wwest

I installed Porsche's bi-xenon headlight assembly in my 2002 996 C2 about 4 years ago (http://www.renntech.org/forums/index.php?showtopic=9851&hl=)

They have worked fine until recently (colder?), they don't ignite on the first turn, but require multiple turns of the headlight switch before they come on. Sometimes, they don't come on at all.

Several others on this forum have complained about the problem, but I have not seen any definitive solution. The choices so far are:

• Headlight switch going bad
  
• Electronic modules going bad (at the same time?)
  
• Lamps going bad (at the same time?)
  
• Not enough initial current to the ignitors (colder temps, 15A fuses)
  

My general approach to problems is to start with the least expensive.

The last item is the most intriguing to me. One poster claims that the OEM Xenon equipped cars have 30A fuses in slots A9 /A10 while the non OEM equipped cars have 15A fuses (which is indeed my case). There may be some merit to that theory because fuses work by generating heat with a bit of resistance, lower amped fuses have higher resistance, so less current to the ignitors. Combined with colder weather -> lower voltages may make some sense.

Unfortunately, I don't have the circuit diagram for my car and so I cannot verify this information (can anyone send it? or verify that claim).

In the mean time, I cleaned the lamp housing contacts and now of course all is well. I cannot further diagnose but would like to solve the problem so as not have surprises while on a trip.

Your help as usual will be highly appreciated.

Install the largest, within reason, electrolytic capacitors (>15 volt rating, polarised) as close as posible directly across the two leads supplying power to the HID ballast/ignitor. Also, make certain sure that the battery/alternator system is operating at proper capacity and charge level.

HID initial ignition requires >25,000 volts, a serious level of DC-to-DC upconverting from the battery's 12 volts. The gap voltage drops to ~70 VDC once the arc is established.

Looking for help in resolving a low voltage situation with my 2002 996 C4 Cab. I installed a pair of LED smoke clear tail lights and I immediately received a PSB/ABS failure message on the dash. I also have the LED brake lights, btw. The overall swap out would have been fairly easy, but in the process I uncovered that the stock tail light harness bulb socket prongs had broken and caused a short. So, after a bit of debugging I was finally able to get beyond that issue. Also, had the usual blinker cadence issue, so I installed resistors and have the blinkers back to the proper cadence.

I stopped into my local Porsche shop here in Scottsdale (Beck's European) and he was able to confirm that I have a low voltage situation, due to the LED tail lights. My conundrum is, where would I need to put another resistor to solve the current issue? The tech at the shop could see the voltage, when the brake pedal was depressed, was below 12v, so the computer is triggering a brake switch error and then putting the PBS/ABS into a failure state.

Would really appreciate any help and guidance on this. Seems I do need to add a resistor(s), but not sure if I need one on each tail light and if so, what wires would the resistor go between?

Anybody work through this issue before?

Thanks in advance...

G

Apparently you haven't yet noticed but your CC is also disabled.

In my RX300 I went in and modified the current flow sensing aspects of the bulb failure detection controller so it was satisfied with the lower (~10:1) LED current flow.

For my '01 C4 I simply added a relay and a 50 watt incandescent bulb in the LED high mount circuit behind the high mount itself. The NC contacts of the relay connect the bulb into the circuit, satisfying the CC bulb "keep-alive" current flow requirement. When a full 12 volts is applied (the brake lights are on) the relay pick sup and takes the 50 watt incandescent out of the circuit.

Hi, thanks for your reply, could you give me any more details on what you did? Is it something I can do or do I need to go the dealership to get it done? Thanks!

If a thermistor sensor is used (highly probable) then you can bridge, parallel in, a 1000 ohn resistor for awhile and if that works to abate the failure warning you defintely have a sensor failure.

...

