ilko

...at one point a got a bunch of lights on my dash. I don't have Adrian's book next to me to decipher their meaning, so I need your help!

There was an oval as part of the course, about 20-25ft diameter, that I had to go around clockwise. The first couple of times I ran tight circles around it, which I found out wasn't helping my times much. The third time I decided to run a bit wide but have more momentum towards the end of the oval and point the car towards the next set of gates. I started wide, but towards the end of the oval I was running too wide than I wanted to so I made a relatively sharp right (so much for being smooth, I know). All of a sudden the throttle cut off along with a soft beeping sound (not buzzing, just a beep about 1 or 2 seconds long) and the "!" + PDAS, and I think either the ANTI-LOCK or the BRAKE light. It all happened so fast that I couldn't quite figure out whether it was the ANTI-LOCK or the BRAKE light, because the next moment it was all gone and I was on my merry way towards the next set of gates.

So, my choices are the following:

A) I can't drive for **** and the car is getting sick of my abuse and I broke something
B) I am the next Hans Stuck and have reached the limit of the car's handling and it just gave up since I conquered her, but I didn't break anything.

Which one is it?

joey bagadonuts

How much fuel were you carrying? Anything under 1/4 tank will cause fuel starvation under hard righthand cornering, i.e. make it seem like you ran out of gas. Your car may have simply stalled causing the lights to go on.

ilko

Yeah, I thought about that but I was at a little under 1/2 tank. Are the above lights/beeps a possible sign of fuel starvation?

joey bagadonuts

Well, the lights will come one when you stall the car but it doesn't sound like that happened (as I reread your post ).

Just one other question. What size tires are your running. If the OD's on a C4 vary too dramatically from front to rear, then you might generate a warning of some sort. But if all the lights are off, I'd say you probably didn't inflict any permanent damage to your car.

ilko

225/45/17 front and 255/40/17 rear. I took the car to Lime Rock for a DE event last weekend and had no warning lights of any kind there, even though I was running at a 1/4 tank towards the end of the day.

The car felt fine on the highway after the AutoX yesterday and I didn't notice any problems.

joey bagadonuts

Those tires would be fine. If you see, hear or feel anything else, you might want to get it checked out but it doesn't sound like you've abused the car.

kgorman

Try checking your brake fluid level, got enough in there?

ilko

Thanks for the tips guys!

Yep, I have enough brake fluid, just had the system flushed a month ago and checked the level again as I was leaving the AutoX.

cobalt

Where was the event. It sounds like the one at the Meadowlands yesterday but I don't recall seeing a black C4 there. If you wee there we missed each other.

I don't know the difference between C4 and C2's but I run the tank down to almost empty and I never have any issues with fuel starvation.

ilko

Hi Anthony, I was in Schenectady yesterday, the event was run by the Hudson Champlain region of PCA. If I were at the Meadowlands I would've definitely come to say hello.

I also don't think it was a fuel issue, possibly ABS kicking in? I've never had it kick in before, so I wasn't sure.

On my Audi I get the ESP light on when the Electronic Stabilization Program kicks in, and I clearly notice when power is cut off to one or more wheels, but never to all at once. I understand that the ESP on a 2001 Audi Quattro is much different than the one on my 1991 Porsche, but the basic premise is that power is transferred to the wheels that have grip. Yesterday I had the power cut off on all 4 corners...

aeroman

I had that same problem. There are various causes like are listed above. For me, what fixed it was tire pressure. I have 18s and was running 33/33 for pressure. Changed to 34/40 and feels much better in corners and don't get warning lights anymore.

993TurboS

Out out of the 100s or 1000s of runs I've taken in my 89 c4, I have gotten that probably 3-4 times. It has happenned when I've gotten myself into some sort of trouble, about to spin or something, and I always have assumed that I did something that the computer couldn't figure out (like perhaps I got a front tire off of the ground, which I know I do, and simulatneously slipped the backs). Don't know.

In any case, the worst that has happened is that I had to turn it off and restart it to get everything back to normal. 10 years later and everything is still working as it was the day I got it. I wouldn't worry too much unless it happens every time you autocross it.

I will speculate, though, that non-stock tire sizes should contribute to the problem if it is what I think: that the compute can't figure out what is going on. I am no expert, but I suspect that the computer is not smart enough to figure out what your tire sizes are and correctly adjust for them. Perhaps someone here knows the answer to that.

As an aside, I was running low pressures too, when I got the errors (30/34 cold).

aeroman

I think you are partially right in that non stock tires can cause problems if they are not inflated correctly or are more that 6% different in diameter than stock. More than 6% and it confuses the puter.

ilko

The stock tire diameter is 25.1" and the one I have is 25.0" so it's definitely within the margin. I also run 36psi all around which is the consensus here for 17" wheels.

aeroman

I think you will find that Porsche and the experts recomend a differential with 17 of at least 3-4 pounds.

Tyre Pressures (tyres cold) front 2.5 bars overpressure (36 psi), rear 3.0 bars overpressure (44 psi).
These tyre pressures also apply to winter tyres.