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Raj Singh
Newbie


Joined: 09 Jun 2019
Posts: 19



PostPosted: Wed Aug 21, 2019 8:24 pm    Post subject: Ongoing PASM Issues - Help and advise required Reply with quote

Hi all,

Having only been in Porsche ownership for a few months, I have one issue which is really beginning to cheese me off!

The car in question is a 2006 Carerra 4s manual with 51k on the clock.

The car itself was purchased approximately 3 months ago from a non Porsche specialist dealer fairly local to me, I collected the car and a few days later I had a PASM failure message appear on the dash, I made contact with the dealer who collected the car, they diagnosed a snapped front coil spring.

We had a brief discussion and decided rather than replacing the front two coil springs for oem I'd rather have eibach springs fitted which they promptly organised. The springs were purchased from design911 and fitted by a local garage by the dealer.

I then collected the car and the pasm error appeared again on the way home, I thought the car may need time to adapt to the new ride height so left it for a few days.

Fast forward a few weeks and the fault would re appear at random, I then deiced that I would get the wheel alignment re done (the dealer already did this after fitting new the eibach springs) and the print out showed the the alignment was way out of tolerance, a bit of a relief that having the alignment corrected may fix the PASM failure once and for all, No luck, the PASM failure is still present!

I then decided it was time to book the car in with a Porsche specialist , I opted to use PH Porsche who are again local to me.
As I arrived the PASM failure message was present on the dash, the engineer plugged in his diagnostics machine as ran a scan on the car, we were both expecting a fault to show up indicating that there was a faulty shock absorber, to our surprise there are no faults logged for any faulty shocks! They only error logged was "Sport mode activation failed" which was expected as sport mode is deactivated when the PASM failure occurs.

PH Porsche spent over an hour on the car testing the resistance on each shock and have also tested the wiring, no faults found. They have suggested dropping the car off for a full days work to diagnose the fault.

I've also spoken to the supplying dealer today and he is adamant that the fault is related to having eibach springs fitted and that the PASM tolerances are not within the limits, I'm not so sure, design911 have confirmed that the springs are 100% PASM compatible and would not cause a PASM failure.

So, any suggestions on what to look for next? I'm in a bit of a pickle now as I asked the supplying dealer to fit the eibach springs, which they are blaming for the error.

I've also added a post in the wanted section for a set of PASM compatible coils springs if anybody has as set, I'll have these installed to rule that out.

So components that have been looked into so far as follows

1. Shocks - no errors present (PIWIS)
resistance check passed.
2. Wiring, Nothing obvious found
3. Battery voltage - Pass
4. Alignment- re done
5. Speed sensors - Pass
6. Steering angle sensor - Pass

Any advise on how to resolve this is much appreciated, and apologies for the essay!
 
  
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Carrerascott
Silverstone


Joined: 28 Mar 2015
Posts: 128
Location: West Yorkshire


PostPosted: Wed Aug 21, 2019 10:39 pm    Post subject: Reply with quote

Don't think this has anything to do with your snapped springs. I had one of mine snap a few months back and did not get a PASM failure message
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kurlykris
Magny-Cours


Joined: 30 Jun 2014
Posts: 2524
Location: Warwickshire


PostPosted: Wed Aug 21, 2019 11:54 pm    Post subject: Reply with quote

Personally, I wouldn`t have non Porsche standard springs fitted to the front only and not the rear, to my mind that would just be dangerous as these cars ae finely balanced, they should have a complete set of matching springs Question

You need to read off the error codes and post them here, although you have stated that there were no error codes present, which seems strange to me, even old codes are stored until erased nooo

I`m going to punt on a wheel speed sensor wiring issue, breaking under flexing, but fine while standing in the garage and being measured on a multimeter.
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Myasinax
Newbie


Joined: 25 Sep 2018
Posts: 31



PostPosted: Thu Aug 22, 2019 5:44 am    Post subject: Reply with quote

Unfortunately, it could be down to a number of things. If springs are changed, could be down to loose wiring, but I had a similar randomly occuring issue when installing Tech9 lowering springs and after a number of weeks of investigation, opted to have the DSC unit installed which took all of the problems away. It also improved the ride no end. There is a separate ECU for the PASM, so if your indy can swap it out and check, that would be beneficial also. I would also echo the sentiments of the above poster to change the rears and fronts to the same springs.
Cheapest option might be to return the springs to OEM, if you can get some PASM ones.
 
