General Revs drop down during normal acceleration

[ivanjuaric]

During normal acceleration in 2nd and 3rd gear when I reach 1900 RPM the engine slows down to 1700 rpm (2.4 MJET 200 hp).
I changed the EGR valve as well but this didn’t change the problem.

?

 

[Radlet6]

How do you mean the engine slows down? Do you mean that the engine revs drop but the car keeps accelerating or does the car slow down too? Can you get the car past 1900 rpm?

 

[ivanjuaric]

Q: Do you mean that the engine revs drop but the car keeps accelerating or does the car slow down too?

A: The car accelerates normally but only engine RMP drops down for 100 RPM.


Q: Can you get the car past 1900 rpm?
A: Yes, withouth and problems

 

[Radlet6]

I take it that you can also hear a drop in the revs too and that it is not just a faulty tacho.

If so it sounds like the clutch is slipping slightly - that can be the only way for the revs to drop and the car not slow down (I take it that it is a manual transmission).

One way to find out is to try and pull away from a standstill in 4th gear and see what happens. The car should stall straight way without any clutch slip.

What does everyone else think?

 

[keithglos]

All our UK 2.4's are Auto, 6 speed sequential Aisin box, Ivan's may not be.
Sounds like the auto changing up a gear?

 

[DoIDon'tI]

I think I know what you mean - and if it is what I think, then it's entirely normal. It's down to the gearbox - there is a lock-up clutch on all gears above second, when you accelerate moderately the gearbox slips (due to the torque converter) until the lock-up clutch engages.

It's more noticeable under hard acceleration, and personally I don't like it (as the engine is just getting into its stride then gets 'pulled back' a little). I'd go as far as to say it's a pain in the a**e when you're towing and things are a little more marginal. I'd prefer to have the lock-up engage when you weren't accelerating but MPG and emissions are obviously more important...

I hope it's normal, mine's been doing it since I bought it 44,000 miles ago

HTH.

 

[Radlet6]

Well this had me guessing a bit as I thought all 2.4's were autos too - but I wasn't going to rule out the possibility of manual cars being available on the European mainland.

I have done some research and all European 2.4 Cromas are supposed to be autos. I assumed that when Ivanjuric was talking about this happening in 2nd and 3rd gear that his was a manual - stupid me should have asked really.

As such Do I Don't I is right it is the auto lock up kicking in - mine does it on my 1.9 auto. It is supposed to give better economy.

Unless of course Ivan your car is a manual box.

 

[ivanjuaric]

No, it is car with automatic transmittion (no clutch). The car drives good, power and everything is fine.

Only at slow accelaration (in tiptronic mode - manual gear shifting - no clucth) I can hear that engine slows down at some point in time and it is visible on tacho as well (either when I drive in 2nd or 3rd gear - witouth chaning the gear up/ down) - constant driving conditions.

I hope this helps.

I will try to make short movie tommorow....