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wwest

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Posts posted by wwest

  1. No such thing as refrigerant leaks (strickly) due to "non-barrier" hoses.......

    My '92 R/awd Ford Arrestor, front + rear A/C, was just in the shop being converted to R134a refrigerant. Normal charge has been ~$160, this time ~$200.00. Difference was due to having to replace leaking o-rings on the rear of the Sanden compressor, something having to do with the refrigerant OVER-pressure relief valve.

    Say WHAT..??

    According to the Ford factory manual if the refrigerant pressure rises to high then the valve opens to atmosphere to bleed off refrigerant, but then "resets", closes, to preserve the system integrity.

    But with the A/C compressor clutch controlled by a binary pressure switch why would the system ever go over-pressure?

    The answer would be an inadvertently overheated engine, cooling system, radiator, heating up the nearby A/C condensor and thereby raising the internal liquid refrigerant pressure.

    While I am by no means stating this as a definite answer for the reason our air-cooled Porsche's consistently lose refrigerant, it most certainly has a ring of truth to it.

    Drive our Porsche's HARD on a HOT day, making full use of the A/C, and now shut down the engine. How high would the pressure go in the rear lid condensor, overall high side, with all that engine heat rising up through the rear lid condensor.

    From what I could find on the INTERNET most automotive A/C compressors included an over-pressure relief valve, at least up until venting R12 to atmosphere was outlawed.

    Could this be the real, actual reason, our refrigerant charge only last 2 years? The stage is certainly correctly set.

  2. PSM is not simply stability control, it also includes traction control and "virtual" LSD functionality. Trac detects rear wheelspin/slip and INSTANTLY dethrottles the engine and will moderately apply brakes, ABS like brake modulation, if the condition persists. Winter tires often have a higher level of siping thus have less CSA for roadbed contact, additionally you mention they are narrower tires.

    All that adds up, for me, that Trac is activating.

  3. I'm thinking about trying the simple "RWD mode" on my .1 C4S ; my understanding is you can just disconnect the half shafts in the front and the car should run just fine. (front diff will still spin but since it's not connected to anything that's no problem).

    Anyway, my question is - are there any DIY's on half shaft removal/install ? Is this a reasonable home DIY?

    Why bother? What do you expect to gain?

    In any case the VC mostly remains flaccid, non-functional, due to Trac activation/intervention so you wouldn't be accomplishing much.

  4. Like most everyone else each spring I have to "top off" the refrigerant, now R134, in my '88 Carrera. A/C specialists have checked over for leaks many times in the past 16 years of ownership, and most recently when it was converted to R134 about 2 years ago.

    First, my theory, and then an explanation.

    When the car is parked with the engine and EXHAUST still HOT, convection airflow will HEAT the rear lid mounted condenser, likely very seriously so. How high might the resulting refrigerant pressure reach on a really hot, BRIGHT, day thrown in..?

    My pressure was at 65PSI this evening simply setting in a nice cool, ~55F, garage.

    Suppose, at the instant the ignition is switched off, part of the condenser, and all of the line to the recvr/dryer, and the dryer itself are FULL of liquid refrigerant, just as should be the case. The evaporator blower has also just been switched off reducing the heat exchanging capability of the evaporator significantly...AND...no compressor VACUUM. The high side pressure, LIQUID pressure, will now leak down VERY slowly.

    Might the high side pressure in that circumstance, BOILING whatever liquid might remain in the rear lid condenser, get high enough to begin leaking around the o-ring couplings...?? System leaks slightly, pressure subsides, until the next time.

    Anyone ever taken system pressure measurements in a situation as above.

    I'm thinking of revising my engine lid condenser fan system so it runs at half power with the engine switched off but with the high pressure compressor disable pressure switch open.

    Note: There is a REASON why my '01 C4 has an engine compartment cooling fan.

  5. So I have a debate going on with myself after someone asked the question, why not just change the direction signal relay to a relay that is 'electronic' instead of the route I am taking by installing power resistors 6ohm/50w for each LED taillight I am installing on my 99C2. The power resistors were like $10 shipped to me and are an easy install and they WILL fix the super quick flash rate of the turn signals back to the normal flash rate - but I'm wondering if the relay is an even quicker plug in fix? I'm not quite sure that there is a plug and play upgrade for 99's as Porsche show 997 part numbers but the relay I would need has the same part 996 number online as installed on mine in the fuse box. Anyone use the relay mod to fix the hyper flash issue for LED's and if so, what part number?

