CSP Miata / TEC3 in Canada

jimm · Posted: Wed Jul 23, 2008 6:41 pm Post subject: CSP Miata / TEC3 in Canada

Uwe at emi told me about this forum, it hadn't come up in a search before so this is great that there is something like this available.

I'm in embedded software/electronics for work and cars for hobby so I find this stuff pretty interesting, and the reason I'm expected to get this system running on the race car!

I co-drive a 1990 Miata autocross car in CSP class and we've just installed a used TEC3 in her. The car has the usual 1999 Miata engine swap but we were, up til now, running the stock 1990 ECU and some other bits and pieces to keep the 99 engine happy in the 1990 chassis and vice versa. These things restrict the power a bit so we're hoping the TEC3 will help in that area. Beyond the engine swap, in CSP we are not allowed many engine modifications other than intake, exhaust and associated control of fuel and spark.

Some notable things about this project are the fact that I'm trying to use as many of the stock engine sensors as possible, exceptions being the crank trigger and we're also using the Electromotive DFU coils. Stock air temp, coolant temp, cam angle, knock, oxygen and throttle position are being used (and others if I missed any). We're also using the stock 99 engine wiring harness and slightly larger yet compatible injectors from a Mazdaspeed turbo Miata. I'm still uncertain about the stock cam sensor, it reads 3 bumps on the intake cam gear (1 for #1 compression and 2 for # 4 compression) so we ground off the two bumps for # 4. I haven't confirmed whether the #1 bump is within the 180 to 6 degrees BTDC#1 yet but I think it is. I'm also adding a pullup resistor to the cam signal line as the cam sensor is an open collector output.

I was going to use the stock idle air control as well but it is a two wire and it would seem we can't use it with a TEC3 (purple case). If anyone knows how we can use the stock two wire then let me know please! This car is not driven on the road though so it doesn't seem like we need it anyway.

So far it starts and runs and we even took it to a small local race the next day where we did all right. The engine idled once warm and even pulled pretty good down low but fell off in the upper half. We had no tune on it whatsoever other than what the tuning wizard in Wintec 3.5.6 gave us. We had the gotcha of not being able to communicate on the fly with the TEC3 because of an incompatible USB to serial adapter. Looking at logs afterwards revealed very lean conditions above say 5000 rpm and high load but wouldn't rev too high because of that. Seems like it went to max UAP and that just wasn't enough. I'll be trying new UAP values asap and now that we've got a working USB adapter (Belkin by the way) we should be good to go.

Cheers, I hope to learn some new things from this board and playing with our TEC3 system.

Jim

**nefarious** · Posted: Wed Jul 23, 2008 7:10 pm Post subject:

welcome aboard, i've messed with a couple miatas on TEC systems, they seem to complement each other very well, i really dont know about the Canadian Maple leaf edition though, Laughing

welcome!
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97' Saturn SC2-Turbo
TEC2 + T3/T4 + FMIC
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jimm · Posted: Thu Jul 24, 2008 4:07 pm Post subject:

Thanks!

I can now report that a stock 99 Miata cam angle sensor works just fine on the TEC3 for synchronization. It is set up as a Hall effect sensor in Wintec, I have +5V going to it to power the sensor, sensor ground, and the cam signal which is pulled up to +5V through a 1kOhm resistor. The 2 projections on the intake cam gear for detection of #4 compression have been ground off so that there is only one projection for #1 compression as the TEC3 requires. Cool

jimm · Posted: Wed Aug 13, 2008 5:46 pm Post subject:

Maybe I was a bit hasty in annoucing the cam sensor works, it does but it seems to always fail once everying is all hot. I have to verify that it falls between 6 and 180 degrees BTDC.

I'd like to know what the failure mode is for this sensor? I don't notice a difference in how the engine runs when this sensor is failing, how does the TEC3 know when to do things if this sensor is failing? Or does it keep track of where it is and once things are working it will keep working on the same sequence?

**Jon@EMI** · EMI Joined: 26 Feb 2008 Posts: 144 Location: Manassas, VA

The TEC does keep track so if the sensor fail after the car has been running for a while it won't really matter. Though I have seen several cars setup in sequential with no cam sync that worked fine every time. The injectors may be out of phase but the fuel still gets in the engine.
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jon at emi.cc
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jimm · Posted: Thu Aug 14, 2008 4:27 pm Post subject:

Thanks Jon, that makes sense then. In fact on the first start with the TEC3 I'm pretty sure the cam sensor wasn't working and it still ran fine. I've since switched the cam signal pull up over to 12V rather than 5V to see if that would help but it still fails. Now that you explained how it works I wonder if in fact my cam sensor is actually detecting the correct phase, if it were outside of the 6 and 180 degrees BTDC then I assume the TEC3 would squirt out of phase.

slowMX5 · Newly Aquired Joined: 24 Jun 2008 Posts: 29 Location: UK

Hi Jimm,

Which cam sensor are you using? The optical or magnetic (both are hall effect but need different mods to make them TEC friendly)? When I installed mine I did some testing with an oscilloscope to check sync to ensure that the signal was occurring at the right time, I'll dig out the notes for you if it helps.
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jimm · Posted: Tue Aug 19, 2008 7:37 pm Post subject:

Steve,

It's the 99 sensor that is on the front of the cam cover, not the rear mounted ones. But it is magnetic with built in electronics to turn the signal into a pulse. We do also have the old-style rear mounted one as well for when we were running under the control of the 1990 stock ECU, it is most likely the optical one.
I didn't verify with an oscilloscope when we got the car running on the TEC3 even though I had one with me!

If you know the timing of the pulse on the 99 engine that would be good info to know!