I've got a problem that seemingly cannot be fixed! - Page 3 - 911/Carrera GT - PistonHeads UK

Gents, i'm suffering with a problem details as best as can descrbe below: I've recently had my car mapped (along with various other mods (997 TB and IPD Plenum, forge diverter valves, nine excellence 1 bar actuators and europipe 100 cell exhaust)) I originally had it mapped by revo but it was feeling rough at low revs and the boost wasn't getting to 1.2 bar. It would go to about 0.7, 0.8 on wot. Strange thing was if i took my foot OFF the throttle slightly then the car would boost more and accelerate! The repo map was removed and the car checked for boost leaks. Found a couple leaks and the car was running well on standard map .8 or .9 boost. Decided to get the car mapped again and am now using softronic as I got the durametric cable from them and they were responsive to all questions I had. The car feels quicker, probably due to the timing but the boost issue is still there! If i go WOT in 3rd or 4th from 2k revs the boost never reaches 1.2. However if i go partial throttle or go WOT then back off slightly I can get max boost. Now i've tried various experts in the field and i've changed the MAF and N75, adjusted the actuators and i'm still nowhere. No other ideas have been put forward. I fairness it's the weekend now and I only asked the questions yesterday but the issue has been going on for a couple of months now when you consider i've been through two remaps etc. Please,please help!!! If you can!

The behavior suggests the DME is pulling timing (and boost falls) due to knock sensors signaling the onset of detonation. I hope you are running the proper octane grade of fuel and it is very fresh fuel? Also, with the new MAP what octane does the MAP manufacturer recommend?

I'm running bp ultimate and that was expected from tuners. Revo and softronic. You really think two mainstream tuners would get a fundental wrong for a fairly standard tune??

I'm running bp ultimate and that was expected from tuners. Revo and softronic. You really think two mainstream tuners would get a fundental wrong for a fairly standard tune??

Have you spoken to 9excellence?

Spoke with ken. He has suggested a few things and now says the Map.

Spoke with ken. He has suggested a few things and now says the Map.

Does the ECU use the LT fuel trims stored at WOT ?

I'm not sure on that one, is there a way I can check?

Not sure Noble but certainly you should be able to clear them to let the car learn again. I've no experience with F/I Porsches only aftermarket stuff on my M3.

Ok thanks anyway.

No takers?

It would be helpful to know if the DME is pulling boost of is it a mechanical issue. The only problem is you best tool for this will be a scope and someone that has an idea about how to use it. It would seem likely its software but without data showing whats happening when the boost is lost its a bit of guess work.

Using the scope to measure what and where? I have a durametric cable and can pull any figures off that might assist.

It would be helpful to know if the DME is pulling boost of is it a mechanical issue. The only problem is you best tool for this will be a scope and someone that has an idea about how to use it. It would seem likely its software but without data showing whats happening when the boost is lost its a bit of guess work. Sorry I don't have a magic bullet for your problem.

Put it back to stock see if it still does it You need to see if it' s pulling timing imo

What i can tell you is that boost is demanded (seen on the boost setpoint parameter). It's strange as the boost is not lost so to speak it just never reaches it's setpoint when I floor it. However if i go partial throttle then it can be achieved. Very strange indeed. Edited by noble1978 on Sunday 9th November 23:06

noble1978 said: I'm running bp ultimate and that was expected from tuners. Revo and softronic. You really think two mainstream tuners would get a fundental wrong for a fairly standard tune?? I'm not suggesting the tuners were wrong. I was just asking about fuel grade and quality/freshness. Sometimes an owner gets a tune that requires a higher than stock octane grade of fuel but for some reason doesn't want to spring for the higher cost fuel and then encounters problems when running the lower grade of octane fuel, even if the grade agrees with the car maker's recommendation. Or the car sits unused and the fuel goes off. While the standard engine is rather tolerant of fuel staleness, to a point, a tuned engine probably isn't. There could be a boost leak still. It could be on the intake side but it could be on the exhaust side. Whenever my Turbo is in for something that requires the exhaust system to be removed the tech always replaces the two metal o-rings (sealing rings) one on each side of the exhaust.

No boost leaks, holds solid at 20psi. Np ultimate fuel 97 Ron or above is all that ever goes in and it's fresh. It's a strange one, out foxing the various experts I have dealt with and the others I have just asked for advice.

