sputtering and high idle

Ive had my 91 mr2 for a couple years now, and have had intermitten(sp) problems with rough performance. I use 91 octane fuel and only high grade, cause if I dont she runs like crud. Occasionally, shell sputter and the tac goes up n down like mad! Even sometimes idleing at like 2k rpm! I had a top engine cleaning done, and have run fuel injection cleaner through her a few times. She hasnt been bad in a while, but occasionally she backfires and I have absolutely NO accelleration(to the point of flipping on my hazards and letting her cough for a bit and slow down to a crawl before regaining power). Shes been on the diagnostic machine and nothin showed up out of the ordinary. She never acts up when my mechanic looks at her! Figures.

Any ideas of whats making her so sluggish!? Im planning on replacing the ingine soon but Im curious as to what the deal is.

Oh yeah, shes got about 190k miles on her.

Thnx

your TPS could be broken...

Is this a turbo MR2 or a no-turbo?

If it is turbo you are using to low of an octane at 91 and if you are in a non-turbo you are using to high of an octane.

How many miles? ... many you clogged cats.

mines done that splutter go slow almost stop thing a few times, i'm going with its my distributer which is a bit loose. I'd be checking your leads, plugs and distributer. what seems to happen with mine is it suddenly loses power completely for a second, but has only ever happened when i first start it and drive off for the day. so it might not actually do it when you chuck it on diagnostics, check your ignition.

next. 91 too high?? damn! they dont even sell 91 in japan do they? i guess they could be tuned for the states... i'm running 98 right now and it's going NICE, definately notice the difference from 96, but i'd prefer japanese fuel at like 100 or 102.

TRD2000 octane ratings in the rest of the world are different from the ratings here in the US. You can't compare the numbers.

Shes non-turbo. I had used the lower octane fuels before, but she absolutely runds like crud on them.

I would suggest starting with some regular maintenance items:

1. Cap, rotor, wires and plugs
2. Fresh fuel and air filter
3. Coolant flush and fill. (generally the bouncing idle in an MR2 is from air in the coolant system)

I suspect if you do these items, you will notice a big improvement in driveability.

octane ratings in the rest of the world are different from the ratings here in the US. You can't compare the numbers.

how are they different? i have always thawt that octane ratings are standard around the world. this is the first ive heard of them being different.

Most of the world uses RON octane.
The United States used CLC Octane:

"The RON method of octane measurement is not used in the United States. In the US, a different method entirely is used, called the CLC method. The number that results from this method is the average of the RON octane number and the MON octane number, so (RON + MON)/2 = CLC octane number. This is the number that you will find printed on a yellow label on gas pumps in the United States. 91 RON octane is equivalent to 87 CLC octane. "

More info here:
http://www.refiningonline.com/EngelhardKB/crep/TCR4_29.htm

i vaguely remembered something about it when you mentioned it... thanks for the clarification, makes more sense now.

Ahhhhh... cheers!