bwoodry

Occasionally I feel a slow throttle response or delay.

What can cause this?
Did complete a search but did not see anything specific to the 964.

Also when you move from 16 inch rims to 17 do you need a different STEERNG RACK SPACER?

THANKS

BW

Adrian

I am afraid you do not provide enough information for either question to be answered properly.
When do you get a delay or slow response from the throttle? Some delay is normal for the standard setup due to its design.
A vacuum leak will cause a throttle response delay.
There are specific 964 issues which can cause this problem because these systems were introduced with the 964, such as the vacuum operated reasonance valve which makes the air intake longer at approximately 5000rpm.

In model year 1992 a 10mm steering rack spacer replaced the 6mm steering rack spacer to improve the wheel rub situation caused on "some" earlier 964s when switching from 16s to 17s. Some minor bodywork modifications were also required.
Not all owners who switched without doing any of the required modifications reported wheel rub. However my experience tells me that "not reporting" does not mean, no wheel rub.
A 5mm wheel spacer can be used instead of the larger steering rack spacers if you are using 7 x 17s up front.
Ciao,
Adrian.

964rh

Adrian

I have 17" cup 2's on my 1990 C4, as far as I know it doesn't have the 10mm rack spacer installed and I didn't notice any rubbing.

I have recently put some 225 tyres on the front, these do rub a fair bit, would 5mm wheel spacer sort this for me.

Also what part of the bodywork needs to be modified?. My tyres rub on the inside arch towards the back.

Thanks

Rob

Adrian

Rob,
The usual rub is at the front and so are the modifications. All are illustrated in my book. By the way you often do not notice any rubbing and a lot depends on where, and how you drive.
A good test is to do some hard turning in reverse, lock to lock.
The 5mm spacer worked for me with 225s.
Ciao,
Adrian.

bwoodry

drian:

Thanks for the response:

In regard the Slow or delayed Throttle response. When the car is sitting at idle and you push the gas to get the revs up for starting out in first gear it hesitates to incrrease the throttle. This usually occurs at regular operating temperatures. So from idle at 890 rms's it is sluggish and or delayed.


Sometime when shifting and you blip the thottle it hesitates as well at high RPM's but not nearly as often as at low RMS's
Last night after

Thanks

Bob

Red rooster

I would fit the extra thick lock stopsas the 100% fix. Easy job but you will need to get an alignment done after .
All the best,
Geoff

Adrian

Using the 5mm spacers is a very cost effective procedure that does not require the labour costs of steering rack disassembly, reassembly and a wheel alignment. It is also a 100% fix.
The spacers can also be removed if you reinstall 16 inch wheels for winter or resale.
The 10mm steering stops reduce the lock to lock steering rack movement (the reason they are called steering stops) which in turn increases the turning circle.
I have them fitted to my C4 because of the 19 inch wheels and now with 16 inch wheels for winter installed I wish they were not fitted.
Ciao,
Adrian.

bwoodry

Adrian:


Thanks for the information on wheel spacers.

Any further thoughts on the Throttle response?

Tks

Bob

Adrian

Not really Bob.
It is back to basics really. I would be looking for oil contamination in the airbox which has got into the ISV and airflow sensor. Maybe either/both are slow to react. I would certainly be looking for a vacuum leak.
I would also check the fuel tank to make sure it is not collapsing as you apply the gas. A colleague of mine had this throttle response problem at idle and it was the tank vent valve stuck open, collapsing the fuel tank.
My first thought would be a vacuum leak.
If you have access to a Bosch Hammer you might want to perform an idle adaption or a DME reset if you don't have access to a Hammer.
I am afraid that I have to go again, books to write, so I cannot get too heavily involved in fore and back discussions. I am hoping that others who will be more reliable in their support level will chime in and help out.
Ciao,
Adrian.