Any 911 owners done this? ;)

My wife loved driving her '05 997 so much we bought an '08 Cayenne S for our dog (we have to drive it for the dog). But we kept the Carrera. And the Boxster. I've been very pleasantly surprised with the fuel economy in the Cayenne - around 20 MPG highway at respectable cruising speeds. You might not do quite as well with the Turbo. The Carrera holds a lot for its relatively compact size, but the Cayenne holds so much more. The back seat is lots more usable for people, too. Many Cayenne parts are a lot less expensive than their Carrera counterparts. While not as enjoyable as a Porsche sports car on twisty roads, the Cayenne does a pretty good job holding its own compared to most other cars on the road. And driving it puts a smile on our faces. But totally different driving dynamics from the Carrera

Enjoy your new Cayenne :D

"..You might not do quite as well with the turbo..."

An understatement if I even heard one.

In order to accomodate turbo boost on the rare occassions of it being appropriate/used the base V8 must must be derated, HORRIBLY derated. The NA V8 is DFI, Direct Fuel Injected, so the static compression ratio is likely close to 12:1, yeilding fairly decent overall FE. The turbo V8's CR might be as low as 8:1 so normal, cruise mode, driving (98% of the time) will have relatively POOR FE.

No substitute for SuperCharging and e/VVT-i, "extended" VVT-i. Keep the engine in Otto mode, 15:1 CR, and transition into Miller cycle mode, (<10:1 "pre-boost" dynamic CR) with FULL boost.

Greetings Porschisiti,

I bought a new 911 C2 in September, and having enjoyed it thoroughly for four months, fancy a bit more practicaility, therefore chopping it in for a Cayenne Turbo!!

Now as much as I loved the 911, there's no doubt the Cayenne offers a similar quantity of excitement, but far more space and a relatively tough old boot in everyday use too, despite the rather scary predicted fuel consumption (C2 averaged 20mpg in everyday use, nearer 24mpg on a run, using it's performance somewhat....)

My main considerations are comfort, toys, practicality and all-weather usability, in which the Cayenne excels, needless to say I'll probably regret selling the lovely 911...

Any 911 owners done this? ;)

Great forum by the way, I'll try to contribute as much as poss... :renntech:

"..Any 911 owners done this?.."

Give up a 911(996/997) in favor of a Cayenne...??!!

It would be my guess that you are TOTALLY alone on this.

I think you will need the GT3 wiring harness for the rear deck lid. It was the same way on the older series (997-1 and 996).

Thanks, I was making it harder than it needs to be. Checked with my dealers parts dept and the harness only runs $52. Should have figured Porsche would have it covered. :D

On the other hand the new high mount might be LEDs whereas the old one was incandescent..??

Other than opening up the current flow detection module and modifying it adding resistors parallel to the LED might be the only solution

I have a 2001 C2 Cab that is having wiper issues. I live in Seattle and it's a daily driver, so it's a bit of a problem. It used to stay in garage during rain, but with the economy ect... we are down to 2 cars.

There are 2 different problems, and I don't know if they are related. The first is that the intermittent wipers don't work at all. Nothing happens when I switch on the wiper control stalk on the steering column. I have regular wipers with the thumb rotary wheel on the dash that adjusts speed.

The second problem is that the wipers don't park when I turn them off. They just stop dead on the windshield. I have to time it right and turn them off when they are at the bottom.

I had an indy look briefly at them last year and he said that it was the intermittent rotary switch on the dash, then I had a different indy look at them last month, and he said it was the wiper motor.

Anyone had this problem?

Johnny

You have only one problem.

There is a switch/mechanism inside the wiper motor gear box that prevents the wiper motor from stopping until it is in the "park" position. This switch has failed in the "open" position. If the wiper motor is never in the park position as designated by the opening of the switch, reaching the "park" position, the time delay never runs.

Can anyone tell me the rough HP Output increase I can expect by putting a supercharger on my 996 C4S (2004).

That depends almost entirely on how much you are willing to derate the base engine performance via lowering the static compression ratio.

The more PRE-COMPRESSED and INTERCOOLED cylinder CHARGE you can make use of via the SC the more ON-BOOST HP/Torque you can get.

