Today my son and I were headed to lunch when a Mazda speed came up from behind and started acting up. I punched it pretty good from about 40 mph to say 90 ( don't judge my parenting skills) and then it all went south, yellow/red light, ASC fail, engine fail safe mode. Limped to the nearest parking lot, turned it off the restarted it and it ran fine the rest of the day. All research leads to a failing throttle body but I'm surprised that would be the case at only 54k on it. All I seem to see is "used" (mines used) or "rebuilt" ones. I don't need the thing leaving me "limping" somewhere. PS, no codes thrown or pending codes.

 

Another day, another failsafe warning thread.

If it didn't go into failsafe mode until you took your foot off the throttle, then it sounds very similar to my TPS failure.
I fully recommend sending to ASI for a rebuild

 

You can try disconnecting the various plugs to the throttle body and spraying them with electronic or contact cleaner, but first disconnect neg. batt. cable.

A couple of members have suggested that infrequent use allows corrosion to occur on contact surfaces in the throttle body and repeatedly flooring the throttle a few dozen times (engine off) cleans them.

But grandell has the final solution if nothing else works.

 

It's my daily so it sees plenty of use, I checked/cleaned all the contacts today. We'll see how it goes tomorrow. Took the XJS to work to show a guy that's interested in it. Hopefully the XJR performs well tomorrow.

 

When you floored it -- you most likely sent both sensors into an area where they don't normally go. They have a double track -- any difference on each track will set it off.

Try moving the throttle throughout the range --

 

+1. That's what I meant about infrequent use. Not of the car itself, but the full range use of the throttle.

 

I started to realize that's what you meant, when I put the hammer down yesterday I really mashed it to the floor. That very well could be what the issue was. Ran the throttle through to WOT 20 times this AM with the engine off just for good measure. Drive to work was uneventful.

 

I did it about 50 times initially ...... gave it another 10 each time before starting out for the next week.

Still do it when I think about it. Good luck

 

From what I've seen in the XK thread, it's not the upper range of the track that's the problem, it's that the lower range wears and cracks, and you lose contact when you come back off the throttle, not when you're flooring it.


TBH there are probably a few common failure methods for these, whether it's upper track, lower track, or the pin connections/plug.