Guys, I could use some advice on a very frustrating and increasingly expensive electrical problem I'm currently in the midst of.

One week ago, I picked up my car from a well respected tuner who installed the following in preparation for a 3 day track event coming up next week: MPSS tires (correct size and previously run on my car), stainless steel lines, new OEM rotors, RSS Tarmac LCA's, H&R Sway Bars front and rear, GT3 brake ducts, Pagid Yellows, brake flush and oil change. Front camber was set to -1.8 from previous -1.4 (which was max within OEM spec allowance).

Drove the car for about 300 miles afterwards, some highway and city but mostly spirited driving in twisties. everything felt great. As I was coming back to my garage in the city in slow traffic, I was hit with ABS and PSM failures, as well as a CEL. Hoisted the car on a nearby lift which showed nothing out of the ordinary. My OBD II scanner showed P0503 -- Speed sensor erratic/intermittent/high.

The next day (this past Monday), I took it to the local dealer who told me their PIWIS says its the brake light switch. They replaced it, and the lights came back on after 15 miles. On Tuesday, they replaced it again (said the previous switch from factory may have been faulty) and the light popped on again after 15 miles. The light comes on at stops or very slows speeds.

For the past 2 days they taken the car apart in the relevant areas looking for any shorts or bad wiring harnesses, etc. They found nothing. The ABS unit appears to be fine, and they say the speed sensors, steering angle sensor etc. are all fine and that they don't think the problem was caused by poor installation of the new parts -- e.g., damaged sensors in installation of the new arms or pinching of the wiring harnesses by the new camber.

Spoke to them today and I could tell they are running out of ideas. They told me they've never been stumped like this before and that their best theory right now is that the stainless steel lines are so strong at braking that they are applying braking ahead of the brake switch, which is confusing the system.

Obviously I'm pretty concerned -- at losing the 3 track days I paid for me and my brother (who was going to share my car), at having to go back to stock on the arms and ss lines and all the costs that entails, etc. without knowing which if any of these moves will solve the problem.

If anyone has any suggestions on how to proceed, on where to guide the dealer tech, on a local shop that specializes in electric, or anything, please let me know. I realize that most people who had these mods have not had any similar issues so please refrain from stating that. Thanks very much in advance.

 

That certainly confuses me, but I'm not at all sure it could 'confuse' the ABS/PSM system.

I know you hate to hear it, but obviously this is almost certainly related to the changes you just made. The random chance of something else failing at this time by coincidence is almost nil.

Too many chores right now to give it detailed consideration, Kona, but has the dealer or that other shop confirmed the alignment settings and given you a computer print-out as evidence? One hazard of going outside the recommended range is you're the test pilot for those settings. Furthermore, if I were the field engineer someone contacted about this problem, the first thing I'd insist on is a review one more time of all sensors close to where the installers were doing the work. And if the mechanic who checked this time insisted they were okay, then I'd insist on backing off the alignment settings next, restoring them to within the factory range so we can see what happens.

With a problem like this, we need to re-establish a working configuration first. Then you can go back and change one thing at a time. instead of all at once. That tells you what I'd be recommending if we can't get things working with the relatively cheap fix of restoring factory alignment: Start putting back the factory parts until you find the problem child.

Other people have made those changes without this problem, so this doesn't mean you can't do those things. It just means you need to get back to a car that works. Then, re-do your changes, but one at a time (if you absolutely must) to find out what went wrong. It's a pain I know, but with any luck it will be the first thing you try restoring that reveals the problem.

Gary

 

Gary, Thanks very much for the response. I keep telling the dealer that it would be a heckuva coincidence if the faults didn't have to do with the new parts, and they agree... but neither of us has wanted to "reset" the mods just yet, since the most common causes for the problem (bad brake light switch, speed sensor, steering angle sensor, PSM or ABS unit, bad MAF) have nothing to do with arms or brake lines. I can't imagine a -0.4 difference in camber is the issue (nor does the dealer tech) but I agree at this point it's worth a shot before resetting, though I may reset the brake lines at least before the alignment.

I'll tell you one thing -- if I take off the mods and it turns out to be a bad sensor or shorted wire, you're going to read about a tantrum the likes of which the porsche-loving world has never known!

 

Kona,

I am guessing you were at the shop on the Island that we spoke about. Have you given them a call?

G-

PS. Did you previously have the GT3 ducts or where they added too?

 

Well, I certainly would start with the least expensive diagnostic path. That means compelling the mechanic to check every sensor that could conceivably be involved, even the one he's sure looks okay and he "can't imagine any reason the installer would go near that one." (People make mistakes. They even drop tools.)

Then go to the next level, which surely is the alignment settings, and don't stop at the previous settings. Go all the way back to the factory recommended caster, camber and toe. You really must find a working configuration before you can do a successful diagnosis, and God knows what interaction between those changes might be going on. Alignment settings that worked fine before may not work with those other changes. Get things working again, and then you can start over to implement the changes.

