I want to advance timing a bit and also change TDC offset. From reading FAQs, factory set timing is +3.5deg advanced, with -0.5deg TDC Offset. I'm running the HP4, turbomaster, and OE injectors. As for the TDC Offset learn I understand that the Tech II programmer must be used. The desired TDC offset for performance is -1.94, but has effect on cold starts in cold climates. As far as I know the timing is adjusted by rotating the head on the pump and reading the time with a scanner, is this correct? How is the TDC Offset adjusted? My question for you, what should I have my truck timing/TDC set to for optimum performance? Is there other scanners that I can see where my timing is set at right now besides the Tech II that can set it?

I am not sure if a Snap On can do it but Tech II for sure and another one, can't remember.

You activate time set first, then look at actual timing, if its around 3.5-4.0 deg's, your pretty close. Now exit and set TDO, it will take a few secs then read and you want -1.5 to -1.94. If you find its over -2.02 then you need to rotate the pump towards the passenger side, clear the code and redo time set and TDO. YOU MUST clear the code and it must be hot or it won't activate. As soon as the TDO sets, you can exit, you don't have to wait 20 secs and if you rev it up, it can change, so you can rev to get your setting if your close, then exit.

car code is also capable of doing this I believe. However if you have the Tech II scanner than by all means use that. indeed -1.94 is the ideal TDCO for our trucks. If you don't have acess to the scanner or car code(its like $120 for the computer to truck interface.) you can have the stealer do it. Just be sure to go over there work in detail, and tell them what YOU want done. Otherwise they may put something else.

Thanks guys, my buddy and I recently timed his 7.3IDI with a DB2 pump and it was really retarded :D. It should have been +8 (+-2) and it was +.5. We had access to a snap on scanner for his. After the timing was corrected it sounded much better, a more pronounced diesel knock, and much improved power. I plan to get mine done at a international dealer/service center, I just wanted to know a game plan before I explain what I want done.

Thanks guys, my buddy and I recently timed his 7.3IDI with a DB2 pump and it was really retarded :D. It should have been +8 (+-2) and it was +.5. We had access to a snap on scanner for his. After the timing was corrected it sounded much better, a more pronounced diesel knock, and much improved power. I plan to get mine done at a international dealer/service center, I just wanted to know a game plan before I explain what I want done.

First off, I'd like to know how a scanner is supposed to see the timing of a mechanical Diesel? A timing meter, but not a scanner. Next, don't take it to an International dealer. They will likely be lost. Best bet is to get Autoenginuity and DIY or take it to a GM dealer.

CarCode and Autoengenuity are both laptop bi-directional scanners that can read and set timing. If you knew your timing was at factory specs you could rotate the IP 1mm to the drivers side and then do the "key on, key off" routine outlined in the stickies.

Leo

First off, I'd like to know how a scanner is supposed to see the timing of a mechanical Diesel? A timing meter, but not a scanner. Next, don't take it to an International dealer. They will likely be lost. Best bet is to get Autoenginuity and DIY or take it to a GM dealer.

I'm not sure if it was a timing meter or a scanner, it was a snap on device that read timing and rpm. Here was the procedure. Before we started the truck we inserted the the chuck end of a 5/16" drill bit into the upper crankshaft timing port a full 1" (until it touches the crankshaft damper). It is down near the top of the harmonic balancer pulley. Once the timing device was hooked up we started the truck. Watching the display while throttling the pump we brought it to 2000rpm and read the timing initially about +.5 degrees. Then we shut the truck down and loosened the nuts and turned it toward the passenger side(advancing). After a few tries we got it back to factory spec. This was all new to me, I want my truck to be timed correctly as well. I would like to do it myself, I need to know exactly what I need and a procedure that is very clear. Possibly a someone who knows what there doing on here can make a step by step DIY for faqs:thumb:.

I'm not sure if it was a timing meter or a scanner, it was a snap on device that read timing and rpm. Here was the procedure. Before we started the truck we inserted the the chuck end of a 5/16" drill bit into the upper crankshaft timing port a full 1" (until it touches the crankshaft damper). It is down near the top of the harmonic balancer pulley. Once the timing device was hooked up we started the truck. Watching the display while throttling the pump we brought it to 2000rpm and read the timing initially about +.5 degrees. Then we shut the truck down and loosened the nuts and turned it toward the passenger side(advancing). After a few tries we got it back to factory spec. This was all new to me, I want my truck to be timed correctly as well. I would like to do it myself, I need to know exactly what I need and a procedure that is very clear. Possibly a someone who knows what there doing on here can make a step by step DIY for faqs:thumb:.

That was using a timing meter of some sort. A scanner will plug into your ALDL/diagnostic/OBD/whatever you want to call it port. The method for the DS-4 is totally different, and the advance/retard directions of the GM are opposite that of the Ford/International. This is because the International uses a gear between the crank and cam and the GM's use a chain. This results in the cam turning in opposite directions, and thus the pumps, which are both gear driven off the cam, in opposite directions.

For setting it yourself, you're going to want a scanner. I wouldn't do it without, though as NVW said, it is possible. Once you have a scanner, it is rather easy to do. Get your first reading (once up to temp) and see where your TDCO is. Do some calculations to figure out where you want it, move it, check again. Pretty sure Engh Motors (GMTDScan Tech creator) has the procedure on their website. When I did it, I used my GMTDScan Tech (OBD-I only) and the information on Engh's site and what gmctd posted over on DTR. Also keep in mind that the lower the TDCO number, the more advanced the pump is. For example, -1.90 is more advanced than +.50.

Great info! The engh motors scanner says 94-95 trucks, what would be my alternative for my '96?

Great info! The engh motors scanner says 94-95 trucks, what would be my alternative for my '96?

CarCode and Autoengenuity are both laptop bi-directional scanners that can read and set timing. If you knew your timing was at factory specs you could rotate the IP 1mm to the drivers side and then do the "key on, key off" routine outlined in the stickies.

Leo

The procedure should be realitivly the same for OBD-II as for OBD-I though, just different "tools" to get it done.

Maybe iamdave0887 will chime in. Pretty sure he observed as he got TDCO done on his 96.

Great info! The engh motors scanner says 94-95 trucks, what would be my alternative for my '96?

As long as the scanner has the oval OBDII connector, your golden, :cool:

As long as the scanner has the oval OBDII connector, your golden, :cool:

So I can get the engh motors software and a OBDII connector to usb? Where can I get a quality connector? I looked at autoenginuity probably about 480 bucks for the connector/software/GM expansion pack. Looks like great software though. Car Code seems to be a better price but not clear on exactly what I need, their website looks outdated. Anyone done this on the timing/TDCO on a 96 or newer and wants to share the procedure?

I just ordered the car code scanner, but don't have the pump tools to rotate it. How exactly is this done with just the scanner and the key on key off cycle. One of you just stated that revving changes it, but I am kind of confused on how to get it as close as you can to -1.94 without going to turning the pump.

Thanks

The only tools you need for the pump are a box end 15mm or fine tooth ratcheting wrench and a pry bar.