utkinpol

Hi,

My PSM for some reason is acting up at Lime Rock, in big bend and west bend as soon as i start going a bit faster it tries to engage front brakes close or just past apex in a normal clean arch with almost no sliding which is total BS, it beeps and even generates 'psm error' message also. So I looked it up in durametric and it says P4420 rate-of-turn sensor error.
I was only aware of PSM acting up due to uncalibrated steering angle sensor - it is not that, for sure, plus i got mine recalibrated anyway.
When I drive with PSM off it at least does not try to break where not needed but still generates this error from time to time. Never does it at NHMS or on street. Does anybody know if it is normal in fast sweepers and where the heck is this bank angle sensor located?

I looked it up on Google, so it is so called YAW sensor. Still not clear where is it located and if there is a way to do anything about it.

RonCT

No issues with my 09 C2S at LRP with PSM on. Sport PASM suspension, but no SC. Red group (instructor), running just over 1 minute laps.

mdrums

Are your overall tire diameters stock or extrmely close to stock?

I know you run some odd tires sizes and I think that might be your issue. I've learned you can not vary much from stock sizes and I know you run 18's so I highly advise you stick with 245/40/18 and 305/35/18 as this is the overal stock diamter of the 19" tire combo....or if you must...255/35/18 and 315/30/18 works too on the track I drive. The 255/315 combo was no faster than the 245/305 combo.

quickxotica

I believe the PSM system uses two independent yaw sensors located at opposite corners of the car. The error message could simply mean that one of these devices is failing intermittently. The fact that it is unique to this track may indicate that some combination of g-load and/or bumps is causing the failure... perhaps as simple as a loose connection? I hope so. Check the documentation specific to your year/model and see if you can discover the location of the sensors and how to access them for a physical inspection... otherwise the dealer may be your only alternative. Good luck!

Land Jet

Just turn it off and it will lower the threshold of PSM engagement to extreme emergencies, if that.

RonCT

To the tire diameter point, I'm running 18" 245/305 RA1s which are about 25.6" / 26.3" respectively, which is pretty much OEM for the 997.

utkinpol

my front tires are only .5" lower than rears. it very much may be the reason. well, I will try to check all connections as well. odd stuff.
I just erased codes again, if it will happen again I will try to get those same codes 3-4 times and then will ask dealer of why it happens, may be they will replace it. it looks those sensors are quite expensive, i do not want to buy them myself.

mdrums

There is .8 of an inch difference between front and rear.....so if you are .5" inch difference I think you would be close enough to spec but you never know because wheel speed sensors talk with PSM. Not sure if .5 is with in the 3-4% tolerence.

Keep us posted on what you find out. Hopefully it just a lose connection

utkinpol

i am just skeptical about loose connection idea as usually car senses that pretty good and gives different codes. error shows up only on 'some' laps when i start going 1min 9sec or faster laps but again, it does not give error at each lap,so, not sure what it wants. it never did it at AX but sharp AX turns at 40-50mph is not same as west bend, so, go figure. i found my car`s electrical diagrams and it shows only 1 yaw sensor somewhere in the middle of the car. I looked it up around center console area but found nothing. will try to search again later next week. as i understand it should be bolted to the frame somewhere.

mdrums

You do have the gyro yaw sensor but you get to it from under the car.

John at BGB Motorsports in Daytona has a great understanding of these systems. He is sometimes on these forums.

onefastviking

Just a thought .....were you using tires aged the same ? Or were the fronts or rears newer than the other ?

utkinpol

tires are both dated 2007. but why would that result in a 4420 CEL related to rate-of-turn sensor error?

Gary R.

No offense meant, but have you considered taking an instructor out with you? Maybe it isn't the car? 1:03's in a 997 should be like taking a country stroll...

924RACR

Correct, that'd be a yaw rate sensor error, bummer you have to get at it from under the car... There is indeed only one.

There are many different ways the sensor can set a fault, from rate to noise etc. So I'd be looking to, #1, confirm that it's plugged in securely and no loose wires hanging or improperly restrained. Also, is there any more detail to that code?

Not likely a tire issue, BTW.

The sensors can go out of spec, FWIW. Unusual/rare, but not unheard of. One option might even be to swap in a spare from another car if possible (short of looking directly at the sensor output).

Lemme know...