8:1 static would not be out-landish IMMHO.

Absent some level of CR derating I wouldn't bother.

You are absolute wrong in your statement. There is no speculation about this, although you always seem to have it. Low boost and high compression has been around for years and if the boost is managed properly, it produces as much power as a higher boosted, lower static compression engine does.

Whether you take a low static compression engine and boost it with 10 psi of boost or a high static compression engine and boost it with 5 psi, the boosted compression ratio of 18:1 creates the same stress on an engine and will deliver the same amount of power, all other things being equal. The engine with the higher staticc compression, however, will perform substantially better in off boost and low boost driving.

There are many good books available that you should read which will enlighten you about FI engines.

Sorry, simple matter of physics, the more, the higher %, of the cylinder charge that can be cooled AFTER compression the higher the effective BOOSTED compression ratio can be without resulting in detonation.

Due to the cooling effects of DFI the new NA engines can have a static compression ratio of ~12:1.

Can anyone tell me the rough HP Output increase I can expect by putting a supercharger on my 996 C4S (2004).

That depends almost entirely on how much you are willing to derate the base engine performance via lowering the static compression ratio.

The more PRE-COMPRESSED and INTERCOOLED cylinder CHARGE you can make use of via the SC the more ON-BOOST HP/Torque you can get.

8:1 static would not be out-landish IMMHO.

Absent some level of CR derating I wouldn't bother.

Well to avoid problems this spring I purchased a battery tender and after I installed it my PSM light is on. Have I won myself a trip to the dealer? How ironic that I purchased a battery tender so I would not have any troubles next spring. Any help would be appreciated. Perhaps I just need to drive it a bit to reset something??

2005

C2S

If you haven't already done it, drive it for awhile and the light should go out. If not, double check that your connections are clean and tight. (Don't over do it just make sure they are snug. Should not be able to move the terminal end if it's connected properly) I have disconnected the battery several times and if I had the PSM light come on it didn't last long enough for me to remember it. Also had a similar set up with a battery tender so I don't think that's the issue unless you're getting current loss from a loose connection or a poor connection caused by a dirty or oxidized battery terminal.

Make sure you always disconnect negative terminal first ( if you just need to cut power to the car ) and reconnect it last (if you're also disconnecting the positive terminal).

The ABS pumpmotor is used to "replenish" brake fluid pressure as/when it is used up via PSM activation. The pumpmotor is relatively small for such a BIG job and therefore draws a "ton" of current from the 12 volt system when it (rarely) has to run. So if the system detects a low battery, even only slightly low, it will reserve pumpmotor operation for ABS only. You can correct the system fault, provided your battery is full charged, by disconnecting the battery entirely for 10 minutes or so.

That 2 second battery disconnect was only/just long enough for the ABS/PSM system to detect a "low" battery.

I've got a 99 996 Cab C2 6-speed with 125,000 miles. Over the past month or so, I've developed a vibration in the steering wheel when I'm turning. It's quite a judder and will even make noise if I'm turning into a driveway or anything uphill or on uneven pavement. It originally was only when I turned left, but now it's starting to vibrate when I turn in either direction.

It feels like there's some bushing in the steering column that's gone missing and it's letting the move up/down and in/out a little bit. However, I'm not sure if there's anything like that in the column. I don't know if I should start opening open the steering column and dash to look in there or if this is indicative of something gone awry in the suspension. Perhaps I should be looking at the bushings on the control arms or replacing my shock absorbers. I don't know. I'm kind of lost when it comes to suspension.

The ride quality seems to be normal aside from this new steering wheel vibration.

Anyone have any ideas? What should I check first?

PSM (if you have it) differentual braking...??

