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Acceleration problem 2000 MR2 Spyder w/manual transmission

Car is normally very responsive. Now from a complete stop it feels like the car is struggling to get to speed. Also on highway having a hard time getting above 60 mph on highway even with gas floored. Mechanic thinks clutch might be slipping. Does this sound right? To me the clutch feels the same and the engine is running smoothly.

Has a mechanic driven the car, or was this an over-the-phone diagnosis?

You should be able to detect a slipping clutch while driving, especially under hard acceleration. If the engine speed increases out of proportion to the car’s acceleration it’s a good chance the clutch is slipping. Here’s a clutch test:

Set the parking brake FIRMLY so the car can’t move. Start the engine. Put the transmission in 4th gear. Pretend you’re starting out from a stop. Give the engine some gas and slowly release the clutch. DO NOT release the parking brake.

If the engine stalls the clutch is not slipping. If you can take your foot off the clutch pedal without stalling the engine, the clutch is worn out and slipping.

If, on the other hand, the clutch is not slipping and flooring the throttle does not provide adequate acceleration there is a problem with the engine management system.

Fuel and air filter, timing belt been changed on schedule?
Did this come on suddenly? Could be timing belt dropped back a tooth.
Get the cam and ignition timing checked.

First, I have a great mechanic but he seems stumped on this one. Nothing registers when they do the computer test. He took it on highway himself and said he got to 80 but he said he’s not sure how my car handles normally. He said he thinks clutch might be slipping (but the rpms don’t seem excessively high) and the mechanic said if it is slipping it’s only slightly and don’t have to fix right now. Funny thing is I can’t try your test as they are having rear brake calipers built which won’t be installed until next week. What is happening is that normally the car is quick off the line but not right now. Sluggish; feels like there is resistance/hesitation when I punch it. Seems a little rough sometimes (not every time) accelerating up to 45 for city driving. When I get on the highway ramp and try to bring car up to speed I get to 60 and then practically floor it to get it above that speed when normally my car cruises right up to 70-75 with ease. The rpms rise but only to about 3,500. If I happen to be on a down incline in the road the car accelerates and feels less sluggish. When I floor it, the rpms are not rising disproportionately. The rpms are between 3,000 and 3,500 rpms when trying to accelerate which has always been normal for my car. It does not sound like the engine is racing but the car feels sluggish and unresponsive. (I don’t know if this explains the problem any better, but I don’t want to go ahead and replace the clutch when it doesn’t feel like a clutch problem.) I had wanted to put the car in and do the brakes and clutch at the same time. Would you suggest fixing the brakes and then trying your test? I know you are only expressing an opinion but all that will happen is the car will have to go into the shop twice. Many thanks for taking the time to reply to my original post.

Air filter just changed a few weeks ago. I asked mechanic about fuel filter and he says not that and that fuel filter is inside engine. He said he checked hoses and belts. This did come on suddenly. Would the timing problem show up when they put car on computer because nothing comes up. They replaced an oxygen sensor which I knew wasn’t the problem because that same sensor has gone out 3 previous times and never affected the car’s performance.

“Would the timing problem show up when they put car on computer”

Maybe not. They might have to remove the valve cover and look at the cam timing marks.

Could also be a clogged cat converter. A check of manifold vacuum might be useful.

I see this is an older thread, but maybe it ill help someone else.
I bet you need to clean the airflow sensor on the intake. this happens a lot and needs to be done often. 1-2 years depending on how dirty the air is/where you drive.
buy some electronics cleaner spray (hobby shop, auto parts store, radio shack) MAKE SURE it is safe for plastics! and just remove the couple screws and the electrical socket, then pull the sensor out. you can look in it it will probably look all dark. spray liberally with the cleaner till it is pouring out. then look in it again, I bet you can see some shiny metal parts now? (as they are now clean) now wait for it to dry out - like 1/2 hour and then put it back in. I bet your engine runs great now.
also, remove the battery power while doing this. which will also reset the computer. let me know if this works. Should be under $10 for the cleaner. and it is easy to do.