Go Back   986 Forum - for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Performance and Technical chat

Reply
 
LinkBack Thread Tools Display Modes
Old 04-13-2015, 07:16 AM   #1
Registered User
 
Join Date: May 2014
Location: UK
Posts: 19
Engine cut out / ECU torque limit ?

Hi chaps

We have an ongoing issue with our Boxster race car.

We've done a lot of mods and it's significantly more powerful (I'll go into the modifications at some point when we've ironed out all the issues).
But for now the ECU has been remapped

Basically the engine cuts out when you come out of a corner and out of pitlane if pushing hard.

I'll try to explain how this happens.

You'll go into a corner as normal. Hit the apex and as soon as you're heading to the exit point and getting on the gas (not even flat) RPM is probably 3500- 4000 + the engine suddenly will go into limp mode (effectively it cuts out. 1000rpm and it won't actually move and will stall). Switch off the ignition and re start it and it will reset. Once over 4500-5000 rpm there's no issue. You can head off the straight at
full revs, foot flat to 7000rpm no problem

It's very much like driving a turbo and blowing off a pipe. You have power and then there's nothing as you come on boost.

Basically accelerate hard from low revs in 3rd gear (it doesn't happen in first or second as far as I can remember nor 4th)

If I ride the clutch a little coming out of the corner then there's no cut out but I'm also not going flat out. I don't think I'm even really engaging the clutch - ie it's not slipping.

To me this seems like I'm hitting an electronic torque limit.
Has anyone heard of something like this before ?
jml911 is offline   Reply With Quote
Old 04-13-2015, 07:45 AM   #2
inveniam viam aut faciam
 
Join Date: Mar 2014
Location: Arvada, CO
Posts: 408
The diagnostics built into the ECU/DME is the place to start. If you have a driveability issue that severe it will have faults in the ECU. It is also helpful to know what year/engine/injection system you have.
__________________
'03 S, manual, 18" Carrera wheels, PSM, PSE, Litronic, 996 Cluster, +
Qmulus is offline   Reply With Quote
Old 04-13-2015, 07:49 AM   #3
Registered User
 
Join Date: May 2014
Location: UK
Posts: 19
Quote:
Originally Posted by Qmulus View Post
The diagnostics built into the ECU/DME is the place to start. If you have a driveability issue that severe it will have faults in the ECU. It is also helpful to know what year/engine/injection system you have.
Well it's a 2000 but we've changed a lot
it's not a 3.2 anymore put it that way - bigger injectors - the lot

We can't read any faults at the track. Our machine for some reason isn't picking up the fault. It's a "soft fault" for sure as it's reset by turning the ignition on and off.
jml911 is offline   Reply With Quote
Old 04-13-2015, 08:23 AM   #4
Registered User
 
BYprodriver's Avatar
 
Join Date: Oct 2008
Location: O.C. CA
Posts: 3,190
Garage
Fuel pressure?,pump?, level?
__________________
2000 S Speed YellowLN 3.6L cylinders & pistons, triple row IMSB upgrade, R&R connecting rods, billet tensioner paddle,oilpump driveshaft.Heads rebuilt by F6I with new valves & springs.Cayman airbox & MAF housing, 996 intake plenum & 75mm T/B. NHP sport converters &Dansk muffler
BYprodriver is offline   Reply With Quote
Old 04-13-2015, 08:25 AM   #5
Registered User
 
Join Date: May 2014
Location: UK
Posts: 19
Quote:
Originally Posted by BYprodriver View Post
Fuel pressure?,pump?, level?
That's a good suggestion
We've upgraded the pump - but perhaps there's something else going on.

We've tried running with a fuel tank and it didn't make any difference.
jml911 is offline   Reply With Quote
Old 04-13-2015, 11:02 AM   #6
Registered User
 
BYprodriver's Avatar
 
Join Date: Oct 2008
Location: O.C. CA
Posts: 3,190
Garage
Quote:
Originally Posted by BYprodriver View Post
Fuel pressure?,pump?, level?
I forgot to add my 2000 S has 116,000 miles all original (fuel injecters & pump,DME) engine, except for 99mm sleeves & pistons. The 3.6L easily break tires loose thruout 1st gear with no torque limiting. Traction control was optional & PSM stability control became available in 2001 for USA.
__________________
2000 S Speed YellowLN 3.6L cylinders & pistons, triple row IMSB upgrade, R&R connecting rods, billet tensioner paddle,oilpump driveshaft.Heads rebuilt by F6I with new valves & springs.Cayman airbox & MAF housing, 996 intake plenum & 75mm T/B. NHP sport converters &Dansk muffler
BYprodriver is offline   Reply With Quote
Old 04-13-2015, 11:52 AM   #7
Registered User
 
Join Date: May 2014
Location: UK
Posts: 19
We're pulling about 200 pound-feet of torque at 3,000 RPM rising to 310 at 6,500 at RPM. That is a lot more than a standard 3.2 early 986 which I think peaked at 226 lbs/ft

I don't know if there's such a thing as an electronic torque limit but as mentioned earlier we need to hook it up and see what error codes are produces.

Oddly - this never happened on the dyno and it was run multiple times over 3 days.

Waiting on our tuning guru to become available to look at it. In the meantime we also need to find the cause of the ABS failure.

