Vman

New MAF in car, old stock airbox with clean filter back in, going to dyno tommorow with fingers crossed. Will deal with the throttle cable after we fix the air fuel ratio problem, thanks for the tip though

Thanks,

VMAN

Your MAF reading at idle is fine, but at speed, it is not registering high enough. This means that the computer thinks there is less air than is actually getting to the engine and the computer is adding too little fuel, causing your lean condition.

Why just 98% throttle. Is this a 99 C2. Your cable may have stretched a little and you need to remove it from the throttlebody and twist it once or twice (effectively shortening it) until you get 100%. This can be tested without driving the car.

What was the MAF reading at idle? Test to see if the program shut off all the error reporting of the DME. Remove the MAF cable from the MAF and see if you get a CEL. Some programs shut off the system so they can push the limits of the engine. Also check to see if whoever did the tuning put a resister inline on the MAF cable to reduce voltage output. This is sometimes done to reduce current to the DME when an intake mod is done a which increases airflow and therefore voltage to the MAF.

The following was taken while running stock Porsche OBD2 program, no inline tuning has been done.

MAF readings at idle (between 695 to 800 rpms) with zero throttle ranges from (.59 to .84 lb./min) or (4.5 to 6.5 g/s). Porsche system tester 2 shows the MAF with no errors.

Other points of reference at 98% throttle position

RPM 3944, Timing -14.5, vehicle speed 125 mph, MAF (lb/min 12)

RPM 4321, Timing, -21, vehicle speed 65 mph, MAF (lb/min) 8.9)

RPM 5169, Timing, -34, vehicle speed 79 mph, MAF (lb/min 22.89)

RPM 7020, Timing, -22.5, vehicle speed 110 mph MAF (lb/min 19.6)

Any help would be great. Any idea if their is a more advanced way in the Porsche system 2 to determine if the MAF is having issues, but not showing a fault.

Thanks,

VMAN

What was the MAF reading at idle? Test to see if the program shut off all the error reporting of the DME. Remove the MAF cable from the MAF and see if you get a CEL. Some programs shut off the system so they can push the limits of the engine. Also check to see if whoever did the tuning put a resister inline on the MAF cable to reduce voltage output. This is sometimes done to reduce current to the DME when an intake mod is done a which increases airflow and therefore voltage to the MAF.

We tested the fuel rail pressure and fuel pump volume flow according to the factory manual. Also, the maf and 02 sensors read no fault on the porsche system 2 tester. Note - O2 readings for both before and after cat banks were over 850 mv above 4,500 rpms. Any ideas would be helpful, we are left to conclude that either we have a bad MAF that is not showing up on the tester, or the porsche ecu just can't handle the extra requirements of the K&N aircharger, racing headers, and high flow cats, in which case we will have to be looking for a piggy back system like a unichip to try and remap the fuel curve. Let me know if you guys think we are missing something, as a custom programmed unichip to pull down my airflow ratio to a safer level will set me a back about $3K.

Thanks,

VMAN

Thanks

Both runs were measured on separate dynos using the right tailpipe.

Well, the first thing I would do it check the other tailpipe to see if it also shows bank 2 is also showing lean at WOT. If bank 2 shows proper AFR, then the problem is with bank 1, (injectors, o2 sensors or exhaust componants). If it shows the same (and it is an accurate reading), then the problem would include a componant that controls both banks, such as MAF, fuel regulator, tuning, fuel pump, vacuum leak, etc. Check what the after cat sensors show...both banks.

Thanks

Both runs were measured on separate dynos using the right tailpipe.

Well, the first thing I would do it check the other tailpipe to see if it also shows bank 2 is also showing lean at WOT. If bank 2 shows proper AFR, then the problem is with bank 1, (injectors, o2 sensors or exhaust componants). If it shows the same (and it is an accurate reading), then the problem would include a componant that controls both banks, such as MAF, fuel regulator, tuning, fuel pump, vacuum leak, etc. Check what the after cat sensors show...both banks.

