apw964

Folks,

First of all - this is a first class source of information, and one I wish I had found prior to buying my 1991 C4.

Although 95% happy with the car, I have a couple of questions which after reading other notes appear to be possibly related to the distributor belt problem. - what puzzles me is the erratic nature of the problem

During cold start the car fires into life, runs at a stable idle, and torque / accelation seems to be smooth with a healthy exhaust note. Once the car is then warm, 1 of 2 things happens, 1. The car continues to perform well under acceleration or 2. The accelation seems to be impaired, with what can be described as a slight reverberating noise.

It seems like an ignition issue to me. Any thoughts on how I can check the cause of the problem - what should be my approach to identifying and resolving the problem ?

Any help would be well received - My car has 73,000 miles, and is due to go in for a major service in 1,000 miles - The distributor vent has not been installed, so I will be asking them to tackle that then.

Randall G.

Hi apw964,

You may have a broken distributor belt. The belt in my car broke at 74k miles. Symptoms: Car ran flat with some break-up at low RPMs. Nothing blatant, but I knew something was amiss.

You can check the belt yourself, as specified by rennlist's own Bill Wagner:

-Go to Home Page
-Click on "The Rennlist Technical Library" near the center of the page.
-Click on "911/964 Automobiles" near the center of the page
-Click on "Engine"
-Look for the article "964 Distributor Belt Failure"

Bill Wagner

apw964:

It could be the distributor belt and anytime someone has a performance issue with one, that's probably one of, if not THE first things to check.

Check out this link:
http://www.pelicanparts.com/ultimate...ML/000006.html

You may also want to check some of the connectors to thermal sensors that the DME monitors. The fact that it's good one day and bad the next, but ALWAYS seems good when cold, seems to imply either a failing thermal sensor or a bad/intermitent connection to one.

I don't understand your "reverberation" comment. Do you mean it's sort of like a bad or misfiring spark plug?

Hope this helps,

Bill Wagner

apw964

Randall / Bill,

Thanks for the feedback. I am becomming increasly convinced that my problem is related to the dist belt. Work is consumming a lot of my time at the moment and the only test I have been able to conduct to proof this was done at lunch time today in the car lot. I removed the coil lead from the secondary distributer and started up the car, the car seemed to start and react as 'normally' as it has been since I owned it. I didn't want to take the chance to drive it with the lead loose. When the w/e comes around I will be removing the dist caps and having a better look at the rotor postions.

I think I've been lucky with the position of the second rotor if that is the case, however unlucky that I've been driving an underperforming car since I purchased it back in April.

If any of you are based in the NY area have you had any experience with PAR in New Rochelle ? I am wavering on their service at the moment

Bill Wagner

apw964:

If you do the exact opposite of what you've done (disconnect the MAIN distributor lead and leave the lead to the secondary distributor entact) and the car won't start at all, then you're distributor belt is shot. I wouldn't push it, and I would check with the manuals about disconnecting one distributor lead and leaving the other open. I'm NOT CERTAIN about this and it's getting REALLY late but I think there may be a warning about the potential existing of damaging the DME doing this.

Check with the manual first about the risks of damaging the DME...it may be (hopefully) me misreading the book (I noticed this when glancing at a section), but it's worthwhile being careful.

Good Luck,

Bill Wagner

Adrian

The DME cannot be damaged by this action.
The only problem is that is will register a fault code. The DME monitors the ignition system.
The DME needs to be reset after such an action.
Ciao,
Adrian
911C4

PS: There is only one thing which can damage a DME. Voltage spikes. It actually doesn´t damage the DME but to the outside person it will look damaged. Some intenral protection devices will need to be changed. They are built to be tough and reliable. They are designed to handle all the abuse that any motorist can send their way.

apw964

Bill,

Thanks for the comments again - I did the opposite when I got home last night - it's confirmed, I'm getting no spark from the secondary dist. I am trying to find someone local to fix it at a responable price.

Adam,

I take it resetting the DME is a simply task that the sevice guys can take care of next service ?

Thanks again

Andy

Randall G.

The good news is, you're going to be in for a treat after your belt is repaired . Let's just say you'll be happy with the way the car runs.