    The flasher relay in your 996 is already electronic. It uses a nichrome link to sense the current flow to the bulbs. If the current flow is low, indicating bulb failure, it goes into fast flash mode. Open up the relay and replace the sensing link with a 1 ohm resistor of 2 watts.

  6. Hey folks,

    Woke up this morning with a screw in my tire so I took it to my local tire shop to get it patched. I also bought the Lifetime Alignment package from them so I asked them to throw it on the alignment rack for me.

    I got a call back from them saying that they'd rather not do the alignment b/c my inner tie rods are worn and loose. Not dangerously loose, they said, but loose enough to undo the alignment in short order and something I should get fixed.

    Looks like PelicanParts sells inner tie rods for $52 each. Unfortunately my tire shop won't put on parts that I bring them, so they'd have to order them from the dealer (and we haven't priced them yet since it's Sunday).

    Anyways, I enjoy turning wrenches as long as I'm confident that I'm not going to render the car undrivable.

    Are inner tie rods something I can do in my driveway with standard tools? The car is a '99 996 cabrio with 70k miles.

    thanks!

    Dave

    You should be aware that this is an extremely typical SCAM...

    You may be replacing two perfectly good parts.

    What tire shop..?

    Oh, your lifetime alignment package probably doesn't apply since you will be "intentionally" mis-aligning the car.

  7. Perhaps I haven't read the problem correctly but, doesn't the A/C compressor run continuously with the HVAC "ON" (in AUTO) if the ambient temperature is higher than 32 degrees F/0 degrees C?

    Bill

    No.

    The compressor shuts off if:

    The high side refrigerant pressure becomes too high or too low.

    WOT.

    The engine coolant "threatens" to rise too high.

    The cabin atmosphere reaches or is below the setpoint.

    OAT is below ~35F

    Evaporator surface temperature, close downstream airflow, is below 33F for more than 2 minutes.

  8. The PTM transmission explains the difference compared with the

    996 Turbo. Sounds like the Porsche Engineers solved

    the problem for the 997 Turbo.

    All this means is you need to buy a 997 turbo

    and sell the 996 4S.

    Paul

    If you want more than 5-10% of the engine torque routed to the front wheels of a 996 or early 997 then the procedure is to drive agressively in a tight circle about 10 revolutions. With that much sustained disparaty between the F/R driveline rotation speed the VC will "stiffen" long enough for the average road course.

    The newest 997 now has an actual functional R/awd system using the same electromechanical clutch setup Ford has used, pretty much UNSUCCESSFULLY, in the Escape and Mariner. Now in use in the new FWD or F/awd 2011 Ford Explorer (yes, that says FWD & Explorer) but with water cooling of the PTO. With the C4S being R/awd the problems Ford has had are unlikely to affect the reliability of the Porsche version.

    Ford...STUPID...!!

  9. While looking for leds, I read that a "colored lens will filter out all but the colored portion of the light"

    So my lens being red, I'm using red led so that a "smaller amount of light will be blocked by the lens".

    Here is the reference: http://www.superbrig...rbulb-notes.htm

    As to why the led doesn't work, I suspect that it is a polarity issue but I'm still waiting for a confirmation from the forum (I don't have voltmeter).

    Thanks. It seems counter-intuitive at first glance, but now it makes sense. Anyway, I would think that the brightest combination would be a Red LED with clear lens, but would be more costly.

    You don't need diodes if you install LEDs in every socket in a given ciruit.

  10. I run my 996 on Nokian Hakkapeliitta R winter tyres (245 rear and 225 front, 18 inch) in the wintery conditions of Northern Norway. The car works excellent, no hickups at all. It's a C2 but with a lot of weight on the rear and the LSD option it still has an amazing level of grip. I haven't gotten stuck or met hills I couldn't climb yet. Everything is better with pics:

    Real, actual LSD or "virtual" (uses braking)..?

    I find that the virtual LSD also dethrottles the engine, not a lot of help, that.

    CIMG4539.JPG

    And an example of how bad it gets up here, my previous car:

    Dramsveien%20-%2018.%20mars%2009.jpg

    Nøysomheten%201%20-%2018.%20mars%2009.jpg

    Use silicone lubricant on the door seals, that should make the work well, even when it's freezing outside.

  11. Early Porsche C4 models using a VC, Viscous Clutch(coupling) have VERY little engine torque at the front wheel absent a SUSTAINED period of wheelspin/slip rear vs front. That level of sustained wheelspin/slip generally can only be attained with TC (PSM) off. The C4's additional traction capability is more often the result of rear engine weight bias rather than any significant level of VC coupling. That, of course, has changed now with the newer C4's making use of the Ford Escape electromagnetic clutch control technique.

