997S.1 Ignition Timing

[ianwallwork]

I'm hoping someone might have some data regarding how much ignition timing (in degrees BTDC) a 997S.1 typically runs at full throttle and peak power (6900 rpm).

The reason for the question is that my car seems to have an ECU problem. When you reset the ECU (disconnecting the battery for a while) it runs fantastically well for the first hundred miles or so. The performance then dips gradually away - the car gets slower and slower over a couple of hundred miles, maybe to the tune of around 30BHP down, and sounds flatter and flatter. Resetting the ECU again restores the performance to normal levels. It FEELS like the ECU is pulling lots of timing and I wanted to compare mine to a 'normal' result.

The car is modified with a full AWE exhaust (headers/cats/mufflers)only.

The car is showing no fault codes on the PIWIS.

I always run 99-RON Shell V-Power Gas

Hope someone can help

[Loren]

Have them run a re-program of the DME using a PIWIS tester.

If the problem comes back they likely need to replace your DME.

[ianwallwork]

Have them run a re-program of the DME using a PIWIS tester.

If the problem comes back they likely need to replace your DME.

Hi Loren, thanks for the reply. My local Porsche independent just acquired a PIWIS but, as yet, hasn't done an ECU reflash. Do you have access to any documents that detail the procedure to reflash the ECU? Also, do you have any idea how the flash files come from Porsche? Are they on CD/DVD or are the various files included the software that gets loaded onto the PIWIS computer?

Sorry for so many questions - hope you can help.

Edited May 13, 2009 by ianwallwork

[Loren]

Have them run a re-program of the DME using a PIWIS tester.

If the problem comes back they likely need to replace your DME.

Hi Loren, thanks for the reply. My local Porsche independent just acquired a PIWIS but, as yet, hasn't done an ECU reflash. Do you have access to any documents that detail the procedure to reflash the ECU? Also, do you have any idea how the flash files come from Porsche? Are they on CD/DVD or are the various files included the software that gets loaded onto the PIWIS computer?

Sorry for so many questions - hope you can help.

The flash files come in the PIWIS updates.

You just enter in the proper IPAS codes for your car (you can get these from any dealer/OPC) and then re-code the DME.

They will need to choose the proper emissions program (from the PIWIS list) for your country.

The whole process might take 30 minutes.

[ianwallwork]

Thanks once again for the reply. I'm having the reflash done next week and will let you know how I get on.

[ianwallwork]

I had my ECU reflashed using the PIWIS a couple of days ago.

I've put approx 200 miles on the car since the ECU upgrade and I'm delighted to say the performance is now improving with miles not getting worse. Other than that, the car now idles better, runs far smoother when cold and has more torque through the gears so I guess the previous file on the chip must have gotten corrupted somehow.

Thanks, Loren, for your input on this one.

[Loren]

:clapping:

[Dave07997S]

I had my ECU reflashed using the PIWIS a couple of days ago.

I've put approx 200 miles on the car since the ECU upgrade and I'm delighted to say the performance is now improving with miles not getting worse. Other than that, the car now idles better, runs far smoother when cold and has more torque through the gears so I guess the previous file on the chip must have gotten corrupted somehow.

Thanks, Loren, for your input on this one.

Ian any updates??

Dave

[ianwallwork]

Hi Dave

Not really - I've had one or 2 minor issues with the car that should be sorted by next week. (Just bits and pieces breaking and falling off, broken windshield all really irritating but almost sorted). I've decided not to go any further modifying this car for now. The lease is up later in the year and I can't justify spending even more money on mods I'll only be able to enjoy for a few weeks.

Interestingly, RSS has offered to swap the plenum I bought from them for their 'Gen-2' version. I'm told that will address the fitment issues I had and maybe I'll also see the performance gains so many others seem to have found but that never happened on my car. Generous offer given I've been quite scathing about the product - good bunch of guys!

So my final spec will be full AWE, plenum, BMC-F1 filter panel, stock ECU. The only dyno runs I ever did on the car were with the knackered ECU prior to the PIWIS reflash. Even then we were getting 325+ wheel HP with a load of timing pulled. The car was running 21-22degrees BTDC at peak power against the 25 degrees it should run. Accoring to the tuners I've spoken to, you see a +3 BHP gain per degree of timing (until it reaches optimal then it starts to lose power) so that would equate to just over 330 wheel HP with 25 degrees of timing. About 385 crank at a guess. Not to shabby! (And the new plenum may give a little more).