  
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MaxA
Albert Park


Joined: 11 Oct 2015
Posts: 1616
Location: Helsinki


PostPosted: Thu Aug 22, 2019 6:10 am    Post subject: Reply with quote

I don't think this is anything to do with the springs, original or otherwise.

It seems tjhat the shocks are fine. So you either have an issue with a sensor, or you have an issue with the PASM software.

Perhaps we can eliminate the software. My suggestion is to try and find someone who can lend or sell you a PASM module, fit it and take the car for a drive. That may fix the problem, and it would be a cheap fix. It only takes a moment to replace the PASM module.

Perhaps there is someone on the forum who is local to you and has fitted the TPC Racing box and has a spare box? I could send you mine, but I'm over in Finland and it'll take a little while.
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zagonda
Silverstone


Joined: 07 May 2015
Posts: 148
Location: Beaconsfield


PostPosted: Thu Aug 22, 2019 6:20 am    Post subject: Reply with quote

I agree, I had a spring snap when I was driving and no fault came on.
 
  
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Raj Singh
Newbie


Joined: 09 Jun 2019
Posts: 19



PostPosted: Thu Aug 22, 2019 6:44 am    Post subject: Reply with quote

Carrerascott wrote:
Don't think this has anything to do with your snapped springs. I had one of mine snap a few months back and did not get a PASM failure message


Just as I thought, Thanks for confirming, That rules out eibachs and the tolerance levels of PASM.
 
  
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Raj Singh
Newbie


Joined: 09 Jun 2019
Posts: 19



PostPosted: Thu Aug 22, 2019 6:48 am    Post subject: Reply with quote

kurlykris wrote:
Personally, I wouldn`t have non Porsche standard springs fitted to the front only and not the rear, to my mind that would just be dangerous as these cars ae finely balanced, they should have a complete set of matching springs Question

You need to read off the error codes and post them here, although you have stated that there were no error codes present, which seems strange to me, even old codes are stored until erased nooo

I`m going to punt on a wheel speed sensor wiring issue, breaking under flexing, but fine while standing in the garage and being measured on a multimeter.


Hi,

The car had eibachs all round, not just the front, I should have stayed that earlier.

In terms of error codes, there wasn’t any present in relation to pasm the Indy used piwis to scan the car and the only that was stores was sport mode activation failure, he also scanned all sensors including brake pedal switch and it all seemed to be working fine.

I’ll have a look into the wheel speed sensor, that’s seems to be a good route to investigate but even then, would a fault code not be stored on the ecu?
 
  
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deMort
Dijon


Joined: 21 Mar 2015
Posts: 7287
Location: Brighton


PostPosted: Thu Aug 22, 2019 7:07 pm    Post subject: Reply with quote

Just my general thoughts ..

When you buy a car and a fault happens after a day or two then this is an ongoing fault with the car .. often it's the reason its been sold as in theory several garages have attempted to fix it .. none have been able to so the owner has sold it on .

Seen it a few times shall we say and basically its usually a bitch of a fault .. hence it was sold .

Broken coil spring doesn't cause this fault .

If the springs fitted were causing it then they couldn't be sold for this model period .. the company would have a sticker / statement saying such .. if not i would assume it's against the sale of goods act .

I am also of the opinion springs cant cause this error , always welcome to listen to someone who can explain how they can be though .. i don't know everything .

