PTEC

What kind of dyno are we talking about here?

I turned the 4 Hex locks on the pcm. The PCM will not slide out. are their any screws that  :help: have to be removed to slide out the PCM. please help.

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Yeah theres a 7mm hex head screw on the passenger side that you need to back out to remove the radio.

Isnt the one touch feature built into the 997? I thought that once you hit over 6 or 9 mph or something that the button was one touch. I know the new boxster has this feature.

A lot of times when this problem happens (ignition switch not returning causing the ac to be inop) you can get by without a new switch. After you start the car just gently move the key towards off. A lot of times thats enough to get the switch to return from "start" to "on" and the AC will work again.

Dealerships are not under any obligation to perform any actions contained in a bulletin. I know for a fact they are for campaigns (which are federally mandated) and I believe they are for Service actions as well. I don't understand why they wouldn't want to perform it though, especially if your VIN falls in the range because there is pretty much no way in hell the warranty claim would be denied.

You should not have to be within arms length of your car to unlock it. I would say anything below 15 ft is cause for concern on a sports car. On a Cayenne you would be considered lucky if it worked that far away. Ask to see the range on another similar car.

I am finally the proud owner of a 2002 C2 996, and I have a lot of questions,

and a lot to learn.  I have already found a whole treasure of information

on this web site, but there are many questions remaining.

I am an avid DIY-er, have worked for many years on my own

VWs and have a reasonable set of hand tools. A cursory glance

leads me to believe that the 996 offers me another excuse to buy

more tools.

o Which Torx sizes are most common?

o Is a set of swivel sockets (~8-17mm?) a necessity to work on these cars?

o Is there any readily available oilfilter wrench alternative other than the P or Hazet?

Thanks

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Swivel sockets can save you a lot of time but realisticly, you dont need a whole set. I dont know what kind of work you're planning to do but I would bet you woulnt find one professional Porsche technician without a 13mm, 15mm, 16mm and 18mm impact swivel socket.

Also the 2169 is the best oil filter wrench for these cars.... period. I think mine cost me like 16 bucks from a Cornwell dealer.

Before you trying replacing your shocks I would suggest tightening the connecting your swaybar endlinks. This is by far the most common cause of a knocking noise in the suspension. Have you had an alignment done recently? If so check your strut tops on both sides. Lugs tight?

Hey Loren, btw I picked up the factory castrol from the dealer and used it for the fill. As I used the off the shelf mobile 1 previously I can say there is a noticeable difference in the shift quality especially when hot and somewhat when cold. I would go with the factory fill again over the off the shelf mobile 1. I also picked up enough to do 2 changes though :) The dealer threw in a few liters for free as it was the end of the container :)

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Factory Castrol? The 996 transmission (G96/00) is factory filled with 75w90 Shell Transaxle Oil.

The purge valve in the engine compartment IS operable by the DME. Its a electromagnetic one way valve. There is a line to the carbon canister on one end and on the other end the line goes to the intake right near the throttle body. Also, there is an electrical connector on the purge valve which goes to the DME. You'll find the evap canister purge valve right above the alternator.

The other valve in the diagram is the shut off valve (or operating air valve or even purge air valve). Its of the same design as the tank vent valve but is located in the carbon canister. This valve is used to seal off the tank system when its doing its leak test. Opening this valve allows fresh air to be drawn into the carbon canister while the system is being purged.

If a persons MAF is functioning properly then its going to read the same as another properly functioning MAF, the engine its installed in doesnt make it read any different.  Its not like every MAF sensor just reads different out of the box.  They are not snowflakes. 

If the MAF is reading high then it is faulty.  If its reading high and not causing an oxygen sensing fault then chances are you've got two problems working against each other.. such as a bad maf sensor and a vacuum leak.

By the way, the source for all of my information is the Porsche Service Training P21 Fuel and Ignition systems book.

Now you understand why many Porsche Technicians can't properly repair their cars.

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Yeah because the factory doesnt know anything about the cars they build..

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You gotta start thinking out of the box PTEC. Of course all MAF are set within the same tolerances. But lets walk you through this. What makes the same MAF read different from one car to another? Could be air filter condition. Could be engine compartment temperature. Could be the pattern layout of the intake screen. Could be difference in resistance in the main harness. Could be a slightly different idle speed.