  12. I'm in the same boat as yourself and have emailed several Porsche dealers with no reply to any of my questions. If one them happens to come through I'll post any replies.

    I am not holding out much hope if the Canadian dealers are as well informed (ahem!) as in the US.

    I doubt the lowering of the ratio of the lowest gear is more than 20% or so and that can't compensate directly for not having a 1:2 transfer case. On the other hand the new Tiptronics seems to be addressing low speed with a special pump to make sure the fluid pressure is high enough at low RPMs.

    One might hope that the viscous coupling could allow a very low speed crawl with enough torque to get over rocks or whatever.

    Haven't I read somewhere that both the 2011 997 C4 model and the Cayenne now use the electromechanical clutch as in the Ford Escape F/awd for coupling in the front drive, VARIABLY coupling...?

    So, i guess my real question is what does the new 2011 manual have to say about this.

    BTW, it is really a shame that these very off-road capable machines are mostly used to shuffle around the suburbs.

    A Shame...??

    No, NOT, more safety aspects for them and YOU on wintertime adverse roadbed conditions.

    That's why the transfer case and the low range is being dropped from the product, 98% of the driver's have no need and the remaining 2% only have need rarely.

    Going off-roading, buy a 4runner...!

  13. Hello guys

    It is obvious that the standard set up on 996 C2 + C4 ( Zimmerman discs+Texstar pads ) could use an improvement.The Texstar pad feeling is plastic and noneffective and the rotors start to veil after some hard braking (the rear at least)

    I know that an big kit upgrade might cure but it is kind of expensive those days

    So i have tried over the time the brembo pads and yes that's an improvement but also i am curious about other pads as Pagid,Ebc(red or yellow stuff),Jurid etc

    I m sure that some reputable members here have also step into this issue.

    Are you testing with or without ABS enabled...?

    The better the braking the more, quicker, ABS will intervene.

    The only valid comparison testing is with ABS turned off.

  14. Hi, I am in the market now for a 997-2 C4S with PDK. I have never been a Porsche owner before, nor anything like it, so I'm a bit new to the whole scene and I'm hoping you guys can answer some of my questions as I get my feet wet. From my research, it seems like a gently used one is usually listed at around the $105k mark, which is a significant savings over a brand new one. First off, I'm wondering if it's reasonable for me to aim for around $95k...do those used dealers have around 10% wiggle room? Or how much if not? If I can find one for that price, I'd probably pull the trigger right away.

    Of course, my criteria is already pretty specific, sort of borne out my desire for AWD, the styling of the S, and wish for PDK as it will be a daily driver. It seems like manual is more common and searching for PDK is tougher. Honestly, I'm not sure where to search, which brings me to my second question...where are the best places to search and what resources do I have?

    Finally, I have noticed a much larger selection in the US just looking on autotrader, but I'm not sure what special considerations there are for importing a 911. Plus it seems like the taxes+fees once stacked up negate any savings of buying in the US. I bought my S2000 new in 2007 and imported that from the US myself, so I am comfortable with the process.

    Any help/direction is appreciated!

    PS. I live in Canada.

    Online..any US factory authorized sales agent, PU at factory....

    Newer 997's have a REAL front drive clutch, DFI, and variable volume lubricating oil pump.

  15. This is my first post. Proud owner of a '99 Speed Yellow/black interior Carrera.

    The Carrera has the optioned LSD and I am curious if you A/B'd one with and one without, what

    would be the noticable driving differences. Not on the track. I got the Porsche for weekend wife and me trips.

    Also, was the limited slip just an option that Porsche put on a certain percentage of Carrera/2's or was is

    ordered? The car was the last item on my "Bucket List". Thank you in advance. Rapewta

    If you have TC, Traction Control, then what you more likely than otherwise have is a "virtual" LSD. That's an LSD implemented via the use of braking to prevent wheelspin/slip.

  16. Have a 2003 996 C4S and my cruise control stopped working recently. At first, it wouldn't hold but light would illuminate then now light will not illuminate and and still not hold. Fuse checked good but I need to know how many relays are involved and where are they located on the relay board and else where. Any other suggestion would also be helpful too.

    TIA! helpsmilie.gif

    A failed, failing (intermittent) rear brake light will result in disabling the CC. Upgrading to LEDs, especially the high mount, will simulate an open brake light bulb/circuit.

