no charge or give the money back if they can't.

Well, I put another ECM in the truck today, the tranny codes didnt come back. Oh, sorry about so late, went on vacation. But now I'm looking for updates for a TECH-1. Anyone know where I can get them cheap? I have a TECH-1 but it only goes to 1992. I think if I get the updates for it I'll be happier myself fixing the problem. Now for another thing, Before I started having these problems, my engine did not have a miss in it, now that I have changed this all if I free rev the engine it will white smoke and misfire. I am going out right now to check the fuel filter. I'll get back here in about 20 min or so.


Thanks again

What series ECM and prom did you start with? & change to?


94 non egr was a special prom for the 5068 pump. Any other ECM will cause problems. Switch prom chips between units or order a gm replacement from prom ID# on original prom.Edited by: quantum mechanic

Quantum, The ECM SVC # is 88961136 AC Delco witha BXRF prom, I went back to the same, the original ECM would not take the TDC offset learn. I still have not had it programmed yet, but I will as soon as I can fin the updates for the TECH-1 or find someone around me that knows what they're doing.


James