I have a 90 964 cab with 130,000. I revved the car up to 4500rpm in 1st and it hit a flat spot. It did this in 2nd, 3rd and 4th. It would rev good up to 4500 hesitate and then go up. Anyone have any ideas what could cause this? I also noticed my car seems to have excessive body roll in the corners and the car feels like I am driving a boat on the highway. It feels like it's floating side to side. It gets a little scary at 80+. My guess is the shocks maybe bad? Any help would be much appreciated!

 

Sounds like the resonance flap in your car's intake system is not operating.

.. Gregg

 

I will check that and see. I really appreciate it.

 

Good luck!

Let us know how you make out ...

... Gregg

 

I'd also check the condition of your distributor belt. Search here for threads on that.

 

Shocks sounds like a good place to start checking. Have you jacked up the car to check the suspension points (tires, shocks, wheel bearings, sway bar drop links, etc). Do you know how old things are?

 

I just put a new distributor belt on little over a year ago. I am trying to check the flap in the intake, but it seems to be fine. I am not sure how to tell if that is the problem. Let me know if anyone has anything else I should check. I have all the receipts from the prior owner, but it does not show any suspension work being done. I did notice several bushing that are dry and crumbly. The care has 130k so I am thinking it's the shocks. I think it has the original Boge shocks. I don't know what else could cause the body to roll so bad. It has me puzzled. I was thinking of going ahead and put new shocks and lowering springs on the car. It needs it anyway. What is everyone's preferance on shocks and springs? Koni, Bilsteins etc. and Eibach or HR for springs? I don't have enough money for coilovers plus I am not using the car on the track. It's just a car for around town. I really appreciate everyone's help!

 

From what I see here, the consensus is Bilstein HD shocks with H&R springs if you do not want to go coilovers. I've ordered this combo and decided on the green H&Rs.

-Mark

 

+1 HR greens and Bilstein HDs. I have them on both of my cars.

 

2nd here, i installed on my old 89 911 C4 and have put the same on my new car, best thing to do.

 

Even though you put a new dizzy belt on a year ago, I would still take tbennett's suggestion to check it's OK because the 4000 rpm rev limit is very often a the symptom of a broken belt.

 

I finally had time to go through and check the dizzy belt. It is intact and functioning correctly. I found the problem after an hour of searching and testing. It turns out it was one of the ignition control modules. I put 2 new dizzy caps and rotors on, but still hesitated. I tested to see if both were functioning correctly come to find out the car was running on one dizzy. I tested both ignition coils and they were both functioning correctly. Then I tested both control modules "BINGO" I found one was not working. I ordered a replacement from pelican. After a quick install I took her our for a run and NO MORE HESITATION!!! You really cant tell when the car is running on just one dizzy. It started and ran without any problems until you got on it hard. Then there was just a slight lack of power and the high rev hesitation.