Go ahead with reverting the brake lines, just on the general principle of "God knows what" that you have to follow in cases like this, but honestly -- except for inadvertent damage somewhere during installation -- I can't see how changing the brake lines would cause those alerts. I can see a hamfisted mistake causing the problem though. It might even fix the problem if a different mechanic removed those new lines and replaced the same ones. But don't bother trying that. Do it right and go all the way back to the factory lines. Then, if the alerts go away, cuss a lot and have a different mechanic re-install the steel ones. (Or the same guy with a new one reamed out to get his attention this time.)

Good luck on a quick result. Keep us up to date, Kona.

Gary

 

They put in the GT3 ducts too -- I forgot about those in my original list, will edit. Thx.

Yes, that shop in LI did the install. I let them about the problem right after I had it. As you'd expect, the initial reaction was "don't let the dealer blame the mods!" but after a few days they've come to realize that it was probably the mods (or the install, but they're not prepared to admit that yet) so they say I can come back and have them take a look at it. Problem is there're about at least an hour away but still I may go that route if I need to reset to stock. Going to speak to dealer today and see what they've got for me and decide from there.

 

It has my wondering if something got knocked loose during the duct install. I am certainly no expert but to me it seems that a sensor or sensor harness may have been damaged or otherwise compromised in some way.

I feel your pain about the trip out there. It is a PITA for me and I only live on the South Shore.

Good luck! Let me know if I can help in any way.

 

first of all - it was bad idea to put solid steel lines, they may crack on a street from vibration/hits. stock lines are also braided steel and are more than enough. it only gets done on track only prepped cars - usually on cup cars that do not have vacuum brakes amplifier so you have better sensitivity on brake pedal.

if ABS goes crazy i would suspect they may be fractured signal wires from sensors in wheel wells. your alignment is nothing - i ran -3 from -2.5 rear camber on my car whole season, now i decambered car a bit to -2.7/-2.2 and never had CELs related to ABS.

they need to double check location of the sensors, check if mounts are solid and do not 'play'. also, on those adjustable arms it should be a special shim to have front lights angle sensor, it should not interfere with ABS but who knows.

I had a 'play' in the outer bolt for front fork arm and it was registered as a CEL for a yaw sensor, go figure. so i woiuld also check if all connections are tight. if you ave a good shop that services plenty of 997 gt3 cars they should know all that stuff, so, good luck.

sometimes road junk may get on the light path of ABS sensors and it also may generate a CEL. check if you do not get dirt/water flying into the abs/speed sensor.

 

yep, exactly that. i would get back to tuners shop and demanded to fix that.

 

Thanks Paul. This is the first I've heard of a downside for stainless steel lines. If I had known that...

The dealer tech claims he's checked all sensors and wiring -- each of the 5 or so times I've asked him, including this morning. I wish I could watch him physically do it but I've just taken his word for now. He has a lot of experience and I believe is trying to get the job done as fast as possible as I have a good relationship with the service manager and dealership manager and he knows that.

The tuner told me this morning (for the first time) that they moved the ride height sensor down a touch to clear the arms. I let the dealer tech know. He is still working on his brake lines theory. I probably give him until end of today then take it to the tuner to try to fix by returning to stock or otherwise. Issue there besides time and cost is they don't have the latest PIWIS.

Anyway, I'm calling the dealer now to emphasize one last time to check all the bolts and sensors. I will keep y'all posted. Thanks again for the input.

 

my mechanic has 4 or 5 such cracked lines on his wall for display and he turned me down when i asked about this 'mod'. again, probability is not very high to get them cracked but it may happen. with stock lines it cannot happen.

 

Paul and Gary,

Just a general comment:

Its great that you take so much time to share your knowedge with us. Really helps make this place a great forum.

thank you

 

Good God, you mean they really are solid lines? In a vehicle? Wonder who's bright idea that was? I just assumed we were talking about a type of line with more dense braiding or perhaps layered braiding mixing Kevlar and steel to 'upgrade' the stock lines. You know, like those golden cables for high definition television that cost $100 for each $5 cable they replace?

Definitely get those replaced, Kona. I'm still uncertain how it would cause the described alert warnings, but solid lines add a whole new set of possibilities and none of them needful. Either go back to the stock braided lines that Paul describes or aircraft-quality braided lines if you're really concerned. (Actually, I wouldn't be surprised if Porsche already uses aircraft-quality lines, but you can check.)

As an engineer, I'm not real happy with solid hydraulic lines on anything that moves or vibrates, but on a vehicle they are out of the question, certainly in any application that has safety implications. In the bad old days when cost made it necessary we had to use all sorts of rubber fittings even on lines running just a few psi above atmospheric, hoping to absorb energy that would crack the lines, and they still failed. With modern braided lines available it is just irresponsible to offer a solid line for an application like Porsche brakes. And feel free to tell your supplier I said so and provide my credentials if you like.

Gary

 

You're always welcome. Got to have something to keep me off the street in retirement.

Gary

 

KK,
Good luck! Those gremlins can be a real pain. I wish I had something constructive to add other than empathy but I'm at a loss. Looks like you're getting reasonable advice from the rest of the crowd though. Hang in there, best,