[Dave07997S]

Hi Dave

Not really - I've had one or 2 minor issues with the car that should be sorted by next week. (Just bits and pieces breaking and falling off, broken windshield all really irritating but almost sorted). I've decided not to go any further modifying this car for now. The lease is up later in the year and I can't justify spending even more money on mods I'll only be able to enjoy for a few weeks.

Interestingly, RSS has offered to swap the plenum I bought from them for their 'Gen-2' version. I'm told that will address the fitment issues I had and maybe I'll also see the performance gains so many others seem to have found but that never happened on my car. Generous offer given I've been quite scathing about the product - good bunch of guys!

So my final spec will be full AWE, plenum, BMC-F1 filter panel, stock ECU. The only dyno runs I ever did on the car were with the knackered ECU prior to the PIWIS reflash. Even then we were getting 325+ wheel HP with a load of timing pulled. The car was running 21-22degrees BTDC at peak power against the 25 degrees it should run. Accoring to the tuners I've spoken to, you see a +3 BHP gain per degree of timing (until it reaches optimal then it starts to lose power) so that would equate to just over 330 wheel HP with 25 degrees of timing. About 385 crank at a guess. Not to shabby! (And the new plenum may give a little more).

Sad to see you getting rid of the S, I read on 6speed that you were considering a GT3 or TT. I talked to several people who have the IPD plenum and they were very pleased with it. I am more interested in the plenum as it can be machined to fit the X51 throttle body, any thought on this??

Dave

[ianwallwork]

Hi Dave

Not really - I've had one or 2 minor issues with the car that should be sorted by next week. (Just bits and pieces breaking and falling off, broken windshield all really irritating but almost sorted). I've decided not to go any further modifying this car for now. The lease is up later in the year and I can't justify spending even more money on mods I'll only be able to enjoy for a few weeks.

Interestingly, RSS has offered to swap the plenum I bought from them for their 'Gen-2' version. I'm told that will address the fitment issues I had and maybe I'll also see the performance gains so many others seem to have found but that never happened on my car. Generous offer given I've been quite scathing about the product - good bunch of guys!

So my final spec will be full AWE, plenum, BMC-F1 filter panel, stock ECU. The only dyno runs I ever did on the car were with the knackered ECU prior to the PIWIS reflash. Even then we were getting 325+ wheel HP with a load of timing pulled. The car was running 21-22degrees BTDC at peak power against the 25 degrees it should run. Accoring to the tuners I've spoken to, you see a +3 BHP gain per degree of timing (until it reaches optimal then it starts to lose power) so that would equate to just over 330 wheel HP with 25 degrees of timing. About 385 crank at a guess. Not to shabby! (And the new plenum may give a little more).

Sad to see you getting rid of the S, I read on 6speed that you were considering a GT3 or TT. I talked to several people who have the IPD plenum and they were very pleased with it. I am more interested in the plenum as it can be machined to fit the X51 throttle body, any thought on this??

Dave

I'm really surprised that IPD didn't make a specific plenum for the X-51 T/body w/ the standard intake runners. If their standard 997 item can be machined than it's the perfect conversion kit to get this part and the X-51 airbox to work with the rest of the intake system.

The only (major) problem I see is the mapping. There's one very obvious one and one that isn't so obvious.

The obvious one is the alpha-n mapping in the ECU - this will be off by miles. This map replaces the MAF sensor signal with a table of pre-defined signal values based on throttle angle and rpm if the MAF fails. The amount of air going into the engine at a given throttle angle will be way more with a bigger t/body so the car would run mad lean. I don't know if this alpha-n map has any function with a MAF connected.

The less obvious one is that all the other maps in the ECU derive their target lambdas and ignition values from throttle angle and rpm. I'm concerned you'd need a serious remap if you used the X-51 t/body as I don't believe the standard maps would work any more. An example. Your map for 20% throttle and 3000rpm returns a timing value of (let's say) 38 deg btdc. This works fine with the amount of air going in at 20% throttle opening with the standard t/body. With the X-51 t/body, a 20% throttle opening might let in as much air as (again, let's say) a 25% throttle opening with the standard t/body but would still pick up on the same ignition value as it would with the standard t/body. As you let more air into an engine, it needs LESS timing so our 38deg btdc may now be 5-6 degrees too much. The knock sensors would then kick in and you'd lose (a LOT of) power - maybe to the point of throwing a CEL. It may also be that with a 25% opening on the standard t/body, the map asks for a richer mixture. This wouldn't happen with the X-51 t/body as the ECU would still use the 20% value, running the car too lean and exacerbating the problem.