Has anyone ever converted a N/A 3.4 in a 01 996 c2 into a turbo, is there a kit or a shop on the east coast that has done this?? I know about the supercharger kits available but I can't seem to find a turbo kit. Yes I know it would be wiser to sell C2 and get the turbo, yes they are cheeper now but I do not want to sell my car for any reason, so that is not an option and I can not have two p cars so that is not an option. Just curious at this point if this is an option or not and what the cost factor would be, Thanks in advance for your anticipated assistance with this. Yes I do track days and autox on a regular basis take direction from execelent instructors with PCA and seat time is a priority for me in my quest to become one with the car but I'm still curious if there is a turbo conversion kit or mod for this engine/vehicle set up. NOS is not an option for me.

In order to get the full benefit of a turbo, assuming intercooling included, your engine must first be detuned, static compression ratio lowered to something in the range of 8:1. That, basically, would result in the car not being very satisfactory for use as a daily driver. Same is true for SuperCharging.

A more satisfactory forced induction solution could be had via the use an intercooled SC(***) and Toyota's new e/VVT-i system. But that would require some really serious engineering design and mechanical engine retrofit work. To summarize, the engine, DFI assumption, could run in standard Otto mode, 15:1 compression ratio, for light throttle/engine loading. Atkinson cycle, 12:1 CR, for moderate throttle/engine loading, and then Miller Cycle, 9-10:1 when Boost is required/used.

*** TurboCharging cannot be an effective solution with an Atkinson or Miller cycle engine. No "waste" gas to spin the turbo.

excel database format data from durametric

anyone have any idea what kind of readings im looking for or what safe operating ranges are?

The data you collected is meaningless. Capture the follwing information all the way to redline in 2nd or 3rd gear.

RPM

Coolant temp

MAF (in kg/h)

Timing

After Cat O2 sensor voltage

Throttle position

LTFT and STFT.

Also show MAF signal at idle with AC off. If you have the ability, measure vacuum at idle and boost at redline.

my interesting findings on run 2 of durametric deal

well i wish i had written down this list to check off when running the durametric deal. i had run some other values just off the hip and interesting findings. i will definately check those options next time im out with her. it just started raining and really couldnt push her or even come close to a redline. no fun...... keep you posted. i also wasnt able to find "timing" and whats LTFT and STFT? dont think i saw those either??

is there anyway to alter durametric software to mph instead of kph and celcius to farenheit? i have fault code P0103 - Heat Film MAF Sensor it displayed. i reviewed the DME 7.2 fault text and codes under that code and having a hard time determining how this chart works.

Your MAF signal is obviously way too high. Check to make sure that the installer made the necessary modifications to reduce the excess MAF signal generated by the increased air flow. Check with TPC to see how they reduce the signal. Because more air is flowing into the engine, the signal generated by the stock MAF must be reduced mechanically. It can either be controlled by reducing the signal with a resistor or modiication of the path of the airflow. Not sure how they do it but it is likely your problem. You need to reduce your idle MAF signal down to around 18 kg/hr.

MAF signal must be reduced..??

Huh..??

MAF signal MUST be proportional to the amount/volume of airflow intering the engine...

At engine idle or light engine load cruising the upstream oxygen sensors are used to control A/F mixture to stociometric standard.

With even moderately high engine loading the A/F mixture is enriched beyond stociometric, oxygen sensor out of range, and the MAF/IAT is used to control mixture.

If you reduce the MAF output signal (to prevent overscale..?) then ECU parametric air volume "multiplier" must be adjusted to compensate.

I looked all over for a picture of the piggy back

system. I must of left it on an old site.

Get Tom to send you a picture. It does

look cool.

Paul

im really not up for a $2500 system that 'looks cool' and if that part is required i will have it soon. also will look into oil seperator per your advice. im just so tired of this project as it has eaten up more than a month of my time shared with my car. getting a little worn out on the idea of 'bolt on' power and 'all inclusive kits' pfft. i can only advise not to ever engage in doing so with your porsche unless your have more time and money then brains. go out and buy the turbo......

