So when I was playing a couple of weeks ago with the TGP I could change the HUD and Speedo displayed speeds very easy by changing the PU/Mile setting and the Pulse Divisor. I could never seem to get the displayed ECM on the logger to move much...most I ever saw displayed was 42 MPH at 60 on the GPS. That was with the stock TGP PU/mile and Divisor settings.

Now I decided for the shits and giggles to hook the logger to the TSTE. Well low and behold the EMC speed display and the speedo are DEAD on what the GPS is showing! :shock:

So what the hell is going on here folks? Do I have a defective ECM? Is my VSS wigging out? Could that also be a part of why no matter the changes I make the thing fails Emissions testing MISERABLY??

Dave...When you set the PU/mile and the divisor to what you gave to me, was the ECM, HUD, and Speedo right on? at least within 2% of each other? If they were then I am thinking the ECM is calculating the signal wrong. With your settings my HUD was off by +2MPH everywhere but not varied. That would account for the slightly different tire diameters we are using. My speedo was accurate by +5MPH all the way up to 45-50 then it would just take off. It shows 120MPH when I am doing 80MPH actual. The ECM with your settings is EXACTLY 50% of HUD and GPS. No matter what speed. I took her up to 135 MPH on the GPS and held it for 1 mile...it showed 67-68MPH for the ECM. The HUD was showing 137MPH.

Luke...You changed that ECM at one time didn't you? or was that on your black TGP? Do you still have the "old" ECM for me to borrow for a little trial and error?

Any insght would be greatly appreciated! :?  8)

Ya Kenny my car is dead on with the SPEEDO, HUD, ECM speeds with those numbers i sent ya.

they match the GPS i have within 1kmph

your VSS maybe messed up....

If it is the VSS why would the HUD be correct out of the box with your settings? :?

Is the VSS a multi-signal sensor? Digital and analog? Do you remember how any wires are coming out of it?

This has me baffled!   :oops:

In the 1g DSM world they had an issue with capacitors on the ECM mainboard leaking and failing causing all sorts of eronious faults and datalogging readings. Wonder if something similar could be happening to the TGP/TSTE ECM's for drivability issues?

Guess I need to pick up a VSS from the dealer (no worries I have a discount! :wink: )

Next question are the VSS's the same body and hook-up between the Auto and the Manual? Maybe just a different gear? Did they have a gear or was it fully magnetic pick-ups?

it's fully magnetic.  i have a coupe of them here if you need one.

not sure if this matters or not, but if Dave is using an '88 282 and you are using an '89 282 then you probably can't use the same PU/mile & pulse divisor settings as him.  the exciter ring (or whatever it's called) inside the transmission that gives the VSS its signal is different depending on year.  the '89 & '90 282 appeared to be the same but the '88 282 had more 'teeth' on the ring.

when my Cutlass had a '90 282, my speedo was dead on accurate.  going to the '88 282 (with no other changes) made the speedo read ~11% too fast.  i'm using an '89 282 now but then i'm also using a TGP chip so i can't really compare the '89 282.

I have a 1989 282 Getrag

2 wires comming out of the VSS i recall...

yes just two wires for VSS.

There are 2 types of VSS's in the 282

There's the actual plastic gear ones...(older)

And the newer hall effect sensors... 1992 and up.

'88+ W-body 282 uses hall effect VSS....no plastic gears.

So how is it that the ECM is so frikkin far off...but the HUD and speedo seem to follow each other with changes to Divisor and PU/mile? The ECM just didn't change till I made a drastic correction by going back to stock settings. Then the speedo was only off by +5MPH...HUD was +10 or 15MPH...but the ECM reading was only up to what I said before.

It just seems to me that the ECM is calculating improperly or at least sending the ALDL data incorrectly.

I wonder if GM still makes ECMs new for the TGP platform or is the ECM pinouts the same between N/A and Turbo?

I need to look into this....but damn it I have no time lately to take a relaxing shit let alone look into this stuff! :shock:  :roll:  8)

The ECM pinouts for n/a 3.1 are very similar to the TGP.I THINK they just added the turbo stuff to the 3.1 n/a code.As for NEW(not a reman)computer GM should have plenty of them.They were used in alot of cars mostly for the VETTE.The problem you're havin is really weird.My TGP speedo and tach are waaaayy off.I sent it out to be fixed in 1996 and it worked perfectly till last year(might have had something with sitting so much over the years)I dunno.Good luck.Later

Well I am going to swap the ECM from the TSTE to the TGP to see if it is in fact the ECM.

I tend to forget I have a "twin" sitting in the garage to try some parts swapping... :oops:

Will do that tonight or tomorrow night... 8)

Yea, I replaced it with another used one from a Lumina. I don't think I have the original one anymore though. It was so fucked up that I just trashed it. (Car wouldn't even run)

Well I swapped the TSTE ECM and still the same thing. I guess I will pick-up a new VSS this week and try that... 8)