Help! CEL, TPMS, no throttle response
 

Hi everyone,

Tonight as I was driving home on the freeway, the check engine light and tire sensor light came on and I lost throttle response. This occurred in sixth gear at about 60 mph. Oil pressure and temperature gauges were normal, and fuel indicator shows half a tank, which looks accurate since I filled the tank this morning.

I pulled over and swtiched off the engine. When I restarted, the CEL was still on, the tire sensor light was off, but I still had no throttle response. The tach showed 2.5 steady and no change when I pressed the throttle.

The next part I'm going to tell you will reveal just how ignorant I am about cars. I read in the owner's manual CEL can be caused by a loose fuel cap. I checked the fuel cap and sure enough it was loose. I tightened it, I restart, and voila, I have throttle back but the CEL is still on. It won't shock me in the least to hear someone say getting the throttle back had as much to do with tightening the fuel cap as a mouse farting.

I was able to drive home. Two questions:

What do you think is the problem?

Is it safe for me to drive the car to my dealership, which is about ten minutes away over the freeway?

I think the CEL will go away after some driving assuming that the loosen fuel cap is the one that triggered the CEL.

The TPMS light probably had to do with one or more tires being underinflated and as the tire warmed up the air pressure increased to within the good range causing the light to cancel. Check your tire pressures cold and set them to the recommended pressure.

The CEL may be related to the non-sealing gas cap or something else. If it is a result of the loose gas cap the CEL will self-clear after a few drive cycles. If it does not cancel, take it to a dealer and have them diagnose the problem.

"The tach showed 2.5 steady and no change when I pressed the throttle."
Does that mean you couldn't rev the engine or that you couldn't "force" the idle to drop by blipping the gas? The engine will idle around that rpm briefly when cold but it should eventually drop to ~750 rpm with a FULLY warmed up engine. Did the idle drop to ~750 after the engine was fully warmed up? If so, this is a non-problem. If it stayed at 2.5k, take it in for service.

damn, 60mph in 6th gear? what RPM is that at? that seems awfully slow to be in that gear.

It means I stepped on the gas and the engine didn't rev, it just stayed at 2.5. This was after about 5 minutes of driving at freeway speed, so the engine was completely warmed.

That's not good. Sounds like the engine was in limp mode. Definitely take it in to a dealer and have them read the error codes and diagnose the problem.

you're kidding right? maybe i'm the odd one, but more often than not, i'm in 6th by 35...almost always by 40.

i also drive it like i bought it and my life's dependent on it, not like i stole it.

boring much?

i've invested my life savings into the car because a quick car is what i've always wanted. just being judicious about my investment. mind you, i bomb around 10% of the time, but prefer to short shift and see if i can get decent gas mileage the rest...i have gotten 22 on a road trip though. so i'm doing something right!

I agree with Go48. I don't know the details for the RX-8, but I have heard of other throttle-by-wire vehicles having a limp mode when an error is detected in the throttle sensors/actuators or any part of that circuit. The car goes into a high idle that is supposed to be enough to get you to the dealer. Definitely get this checked out.

You're not doing the car and yourself any favors if you are operating outside the power band. Keep the car at 3K rpm or greater, run it to redline occasionally and it will thank you many times over. :)

You gotta let him know why he needs to redline it every so often! :)

I know why but you pointed it out!

Is the CEL steady or flashing?

I drive it like I bought it, my life's dependent on it, and like I enjoy it!!! Life's too short to drive an exciting car sedately.

And the winner is...

Marc_GS. The dealer says the problem is a faulty throttle position sensor. I should get the car back tomorrow.

The owners manual says to shift into 6th gear at 46 MPH.

The shift points it lists are:

14
22
29
36
46

I generally shift into 6th when I'm cruising down the highway in 5th and I suddenly remember "Oh yeah, there's another gear! Might as well use it..."

FYI- The oil pressure gauge is a dummy gauge. It's just there for looks.

Good Luck.

and what a fantastic ride THAT would be. honestly, who the heck shifts like that? if you did, you'd be rear ended by the 80 year old woman behind you trying to accelerate past you in her '85 Yugo.

i routinely travel about town in 6th at 42-45 mph

My car did that same thing this afternoon, I was doing about 90mph in 4th when the cel came on with a small SPUT noise from exhaust sounded more like a miss fire in the plug and the throttle came to 3000 and When ever i tried pressing the response started to shut me off. I pulled over, called a friend who has an RX8 , he came over and disconnected my battery for 3 mins and re connected it, and the throttle problem was gone along with the CEL light and car runs just fine. I am just confused what should i do now. I drove about 2 hours after that with high rpm and at very very high speeds and no problem seems to be found. Any ideas guys what might have happened? I think I did sort of went to 9500rom while shifting from 3rd to 4th....