TECH 2 1994 6.5 Timing Help

[HALFGIG]

Does anyone have a link or be kind enough to walk me through the entire process of timing my Injection Pump with a Tech 2 including how to disconnect the Stepper Motor through electrically through the scanner? (It’s not a knockoff Tech 2). I’m getting frustrated looking around and coming up empty.

[Kennedy]

Do you have the OBD1 software and connector for the Tech 2?

If memory serves I always had to use an alternate 3 in 1 software on the OBD1 trucks. Tech 1 no problem.

[HALFGIG]

I wish I had a Tech 1 now. I’m assuming my Tech 2 has the OBD1 software since I’m getting real time data. The offset is 1.23*. I just got the truck running a few weeks ago. It has been a very long saga. I will tell you (post it) someday.

I put in a refurbished PCM and had a new PROM (I found on EBay) and had a towing tune flashed from Heath. Thank you Bill and Cameron. It runs great now but when I hooked up the Tech2 the Desired timing was around 6.5-8* at startup. It bounces around a lot throughout the rpms.

I moved the IP toward the passenger side 2-3mm And at cold startup the desired and measured timing were approximately 13*. This baffles me. After letting it warm up the numbers a came down and move around a lot throughout the rpm changes. At this setting it would run rough when I ran it up to 2000rpms. I never drove it like this.

I moved the pump again this time going toward the drivers side approximately 2-3mm from where it was original set when I first got it running a few weeks ago. It runs great like this also but the timing is now showing around 13* (Again) at cold startup. I was expecting to see a solid number value for the timing. I guess I have some or a lot of learning to do.


I was told that the stepper motor needs to be disconnected with the scanner before timing can be completely done. I haven’t found that screen yet.

What are good fuel rate Numbers? The screen shot shows around 9mm and when I drove it yesterday it was around 11mm after the second timing adjustment.

After putting in the refurbished pcm and new prom I haven’t performed an offset yet. It is running so good I really don’t want to touch it but I also don’t want to damage my new Optimizer 6500 engine In my 94 Suburban. It’s been a 2.5 years saga. You won’t believe the story.

I did a fuel run on the original IP setting and got 19.3 mpg. I was actually wanting to see more but that’s still pretty good for a rig that weighs 6700lbs.

The only issue I have now other then figuring out the timing is the voltage at cold startup on the coolant sensor is only 2.5 instead of 5 which leads to a smoky coughing startup for about 10 seconds. This happened also on the original pcm. I’m assuming it’s a short. I gotta track this down. On the original pcm I wired a switch to the ground wire on the Coolant sensor and disconnected it at startup and all was good. I was told by someone I shouldn’t do that. I’m assuming it may hurt the new pcm? Don’t want that now it running so well but it sure chugs a spits smoke at first. I hate it.

[JohnC]

It's been 15 years...

Run the TDC offset learn process. You want it to "learn" between -1.6 to -1.95, IIRC. Hopefully, someone like JK will chime in with the optimal value, or, I'm sure there's some old threads around with all the gory details. Adjust the pump and relearn until you get it right. Done. Ignore any other values the scanner shows you.

[HALFGIG]

I just remembered this morning about finding the timing value when doing the Offset. It’s been 8 months since The last time I timed it with Leroy’s software and I simply forgot About it. It just runs so good where it is at now but I’m going to get it warmed now and see where It’s at. Still learning the Tech2 scanner. Thank you very much

[HALFGIG]

I performed the TDC offset and I’m now at -2.02 which a past email with Heath is within the parameters. I forget what he said was the low parameter but the high number was -2.02.



Below is what I was sent about 9 months Ago. The one thing I could not find is where/how to disable the stepper motor on the Tech2. Below it says that during the learn Process the Desired should read 0*. I’m at 9*. I need to find out where to read the actual IP timing. It fluctuates 4-5* with increased throttle. Of course I’m reading The value (for timing purposes) at idle but the last 2 times I moved the pump and the values did not correlate with the movements on the Tech2 Data Display.

————————————————†”———-
Gotta use only a TECH 2 made by Bosch to set up. You must begin with a TDC learn procedure, then set TDC offset to -.25 to -.75. I'm surprised it runs as well as it does at -1.32. Base timing must be set to 3.5 with the stepper motor disabled, all thru the TECH 2. To confirm its disabled, "desired" timing MUST read ZERO in order to set "actual" timing to 3.5. If desired is not zero, timing cannot be set.

[Kennedy]

-1.94 is target. At -2.02 you may be past the limit if memory serves. Try the learn several times and see if you can get it to land on -1.94. If it always comes up at -2.02 then you are past the limit. and need to move the pump.

[HALFGIG]

I moved it toward the passenger side (again) this morning and ended up with -0.97. I’m going out again while it’s still warm and do another Re-Learn. If I can’t achieve a closer number To what you suggest I will move the pump again. Thank you all for the Help. Enjoy your Day!

