Patrick L

My C4 had LWF and SPEC clutch installed previously. Due to very heavy clutch pedal and stalling issue, I changed them back to standard DMF and clutch last week. The clutch pedal now feel much lighter, but the stalling issue still exist. When comes to a stop at traffic light, rpm drops low then pick-up, but sometimes it just won't pick-up quick enough then died, especially when AC is on. It feels just like the LWF, but less serious (still annoying). Idle is stable with very minor hunt (maybe something around +-20~40rpm)

My engine was rebuilt about 3 years ago with around 10000km only. I had different cam shaft installed with intake at 248(.040")/242(.050")/.490"(valve lift) and exhaust at 234/228/.455", centerline 112 and setting 2.0mm.

Technician told me it may be the AFM or wrong valve timing, but can't be sure unless drop the engine to check.

Any idea on this issue? Will idle adoptation help? (I had ECU reset by disconnected battery for about 20mins but no help)

Thanks!

Flashtv

not that this is the right technical term by any means but I had similar 2years ago and i think it was a small air line or vacuum hose? basicaly making bad seal...simple fix, sound right to anyone else?

joey bagadonuts

Are you still using the stock chip? Also, have you checked the AF ratio? A dyno with AF meter could do that and would be considerably cheaper than an engine drop.

Just some ideas. Good luck!

ilko

You can do a simple check before you start dropping engines and such...

There is a throttle microswitch on the back of your air intake. It has three clicks - idle, gas, WOT. Pull the throttle cable with your hand, then release it quickly. Does the idle click immediately? If not, that's your problem and you may need to adjust the length of your throttle cable.

I don't know how likely it is that this may be your problem but it's a simple check.

cobalt

Heavy clutch pedal with a LWF??? Mine is actually very light. Compared to the turbo it takes half the pressure. Sounds like the LWF wasn't the problem.

ilko

Hmm, FWIW my LWF is pretty heavy too...

cobalt

Really? Mine is rather feather like in comparison to the turbo. Although I guess we would have to compare it to the turbo first. I had been told that clutch pedal pressure could be adjusted, not sure how and by how much but it might be a simple adjustment to regulate pedal pressure.

ilko

We'll have to do this next time we meet. I feel the clutch pedal on my current LWF RSA is heavier than my previous DMF C4. Doesn't bother me since I've yet to drive the RSA in stop-n-go traffic, but if there was a way to make the pedal feel lighter, I'd try it.

f468357

I had the same problem and it was cured with a new coil and O2 sensor. Did them both at the same time so do not know which part solved problem or both. I would suggest checking coils. Also make sure you let the engine idle (no touching throttle) for 5 minutes or so after the ECU reset. I use to not let it idle and the results seem better when idled.

1990-964

That's interesting about letting it idle after an ECU reset. I've had a couple of respected P car guys tell me that the ECU is a learning unit and after a reset you should drive it in the manner that you would normally, whatever that may be so that the computer will respond according to the normal driving style of that particular car.

HalV

I was about to post about something similar. The previous owner put in an RS clutch but left the stock flywheel. Normally, when I put the clutch in, the RPMs drop quickly and then recover to idle. The other day it was hot and raining, so I had the wipers, A/C, and radio on all at the same time. As I approached my first stop, the car stalled. I shut the A/C off and didn't have any more problems. I also had my kids with me so I didn't want to go deep into diagnostic mode. I've only had the car a couple weeks, so I'm not sure if this is a common occurrence, I didn't let the car warm up properly, or I have a malfunction?

1990-964

Hal,

Your situation sounds interesting indeed. I have been of the belief that it is the lack of weight in the LWF that is the culprit to stalling. Not sure if the disk itself could be of enough of a difference in weight to make a difference but it would seem so for you. I do not have an issue with stalling with the LWF in my car but I am crossing my fingers. It has only been 2000 mi. so far and no problems to speak of. When you get yours sorted please post the results.

HalV

Will do...I'll try to drive it a bit more with the A/C on to try to see if I can get it to stall again. I'm not a big fan of A/C and enjoy driving with the windows and sun-roof open.

kos11-12

Hi guys,
just got mine back with new LWF and clutch; I drove it back home from about 1 hour through traffic to heavy traffic with aircon on 18 deg and fans at 3 ,I stall it 3 times and that was it; the problem for me was at low speed 50 kpm going from 3rd to 2nd the rev drop suddently from 2200 rpm and pick up again if I keep the clutch out ,the way I see it is to keep it on the boile and not cruse and blip the throtle and keep slitly the clutch pedal in longer when going to stop at red lights ,my mechanic said it 's from far the worst he have seen and try to remap it would may be a waist of time and money it is not the most plesant drive in traffic but as soon as the road open it's fantastic the accelaration is great and I would not return to the DMF it will always be a compromise I suppose been so light , maybe the problem that Patric have is due to the camshaft been to radical as some racing camshaft are design to work well on a very hight power band range like maybe between 5 to 7000 rpm,
my car is a C4 92 with a Cartronic kit LM220 German company ( chip ,air mass metring ,mod throtle body, drill box with K&N by pass and cup )

Konstantin

Patrick L

Just plug my car to the computer and looks like the idle switch reacts ok and quick, and no error codes.

However, I found that although I can run the car with 1 distributor (either one), the throttle response is very slow and hesitate, compared to other 964s (1 '90 tip, the other '91 C4). Then I found one of coils is like below:



The ignition wire connected to this coil has green rust inside. The other coil is clean and wire is also fine.

Will this be the problem? I will go cleaning the coil and replace the ignition wires to see if the issue solved.