110 Octane is leaded only so say good bye to your cats, a mix of 104 unleaded racing fuel with pump gas 50/50 to 30/70 will get you good HP numbers. If you are set on running 110 you will need to map your car for ROW DME (it does not look for an after cat 02 sensor and buy some cat bypass pipes.

What about using racing fuel say 110 Octane. ??

Both runs were measured on separate dynos using the right tailpipe.

Yes, runinng that lean at WOT will increase the risk of frying your engine. How was the afr measured? Left, right or both tailpipes? I find it hard to believe that you would run that lean. Maybe a problem with dyno's sensor. Take a look at your after cat O2 sensor readings at wot above 4500 rpm using a scanner. What are their values?

I have a 1999 996, in the process of doing some dyno work on both Dynojet and Dyno Dynamics Dynos (load bearing), we discovered that the car was producing a max of 258 hp, but that the air/fuel ratio started at 16 and went down to 13 betwen 3,500 and 4,500 rpm, the problem is after 4,500 rpm the air/fuel ratio kept rising up to around 14.5 and no lower than 13.6. The car is running a U.S OBD 2 program with a K&N aircharger, Scargo headers, high flow cats and stock mufflers. The airfuel/ratio problem was the same with the stock airbox. We have about 300 miles driving the car since loading the US OBD 3 program.

Is this a dangerously lean situation? How would you go about improving identifying the problem, as I am told your fuel air ratio should be around 13 to 13.5 to generate maximum power or this okay?

If it is a problem, how should we go about fixing it?

Fuel filter - has been changed

Bad fuel pump relay - how do you test?

Bad fuel pump - how do you test?

Bad fuel sytem relay - how do you test?

Bad injectors - anyway to test? Does the Swepco injector cleaner work?

Note - before I purchased the car it was running on a mix of 110 leaded race gas and pump gas and had no cats, it was running the ROW DME program and producing about 275 HP on a dynojet dyno and averaging about a 13.2 air fuel ratio above 4,500 rpm...Note - the last dyno test on the car before me buying it and changing to the US DME program and adding back cats is less than 3 months old

Thanks,

VMAN

Thanks guys

My RoW car does not have O2 sensors after the cats - only before.

In the DME Control Module Programming option of the PST2 there are 4 options:

Read Out Control Unit.

Program Control Unit - this is for programming a new DME and goes through all the options (Map, Data and Immobiliser Code).

Map/Data.

Program Immobiliser Code.

As Loren shows (step 5) you should read out the control unit before installing a new DME module. Reading out the control units doesn't allow you to see what options are selected, unfortunately. I think (and emphasize "think") that this process stores the data of the old DME, so that when you fit the new one it will have recorded the settings for the new one, allowing you to choose them by default in the programming step choices.

My suggestion would be that you read out the control unit, and then try and reprogram the map/data. I have a feeling that it will default the programming steps to the settings that are stored when the data is read out. This might confirm that the right cat settings have been made. Worth a try, perhaps.

I just had to add cats to a 1999 996 car I imported from out of state, I live in CA. The prior owner had flashed the car with the ROW factory DME program, which apparently ignores after cat O2 sensors so he could run the car with no cats.

My local shop tried to flash the car back to OBD2 (I say try because I am not sure it took), while we are getting volatage values for all o2 sensors we are not getting a check engine light when we unplug the after cat 02 sensor. Does anyone have any idea on how to confirm which program you are running, in looking at porsche black box programmer laptop it shows which program you can load but does not seem to show which program is in the car.

Thanks,

vman

Might try Gert at Carnewal.com . Not something that he lists as I recall but he might be able to get it. With the exchange right now it might not be pretty though.

I just finished installing two differentials in my 996's. First the factory limited differential is a 22(on throttle)/40 (off throttle) and needs to be rebuilt or at least checked every 50,000 miles. The Quaife is torsen sensing, so its results are said by many to be inconsistant and not really as good as a true limited slip, particularly on the track. The best maker of after market limited slip diffs is Guard Transmission, http://www.guardtransmission.com, I just bought a 40/60 Guard limited slip. The guard unit is not cheap it will cost about $2,600 then another $600 to buy 993 G50 flanges to fit in a 996, plus about 6 hours of labor (assuming you can find a shop that knows how to drop a transmission without taking out the engine). Note - factory GT3's use a 40/65 limited slip ...beware if you are going to use the car on the road as well as track to not go much more aggressive than a 40/60. Finally stay away from no name groups, there are some dirt bags out there in the tranmission arena.