Sc or Turbo, it doesn't matter, anytime you add forced induction to an engine that didn't come from the factory that way you had better be WELL SCHOOLED on ALL the issues.

well im a firm believer in learning from experience regardless of outcome.

We can only hope that your learning experience is completed before that engine goes TU.

i was getting impatient as it has been over month with everything said and done.

heres the current update if your curious B)

everything is correctly installed i just put 100 miles on her tonight! i think because the ECU was remapped it still had to adjust, which it does automatically when unplugged from the battery. thats my understanding from installing a battery previously. i noticed the car did not respond like it use to and that i had to drive her in order for the ECU to adjust to how i drive. same thing now and i have noticed since i first got the car (cold) it ran poor and now its a champ again! filled her up with 100 octane and felt her out. a lot is different and i will take some notes tomorrow with some thoughts i have. i will also plug in the durametric deal and get some data. pics and video soon too!

paul i think i saw ur car today on laurel lol.

I looked all over for a picture of the piggy back

system. I must of left it on an old site.

Get Tom to send you a picture. It does

look cool.

Paul

im really not up for a $2500 system that 'looks cool' and if that part is required i will have it soon. also will look into oil seperator per your advice. im just so tired of this project as it has eaten up more than a month of my time shared with my car. getting a little worn out on the idea of 'bolt on' power and 'all inclusive kits' pfft. i can only advise not to ever engage in doing so with your porsche unless your have more time and money then brains. go out and buy the turbo......

Sc or Turbo, it doesn't matter, anytime you add forced induction to an engine that didn't come from the factory that way you had better be WELL SCHOOLED on ALL the issues.

I replaced the two 5 watt halogens within the headlight assemblies with lumiled 2 watt LEDs using tight focus colimators.

Oh boy, I am still shaking, just escaped a MAJOR ACCIDENT!

Was coming home from parents, ONE BLOCK from home, in close to freezing conditions, in a relatively dark main street, a FREAKING HUGE VAN (80s) with NO WORKING HEADLIGHT pulled in front of me from the oncoming lane to turn left (illegally).

I was going at around 60-65Kmh (40ish miles) and he pulled 20-30 feet in front of me. I HAVE NO IDEA how he couldn't see me, this was under a bridge column and it's possible I was in his blind spot.

I immediately slammed on brakes and got into ABS, just realizing that there's no way I can stop the car before I hit the van (he didn't stop), so while braking swevred to the left lane and missed him BY A WHISKER! It would have been a horrible T-bone accident otherwise.

This was the closest call I've had in 10 years (college), when I put my MK3 Golf without ABS into a light pole in very similar situation, but that time car didn't steer at all and went straight ahead!

Amazingly, I practiced a similar accident avoidance manouver 3 weeks ago in Quattrofest (brake hard and change lane by following a green light).

Oh boy, feel lucky and wanted to share. Porsche amazing handling, ABS and Driving school literally saved my life (or at least my car).

I know most 911 guys track their car, but if anyone haven't tried driving school, I HIGHLY RECOMMEND ONE! Totally makes the difference between accident and coming home safe!

Cheers... gonna crack a beer now!

In the past ten or so years I have twice rear-ended another car. First time was about 2000 in a 1992 Jeep Cherokee Limited, when the car ahead of me stopped abruptly as it was turning into a gas station. The driver suddenly realized she didn't really need to gas up and stopped still partially blocking my path. Full daylight, my speed was "dead slow", the concrete roadbed was dry, there was no opportunity for stearing around, and the Jeeps ABS kicked in. Damage to the other car consisted of a passenger side rear bumper scrape. Driver settled for a $200 check. Jeep wasn't damaged.