You see, there are many variables in what determines the reading of the MAF and these variable are commonly different from car to car. That is why they establish a "range" for these sensors.

As far as the book you are using to get your information...if that is the book that states P1123 and P1125 means the engine is running lean, then I suggest you throw it out, because that information is wrong. Just because you read it in a book doesn't make it true.

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I agree there are tiny differences such as the air filter, but even then thats going to make the air mass read low, not high. Two of the same cars under the same condtions should read the same air mass maybe give or take a .25 kg/h. It sounded to me like you were trying to say that two different air mass sensors would have two different readings just because they were different sensors. If thats not what you were saying then I misunderstood you.

If you read my post, you should have seen I already admitted I was wrong about the engine running lean. I made that assumption based on the fact that I didnt know the conversion for grams/s (which is the aftermarket unit for airflow) to kg/h (which is what the factory tools report). I saw what I thought was 5kg/h (way low) of airflow and postive fuel trim. I misread the picture he posted... newflash: I'm not perfect.

Ill refrain from posting any other ideas about what is wrong with his car until he comes back and posts data after the battery reset.

Why haven't you recommended checking the fuel pressure?  Cheap, but not easy if you don't have the right equipment.

mumeh - your MAF readings are within the specification of the diagnosis section of the manual.  Idle is on the top limit (680 +/- 20).

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First off, he checked fuel pressure already.

Secondly, do the math. His reported air mass is 5.34 g/s. Converted to kg/h thats 19.224. Too high if you ask me AND out of spec according to the pdf you posted.

Also the purge valve is not servicable. Pretty much all it is is a one way valve with a line coming from the carbon canister and runs to the intake manifold. The valve is electronically opened (PWM) by the DME. The DME also monitors changes in the exhaust gas resulting from the purging of the canister and compares the duty cycle of the vavle to the change in the exhuast gas. If the results do not match up, then a fault is generated and the MIL light is illuminated. These valves do fail occasionally but when they do a DME fault is registered along with it (which he doesnt have). 1999Porsche911 gave pretty much the only way to test them. With the valve electrically unplugged it should hold vacuum.

While I have never changed one myself, I seem to remember the Evap purge valve (sometimes called by Porsche the Tank vent valve) being in the engine compartment right above the oil filler tube.

If a persons MAF is functioning properly then its going to read the same as another properly functioning MAF, the engine its installed in doesnt make it read any different. Its not like every MAF sensor just reads different out of the box. They are not snowflakes.

If the MAF is reading high then it is faulty. If its reading high and not causing an oxygen sensing fault then chances are you've got two problems working against each other.. such as a bad maf sensor and a vacuum leak.

By the way, the source for all of my information is the Porsche Service Training P21 Fuel and Ignition systems book.

Now you understand why many Porsche Technicians can't properly repair their cars.

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Yeah because the factory doesnt know anything about the cars they build..

Out of curiousity, can somone else with this software, and a known good MAF, take an air mass reading on a WARM engine, at idle, with the AC switched completely off.

I would definately recommed disconnecting the battery for a while. This while reset the adaption values in the DME. Reconnect the battery and start the car and it idle. Once the car begins regulated operation (aka closed loop) watch your STFT ( I hate using that term as it has no place in a Porsche since Porsche doesnt even use that system).

The most common reason for a car to go negative is a faulty air mass sensor. 90% of the time when an air mass sensor fails it reads high.

The most common reason for a car to go positive is an intake leak, and of those by far the most common is a hole in the bellows tube on your oil separator. When you have an intake leak, your indicated air mass will be low. The reason for this is your engine is getting air that isnt getting metered by the air mass sensor (aka unmetered or false air.)

Lastly it appears as though I was incorrect about the engine running lean. P1123 and 1125 indicate the DME has adapted as far as possible to the lean threshold, aka fuel trim numbers are negative. I made a false assumption based on my misreading the units the air mass reading was given in and the fact his LTFT was going positive. When I first started replying to this thread, I didnt see the units the airmass was measured Grams/sec. Then I reread the thread and I saw the conversions for G/s to kg/s. Using the conversion factor given, his indicated airmass is 19.224. Now I know I said his air mass reading looks low earlier in this thread, but now I'm saying I think 19 is high. I usually see about 14-16kg/s on a 996 at 1500 ft elevation, warm engine, no AC.

