GMTDSCAN TECH ?

[ak diesel driver]

So I was helping Steve53 time his IP Saturday and I have a couple of ?s. When I first hooked up the scanner the TDCO read-.85. So we thought we might as well see if we could it a little lower. We pushed the time set button and it started running really rough and then when we pushed TDCO set it read +2.02 and that was the only number we could get. So my first ? is I'm assuming that we couldn't get any other number because it was maxed out and wouldn't read any higher. Am I correct in this assumption? So we loosened the IP and moved it a couple of mms to the drivers side and rechecked. When we did timeset it ran much smoother than the first time and when we pushed TDCO it actually showed about 4 or 5 diff possibilties for TDCO. The TDCO numbers were still lower than we wanted so we moved the IP again. It was extremely hard to move compared to my 96 so it took both of us one holding the pry bar and one tightening. When we rechecked things the only 2 numbers we could get was -2.02 which was most of the time and occasionly -1.85. I managed to snag -1.85 but here is my 2nd ? Did we move the IP too far? When I used Carcode on my 96 I got alot more possibilities for TDCO numbers. So my next ? Is that a software difference or a obd1 vs obd2 difference?

 

[bk95td]

Easiest explanation i've gotten was: go for 3.5 actual WHILE in timeset. Then set tdco to -1.94 or less.

 

[packers905]

Does the tech 1 do timing relearn?

 

[ak diesel driver]

I've heard no

 

[Acesneights1]

Does the tech 1 do timing relearn?

It would think it would. It was what was used at the time of OBD1. AFAIK It can on Obd1 but not OBD2

 

[buddy]

This is the wonderful OBD1 timing, that I love to do, and try to explain the differences to OBD2. Ive done it so much on mine I could do it in my sleep.

What you had was a pump that was replaced and never timed correctly, happens so often and even advised by some members here in the past, which is shocking to me. Although I'm sure if someone marked it and then tried to get it back to same mark it would be fairly close to correct, but not right for a system meant to be precise.

You are fine with what you got, and correct that it will not show past +/-2.02. As long as its less than -2.02 and you did not set DTC88 you are all good. It will probably work better now.

The OBD1 does not move around as much because it doesnt push idle to 1000rpm, stays at 600rpm. Although mine will move around a little and it goes down if I rev it up. Having it not move around a lot is a good thing, maybe the timing chain is nice and tight and the CPS and OS are working in concert. Several times I would get -2.02 after moving IP just a little, but I rev it and it would hit -1.94 and I'd stop it there.

 

[ak diesel driver]

Yes you are correct about the pump being replaced he said he thought it was replaced by the dealer. So will obd2 read higher or lower than 2.02 cause with carcode mine read +3.95 when I first started messing with it.

 

[buddy]

Yeah OBD2 will show you past 2.02, but codes at 2.20 according to the timing sticky, but never heard of anyone setting it past -1.94, so I assume it codes at 2.02 as well.

I guess I can disable DTC88 in the programming and see if it will read past 2.02. That could be my next performance mod, TDCO of -2.94 with no codes

 

[STEVE53]

My truck has been running good since AKDD helped me adjust my timing. It has set no codes as of yet, and hopefully won't. I have not been able to see if it starts better at cold temps as of yet because it has been so warm here lately (low 30's to low 40's). The hard 'cold starts' are the biggest issue that I have had, and AKDD offered to help me check and adjust my timing.

Steve

 

[ak diesel driver]

Steve53 has a nice clean truck. Wish mine was that clean.