Just weeks ago I rear-ended a new Nissan (Versa?) about 8PM, dark, with my '01 F/awd RX300. The young lady driving the Nissan was not familier with the area and was taking directions from her boy friend seated behind her. Her mother was in the front passenger seat. We came to a "Y" STOP and merge point and her boy friend had told her to turn right. A n advisement for a slight right turn would have been more appropreate. aShe stopped, checked traffic, and proceeded forward expecting to see a quick opportunity for the right turn her boy friend had inadvertently/unwisely advised her to take. When there was no obvious place to turn right she stopped, apparently in confusion, about 10 feet beyond the STOP "line". In the meantime I was myself looking over my left shoulder (120-150 degrees) checking traffic for a my merge, none was there so I started accelerting forward. By the time I again looked forward the other car had stopped. Panic braking, the ABS kicked in.

Shattered the plastic surround on my front license plate and there was no visable damage to the Nissan. $2200 to repair the Nissan since the shop disassembled the rear of the car far enough to find a slightly bent "structural" bracket between the trunk floor and the rear bottom of the trunk lid opening.

I got a traffic citation for "inattentive driving" for which I was anything but.

In both cases I am of the quite firm belief that had ABS not activated, thereby elongating my stopping distance, there would have been NO CONTACT.

How soon will the automotive industry begin using an accelerometer (THE longitudinal accelerometer already present if you have stability control), along with stability control system signals, to prevent ABS activation if G-forces are appropreate to the level of braking AND the stability control doesn't activate..?? If there is no "threat" to directional control or directional stability then ABS will oftentime serve ONLY or MOSTLY (not always, agreed) to elonggate the stopping distance.

hey ive got some news! the timing is off. spoke with tpc today and cars going back to installer. seems to be some kind of crankshaft ventilation pipe. either its plugged or not plugged from what i gathered... im not a mechanic but maybe something to consider if your going to put one on your 996. anyway will keep you guys updated as car will see the garage again tomorrow. pics will be here soon along with some possible video. btw i do have a durametric kit.

hey west and 1999 wheres your registry entries of your sweet porsches?

Hmmm..1978 SC Targa...buy that in Fresno..??

hey ive got some news! the timing is off. spoke with tpc today and cars going back to installer. seems to be some kind of crankshaft ventilation pipe. either its plugged or not plugged from what i gathered... im not a mechanic but maybe something to consider if your going to put one on your 996. anyway will keep you guys updated as car will see the garage again tomorrow. pics will be here soon along with some possible video. btw i do have a durametric kit.

hey west and 1999 wheres your registry entries of your sweet porsches?

1978 911 SC Targa, Seafoam Metalic Green, BBS-RS, on loan to my Nephew in McCall ID.

1988 911 Carrera, SE (Special Edition).

2001 911/996 C4, Wimbledon Green, Natural Brown Leather.

Previously owned.

1978 SC Targa, as above, less BBS, gift to grand-niece.

1979 SC Targa, Forest Green, BBS-RS wheels, gift to Nyssa OR Mayor.

1999 911/996 C2, Blue/grey, Charitable donation to TeamSeattle.com

wwest, hi there and thanks for your thoughts! first of all, im already running 103 octane. im sure the timing and air/gas ratio is off, i desperately need to get her on the dyno then i think this problem will be corrected.

btw when you refer to compression, are you suggesting a compression test? i asked for this test at a dealer prior to install of SC and they said it was not a good idea at that time. i have booked some time for a dyno this week and after that i guess im going to a dealer for a compression test. will a dyno produce these compression results?

where would one read more about knock/ping sensors on the 2nd gen 996?

"....suggesting a compression test?.."

No.

Your Porsche engine came from the factory with the MAXIMUM compression ratio assuming a FULL cylinder charge at WOT.

I simply do not see the object in adding an SC absent lowering the factory compression ratio in order to take full advantage of the external compression and intercooling.

Other than making the SC virtually or mostly non-functional I don't see how you could now "tune" your car for decent engine operation.

So, please explain the differnce in risk with running 1.2 BAR of boost on an engine running a 9.6 CR

Not just boost, but INTERCOOLED boost.

and 0.4 BAR of boost on the same engine running a 11.3 CR?

Intercooling of a larger MASS of precompressed air in the case of the lower CR engine.