By the way, the source for all of my information is the Porsche Service Training P21 Fuel and Ignition systems book.

Before I reply to your long post above I need to ask you another question (socratic method, I guess).

If you state that the adaption threshold is 25%, why does he have this fault?

Oh and by the way, P1123 and P1125 are the exact same fault but are for the rich threshold.

The P1123 and P1125 errors really have nothing to do with the fuel trim...

Call your dealeship and ask to talk to a technician. See what they say when you tell them that.

Answer me just one question, please. If he has any of the problems you guys mentioned (fuel pressure too high, purge valve stuck open or leaking injectors), then why are his fuel trim numbers positive?

PTEC:

His MAF reading is fine at 5.34 or so.  If he is fully warmed up and his idle is 700 it is common to see such a low reading.  A reading of 13-14 grams/s at idle would definitely set an error code.  You may see a reading of 11 or slightly more when the car is just started and cold.  Also, the fuel trim readings (he only shows bank 1) look fine. I would like to see what the other bank reads.

In my experiance (virtually zero with generic scan tools), I have never seen a air mass reading that low, ever. Perhaps again this is just something that generic scan tools display differently than the PST2/PIWIS. Either way, the car is getting MORE air than it thinks it is as the fuel trim is in the plus.

His LTFT IS NOT even near maxed out.  (25% is limit and he is showing only 9%.  I run -11 and -18 on my engine).

In that case, here is my question to you. If you state that 25% is the threshold for LTFT, then why does he have a check engine light and his LTFT is at 9%?

The error code is NOT telling him the engine is running lean, but is running rich, and the O2 sensor is telling the DME to shut down fuel delivery.

I disagree. The car is having to add fuel. Look at his LTFT number, its positive. The o2 sensor is reporting a lean a/f mixture and the DME is trying to adapt by adding fuel, hence the positive LTFT number.

If the MAF was reading too low,  the DME would be told to reduce the amount of fuel injected and the engine would be running too lean and the o2 sensors would have to tell the DME to increase fuel. This would give the error codes 1124 aqnd 1126 is the sensors tried to adjust past their range limit.  I would like to see the readings of the primary o2 sensors at idle.

Exactly. If the air mass sensor only reports 5 gm/s of air flowing into the engine, its only going to inject enough fuel to burn 5 gms of air. If the air mass sensor is defective and reading low, there is going to more air going into the engine than it thinks. The mixture will be lean, the o2 sensor will report this, the DME will add fuel up to its threshold, and the CEL comes on. P1123 and P1125 are the LEAN threshold, the car is too LEAN for the DME to adapt.

He may have a bad EVAP valve, a leaky injector or too high of fuel pressure.  It may also be a faulty ground as the operating parameters he has shown us look fine.

If he had any of those problems his fuel trim numbers would be negative, as the DME would be subtracting fuel to compensate for the extra fuel that a bad evap valve, leaking fuel injector, or too high of fuel pressure would deliver. The fact this his fuel trim numbers are positive screams either bad maf or vacuum leak.

Thats my two cents.

That must be what it is.  I can see a hole in the line (the larger of the two).  The A/C still seems to work okay though.  Is there a patch kit for these lines or does the whole line need to be replaced?

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If you have a hole big enough to see then your AC would definitely not be cooling, its just not possible. Is the ambient air cool enough to maybe make you think that it is? You will need to replace the line, as well as recharge the system with refrigerant. It sounds as if you will need to replace the line that runs back from the joint in the front right (passenger) side wheel well back towards the compressor to another joint in front of the passenger rear tire, but I don't recommend AC system work to anyone but professionals.

First thing I see here is that the sensed airflow is EXTREMELY low. It looks as if your air mass sensor is only reading 5 grams per second; around 13-14 grams per second (at idle, no consumers) is pretty normal. Although when the air mass sensor usually fails it will read higher air flow than reality, they do also fail in the opposite direction (or seeing less airflow as well). The probable reason why you didnt have P1125 before is that you werent at the threshold yet, but were very close and the last bit of driving put you over the limit and tripped the P1125.

