Wierd Revving Or Normal?

[T_T]

I have been driving recently without any music/radio, and although i have owned an MR2 for about 3 years now and never noticed anything, i began to 'hear' the engine revving as i began to accelerate after each gear change. The revs seemed to rise then fall even though i had my foot down, mainly noticed in 1st, 2nd, 3rd and 4th gears as i was on a 30mph road. The acceleration didn't seem normal but then i'm wondering if i am scaring myself into thinking there is a problem because i have heard something i can't remember hearing before!?

The conditions were wet, engine was cold, later on as it dried up and the engine warmed up it didn't appear to be doing it!? it is difficult to explain, was wondering if the vvti had anything to do with it (btw what DOES the vvti do?) any ideas guys?

[T600]

I have been driving recently without any music/radio, and although i have owned an MR2 for about 3 years now and never noticed anything, i began to 'hear' the engine revving as i began to accelerate after each gear change. The revs seemed to rise then fall even though i had my foot down, mainly noticed in 1st, 2nd, 3rd and 4th gears as i was on a 30mph road. The acceleration didn't seem normal but then i'm wondering if i am scaring myself into thinking there is a problem because i have heard something i can't remember hearing before!?

The conditions were wet, engine was cold, later on as it dried up and the engine warmed up it didn't appear to be doing it!? it is difficult to explain, was wondering if the vvti had anything to do with it (btw what DOES the vvti do?) any ideas guys?

Sounds like the clutch could be beginning to slip. The only way engine revs increase without a simultaneous wheel speed increase is if the clutch is slipping.

[T_T]

uh-ohh, that sounds expensive! it fitting a new clutch a big/expensive job?

[T600]

uh-ohh, that sounds expensive! it fitting a new clutch a big/expensive job?

I'm not saying that it's definitely that; just that it could be. You'll find out though as it'll get worse over time if it is. Also watch the rev counter when this happens to see if the revs really do go up without speed increasing when the noise occurs.

If it is the clutch then slip can be caused by things other than the plates wearing out, e.g. oil or water on the plates; the fact that it's going away after a run is encouraging too as maybe the plates just need cleaning and a good run does that to them. If that is the case then you have to find out what's getting onto them which could be as big a job as changing the clutch. Another possible cause is the clutch pedal not coming right back up when you take your foot off it - check nothing's obstructing it.

I don't think it's a huge job on your car though. Mr T will tell you, but do a search too to see what others have paid. IIRC paid about £300 at Mr T for the clutch on a Mk 2.

[T_T]

hey, cheers for the information mate - i'll do that and see what happens! I'm never shy of taking it for a run so i'll try that first!! ;)

[T600]

hey, cheers for the information mate - i'll do that and see what happens! I'm never shy of taking it for a run so i'll try that first!! ;)

Cool. By the way, interesting thread on Celica-Club at the mo, by someone who had slipping clutch which seemed to then cure itself. One of the replies is by someone who says that they had slippage which cured itself 2 years ago and is still working fine. Their suggestion is that perhaps rust on clutch splines was to blame and use of car/clutch cleaned it up. I think another possibility is that clutch perhaps was contaminated as described above, or perhaps glazed and usage recovered it.

Interesting though that some slippage may not necessarily mean that clutch is about to die completely.

[T_T]

just a thought - this car is a second car hence doesn't get used too much, maybe once during the week and at weekends. do u think this may be adding to the problem? will check out that thread

[T600]

just a thought - this car is a second car hence doesn't get used too much, maybe once during the week and at weekends. do u think this may be adding to the problem? will check out that thread

Yes, I was wondering whether it got used much. My MkII used to regularly suffer from a slightly slipping clutch when first driven after a week or so in the garage. Went on for a couple of years but eventually I had it replaced as it started to get more frequent and didn't go away after a bit of driving. I suspect that whatever the initial problem was, it probably did a bit of damage to the clutch each time it happened.

[innocent]

When you say you 'hear' the engine revving, do you mean its louder than normal, the revs are rising without you hitting the throttle, or the revs are staying high when you take your foot off?

First of all, i'd clean the MAF sensor. Takes 5 mins, the carb cleaner costs 3 quid, and it sounds like this could be your problem if you're losing acceleration and the revs are staying low when you mash the pedal. I had this, cleaned the MAF and its better than ever.

If your revs are rising on their own then its very likely to be the clutch slipping and you've got some good advice above. Like i said, clean the MAF anyway (I'm gonna do it monthly now!) but its unlikely to help rising revs.

If if its just an issue of a noisy engine and a lack of power, and cleaning the MAF doesn't help, check for holes in your air intake & exhaust system - holes cause a pressure drop on the way out and more seriously, vacuum loss on the way in and make your prize bird magnet sound like a tractor.

If the revs are sticking high when you take your foot off, the throttle butterfly is likely getting stuck open. Clean the throttle body out and check that the spring is shutting the butterfly properly. Read the thread below, its an easy job and also a good thing to do that you wont get on the average service. (You'll need to remove the Battery to get to it on an MR2)

http://www.mobil1.com/USA-English/MotorOil...tle_Bodies.aspx

Good luck, and post your progress!

[T_T]

sorry, when i say hear, i should have said noticed more. got the car in bits at the mo just checking everything over will let u know, cheers.

[i30i3i3y]

This might be unrelated but I've noticed in my mr2 that at each gear change the revs jump up. Not something I noticed in my Avensis. I thought clutch-in makes the revs drop then go back up once re-engaged. Is this normal or an indication of a problem?

P.S. Apologies for the thread hijack.

[Black Knight]

Does happen on the Avensis too but kind of depends on your driving style. It's something to do with temperature control of the catalyst apparently.

[T_T]

Hey dudes, took her fur a couple of good runs and my baby seems to have (most of) her zip back!!! :) It IS the clutch slipping but I've just taken it out for a test drive and gave it a bit of stick and apart from a couple of slight slips - nothing to report! i'll keep my eye on it and try to drive it more often i think.

Hey i30i3i3y, the 2 does tend to give a satisfying little 'blip' at each gear change, well.. mine does anyway :D