Firmware 1.5.x Open IAC on WOT

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prof315
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Firmware 1.5.x Open IAC on WOT

Post by prof315 »

I have to say I love the new Open IAC on WOT feature in the 1.5.x firmware. I have a customer who runs a race car in a class that requires a stock intake manifold and throttle body. We have always felt that the engine was choked by either the intake or throttle. Thanks to the new feature we know its the throttle body. Using the stock Bosch idle valve, the math said we would increase airflow potential by 20% if it were open at WOT. Well we saw a 20% increase in power and torque and the redline (the point where power starts to fall off rapidly) moved up nearly 600 rpms! I have a number of other customers who could very possibly benefit from this but many of them run MS2 based hardware...... Any chance this could be back ported to MS2?
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Magovit
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Re: Firmware 1.5.x Open IAC on WOT

Post by Magovit »

I loved it too.
For street car it's a cool feature for really.

If James can possibility one adittional configuration to smooth the close of the valve after de WOT released will be great!!
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Re: Firmware 1.5.x Open IAC on WOT

Post by dontz125 »

You could set it up with a programmable output grounding the OPEN pin on the valve, going active if TPS > 90-95%. I'd suggest a fairly large hysteresis, perhaps 15%; this will allow you to modulate the throttle without the idle valve snapping on and off. Checking that WarmupEnrich < 105%, ensuring the engine is nice and warm, probably wouldn't hurt either.

Repurposing the AC Idle-up might be a little more elegant for PWM, and is the only way short of codework to do this for a stepper. A limit switch on the throttle or pedal activates the idle up function, which then adds LOTS of either steps or duty. Without a switch, you'd still need to use a ProgOut to ground the input pin based on TPS value.
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prof315
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Re: Firmware 1.5.x Open IAC on WOT

Post by prof315 »

Another question concerning this feature. I have quite a few race car customers who run MS3 on 80's-early 90s VWs and would benefit from this feature as they must run the undersized stock throttle bodies....most of them don't have TPS. Is TPS mandatory for setting up WOT in engine states?
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Re: Firmware 1.5.x Open IAC on WOT

Post by dontz125 »

A WOT switch connecting 5v to the TPS pin (perhaps through a 90% voltage divider to avoid out-of-range concerns) might help.
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prof315
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Re: Firmware 1.5.x Open IAC on WOT

Post by prof315 »

dontz125 wrote:A WOT switch connecting 5v to the TPS pin (perhaps through a 90% voltage divider to avoid out-of-range concerns) might help.

I thought about that.... These old VWs actually HAD a WOT switch but they are fragile and no longer available. Since they are race cars I will probably turn off idle control and Generic PWM the idle valve using MAP and rpm if I can't use the feature without TPS.
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Re: Firmware 1.5.x Open IAC on WOT

Post by dontz125 »

There've been several folks who've posted about adding limit switches on their clutch pedals for triggering launch mode etc. Perhaps something could be bolted up to the gas pedal, or next to the cable pulley on the TB? Mouser mostly has fairly pricy industrial-class stuff, but Digikey has quite a selection of small switches.
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Re: Firmware 1.5.x Open IAC on WOT

Post by Matt Cramer »

dontz125 wrote:There've been several folks who've posted about adding limit switches on their clutch pedals for triggering launch mode etc. Perhaps something could be bolted up to the gas pedal, or next to the cable pulley on the TB? Mouser mostly has fairly pricy industrial-class stuff, but Digikey has quite a selection of small switches.
For that matter, they have some pretty cool non contact Hall effect sensors with a 0-5 volt output that you could stick on the gas pedal.
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prof315
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Re: Firmware 1.5.x Open IAC on WOT

Post by prof315 »

I'll look into the non contact Hall effect stuff... Keep in mind these are road racing cars with stiff suspensions and they often race on bumpy tracks. Vibration can be a big issue, that's what kills the stock WOT switch and every add-on TPS I have ever seen. Reliability is a must. Don't want to have a failure and suddenly lose 10 or more hp (see my first post, we no fooling, saw a 20% gain in power and torque!).
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Matt Cramer
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Re: Firmware 1.5.x Open IAC on WOT

Post by Matt Cramer »

prof315 wrote:I'll look into the non contact Hall effect stuff... Keep in mind these are road racing cars with stiff suspensions and they often race on bumpy tracks. Vibration can be a big issue, that's what kills the stock WOT switch and every add-on TPS I have ever seen. Reliability is a must. Don't want to have a failure and suddenly lose 10 or more hp (see my first post, we no fooling, saw a 20% gain in power and torque!).
I've heard these non contact Hall sensors are what are being used for many Pro Mod builds and other extreme builds.
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Re: Firmware 1.5.x Open IAC on WOT

Post by dontz125 »

A comment by James in a recent thread had me doing a head-bonk for not remembering; he's using a motorcycle spring-pull brake switch (with a bit of light chain as an extension) as a clutch / launch switch. There's no reason I can think of why you couldn't use the same thing as a WOT switch. They're cheap, available everywhere, and actually pretty rugged - they're meant to be hard-mounted on the outside of a bike, after all!
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