No fault codes is the interesting part .. the system has shut down due to a fault .. and it hasn't recorded what fault caused it to shut down .. hmmmm

That's not how these systems work .

So .. going with logic here ..

Either there is a fault with the control unit and its not registering an intermittent fault ..

or there is a fault with the equipment being used to check for this fault .. ie .. do they have piwis , do they have autologic .. testers that can see all fault codes basically ..

Was there a fault code that was listed as unknown ? .. that's poor equipment not being able to report the fault .

Values when looked at will be correct if the fault IS NOT PRESENT at time of checking ... this is an intermittent fault and probably for a split second in a certain set of circumstances .. ie a corner at a certain speed .

My logical guess .. control unit .. which will be dam expensive and i would want to test that to the hilt before going down that route .

Gut feeling , which isn't logical .. a shock is faulty .. proving it though .. now that's going to be problematic .

EDIT .. they used piwis .. i just read that .
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RichardKS
Monza


Joined: 11 Nov 2011
Posts: 175



PostPosted: Thu Aug 22, 2019 9:17 pm    Post subject: Reply with quote

FWIW our 997S has Eibach springs fitted. They’ve never caused any ‘problem’.

The only time I’ve known any suspension warning light to come on was on the karussel at the ‘Ring - it stayed on until the end of the lap but reset itself once we’d stopped and restarted (this when the car was on o.e. springs).

Hope you get sorted.
 
  
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Matt Seabrook
Monza


Joined: 27 Apr 2014
Posts: 186
Location: Cornwall


PostPosted: Fri Aug 23, 2019 8:37 pm    Post subject: Reply with quote

deMort wrote:
Just my general thoughts


Gut feeling , which isn't logical .. a shock is faulty .. proving it though .. now that's going to be problematic .


Just a thinking out loud. I take it the shocks are just two wire actuators ie not monitored? Second guess are they controlled by PWM? If so one way of testing would be the measure the resistance using ohms law work out current draw and both current flow and signal could be measured with a scope. You would soon see if one shock was drawing an abnormal current load. I understand that this is beyond the scope of most diy jobs and some garages for that matter. If they don’t work like I have described then I have just waisted two minutes of your life reading this sorry Grin
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deMort
Dijon


Joined: 21 Mar 2015
Posts: 7287
Location: Brighton


PostPosted: Sat Aug 24, 2019 6:52 pm    Post subject: Reply with quote

Matt .. young man you need to post more !

Yup it will be PWM controlled .

Current flow would work .. you would need a 4 channel scope connected and then compare readings after data logging on a road test .

The difficulty would be knowing what was a fault and what was the car altering each shock in turn due to road conditions and the predefined map .

If you measured a drop to zero at any point on a single shock then that would prove it ... open circuit .

But then that might also be a wiring connection .

Sticking valve in the shock... car expects a height change or not and doesn't see it according to its map .. current flow would in theory increase to alter the shock but that again is map dependant .... i would expect it to stay the same .


In short it's worth trying just to see what the results would be .. And if i ever get the chance .. i'll be doing this
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Matt Seabrook
Monza


Joined: 27 Apr 2014
Posts: 186
Location: Cornwall


PostPosted: Sat Aug 24, 2019 9:09 pm    Post subject: Reply with quote

Cool a four channel scope could do two shocks at a time then. You could measure duty cycle and current flow on a pair of shock with four channels. Ball park figure say the shock was 14 ohms then 100% DC would be 1 amp so 50% DC would work out at 0.5 amps. On the pico scope I use at work a maths channel could be employed to check plausibility of expected and actual current flow.

You are correct that if the wiring or module was at fault they could give you abnormal readings. Once the corner was identified that was causing the issue though a substitute resistor could bypass the shock and would prove where the problem was.

This is a lot of work though and I would only go this fare if no fault code gave me some direction.

I love this sort of problem at work and trying to devise a test plan to find the issue.
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