Not having a great time of it at the moment !
jml911 is offline   Reply With Quote
Old 04-13-2015, 06:28 PM   #8
Registered User
 
jsceash's Avatar
 
Join Date: Aug 2009
Posts: 1,403
Garage
I don't know what happened to my car at the track last year. But it has some similar issues. My configuration is a 3.6 and 5spd with a remap, 987 air intake, and sport exhaust. While running out 4th gear 5000 to 6000 When coming out of one turn to another (Esses). it would go to limp mode. I could quickly switch the key off then on and it would come back full power???? Suggestions were to replace the fuel pump and the filter, which didn't help but cost me about $500. I could run 2nd or 3rd gear to 7000 no issue. I could not reproduce the problem off track. I was at the same track 2 time earlier in the year with no problem the only change between was I had changed the front motor mount to a Wevo Semi solid. I went back to the 987 front mount and the last 2 track weekends I had no problem at all.

It was amost like the motor vibration + the G's reversing in the turns shut it off. Just like your problem there was no code saved or current able to be read by Durametrics or my Dyno Scan software.
__________________
2003 Black 986. modified for Advanced level HPDE and open track days.
* 3.6L LN block, 06 heads, Carrillo H rods, IDP with 987 intake, Oil mods, LN IMS. * Spec II Clutch, 3.2L S Spec P-P FW. * D2 shocks, GT3 arms & and links, Spacers front and rear * Weight reduced, No carpet, AC deleted, Remote PS pump, PS pump deleted. Recaro Pole position seats, Brey crouse ext. 5 point harness, NHP sport exhaust

Last edited by jsceash; 04-13-2015 at 06:30 PM.
jsceash is offline   Reply With Quote
Old 04-13-2015, 09:55 PM   #9
Registered User
 
Join Date: Sep 2013
Location: uk, notts
Posts: 141
knock sensors?

Think they can be coded out..or just undo them from the block and fasten out the way!

Would explain the 'soft' fault, as they are just doing their job, albeit rather more drastically than a normal timing pull.
jimk04 is offline   Reply With Quote
Old 04-14-2015, 11:52 AM   #10
Registered User
 
jb92563's Avatar
 
Join Date: Apr 2012
Location: Riverside, CA
Posts: 1,664
High G's and transitions make me think of loose wiring connections/shorting as the computer is going into limp mode.

It also makes me think of the crazyness I had going on with my MAF. It was intermittent in nature.

I took the MAF cleaner to it and the wire harness/plug connectors and that fixed it up.

I also pulled the filter and inside the filtered side of airbox in the drain I found bits of loose paper that looked like a parts number label, maybe from the filter element?

Since I cleaned all that out all the codes went away and it runs like a champ.

Since the computer is only responding to inputs that don't register as sensor faults, yet drastic enough for limp mode, but intermittent with the G's, I would also suspect the connections/shorting somewhere.
__________________
"It broke because it wants to be Upgraded "
2012 Porsche Performance Driving School - SanDiego region
2001 Boxster S, Top Speed muffler, (Fred's) Mini Morimotto Projectors, Tarret UDP,
Short Shifter, Touch Screen Dual Din Radio, 03 4 Bow glass Top (DD & Auto-X since May 17,2012)

Last edited by jb92563; 04-15-2015 at 05:48 AM.
jb92563 is offline   Reply With Quote
Old 04-14-2015, 12:18 PM   #11
Registered User
 
Join Date: May 2014
Location: UK
Posts: 19
It can happen coming out of the pits though.

Hopefully I'll have the car on the diagnostics tomorrow and it will show some errors after the engine cuts out.
jml911 is offline   Reply With Quote
Old 04-14-2015, 01:10 PM   #12
Certified Boxster Addict
 
Join Date: Nov 2010
Location: Los Angeles
Posts: 7,429
Here are a few of my thoughts;

Engine sensor - knock sensor, cam position sensor, crank position sensor, etc.

Blocked intake - I had similar symptoms ultimately found to be debris in intake. Take it apart and check everything!

ECU - check the re-map.

Variocam - make sure that the variocam system is operating properly
__________________
1999 996 C2 - sold - bought back - sold for more
1997 Spec Boxster BSR #254
1979 911 SC
POC Licensed DE/TT Instructor
thstone is offline   Reply With Quote
Old 04-15-2015, 08:46 AM   #13
Registered User
 
Join Date: May 2014
Location: UK
Posts: 19
Here's the code
It's a P1508 Function Monitoring Torque Comparison

From what I can see online the most likely issue is that I'm hitting the torque limit - so hopefully it's just a matter of raising this limit in the map.

The lesson here is always get the codes but it's actually exactly what I thought it would be. Waiting to hear from our tuner to when he can look at the car next.
It is a possibility that it could be a MAFF issue. But we've replaced that and with have a new CDA airbox on the car - so it's unlikely. I'll update you when I know more

Last edited by jml911; 04-15-2015 at 08:49 AM.
jml911 is offline   Reply With Quote
Old 05-03-2015, 02:33 AM   #14
Registered User
 
Join Date: May 2014
Location: UK
Posts: 19
Just to close this off. The measure mass flow wasn't able to compute the throttle angle and throttle position. It was happy enough at full throttle because it was close enough to what it was expecting but at half throttle it didn't like it.

So it's been re flashed and calibrated and it's superb now. Smooth power throughout the range and no cutting out.
jml911 is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -8. The time now is 08:35 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page