BP never worked in my TTRS that well, so never used it again. You need to do run WOT runs and watch timing if the timing is pulled you lower it, you want to run as low a boost as possible but as much timing as possible. That gave me the fastest car. IF you had the revo you could use the module where you can alter timing, boost and how lean it runs. Timining pulls kills the performance. too much boost can also cause timing pulls. that's why I hate fixed mapps, you need to be able to alter them and in the winter you can realy tune them up to go much faster at 30oc mid summer with a turbo it's all about limitations. Switch fuel to shell and lower boost and timing, if still am issue you need to run the car stock to see if there is a fault. does a turbo car really need a 997 TB and IPD Plenum have to worked out air flow and much much you need in ? IF you cannot change any setting take the car to the mappers and ask them to fit it or take it off for a refund. Edited by mrdemon on Monday 10th November 09:18

When I had the Revo map initially I sat with the mapper and did various runs adjusting boost and timing. I do not believe the timing is the issue as it was the same symptom with timing retarded.

noble1978 said: I'm running bp ultimate and that was expected from tuners. Revo and softronic. You really think two mainstream tuners would get a fundental wrong for a fairly standard tune?? Put Tesco 99 or V power in, We find BP ultimate barely has any more knock resistance than 95!

boost then maybe ? it's over boosting which is pulling timing I know nothing about tuning, only what I did to get my TTRS fast, which was lower boost more timing. I would next question the air intake with TB and IPD are these needed on a x50 car ? that's all I have left to offer as it's not my field

The mods were all recommended by 9excellence. Hopefully they know what they are on about. The boost was lowered too during the revo trials. Same symptom. I'll try shell v power in when I can. However is there not something I can monitor on the durametric to see if it's knock? Also if it was knock why would it be ok at 75% throttle?? Doesn't make any sense.

Right I'm no 911 expert but do quite a bit of diagnostic work on a day to day basis. That said an engine is an engine and they all work on a similar principle. It's just some of the finer points need to be looked at to get a good diagnosis for each model. The boost pressure is measured before the throttle butterfly on these cars as far as I know. To generate pressure in anything you have to have a restriction ie you have to have more of something (fluid or gas) air in this care going in than is escaping or being consumed. If the throttle butterfly is backed off this is going to cause a restriction in flow and thus could be why your boost pressure is increasing at part throttle. It sounds like the equipment and your understanding of this possibly beyond your capability. Ken could well be right re the map, he has seen more than most. The fuel may be a good point to check and change so give it a go first. If not it would be a good next move to book the car in with Ken and get him to go over it as the last thing you want is to cause damage to the engine. I have seen some duff data logs from what I would class as poorly mapped engines. These engines are too expensive to take a risk with IMO. Good luck and hopefully its sorted soon.

This may be a stupid question (something I'm good at!) but is the map you've had installed on your car designed specifically for the x50 version of the car? If it's a generic map intended for a standard 996 Turbo, then it will fail miserably on the uprated x50 engine and would likely give many of the symptoms you describe.

Yeah the map is designed with x50 in mind.

Matt, are you saying the throttle body is too big therefore not allowing enough restriction when fully open?? If this is what you're saying I think you may be wrong on info that I've already obtained (not posted here so you weren't to know). Anyway the info is that the throttle body, when boosting correctly is open 100%. The throttle position is not 100% which is the strange part. My guesses are an insufficient spring in the diverter valve and the boost pressure recirculating rather than going through the throttle body. I've been assured I am wrong by Ken as he states they are supplied by forge and there is no adjustment available so I'm lost again. This theory ties in with the fact it only happens when a large immediate demand pulling the spring up. Also with the fact that these and the throttle body are new parts and 9 times out of 10 it's where you were working last the problem lies!! I am good at fault finding but I don't know enough of how exactly everything works and interacts to make any good testing. Hard to find good descriptions of operation of the system as a whole. I've got the workshop manual but it's more of a "fitters" manual than a technical manual.

Hmmm.... Well I did say it was likely a stupid question! If the map's x50-specific, the only other thing that I can think of that makes any sense is that 997 TB. I'm assuming this is a larger diameter item than the standard 996 TB? I've seen issues (on N/A engines, admittedly) where a bigger TB can make a mess of the mapping (unless the map is designed to account for the bigger TB). In essence, a larger TB will flow more air at any given angle than the standard one. The resultant flow rate can fall outside the expected parameters for flow at a given combination of manifold pressure, rpm and throttle angle, causing the ECU to go temporarily into a 'safe' (or safer) mode. It can also cause some really weird adaptation values to be stored. I'd be very tempted to try the stock plenum and TB back on the car, together with your existing Softronic map to see if it runs properly. If it does, we've found the culprit. If you wanted to go back to the bigger TB, it would just be a case of having the map adjusted to include appropriate parameters for the bigger TB. If it makes no difference, then my apologies, but at least it was worth the try in the absence of any other solution.