VMAN

Does anyone know on throttle off throttle lockup for the factory lsd on a 99 carrera C2 I have heard 25/45 and 40/60? What is the right number for what I believe to be and M220 option.

thanks,

Vman

Any idea how to id a limited slip differential before or after cracking open a transmission. I looked up PET and it gives a number of 996 300 020 (00-02)

The bottom of my tranmission says G960 020 07746. apparently the diff part says 950 332 08 301..none of which I can find in the retail version of PET.

VMan

Does anyone know on throttle off throttle lockup for the factory lsd on a 99 carrera C2 I have heard 25/45 and 40/60? What is the right number for what I believe to be and M220 option.

thanks,

Vman

I shopped around and ended up using:

Bill DeMoise

DeMoise Trk-ing, Inc

Email: dispatch@demoise.com

http://www.demoise.com/index.html

Phone: 864-609-9390 Eastern

Fax: 864-609-5476

I used them to move a 996 from the Cleveland area to Phoenix. Fully enclosed, door-to-door service, with fabric straps (as opposed to chains). Very good about calling with progress reports. Cost me $1,425 insured, vs. $1,800 quote from Intercity, who also have a great reputation.

The truck was also carrying two Ford F40s to SEMA when they delivered my car.

Thanks, I ended up using intercitylines, same deal as you got $1425 seattle to sd

Guys,

Just bought a new 996, this one is lowered and needs to makes its way from Seattle to San Diego. Does anyone know of a reliable company that can move the car in an enclosed trailer? Also, any tips to make sure the move does not screw up the car?

Thanks,

Vman

I tried Fry's and Radio shack a long time time. They do have round pin electrical pin removal tools but none were even close. The AMP connector has an odd size metric pin used for European automotive apllications.

So I went to Peter and he showed me the factory electrical tool kit. Then we measured the inside and outside diameter of the tool for the large round pins used for the litronic retrofit. I tried to order the factory tool with no luck. Then another mechanic I know showed me a Sir Tool catalog and the specs on their medium pin removal tool matched. Strange that Sir would discontinue the tool as it can be used on many other connectors used in the 996/986, such as the amp and cell phone connectors.

confirmed the Sir Tool is no longer available, for some reaosn they discontinued it, but the nice lady on the phone said they may come out with a new tool in a couple of months. Sir Tools knew of no competing products either...so for now it is risk solder and splice or go to the dealer and get ripped off on the install.

Vman

I made the mistake of ordering my litronic kit and trusting the dealer that I did not need any special tools, for the install. I am halfway into install and it is obvious I need the porsche pin removal tool or a good way to get the pins out and reconnect the wiring.

I would really like to wrap this thing up this weekend, so if anyone has a method that works for popping out the electric pins or a non-special order tool (one you can buy at a national store..sears, radio shack) please let me know.

Thanks,

VMAN

Below is how the Boxster traction control system supposedly works in a 1999, does anyone know if the 996 C2 Traction control system works the same way?

Option P37, Traction Control consists of two separate items, Active Brake Differential (ABD) and Anti Slip Regulation (ASR). When one of the rear wheels begins to lose traction, the ABD applies the brake to that wheel. If both wheels lose traction, the ASR reduces engine power until traction is regained. The Traction Control switch on the dash turns off the ASR, but not the ABD. The ABD is always in effect until you reach 62.5 mph, at which time it automatically deactivates. Because the ABD is always in effect and is applying braking not under your control, control freaks may not wish to order this option.

In particular is ABD always on for the 996? in Autox it seems that it should not matter if you turn Trac on or off as speeds are usually under 65 mph. Has anyone tried disconnecting the system and adding in a Quaife Differential?