Swapping throttle bodies just isn't a simple exercise in a Motronic car!!

Anyone else care to comment on the above?

[Dave07997S]

Hi Dave

Not really - I've had one or 2 minor issues with the car that should be sorted by next week. (Just bits and pieces breaking and falling off, broken windshield all really irritating but almost sorted). I've decided not to go any further modifying this car for now. The lease is up later in the year and I can't justify spending even more money on mods I'll only be able to enjoy for a few weeks.

Interestingly, RSS has offered to swap the plenum I bought from them for their 'Gen-2' version. I'm told that will address the fitment issues I had and maybe I'll also see the performance gains so many others seem to have found but that never happened on my car. Generous offer given I've been quite scathing about the product - good bunch of guys!

So my final spec will be full AWE, plenum, BMC-F1 filter panel, stock ECU. The only dyno runs I ever did on the car were with the knackered ECU prior to the PIWIS reflash. Even then we were getting 325+ wheel HP with a load of timing pulled. The car was running 21-22degrees BTDC at peak power against the 25 degrees it should run. Accoring to the tuners I've spoken to, you see a +3 BHP gain per degree of timing (until it reaches optimal then it starts to lose power) so that would equate to just over 330 wheel HP with 25 degrees of timing. About 385 crank at a guess. Not to shabby! (And the new plenum may give a little more).

Sad to see you getting rid of the S, I read on 6speed that you were considering a GT3 or TT. I talked to several people who have the IPD plenum and they were very pleased with it. I am more interested in the plenum as it can be machined to fit the X51 throttle body, any thought on this??

Dave

I'm really surprised that IPD didn't make a specific plenum for the X-51 T/body w/ the standard intake runners. If their standard 997 item can be machined than it's the perfect conversion kit to get this part and the X-51 airbox to work with the rest of the intake system.

The only (major) problem I see is the mapping. There's one very obvious one and one that isn't so obvious.

The obvious one is the alpha-n mapping in the ECU - this will be off by miles. This map replaces the MAF sensor signal with a table of pre-defined signal values based on throttle angle and rpm if the MAF fails. The amount of air going into the engine at a given throttle angle will be way more with a bigger t/body so the car would run mad lean. I don't know if this alpha-n map has any function with a MAF connected.

The less obvious one is that all the other maps in the ECU derive their target lambdas and ignition values from throttle angle and rpm. I'm concerned you'd need a serious remap if you used the X-51 t/body as I don't believe the standard maps would work any more. An example. Your map for 20% throttle and 3000rpm returns a timing value of (let's say) 38 deg btdc. This works fine with the amount of air going in at 20% throttle opening with the standard t/body. With the X-51 t/body, a 20% throttle opening might let in as much air as (again, let's say) a 25% throttle opening with the standard t/body but would still pick up on the same ignition value as it would with the standard t/body. As you let more air into an engine, it needs LESS timing so our 38deg btdc may now be 5-6 degrees too much. The knock sensors would then kick in and you'd lose (a LOT of) power - maybe to the point of throwing a CEL. It may also be that with a 25% opening on the standard t/body, the map asks for a richer mixture. This wouldn't happen with the X-51 t/body as the ECU would still use the 20% value, running the car too lean and exacerbating the problem.

Swapping throttle bodies just isn't a simple exercise in a Motronic car!!

Anyone else care to comment on the above?

Ian, there is a memeber on this site that did just what I wanted to do, which is use the IPD plenum with the larger X51 throttle body. He is running OEM software with no issues. That doesn't mean he isn't running lean though. Also, even though it is a motronic car the 02 sensors are gross adjusters so they should be able to adjust accordingly from my understanding, after all that's the point of a MAF vs. a Speed Density system. Unfortunately not to many people are aware of the differences between the X51 and non X51. As ususal always love your input...

Cheers..

Dave