Cheers Ian. I have spoke with Scott at Softronic and the throttle body should not be a problem. Thanks for your input though, I'll maybe get round to putting stock items back in soon though. Seems a waste of money though as I've spent a fair bit now!

No takers?

You obviously need a proper diagnostic path following by an expert, starting with the basics before getting involved with mapping issues etc, have seen partially blocked fuel filters cause havoc with these engines though, there's a long interval between changes & there not always done even, easy enough to change HTH

I wish it was as simple as that, i'm in touch with various experts with no success.

Have any looked at it or have you just asked for advis so far?

I live in Scotland. Softronic are in the states and nine excellence are in Surrey. They have been getting me to check things and I've been reporting back. So far with no success.

Have you spoken to Stu at SPautobahn ? At least he's in Scotland (Stirling) and you could maybe leave it with him a few days.

I know its not easy to do diagnosis over the phone or net so saying it can't be fixed is a little off, unless you mean it cant be fixed by you. You have demonstrated to me already in this thread that the communication barrier of the net is stopping you from understanding what is being told to you. IE I tried to help you see how a smaller throttle angle could cause a higher boost level, I never said your throttle body was too big. I hope you get it sorted as its spoiling your enjoyment of the car and sound as though it was better to drive before you started modifying it.

Might be worth checking the throttle parameter, does it reach 100% (or close to) on WOT?

Matt, I understood you perfectly thanks, you were saying that you need a restriction to build pressure. Therefore i could get more boost by closing the butterfly throttle slightly. Therefore if you think I need to close the throttle slightly it seems you are suggesting it is too big when open fully? Is that not true? However I do not want to have to back off my throttle to create the best acceleration. I want max acceleration at max pedal input and proportional control through the range. Yes it's difficult to diagnose things over the phone and net and I know they are doing their best, i'm not bad mouthing anyone as I know they are trying.

The throttle parameter seems a bit strange. I did a log yesterday and it shows the throttle open 100% at full pedal depressed. However when I back of and get my full boost I had the pedal at 60% and the throttle was open 100% ! strange!!

I was going to suggest throttle opening as an off the wall thought. Recently had to check mine after fitting a different pedal. Durametric only shows 83/84% with throttle fully open due to the scaling differences from voltage. Are you saying yours is showing 100% ? I'd open the butterfly manually by hand and note what's shown and then repeat from the pedal.

yeah, mine does say 100% I'll try doing it manually later (going away for a week), cheers.

noble1978 said: The throttle parameter seems a bit strange. I did a log yesterday and it shows the throttle open 100% at full pedal depressed. However when I back of and get my full boost I had the pedal at 60% and the throttle was open 100% ! strange!! That does seem a little odd. However, your reading of 100% throttle at the point at which you are currently achieving most boost suggests your problem may lie elsewhere. Back to the drawing board..

I believe there's an easy reset for fly by wire throttle ? (Mine has a proper cable !)

They reset every time you switch on the ignition. They have two position sensors inside, the ecu takes a reading from each then briefly opens the throttle and takes a second reading to find full open/closed. If you listen closely you can hear it click when you switch on the ignition. My comments were more aimed at the throttle pedal which, when worn, sometimes don't achieve WOT, which will cause the throttle not to open fully, yet will not generate a fault code..

ArcticGT3 said: I believe there's an easy reset for fly by wire throttle ? (Mine has a proper cable !) Yes, put the ignition into the second position (just before it engages the starter) and leave it, after about 30 secs you'll hear the noise from the rear as it adjusts itself. Switch off and restart!

damiangt3 said: Yes, put the ignition into the second position (just before it engages the starter) and leave it, after about 30 secs you'll hear the noise from the rear as it adjusts itself. Switch off and restart! The newer model cars must be different then. The e-gas system recalibration is (was) something like this: With the ignition off and with no pressure on the gas pedal, turn the ignition to the on position. Leave the ignition on for 60 seconds. After 60 seconds turn the ignition off. Wait 10 seconds. The e-gas system is recalibrated. BTW, that "60" is just the minimum. When I do this -- about every 5K miles -- I always run a few seconds over the 60 seconds with no issues. The correct steps for the car's e-gas recalibration should be in the owners manual, so one should rely on that.

Gents, i'm back from hols. Today i've replaced my oil cap and checked all vacuum hoses were secure etc. What i'd like to know now is what the voltage should be at the input to the N75 boost controller and what controls it. Is it a proportional solenoid or on/off? i'm assuming it should be 12v or 0v for on and off?

reverted to normal map, this cured all the throttle issues. very strange it happened with two different maps. Sold it now.