Short story:

Started 24-hour ChumpCar race with a broken transmission (no 4th synchro), were leading the race, and suddenly lost power and started making horrendous noises.

45ish minutes later, noise was traced to a missing throttle body screw head, which had popped off and was dancing around cyl #1.

Went back on track, spit out screw (through turbo....) and kept racing.

Screw beat the **** out of the turbo. Kept racing.

Transmission got stuck in 3rd gear. Kept racing.

Finished 2nd overall.

Now, the question:



We got a new 1.6 throttle body to replace it, did the JB Weld fix on the throttle body screws recommended by Emilio at 949Racing, and went to swap over our 4-wire Automatic TPS sensor (our car used to be an AT and the ECU still thinks it is.) and we found the problem above.

Dirty TB on the right is our old one. Shiny one on the left is the new one (from Alex at 2ndchanceroadster.com). Clearly there was a major design change at some point...

Anybody know which cars were like the one on the right? We're coming up on another 24-hour race and we're dead in the water without a throttle body.

-Dave

 

The TB from my '93 looks like the one pictured at left. Perhaps the AT and MT had different throttle bodies?

*edit* checked on the mazdaspeed site and sure enough the MT and AT have different part numbers. Castings appear to be the same, perhaps you can swap throttle shafts? Hope that helps.

 

pic isnt loading... difference in the shaft is what we are looking at?

 

The auto and the manual where physically different units. I have one here I am not using that I could donate to a good cause.

 

Pic is loading now.

Dirty one is an auto TB, cleaner one is a manual. The shafts are different...I wouldn't swap shafts, then you'd have to remove the screws to even get it out. They'll never tigthen back up the same (if they even come out) and you might lose another even with the JB weld.

Cut off the shaft, drill/tap for the brass thing that turns the TPS, screw it on and make it work.

 

I can't help you with your questions but I wanna say that you guys are my miata heroes!

I am very interested what you will do when the new hood requirement goes into effect.

 

Or instead of drill/tapping the shaft for the brass flapper, weld it on. That's what I did to my 1.6 throttle body. There's a few ways of doing it.

You made so many other things work, why is this any different? Make "B" look like "A" with whatever means you have available.

 

OR go find a BMW VTPS. Just installed one yesterday in my car.

 

When using a MS PNP on an NA6 harness, we like to use the auto TB and TPS to convert to VTPS. Much easier to dial in tip in, particularly with F/I.

 

probably doesn't help, but the 4 wire auto tps is better for fuel tuning... it has a constant read signal instead of just three signals, closed, open, and WOT. terms escape me right now

 

That's the V in VTPS, variable. That's why he was using an automatic throttle body, they have VTPS.

 

Fixed it. Got another auto TB from Aleks at 2ndchanceroadster.com.