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JOESELLSVW
03-24-2006, 06:15 PM
Hey guys,
I'm finally getting back to completing the GTI after taking a year off after the birth of my daughter. The crew and I are putting an effort together for the 12 Hour at Summit. One of the things that we're running into is the OBD1/2 dilemma. My car is a 96 GTI which is OBD 2 rather than the earlier OBD 1 cars. I want to yank the emissions equipment out of the car and plug the head and run an OBD 1 ECU. This all seems to be within the scope of the IT rules and spirit, but I figured that it'd be best to throw it out and see if anyone had any problems with it. What do you think? I've learned that there are differences with the heads of the cars so just swapping the head alone is beyond the scope of IT. Eventually I'd like to do a race spec motor, but that isn't in the budget for this season.
Next question, what do you guys think I should do for a R&P swap? In the old car I'd bought a 4:32, but wasn't sure what I should do in this trans. I think I'll end up with the clutch type diff from Bildon and a full rebuild from them as well. Any input?
I'm looking forward to getting back on the track this season. I feel like it's been forever! Joe

Knestis
03-24-2006, 07:52 PM
I'll comment, as long as people understand it's not in a NERD capacity, and in the VW forum...

The way I read the rules, and understanding the differences between the OBDI and OBDII MkIII's, you can transplant all of the OBDI management system onto an OBDII car. You can't mix and match the parts from that system (e.g., the ECU), without taking all of the other bits that are different.

Of course, you can remove emissions stuff, so that becomes a non-issue where there are differences between the two.

As to the details? Cameron?

We run a 3.96 FD simply because it was free and anything else would have been beyond the current budget but (unsupported theory warning) I have a suspicion that the additional torque of the 2.0 makes the final drive ratio less of an issue. The upshift splits in higher gears ARE more favorable but when we started short-shifting at the Summit 12 last year, the car actually went FASTER. Zinging is not necessary, i don't think.

K

Conover
03-24-2006, 10:32 PM
The only thing I might suggest is, maybe you should save the OBDI gear for when you have the capacity to do the engine build. It will make things quicker and easier to just plug in your OBDII engine and go, not to mention that we have found the unmolested OBDII engine was very reliable even with Greg Amy hot-shoeing it at VIR and Summit enduros.
Reading your post I'm thinking your planning to run an OBDII engine on OBDI? shouldn't be a problem. your right that just swapping the head isn't Kosher, but your free to kill off any emissions stuff. There are some things to consider when doing your ECU swap and eliminating emissions components though, like, does that ECU think it's getting plugged into an EGR car?
Another note, I've got the 020 rebuild program up and running, let me know if your interested.
Cameron

JOESELLSVW
03-25-2006, 12:34 AM
Thanks for the input guys. I wanted to go to the OBD 1 ECU for the ease of tuning and also the fact that I was able to get a Techtonics header on the car which doesn't have the threaded hole for the second o2 sensor. I should be picking up a 95 Jetta as a parts car this week. I don't think that this will be super difficult, but I'm saving all of the OBD 2 stuff just in case. I could always buy a resistor to fake out the second o2 sensor, but I'd rather be able to have the tunability of OBD 1. Joe

Dave Zaslow
03-25-2006, 04:53 AM
Joel,

Reach for the Bentley manual and go to the section that concerns testing the electrical components, including those that report to the ecu. From memory, there is no difference in the signals the ecu is looking for, except for the addition of the 2nd O2 sensor.

On either, when you remove the emissions equipment you will get a CEL. The cure is strategically located black tape.

Dave Zaslow

Bill Miller
03-25-2006, 07:14 AM
**Warning, Rules Nerd Post**


are some things to consider when doing your ECU swap and eliminating emissions components though[/b]

I know the internals are free, but I don't think you can just drop an OBD I ECU into an OBD II car. However, I guess that if you take the whole OBD I harness, you can do it through update/backdate.

JOESELLSVW
03-25-2006, 04:06 PM
Thanks for the input guys. This is what makes IT a great class, you can go to your competitors for advice and info. I think that we're looking to get the suspension finished and the car squared away for MARRS 1. That same weekend the DelVal BMW club is doing an event at Jefferson Circuit with a follow up at the big track on Monday. Between the Friday test and tune, MARRS 1 , and the driver's school, we should be able to shake the car out pretty good.
Thanks again for all of your help, I'm sure that we'll have more questions as we get closer. Are you guys going to put a fuel cell in the new car? I think we're going to stay stock unless one of us wins the Powerball Lotto or something! Could you guys get two hours out of one tank? Joe

Knestis
03-25-2006, 05:04 PM
We came up short of 2 hours, if I remember correctly but not by a lot - notes are buried in the filing cabinet right now. We stuck with the OE tank, partially because the technical aspects of implementing an FI cell are a PITA, partially due to cost, and partially because I actually have a lot of faith in the VW design.

K