How does boosting a high compression engine that adds more the 40% hp make it non functional?

4040% increase would take a 300HP engine up to 360HP, undoubtedly pushing the "edge".

First of all we should assume, MUST assume, that an engine with a CR of 10:1, 12:1 for DFI, could only run premium fuel with a factory standard mixture (HIGH engine loading mixture) without detonation, pre-ignition, ignition due to the heat of compression rather than "waiting" for the ignition spark. Assuming the forced induction air is intercooled the effective CR, WOT/Full boost, might be as high as 12:1(non-DFI).

When the cylinder is being fully charged then the greater portion of the charge that can be precompressed and then intercooled the less likely is the possibility of detonation due to the heat of compression. The same reason the new DFI engines can have a 12:1 static/native compression ratio. First, the fuel is NOT in the mixture, cylinder charge, until very late in the compression cycle, and then when it is injected it serves to partially cool the just pre-heated air "charge".

SFI results in the fuel being preheated as it passes through the intake, intake valve, and then is additionally preheated by compression. DFI fuel reaches the entry into the combustion chamber as a liquid, a comparitively COOL liquid.

An ideal system would have have a CR of 1:1, the air charge FULLY pre-compressed and then intercooled, allowing the effective CR to rise as high as maybe 18-20:1

Alright, so based on your statements, a lower CR engine needs a more efficient intercooler.

No.

A low CR allows an SC/intercooler combination to be more "efficient".

Assuming WOT and reaching a FULL cylinder charge, with a low static CR more of the "charge" will have been intercooled AFTER compressing. That would allow a higher effective CR with boost vs having a smaller portion of the charge intercooled with an already high static CR..

Using the same intercooler for 0.4 bar of boost on a high CR engine would be even more efficient.

No.

A 40% increase on a 300 hp engine is not 360 hp but 420 hp. There are a few otherwise stock 996 engines running far more hp than 420.

My bad.

I won’t even address your comments on a DFI engine since we are in the 996 forum.

So, I’ll ask again, why does supercharging a stock 996 make it non functional?

Why don't we just wait and see what turns out to be wrong with your SC modification..??

wwest, hi there and thanks for your thoughts! first of all, im already running 103 octane. im sure the timing and air/gas ratio is off, i desperately need to get her on the dyno then i think this problem will be corrected.

btw when you refer to compression, are you suggesting a compression test? i asked for this test at a dealer prior to install of SC and they said it was not a good idea at that time. i have booked some time for a dyno this week and after that i guess im going to a dealer for a compression test. will a dyno produce these compression results?

where would one read more about knock/ping sensors on the 2nd gen 996?

"....suggesting a compression test?.."

No.

Your Porsche engine came from the factory with the MAXIMUM compression ratio assuming a FULL cylinder charge at WOT.

I simply do not see the object in adding an SC absent lowering the factory compression ratio in order to take full advantage of the external compression and intercooling.

Other than making the SC virtually or mostly non-functional I don't see how you could now "tune" your car for decent engine operation.

So, please explain the differnce in risk with running 1.2 BAR of boost on an engine running a 9.6 CR

Not just boost, but INTERCOOLED boost.

and 0.4 BAR of boost on the same engine running a 11.3 CR?

Intercooling of a larger MASS of precompressed air in the case of the lower CR engine.

How does boosting a high compression engine that adds more the 40% hp make it non functional?

4040% increase would take a 300HP engine up to 360HP, undoubtedly pushing the "edge".

First of all we should assume, MUST assume, that an engine with a CR of 10:1, 12:1 for DFI, could only run premium fuel with a factory standard mixture (HIGH engine loading mixture) without detonation, pre-ignition, ignition due to the heat of compression rather than "waiting" for the ignition spark. Assuming the forced induction air is intercooled the effective CR, WOT/Full boost, might be as high as 12:1(non-DFI).

