Wrong RPM Timing

[fknjexx]

Hey Mx5CarTalk,

After getting my car serviced I seem to be getting the wrong times with my rpm and speed.

Whenever I'm highway driving going 100-110, gear in 5, my rpm is on 4000 constantly. Is there any reason onto why and what can be done to solve this situation?

Cheers.


Sent from my iPhone using Tapatalk

[smy0003]

What kind of service?
Is your clutch slipping?

[fknjexx]

What kind of service?
Is your clutch slipping?

Major service (spark plugs, oil, filter, fluids, brakes). It feels like the clutch is slipping, could that cause the problem?


Sent from my iPhone using Tapatalk

[davekmoore]

Clutch slipping will result in engine revving more without speed going up, then clutch failure shortly thereafter.

Where do you put your left foot when you're not pressing the clutch pedal down?

[fknjexx]

Clutch slipping will result in engine revving more without speed going up, then clutch failure shortly thereafter.

Where do you put your left foot when you're not pressing the clutch pedal down?

That's possibly why then, after all my clutch hasn't been changed ever since. luckily I have a heavy duty clutch ready to go in. I'll keep an update to see if this solved the problem.

I put it on the foot rest next to the clutch.


Sent from my iPhone using Tapatalk

[davekmoore]

If you're using the foot rest that rules out the clutch slipping because your foot is on the clutch.

If the car is 20 years old and on the original clutch it's probably due a replacement.

Do the revs go up without an increase in car speed if you give it full throttle in 4th at 50 going up a hill?

[Magpie]

Any modifications to your car? Is it a 5 speed box? What tyre size? Final drive ratio?

At 4000 and in 5th (of a 5 speed box), 185/60/R14 and a 4.3 = 123 kmh. At 100 the revs should be about 3,250. What speed are you doing when the revs are at 3,250?

4000 and 105 km in 5th suggests a final drive ratio around 5.0...

Find a quite section of road. Have the revs between 2,500 and 3000 then put the car in 4th (1:1 for a 5 speed box) and floor it. If the revs rise and speed do not rise concurrently then the clutch is slipping. Stop testing and replace clutch.

[project.r.racing]

But why is it slipping is my question? Worn pressure plate normally you just hit a rpm amount and it slips/revs like you are in neutral.

Actually being about to hold a constant rev point at a constant speed has me asking other questions. Why from the morning it showed 3250rpm @ 100kph, and in the afternoon it showed @ 4000rpm. I'd be taking it back to whom did the service. Maybe they touched something within the clutch system you have failed to mention or they failed to mention to you.

Can the car still rev to 5000/6000 rpm?

[Steampunk]

If the clutch is slipping that badly it wouldn't be able to hold that much load in 5th gear constantly, it will simply rev higher and higher due to the plate not engaging properly and you wouldn't get up to speed and this will exponentially become worse daily and thus virtually no clutch within a matter of days....thats IF its a slipping clutch

OP needs to describe symptoms better and do the usual test of revving it to above 4,000rpm, and dump the clutch in 4th or 5th and see if it grabs. Maybe get someone to do ut who is more mechanically knowledgeable.
Check the speedo cable on thr gearbox, maybe they fiddled around with it and it's loose thus giving inconsistent reading.

[bruce]

Are you really in 5th? I have heard sillier things.

[fknjexx]

Problem solved! It was the clutch slipping, replaced it with a rpm heavy duty clutch and it is now running fine. Sorry for such a late update but thanks for the help guys!!


Sent from my iPhone using Tapatalk