Lately while doing my highspeed runs in Mexico, I've been getting PSM and ABS failure lights coming on. Quite scary in my opinion. What could be causing this? If I restart the car, everything is fine. Any suggestions?

alignment
steering angle sensor
mass airflow
speed sensor

one of those 4

This seems to happen fairly often with guys who do high speed runs then come down to a stop or slow down....the ABS/PSM light comes on.....I just pull over, turn off the car, then restart it and it clears. We haven't been able to figure out why this happens, but the speculation is that it may be related to the MAF and the turbulence and/or AFR from the high speed run....try cleaning the MAF. It doesn't happen all the time, and since I put in a new MAF, it hasn't happened at all. It could also be related to fouled plugs. I dont' know why it triggers the ABS/PSM lights though....doesn't seem logical.

I guess that would make sense about the MAF.

I just had my GT700 kit put on with a Hitachi MAF. Before I had a stg 2 and all my highspeed runs were great. Now it seems like everytime I go 170+ the lights will come on.

Exactly same problem here.

Change your MAF i had some problem . Now its gone

Why dont you invest in a cheap OBD2 scanner and pull the code? I got one for $50 at pep boys.

I second the getting a cheap code scanner, I thought my issue was MAF but after pulling codes it ended up being a P0301 (cyl 1 misfire). Turned out a new plug I had installed was defective from the factory.

Search for a similar thread about this. Some people have traced the issue to a bad alternator. I had this a few times, switched out my alternator and it mostly went away. The other day it came on again so I decided to do the MAF as well just in case...

I have a code reader and when I get these lights, no codes were being thrown...?

I've read about the alternator thing too...also a bad battery...but most of the time it's after a hard run. I had the "P" series go off on me too..."random cylinder misfires" along with misfires in #3 and #5....but then the problem would just go away. I was wondering about maybe some carbon busted loose from a piston or valve and fouled a plug?? I went to AutoZone and borrowed their reader and read out the misfires, but then when I'd shut off the engine and start it again, there's no record of the problem. Finally one time it stayed on as cylinder misfires, and I had it flatbedded to Porsche.....they changed out the MAF under CPO and I havent' had any problem since then....but I still do throw a PSM/ABS CEL once in a while after a hard run. I think it's just a Porsche gremlin possibly related to the MAF during hard runs with air intakes that may gum up the MAF??....happens to quite a few guys. The fix is to turn off the ignition and turn it back on....all OK then; and if you take it in to Porsche and have them put it on their computer, there's no record of the event....so you tell me????

I had similar episode happen as well although mine were accompanied by a rough idle and abrupt stalling. Tried the obd scanner and cleaned and replaced the maf, all to no avail.

Turned out to be a bad throttle body...

GL

Sameer

Anthony said it happened because you probably hit a bump and spun the tires while airborne

I thought I had this problem solved and just got another CEL today (after having the PSM/ABS light. I then replaced the plugs, coils, and MAF and the problem went away for awhile). I'm thinking its either the alternator or has to do with the new Speedtech exhaust I installed (possibly cat ineffeciency code)? I need to pull the codes from the car when I return home tomorrow.

I don't think its bumps. I've gotten airborne many times with my stg 2 with stock maf and nothing happened. Now it just happens when I go fast.

You know what might help, maybe you should send me your entire gt700 kit for 'independent testing'. That way we can see if its related to the new MAF or not