Engine revs

[lookingfora944]

Some observations
I am still loving my 944 S2. As an everyday car in London I find it an absolute joy and actually very comfortable and easy to drive in traffic.
I have noticed however, that if I am in particularly bad traffic, it does run a little hot, but this soon sorts itself out when I get moving again.
I just had a question about engine revs. Is it a feature of these cars that they lose revs very quickly upon taking your foot off the accelerator?
I am finding it hard to change gear smoothly when going flat out. The car jumps as a result of engine speed not matching the road speed, I guess. Is this because its a very large engine for a 4 cylinder. Or is it just my car? How do people deal with this. Is it a case of blipping the accelerator before changing up, once it is neutral for a second?
I am trying to figure out the best way to change gear at speed and I suppose it takes a bit of getting used to having only driven things like minis and beatles in the past :$

 

[Hairyarse]

Are you saying that the revs are slow to drop when you put the clutch pedal down? If that's the case it doesn't sound right. My idle issues seem to be sorting themselves out but if you look at my thread here it would give you an idea of the things worth checking. Idle stabilisation valve I guess would be top of the list.

http://www.porscheclubgbforum.com/tm.asp?m=606460

 

[Alexw]

Mine does lose its revs quick too, I wasn't sure if it was my car or they are all like that. I think its one of the reasons the short shift kits are popular. I only struggle going from 1st to 2nd though, above that I'm fine.

 

[Lowtimer]

Andy, actually I think he is saying the opposite - that the revs drop off very quickly.

Lookingfor a944, I don't know what you have been driving up to now but it is a fact that in more recent years cars have tended to be fitted with engine management systems which mimic very heavy flywheels so that the revs do not drop very suddenly when you let off the throttle between gears on the way up the box. This is for emissions purposes. The 944 is of an earlier age and has an engine which is more directly responsive to the throttle. You don't have to blip the throttle, changing up, but by the same token you don't need to lift it off all the way either. For example - when stationary in neutral, have a play with the throttle to find the throttle setting where the engine naturally holds 2000, 3000, 4000 rpm in neutral. Then when driving you need to anticipate the revs you will want. Changing from 6000 rpm in 2nd to 3rd, you will want the 4000 rpm position, so when you lift off, lift off to that foot position, not to throttle closed. That way you will smoothly be holding the right revs and as the clutch goes home you go pack to full throttle.

 

[lookingfora944]

Thanks Lowtimer, this is exactly what I was saying, like Alex above, it is only really noticeably when going from 1st to 2nd.
Your answer is very informative and I shall give it some practise today.
Cheers

 

[Diver944]

I drive lots of different new cars every day as part of my job, but when I jump back into the 944 I don't notice this sort of problem described by 'Looking'. What I do know is that 944's have never been known for their quick gearchanges, it's definatley an out of gear, into neutral and into the next gear scenario.

Worn linkages at the gearbox and at the lever can make this more noticeable.

I can't think what could cause the revs to drop too quickly when you let off the throttle? Does the car jerk when you come on and off the throttle while its still in gear driving along?

 

[sawood12]

For your engine heating issue it might be worth a change of coolant and a rad flush and maybe replace the thermostat, and check the fan is working as intended. You shouldn't see the temp increase significantly in standing traffic. My turbo could sit in traffic jams on a hot day with the A/C running all day without the temp gauge moving so the cooling system should be more than man enough for any traffic situation.

I actually think the 944 engine is quite a lazy engine - I guess there is alot if inertia with those big pistons, over-engineered bottom end and two balance shafts all wizzing round and alot of people seem to spend alot of money trying to make the engine zippier like installing lightened flywheels for example. And with the 968 they moved to a twin-mass flywheel. So if you think the engine is quite responsive then that is a good thing in the eyes of alot of other people!

What I find I needed to do when climbing out of the 944 into other cars with more modern engines where they are more responsive is put the throttle in before lifting the clutch between gear changes - so i'm not so much blipping the throttle, but just leading with the throttle more to match the engine revs upon clutch engagement to the required road revs, so it is nothing a slight tweak to your throttle/clutch timing shouldn't be able to sort out. I can't think there is anything wrong with your car that would give it that characteristic - unless maybe if your balance shaft belt has broken and you've got less inertia going on, but then you should notice rougher running.

 

[GPF]

ORIGINAL: lookingfora944

I am finding it hard to change gear smoothly when going flat out. The car jumps as a result of engine speed not matching the road speed, I guess.

.....it is only really noticeably when going from 1st to 2nd.

Are you sure it is because the revs have dropped too quickly? Could it be that the car is hesitating when you floor it after the change into 2nd?

 

[Neil Haughey]

The really odd thing is I find the complete opposite in my race car which after all has a completely standard S2 drive train. Stephs old mk3 MX-5 OTOH I always found very difficult to drive smoothly. For some reason the S2 is for me easier to drive smoothly if driven quickly, and no you don't need to push the clutch all the way up and down and spend time in neutral. If anyones car is like this there must be something wrong with the gear linkages, clutch or gearbox. With a new clutch you literally just push it up and down quickly and flick the lever about as quick as you can [8D].

 

[944Turbo]

Engine will heat up when you stop moving - should go up, the fans will cut in and drop it back down, I think the single line below the red is the point they fully cut in, if its not crossing that I wouldnt worry too much.
Tony

 

[zcacogp]

Can't really help, but if the revs are dropping quickly (and whether this is "too quickly" or not is best determined by comparing with another similar model) then a logical explanation could be too much engine friction, for some reason or another. Maybe worth checking the tension of the belts and the condition of the cam chain tensioner. Does it sound particularly laboured when cranking on the starter motor?


Oli.