Thanks,

VMan

Loren what do you mean ALA GT3...didn't the GT-3 always come with 235/295 and 8.5x 18 and 11 x 18 wheels?

The RoW GT3 mark I (not sold in the US) came with 8 x 18 fronts and 10 x 18 rears in MY99 to MY02. Just as today that car was the basis for the GT3 Cup and GT3R race cars.

Also, more importantly, I assume there is nothing wrong with running 225/265 with the 8x18f, 10x18R, other than the car will have less understeer..read more likely to oversteer than a car with 285 in the rear?

I wouldn't say much more oversteer perhaps less understeer.

So no real problems in running the 7.5 and 10 wheels with a 225 front and 285 rear? Other than you may get a bit more understeer?

1. 285's with the caveat that you need at least 8" front wheels to balance out the handling. Ala GT3 mk1.

2. As negative as suggested specs allow. A little more tire wear but improved handling.

Loren what do you mean ALA GT3...didn't the GT-3 always come with 235/295 and 8.5x 18 and 11 x 18 wheels?

Also, more importantly, I assume there is nothing wrong with running 225/265 with the 8x18f, 10x18R, other than the car will have less understeer..read more likely to oversteer than a car with 285 in the rear?

I am asking as I have some old 18 inch turbo twist wheels in 7.5 x18 and a second set in 8x18 and want to run one rear tire size on the car.

For ramps, something I learned from another member is to make them with a 2"x12"x10' lumber. Cut them into 24", 18", 12" lengths. The last piece cut in half. Then assemble (nail, screw, glue) them as a stair step, all flush on one side. Attach the last piece to the end as a stopper. Works great for mostly anything you do on the car rear and it is cheap.

Sears has a great $69 3Ton jack that extends to 21", also low profile and fits under car. I like the extra lift to get under the car when I need to do do maintenance. They have a kit that comes with jack stands too. Look in the DIY section for the "how to jack" the 911, and where to put the stands. Don't forget a wheel chokes so it doesn't roll on you when jacking (an experience you will never forget).

For the wheels, 19 mm is the size. Make sure you have a deep socket or extension for the wrench for the rear wheel bolts. Also, I find a breaker bar very handy when removing the bolts. A 24" should do.

Have fun, and don't forget the safety glasses and to remove your watch when sticking your hands in the car mechanics.

I am heading down to Sears for the jack. On the wheel chokes, I assume you would only need them if you jack the car up from the rear without first putting the front up on jacks. When jacking the car up from the side rear jack point, (in front of the rear tire) as one half of the car is still on the ground I assume it would not be a problem. Please confirm if I am getting this wrong.

VM,

Try sending your question to Dave Martin @ Wheel Enhancements.

David Martin [dave@wheelenhancement.com]

He's a good guy, propbably has unmounted front & rear 5-spoke rims he could weigh for you. Or, he probably already knows the answer from shipping so many of them across the country...

Good luck.

DBudd

thanks

I just bought a set of 5 spoke 2002 Carrera wheels for my 1999 C2. Does any one know how much the front 8x18 and rear 10x 18 weigh?

thanks in advance.

The correct weight of these wheels is W=(VM-(vm-CW)).

You can derive this with your bathroom scale. :eek:

the wheels are already mounted with tires, I would like to know the weight without the tires...without having to unmount the tires. Anyone with an 2002 later car ...please open your owners manual and give me the weight for the wheels listed in the back, I would really appreciate it.

Thanks,

VM

Just go to Sears. You can get a very nice quality torque wrench, jack stands, floor jacks, and even ramps there.

You can get a nice "soft" socket for wheel bolts from Boothedesign.

The owner, Ralph Boothe is one heck of a fellow, and a great automotive engineering legend.

Thanks

Guys,

I need to do some work on the car, but before doing so need to buy the following

1) jack stands

2) Floor Jack

3) Ramps

4) torque wrench and socket that will fit standard 996 wheel bolts.

Can anyone recommend high quality, but reasonably priced products and where to get them?

Thanks in advance.

P.S. anyone know how to change wheel lug bolts without scratching them and then having them develop a nice coat of rust?

Vman