94 Truck w/5521 pump (Tech 1)?

[gerry1]

I have been troubleshooting my IP with a Tech 1A and have been getting not so good results.
My first read showed a TDC offset of -1.57.
After a TDC learn it showed -2.00 and set a code 88. I adjusted the IP to the drivers side and now I read a TDC ofset of 0.00 and codes 34 (stepper motor) and 88. I have tried the TDC offset learn several times and still come up with 0.00 and the same two codes.
Also the desired inj time is 9.4 and the actual inj time is about 14.0.
I have heard that a Tech 1A may not work with a 94 truck with an updated 5521 pump.
I have a rebuilt JK pump ready to install, but am not sure if my Tech 1A will work with it?
So I'm sure if the pump is acting up or if my Tech 1 is messing it up.

Thanks,
Gerry

[ 12-13-2003, 05:43 AM: Message edited by: gerry1 ]

[Barry Nave]

Tech II is needed for the offset learn

[S\W Off Road]

The Tech-1 will work on the 94 and 95. I use it on my 94 and am able to set the off-set. Keep working with it and you will get it. I read one of the old feature artical books that tells how to do it. I don't know which edition it was but if I get the time to find it I will post which one it is or you can contact More-Power and he will inform you of the correct volume needed. Keep the Tech-1 for your 94 or 95, some people would love to have one for their truck. You can do a lot of checks with it, shut off one injecter at a time, put the transmission in differnt modes, check the intake temp and alot more. Good luck.

[Barry Nave]

S/W Offroad
Your right on. 1999 Feature Articles,Page 27 tell's all. Tech I on 94-95 and Tech II 96-99.
TDC Offset Learn Procedure is a long page.
I have always bought all Articles and would pass on to any one to get back issue. smile.gif
Jerry, E-mail?
bdnave@comcast.net

[gerry1]

I have Featured articles on setting TDC offset. In the article it notes that you may need the Tech 2 for 94-95 trucks with the latest pumps.
I'll keep trying the Tech 1 and keep my eyes open for a Tech 2.

Gerry

[JohnC]

If I understand your post correctly, I think you turned the pump the wrong way and now it's outside the range it can work in. For that matter, I think it was pretty much right on before you moved it. 1.94 is the highest reading you can set without having problems, and it looks like you prevoius setting was giving values between 1.57 and 2.0. Put it back where it was and try the offset learn until you get the reading you're looking for.

[gerry1]

I very well could have gone the wrong way with the pump.
I swapped this pump from my old to a new motor. My thinking is that the -1.57 is the setting from the old motor and the -2.00 was the initial TDC learn on the new motor. My efforts were to move the value from -2.00 to the range of -.25 to -.75
I guess my confusion was that: Is raising the value meaning a larger number (more negative) or more positive number (less negative)?
I believe this pump has some problems, and have a new pump ready to install. Right now I am just doing a little OJT with the old pump before I install the new.

Thanks
Gerry

[ucdavis]

Gerry,
I have a '95 & use a Tech2 equiv. cartridge in my Vetronix mastertech scanner to do TDC offset. Cartridges are supposedly interchangeable. It worked w/the OEM "blue-tag" pump as well as the new 5521 I now have.
The TDC Offset & TDC Learn are two different functions (not sure from the post if you spotted that). Learn reads the current engine rotation while running to find & store TDC on the crank vs. IP. Offset "sets" the desired offset. In my software, when I start the Offset function, the scanner cycles thru offset values from -2.00 to zero IIRC, then back up, then back down... till I choose the offset I want by hitting <enter>. I had to figure this out as it has no instruction telling what to do. I believe it goes in steps of: 2.00, 1.84, 1.57, 1.25...
Hope this helps.

[JohnC]

Actually, if I may disagree...

TDC offset is the difference in degrees between crankshaft TDC and the pump's internal "TDC" which is a reference point in the pump's rotating mechanism. A negative value means the pump reaches TDC before the crankshaft, or is advanced relative to the crank. TDC offset learn is the process by which the PCM learns that value. The pump has a wheel inside with index marks on it that the optical sensor reads so the PCM knows where the pump is relative to this reference point.

The value is stored in the PCM and that value is not affected by changing the pump or even the engine, although the value will have little to do with the actual engine parameters after any such changes.

Once the value is learned, moving the pump (or timing component wear) will not affect injection timing, as long as the change is within the range the timing stepper motor can compenstate.

During the TDC offset learn process the pump cycles through the timing stepper motor range and also the value fluctuates from timing component slop. True, you can force the PCM to learn a value as it passes by on the scanner, but that value may or may not be an accurate reflection of the nominal value.

I recall that the factory setting range is around -0.25 to -0.75. Diesel Page lore suggests (strongly) that performance is improved by setting the pump position such that the value learned is toward the negative end of the scale, i.e. -1.94. (-1.94 is the most negative value the ODB 1 PCM will accept without setting an error code.) I suspect it is possible to further fool the system by choosing the reading closest to the positive end for a given position, causing the PCM to think the pump is less advanced than it really is. I have no emperical proof other than that when I set it this way my mileage seemed to improve noticably. I further hypothesize that the optimal setting would the most advanced pump setting that still permits grabbing an in-spec TDC offset value, -1.94.

YMMV, batteries not included.

[ucdavis]

Hmmm, and my answer sounded so good.
Now I wonder what I've been doing w/my scantool besides amusing myself. Guess I'll hook it up again & see what I did (if I can figure it out ;).