[DmaxMaverick]

Since you're all in and hands on, it might help to know why you're doing what you're doing....

The reason for the -1.94° TDCO learn is mechanical, on your electronic fuel injection system. The pump is mechanically limited with how much timing compensation it can deliver when commanded by the PCM (it's actually a bit more than that, but the PCM assumes that all it's gonna get). All you are doing is physically moving the pump against that limit. -1.95° will cause the PCM to default and set a code (and the MIL), and/or reject the relearn, so we use the optimal value of -1.94°. What this does is limit the very "soft" timing map of the PCM, meaning, it likes to run on the retarded side of advanced, so by moving this available compensation range, we force it to run on a more advanced minimum limit of retarded.

That said, you are now at -0.97°. That means you need to advance the pump 0.485° to get it to the optimal TDCO. That's about a mm (more or less, I don't recall exactly) at the timing cover scribe marks. Do what you have to do, repeat the process however many times it takes to get it spot-on. It's worth it.

Just a reminder (because some of us need it, and male pattern baldness doesn't need any help, if that's an issue): the pump rotates opposite the engine. ....That DOH!! moment.

Once you get it close to the target, repeat the process before moving the pump. The timing set (sprockets/chain/gear) aren't zero-tolerance. This little bit of slop (more on higher mileage engines) allows it to vary some from learn to learn. Once you get it to learn, it will lock it in, so that variation won't matter any further. The key is to teach the PCM that's all it gets, and be happy with it. It will.

[HALFGIG]

I will keep playing with it. I’m So close right now and it’s running so great! So sick that I’ve paid 3 shops to time my engine with zero success. I will mention now that I have over $56,000 in my Lovely Suburban. It’s a Heck of a Crappy story. I have to post the story soon. Just wish to figure out a good Title to post it under plus there is a lawsuit going on with this so I need to be cautious. Yes, OVER $56,000. I’ve paid less for an investment house. Enjoy your day my Friends!

[DmaxMaverick]

Good luck with it.

If you're engaged in any legal issue with it, please do yourself a favor and save the related stories until it's settled. We'll wait for what sounds like an interesting story. Your intentions mean nothing when lawyers are involved, and they will find a way to use anything against you. I'm not a lawyer, but I spent a career working with and opposing them (LEO, retired).

[N9Phil]

There are a couple of things that I had to do when timing my 6.5 The first thing I had to remember was to make sure that the engine temp was at least 185 degrees or when you thought that you had it set it would not hold. The next thing was when you are setting the timing and the engine is over 185 degrees you some times have to increase the engine speed a little or let it drop a little and when you are close to the 194 set it and it will stick. I use a Tech 1 to do my timing and if you don't have the temperature high enough you will think you are all set but it won't start right if at all. Once you get the true 194 you will be very happy.

[HALFGIG]

I will turn the pump again tomorrow and achieve the -1.94 TDCO. I do have the engine over 185* when I do the Offset. Thank you all once again. I hope all is well.

[Kennedy]

Looking back to the first time I did TDCO. Man what a pain having only a limited understanding back then. That was 1998. By 2000 I had a very good handle on it. I forget how many trucks I did at Bigley's place during the 2000 Rendezvous, but as I recall it was double digits. A handful more in 2002 at Dayton including one that was out of range which can cause a convoluted mess that needs to get unraveled.

One of the best ways to look at this is as if it were an imprecisely loaded roulette wheel where the numbers wanted to favor about 4 or 5 slots. If you are close just keep trying without moving the pump. As stated earlier -2.02/+2.02 is the largest number it will read so stay off of that because it could be -2.11, -2.20 etc but it cannot show it.

[HALFGIG]

Without moving the pump 2 days ago I got the Offset to -1.14. I tried again this morning and while the Offset was going on it jumped to -1.32 then settled back Down to -0.97. I moved the pump 4 times a few days ago. Moving it a half of a scribe mark at a time and never attained anywhere between -1.14 and -2.02. It never settled between those 2 values. I may try again in the next few days. To busy for today and tomorrow. I’m wondering if I’m using the Tech2 correctly. When I get to the Time Set Screen I push the ON button which makes a physical change with the engine (It sounds like there is a drag on the engine, rpm’s drop) and It takes the desired timing to 0 and the Measured timing to 3.5. I believe this step also deletes the stepper motor. But in order to do the Offset (I’m assuming) I have to back out of that screen (which makes the engine sound like It Gets back to normal idle) and then do the Offset. I’m just wondering if the stepper motor is still disabled during the Offset process. My truck runs great! I love it! Just wondering if I’m hurting the engine with these numbers and how I will benefit by achieving -1.94? I will try again soon. Going for a mileage run in the next few days. I have moved the pump so many times (tiny movement’s) I’m flat out tired to try and achieve-1.94. I need to post a few pics of my special tools I made for moving the injection pump. I will do that soon. Enjoy your day!