This came in to the Miata.net Mailbox. We thought we should pass it along to autocrossers.
During the last two months, the throttle has stuck open three times on my Miata! Fortunately, no one has been hurt. I have now discovered how this happened. Since it could happen to any Miata autocrosser, I am sending out this warning.
There is a problem with the Mazda Miata that can cause the throttle to stick wide open. What is worse, the root cause can occur and go completely undetected during normal maintenance and inspection. Clearly, this is a potentially dangerous situation!
Normally one would suspect lubrication of the throttle body, or the tension in the cable. Unfortunately, the real cause is far simpler and more diabolical. The accelerator pedal is a perforated metal plate with a ridge around the periphery to add stiffness. The ridge points away from the driver's foot, toward the carpet. (Remember, floor mats must be removed for Solo II competition). What happens is the ridge on the bottom of the accelerator pedal wears a crescent-shaped slit in the carpet. Once the slit is all the way through the carpet, the next time you "floor it", the corner of the pedal can slip into the slit and get caught under the carpet! Remember, the carpet is black and fuzzy, and this area is poorly illuminated and normally out of sight. So, unless you know what to look for .... Well, you get the idea. If you ever drive a Miata without floor mats, check for this problem--it could save you grief or worse!
Mazda Motorsports has been notified and plans to send out a bulletin in the near future. SCCA Rally/Solo has been notified also. They plan to examine Miata's at the ProSolo2 at Peru, IN next weekend, then decide what action--if any--they should take. Feel free to forward this warning to any group who may benefit.
I saw the warning about the throttle getting stuck wide open on miata.net and it is absolutely true!!
I have a 92' and race with SCCA Road-Racing, Class ITA. When I removed the floor mats and was reaching top speed in the straight away at HAIR (Holtville, San Diego Region) the gas pedal got stuck and I was going over 95MPH! I was able to slow down by engaging the clutch and bracking hard. It was a test day so I was not in competition with other race cars.
I applied duct tape to the floor area under the gas pedal, but intend to cut out the carpet where it makes contact.
VERY IMPORTANT NOTICE FOR ALL RACERS/MIATA OWNERS
Patrick Langdon
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