LP944

Noone so far has gotten thses syptoms in their 944 based on my search here.
*Stuttering noise from exhaust at 5200+ RPM
*Clanking/knocking noise from right rear when taking a sharp right turn at mild speed (area of fuel pump).
*Sudden hesitation and power loss under max acceleration (loses and regains power splits seconds at a time, like pushing the clutch in and put while driving)

The clanking/knocking noise was there before the wiring harness was replaced, the rest came after, could it be electrical or definitly fuel?

I greatly appreciate anyone who can help me out on this one because I REALLY need the help, been trying for months now.
THANK YOU

*UPDATE*: CAR HAS DIFFICULTY STARTING MOSTLY ON ANGLES LEANING FORWARDS OR BACKWARDS, MOSTLY SEMI STEEP LIKE 20-30 DEGREES BUT SOMETIMES ON SLIGHT TOO.


*UPDATE 2* THE CAR BACKFIRES (POPPING NOISES) FROM THE EXHAUST BETWEEN ABOUT 3500-5000 RPM, THEN STUTTERS A COUPLE HUNDRED RPMS UP. aLSO THE HESITATION IS WAY LESS NOTICABLE TO NO HESITATION IN THE LOW GEARS AND RPMS IF I ACCELERATE AT FULL THROTTLE. I DONT KNOW IF ITS NORMAL FOR THE CAR TO BACKFIRE A LOT MORE WHEN YOU HEEL/TOE BUT IT DOES QUITE A LOT.

*HOPEFULLY FINAL UPDATE!!* MY CAR CURRENTLY RUNS ABOUT 12.5 VOLTS, LESS THAN THE FACTORY STANDARD, MIGHT HAVE ANYTHING TO DO WITH IT?

johnnykrand

In answer to the surging of power, check your fuel pump and fuel filter. Probably just dirty filter or something for the surging. What kind of stuttering do you mean with the exhaust?

Grandpa#3

The clanking noise on a right turn sounds like CV Joint needs to be checked out inspected for worn joints, loose bolts and repacked. A new axel and joints doesn't cost that much from Auto Zone. We done that on my son-in-laws 944 not too long ago. The stutter in the exhaust could be related to the power loss. Check out the link below for CV Joints.

https://rennlist.com/forums/924-931-...cv-joints.html

Cheers,
Larry

cb944

clanking/knocking... can you be a bit more descriptive? Is it a low thump/knock? How repetitive is it? Does it appear to be speed related or is it just an occasional random clonk?

Not quite sure, but I'd guess some like a CV joint or something loose around the wheel/suspension area. Does depend a bit on what it sounds like really. Does it all look/feel OK around there when you jack it up? I remeber having a horrible clattering noise coming from the rear right on my 944 with cookie cutters on... turned out the center cap was hanging off and bizarrely made a weird noise as the wheel turned!

Misfire and hesitation - I'd agree with fuel first unless you suspect the electrics... but really could be anything from air/fuel/ignition. Check the condition of your spark plugs.

Chris.

peanut

could be a rear wheel bearing. Easily checked if you jack the car and give the rear wheel a good hard wiggle .Should be zero detectable play.
I believe the wheel you are referring to is not the drive side but I suppose it could be the CV joint. again it can be checked by jacking the rear putting car in first gear and turning the drive wheel back and forward to check the slack in the transmission.

Re the stuttering it could be literally anything in the ignition/fuel system ECU and input sensors. If it starts and runs fine otherwise I'd be inclined to systematically check everything using the Clarkes troubleshooting guide.

Check out Nick Cannel's site too it has some excellent Bosch faqs and troubleshooting guides which will give you a better understanding of how the Motronic system works
.

LP944

It happens 5K or above, it makes a fast rattling noise and theres no power, the car seems to hit a wall in the powerband, it keeps going but not faster. I dont know how to explain the sound, like a rattling thumping noise, like extremely fast backfiring.

LP944

Thank you for the reference

LP944

The sound I can only describe to the best of my abilities is to sound like extremely fast backfiring noise. The car hits a wall during this. My harness was just replaced, I did have starting problems and I continue to have some of those but now I also have the rattling issue at high RPM.

LP944

Sometimes it takes me a good 10 minutes and 20 attempts to get the engine to start. It does all but the final bang for it to start. I also feel hesitation around the 2000-3500 range. I recently had all the spark plugs, spark wires, distributor, the whole ignition system replaced so I dont think it is that. I did though have my wiring harness replaced 2 weeks ago.

johnnykrand

Hmm im a bit stuffed with ideas on the rattling. Did you have a look at your fuel filter? Or is the surging and the rattling all one combine problem.

LP944

I have not looked at the filter, could it have gone bad standing with 10% ethanol for about 7 weeks? The surging comes before the rattling but when the rattling occurs the car just doesnt accelerate anymore, just continues on same speed but RPMs are rising. It must be a fuel thing because my car does not want to start whenever it is mostly on a rear slant for some reason. Or it doesnt want to period for around 10 minutes and 20 attempts.

peanut

this is not a blocked fuel filter issue. The car would never run up to 5000rpm with a partially blocked filter.

My guess is it is a bad connection or a bad conductivity in the high tension circuit.

The problem you have now is that you have replaced or disturbed so much that its almost impossible to suggest a solution from a distance.

If it got worse since replacing the loom then its obvious that at least the new problem/s are down to the new loom.Either there is a bad connection or you have disturbed something.

If you use part substitution method to find and eliminate a fault it is important to put the original part back if there is no perceptable change. Otherwise further down the line you don't know which of the changed parts has suddenly made a difference.

Clean ancd check all your connections . Check especially the ignition system .
Have you done a fuel flow check yet ?
have you done a fuel pressure check ?
At least eliminate the fuel system

Lastly disconnect and clean all your earthing points thoroughly .
You might try running the engine in the dark and check for high tension leaks or shorts

peanut

I've re-read this thread and noted the starting dificulty.

I'd also be inclined to check out your fuel injectors. Wouldn't hurt to have them cleaned and their spray pattern checked. Include the cold start injector if there is one fitted.

If you do a fuel pressure check it might highlight a poor delivery problem at high demand but my money is still on the ignition system.

Have you checked the entire vacumn system for leaks ?

Mike C.

Is this a 'known unknown' or an 'unknown unknown'....

Jfrahm

My guess is spark scatter from bad S/R sensors or a distributor cap problem.