ianwallwork

Or try this little gadget. Gives you full manual control over your PSE, stops it going quiet at certain rpm and lets you have the exhaust loud with the car in normal mode - perfect! Go to http://www.carnewal.com In the menu, select exhaust. Then scroll down to P97-1 and look for PSE Manual Control with Remote

Keep a VERY close eye on this one. If you're getting a reduction in oil pressure under acceleration, it could mean that the engine's being starved of oil. I had the very same problem on a 996. The stealer also thought this was a faulty sender, but a new one made very little difference. The real problem was quite difficult to diagnose. What was happening? Simply there wasn't enough oil in the sump under running conditions. It was OK with the engine off, but whilst running, the level was going dangerously low and the oil pickup was being starved of oil. How? Good question! The M96/7 engines have 3 oil pumps. The main one that picks up oil from the sump and pushes it round the engine under pressure and one in each of the cylinder heads that 'scavenge' oil from the heads and return it to the sump. It needs these scavenge pumps as gravity won't return oil to the sump from the 'outside' cylinder head when cornering (amongst other things). On my car one of these scavenge pumps had failed and oil wasn't getting back to the sump as fast as it was being pumped out of it. On the level, it was just about OK (like your car) but as soon as the oil in the pan surged under acceleration or cornering, it shifted away from the pickup and pressure was lost. Replacement of the scavenge pump restored things immediately to normal. I've never heard of a similar failure before or since but it's possible! Ian

Hi everyone, I'm hoping someone (maybe with access to a Porsche parts system) can help me with a problem relating to the clutch release mechanism on my 997S.1. I'm currently having the gearbox replaced on my car ('05 997S.1) due to my the original 'box breaking a tooth on 1st gear. Whilst there's no 'box on the car, I'm having a couple of bits and pieces sorted. This includes new RMS and Intermediate shaft seals as both were 'weeping'. The biggest and most irritating problem we're loking to address, however, was a squeaking clutch. Every time the clutch got warm it squeaked at the gearbox end of things as you depressed or released the pedal. My local Porsche independent has got the clutch in pieces on the bench and for the life of us, we can't find any reason why this should be happening. The cluch plate, cover, release bearing (do you colonials call that a throw-out bearing? :-) ) and slave cylinder were all new about 5000 miles ago. The only thing that looks 'odd' to me is where the slave cylinder engages a 'dimple' in the clutch release arm. This looks like metal to metal contact - the nose of the slave cylinder seems to sit in the 'dimple' with nothing but a blob of grease to lubricate the interface between the two. So my questios are: 1) Is it correct that the metal 'shaft' of the clutch slave cylinder should engage the metal 'dimple' of the release arm directly or is there supposed to be some sort of hardened plastic part to keep them apart and take the load? 2) Does anyone have the exploded diagram of the clutch release mechanism to confirm? 3) If the above is normal, does anyone have any idea what might make the clutch mechanism squeak? Hope you can help Ian

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?

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).

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.

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

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.

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

I'm having a custome remap done on 1st May. I think this is the best way to tie together any mods as the mapping , if done cirrectly, will work perfectly with the hardware on the car. It also takes into account the slight differences between production engines, the grade of fuel you use and (to a point) your driving style. The remap is being done by a UK tuner who does the mappings for most of the Porsche Chalenge Cup cars in the UK. They have a fantastic reputation and I can't see all the race teams going there year after year if they're not good at what they do. I'll be reporting back with dyno plots and results here and on 6-speed once it's done. I'm also hoping to gain a lot more knowledge of the inner workings of the engine control systems and will share everything I find out with other forum members both here and on 6-speed.

Ian, glad to see you here as well and always look forward to your input. However, the X51 heads from my understanding are nothing more than some bowl work and a stiffer exhaust valve for the increased rpm to 7450rpm. The stock non X51 heads have to flow pretty darn good to get to 93hp/litre while limiting rpm to 7300rpm. In my own experience heads without updated cams and more rpm is probably at best 5-10rwhp and in my opinion are a total waste of money for what Porsche wants for the X51 heads. You layed out a good plan for getting the hp to at least X51 levels with only half or less of the expense. Obviously if you start with more power you will end up with more power. On 6speed we discussed that I was considering the intake manifolds from the X51 and I have to be honest, from the people I talked to I figured it wasn't worth the expense (as you thought) of going down this road for what will at best be 10rwhp for the huge expense. I will still do the X51 carborn air box as I think it is so pretty and really is not a bad investment for what it costs (a lot cheaper than some of the non OEM intakes out there) and only having to deal with cutting out the upper deck lid for the other inlet. Dave Dave - really good to see you on here too. This is one of the best forums on the 'net for Porsche owners and I wish more 6speeders would take the time to post (and contribute). I agree totally with your comments above - of all the intakes for the Mk1 997S, the X-51 is probably the best. However..... I've mailed Fabspeed today to beg them to produce a version of their (superb) high performance intake (that they only provide for 997S/2 currently) for the 997S/1. I'll be posting on 6speed about this soon too. Their new intake is the best I've ever seen and I think all us addicted modifiers would snap it up for our Mk1's! See you on 6speed again soon. Ian

That is interesting about the plenum. The 3.4 is a very different engine to the 3.8 and as such will have totally different intake characteristics. Maybe this engine responds well to the changed flow patterns the plenum causes in the induction system whereas the 3.8 seems not to. I'd be intrigued to see some dyno plots on this one.