While I am familiar with what STFT and LTFT mean (which are are generic OBD2 terms), I dont 100% know how to relate "Long term and Short term fuel trim" to the actual measurements Porsche uses for this car which are TRA (idle range) and FRA (off idle range) but I would imagine that if you disconected the battery (which will reset your idle range adaption values) and let the car idle for 10 to 15 minutes with your tester on, you would see the STFT numbers go positive pretty fast, though I dont know for sure as again, I'm not sure how those generic terms relate to Porsche's terms.

I would lean towards your air mass sensor having failed. If I didnt see such low air mass readings here, I would recommend you look in another direction but 5 grams per second is way too low. If you look at your LTFT its pretty much maxed out. Im thinking the reason for this is your air mass sensor is seeing WAY less air than is really going into your engine. Therefore its only adding enough fuel for that small amount of air. Your oxygen sensors are seeing this and saying "HEY DME, add more fuel!" As you know, the DME can only add so much fuel before the check engine light is illuminated. Pretty much the only reason you need to repace oxygen sensors is when you have heater circuit faults and ageing faults.

Hope this helped.

Having a tiptronic doesn't in anyway effect the difficulty of replacing that valve. Because the book says one thing, it doesn't make it right every time. The book will also tell you that you need to pull the engine to remove a transmission on a 996 turbo. I can tell you firsthand, that is false.

After removing the camshaft you would have to re-time the engine, which is something I have never done on a 996, but the person I saw perform this job apparently didn't have any problem with it as it was done at a dealership.

Hi, can someone tell me how hard it is to replace the coolant tank, on a 1-5 scale (5 being hardest), and about how long it will probably take for someone who is a plodder (slow and careful), rather than a quick wrench.

Are any parts needed, other than the new coolant tank?

I read where someone was told by the dealer that the motor had to be removed.  But from looking at Ninerguru's site, that doesn't seem necessary.

Lastly, does everyone buy their OEM parts from their local dealer, or is there a cheaper source for OEM parts.  I checked out many online parts sites (which all appear to use World Pac as a source), and the tank is not available.  The local dealer said $234.86 for the tank.  Not that bad (unless you consider it is solid plastic).

Thanks.  :thumbup:

Dean

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Its not that difficult, though I would say it would take a slow plodder up a to a few hours. Luckily you have an older car with a smaller tank that is about 10 times easier to remove.

I would get a new tank and a new cap to be safe, though its not necessary.

You DEFINATELY do not need to remove the engine to replace the coolant tank. Warranty doesnt pay for that so neither should you.

Good luck, make sure to tighten those fuel lines when you go back together.

If you dont see coolant around the area of the cap then its almost definately a tank issue if you have steam in the rear trunk. I think the steam coming from under the rear carpet is the deal cincher.

You can remove the carpet back there and have a look for yourself witout too much trouble. Basically all you need is a phillips screw driver and something to pull the plastic plugs out that hold the carpet in.

1. To adjust the door striker you're going to need a size 8 tripe square socket. If you look at the striker and close the door as far as you can while still being able to see the striker with a flashlight, you should be able to see how high to position the striker.

2. While I've never done this and I don't know if it would work for sure or not, I would imagine you can loosen the bottom 10mm nuts on the window regulator and push the bottom away from the car so that the window will up towards the car more. If you want to try this there 4 rubber plugs on the bottom side of your door, remove them and loosen the 10mm nuts. Either scribe or take note of where the bolts were positioned before you undo them, so you can go back to where they were if you don't like how you have changed it. Push the studs away from the car and retighten. I would probably try this with the window in the up position. Again, I don't know if this will work or not but I've thought about it before.

Make sure they know whats wrong before they pull the engine. Or at least elimate a broken valve spring before the engine is removed because I know for a fact that you can repace a valve spring with the motor in the car. If its not a broken spring, then yes, you have some choices to make.

Also I believe replacing all the springs is a bit excessive, as I've only ever seen or heard of one break

You need to know what DME faults you have. If you have misfires for cylinders 4, 5, and 6, then its likely your solenoid. If its only 4, and you have no compression then you have a mechanical problem.

For what its worth I have seen a 996 break a valve spring.