When the cylinder is being fully charged then the greater portion of the charge that can be precompressed and then intercooled the less likely is the possibility of detonation due to the heat of compression. The same reason the new DFI engines can have a 12:1 static/native compression ratio. First, the fuel is NOT in the mixture, cylinder charge, until very late in the compression cycle, and then when it is injected it serves to partially cool the just pre-heated air "charge".

SFI results in the fuel being preheated as it passes through the intake, intake valve, and then is additionally preheated by compression. DFI fuel reaches the entry into the combustion chamber as a liquid, a comparitively COOL liquid.

An ideal system would have have a CR of 1:1, the air charge FULLY pre-compressed and then intercooled, allowing the effective CR to rise as high as maybe 18-20:1

wwest, hi there and thanks for your thoughts! first of all, im already running 103 octane. im sure the timing and air/gas ratio is off, i desperately need to get her on the dyno then i think this problem will be corrected.

btw when you refer to compression, are you suggesting a compression test? i asked for this test at a dealer prior to install of SC and they said it was not a good idea at that time. i have booked some time for a dyno this week and after that i guess im going to a dealer for a compression test. will a dyno produce these compression results?

where would one read more about knock/ping sensors on the 2nd gen 996?

"....suggesting a compression test?.."

No.

Your Porsche engine came from the factory with the MAXIMUM compression ratio assuming a FULL cylinder charge at WOT.

I simply do not see the object in adding an SC absent lowering the factory compression ratio in order to take full advantage of the external compression and intercooling.

Other than making the SC virtually or mostly non-functional I don't see how you could now "tune" your car for decent engine operation.

more recently installed a supercharger and first time driving it feels like a totally different car. heres what im working with currently:

02 996 C2

- tpc supercharger kit

- ecu remapped by tpc

- 3rd radiator installed

- lightweight flywheel

- stage 1 clutch

prior to install of supercharger car had all the same modifications except the ecu was not remapped, that came with charger install. i know i have to get her to a dyno and check a number of things but my short test drive i experienced a "floggy" first gear and super low power at lower rpm ranges (2300 or less). im pretty sure its the ecu map.

And I'm pretty sure that the knock/ping sensors were screaming "HELP, HELP"..!! Probably enriching the mixture so high ignition began failing.

i have a durametric kit but i dont think i can write/flash the ecu. any ideas on how i can reflash the ecu myself or fix my first gear problem?

wondering what the car is like? its wicked past 3500 rpm :thumbup: she still needs her differential work done. got any clue where i can pick up a true lsd other than the oem gt3 or quaife option.

best,

tecra :renntech:

I would suggest trying some 100 octane LL aircraft fuel and if the low end performance improves then the native/static/base engine compression is still too high to accomodate unlimited BOOST without knock/ping.

By how much was the engine static compression ratio lowered when/as the SC was added..??

I'm pretty sure you, nor anyone for that matter, would NOT wish to reprogram the ECU so as to ignore the knock/ping sensors.

So we're left with...just what additional action might the engine ECU do to abate knock/ping once it has changed the timing and mixture to the "outer limits" OEM/factory limits.

Probably a temp. sensor fault (outside or inside sensor, or implausible signal between those sensors and the control box). A diagnostic tool can help you out.

I seem to remember that if a system is low on refrigerant it will sometimes still work if the OAT is so low that cooling is not required.

So coming from BMW and Mercedes, I have to say the Porsche initially feels more 'nervous' at very high speeds because of the shorter wheel base and the very sensitive suspension and steering.

As I drive it more I realize it is really just a more involved driving experience - and can carve the road more accurately at high speeds.

It is not a cruiser - but it makes it much more fun to drive.

Maybe you're just not used to it yet?

In any case you should definitely get the alignment checked.

+1

And I would say "darty", quick and certain reaction to even the slightest stearing input, rather than skiddish.

My first reaction to driving my '78 "at speed" was to compare it to flying our Cessna 210, constant attention required, exceedingly tiring.