There really is some utter cr*p talked about how to get power from a naturally aspirated engine - especially regarding how much is available from bolt-on mods. I think it's about time we discussed what does and doesn't work on these engines.... The 3.8 engine in stock tune produces 93.4BHP/litre. Not stellar by today's standards but still high enough that there's not a lot of 'low-hanging fruit' to be had. Also bear in mind that most engines that do a lot better are either forced induction or (more importantly to this discussion) rev much higher. The max BHP obtainable from an engine increases dramatically with more rpm (assuming the rest of the engine is engineered with the higher rpms in mind). Unfortunately, the 997S engine cannot be revved higher - it explodes. So 93.4BHP/litre is a good result for an engine that only revs to 7300rpm. So what can be done. Well let's address the OP's question. There are 2 ways to get 400BHP from this engine without forced induction. The first is to have the capacity increased to 4-litres plus, the other is to start with the X-51 engine (the factory 381BHP upgrade). You simply cannot get the stock 355BHP engine to 400BHP. Period. So what works on these engines? Well sorry guys but here's the absolute truth: 1) Induction kits. These have no proven effect whatsoever apart from noise. The standard airbox is very, very good and keeps intake air temps in check very well. A BMC-F1 panel filter is good for 3-4BHP but doesn't filter as well as the paper one. Your choice. 2) Plenums. Just don't go there. There were hundreds of discussions on 6-speed over these and eventually a lot of third party dynos. Trick plenums lose power in the mid band and give no gains elsewhere. (I bought one, installed it, found a performance loss, removed it and wasted my money so I'm well-placed to comment)!! 3) Exhausts. On the 3.8, the dire-looking pressed steel headers are far better than they look. The work well at low/mid rpm and only very slightly strangle the engine at high rpms. Good quality headers will give 6-7BHP in conjunction with a full exhaust system but only over 5000rpm. You may also lose some low and mid-band torque. The stock mufflers again flow very well and replacing these alone will give little to no gain (5BHP max). The standard catalytic converters however are very restrictive and a good pair of 200-cell cats will give 15-20BHP on this engine. The best solution is a good, matched system (headers, cats, mufflers) that will give 25BHP or so. Nobody has ever (to my knowledge) got to the +40BHP claimed by certain exhaust manufacturers. 4) Re-maps. This is so hit and miss. What does a remap do? Simply, it can alter the mixture or ignition timing at different operating phases of the engine. The standard Porsche maps are designed to run 98-RON (93-PON?) fuel and fuel the engine more or less optimally for max power so there is almost nowhere to go for a stock engine (despite the claims). Blindly adding-in timing (as some generic maps do) will just cause the knock sensors to wind it out again and the whole car will run dreadfully. Unfortunately some 'tuners' just alter the throttle mapping to give the illusion of more part-throttle power - naughty! The time when re-maps DO work is with other mods. Change the hardware (e.g a full exhaust) and you have changed the engine's volumetric efficiency at certain rpms. This usually requires the ignition timing to be changed by a few degrees to work optimally at those rpms and extra power will result, but it's very unlikely to be more than single digits. So with a stock engine, a full exhaust, custom remap and BMC filter can give +30-35BHP (crank) and this is as far as this goes without very extensive further internal and external modifications to the engine. The X-51 engine is a different beast however. Totally different intake system, bigger throttle body, high-flow airbox, gas-flowed heads, different exhaust headers and electronics mapped to suit make this a much better platform. This engine retains the stock catalytic converters that are now more restrictive than ever and a full exhaust on this motor will give you 25-30BHP with no trouble. There's your 400+BHP. If you want 400+ BHP with massive torque, look at 9ff (German Tuner)'s large capacity, crated engines. Expensive, but will give you the fastest 997S out there. When all is said and done however, to get 400+ BHP is so expensive that you could have one of the better cars Porsche already makes with 400+ BHP out the box (GT3 anyone). A full exhaust, remap and BMC filter combination however, is sensible money and makes the 997S go and sound like it should whilst giving 385-390BHP on a good engine. This would be my preferred route.

I've had a chance to look through the file you sent me - many thanks indeed, it's going to be really useful. The only thing it doesn't have is procedures for using the PIWIS. It would seem there is a separate section in POSES dedicated to Diagnostics which I assume will have this info. Is the 997/S diagnostics file one you might have?

You can also try here: http://www.1stchoice.co.uk/Cars/Porsche/