  17. maybe some of our more technical brothers have access to a diagram and operation of our airconditioning system. a general schematic would be very helpful. maybe a parts diagram from the PET would also be of assitance. like i mention i am a bit apprehensive that Porsche did not put a filter before the evaporator to clean incoming air in recirculation mode. No problems with recirc mode in off due to the pollen filter.

    There is very little, of any, "incoming" airflow in the recirculate mode.

    The presumption seems to be that if recirculate is being used then any airflow reaching the evaporator has been filtered previously upon initial entry.

    I don't think many of us would have an alternative incoming airflow path open, window, ect, when trying to heat or cool the cabin.

  18. For an '05 Carrera tip with 60+K miles: Today driving back from getting my right rear tire patched with multiple 2" screws sticking all the way in to against the wheel, the "Check Raised Brake Light" warning came on intermittently on the dash display. Then it would go out. I wasn't pressing the brake when it happened. Only one did the red exclamation mark appear on the dash display, and when I checked the OBC, the Info option said "Check 3rd Brake Light". I drove to my local dealer, and checked the brake lights with my service advisor - all were good. So I drove back to the head mechanic, who spent about half an hour trying to figure out what was going on, and thought it might be a loose connector. I'm going back next week with some contact cleaner for him to pull things apart. Besides a loose connector, is there anything else we should be looking at? No codes or stored errors showed up in the PIWIS. Everything seems to work fine, but it's always annoying to get warning messages when driving!

    The cruise control system monitors the 3rd, high mount, brake light in order to cancel CC if voltage is applied. To check for circuit integrity there is a "keep-alive" resistor that always supplies a fixed level of current flow to the high mount bulb(s). So if the bulb goes "open" even momentarily that will be detected and CC will be disabled. The use of LED bulbs is now common but must be compensated for by used a parallel resistor of the correct size to simulate the actual incandescent bulb filament resistance which is VERY low prior to illumination, full 12 volt application.

    I used a 12 volt relay and a 50 watt halogen bulb to defeat the CC monitor. With the relay not energized the bulb is connected through the NC contacts but with relay activation only the lED bulbs remain in the circuit.

    If you replace burned out bulbs in the high mount brake light be sure to use the correct bulb wattage as replacements.

  19. Doesn't ABS pretty much "compensate" for additional braking capability...??

    The faster the brakes bring the wheel/tire to the point of impending lockup the quicker ABS will activate to begin moderating, modulating, the braking HP.

    It would be better to simply find a way to disable ABS unless/until PSM indicates the need for allocation of more front wheel traction to directional control.

  20. So a couple of weeks ago I traded my 02 986 for an 02 996 C2 Cab with 35K miles on it. Over the last week I've been having some issues with it.

    First issue, when I start the car and attempt to drive off it feels like it's going to stall out through first and second. I have to ride the clutch a bit and give it some revs to get up to speed. Once I've pushed some gas through in first and second it seems to be fine. Clutch, fuel pump, spark plugs? Any ideas?

    The other issue is that a couple of times now the anti-lock brakes have kicked in briefly during mild braking. Brake pads going bad.

    I still need to get the car to the shop to get it looked over. I bought it at the worst possible time due to the hours I'm having to put in at work. Any leads or suggestions would be appreciated.

    "..during mild braking.."

    Wet, oily, roadbed, bumpy roadbed, railway, crosswalk paint stripping..??

    ABS only kicks in, activates, when TOO much braking is being used for current roadbed traction conditions.

    But ANYTHING that results in a tire loosing contact with the roadbed during even light braking will oftentimes result in ABS activation.

    To help you maintain directional control during braking, any LEVEL of braking, ABS detects IMPENDING lockup by monitoring the rate at which end individual tire is slowing and if the computation indicates the tire will soon reach lockup the brakes are momentary released.

  21. Anyone heard of this?

    Wife's C4S with under 10K and a baby'd car........on a drive trip to VA, in the rain at interstate speed, I feel an anoying pulse in the pedal with brake application. Much slower pulse than ABS and if I had to liken ot to anything it would be the way a warped rotor feels. A couple days later, the sun is out.....it occurs to me that the brakes no longer have that feel. They are fine.

    I asked for an opin at the dealership and they gave me an explanation I had never heard before.

    Rain sensor tells brakes that it's raining. Brakes then (automatically) engage in light periodic action to keep them warm and dry.

    When I do apply brakes for real there may exist some glazing on the rotor or pad that causes what I feel...........also that my lower offset Techart wheels may be contributing to or agrivating the problem.

    OK so it all sounded like a fairy tale to me, but I just listened.

    Does the rain sensor on a 997.2 really provide info to the braking system?.......is lower wheel offset really the cause of all evils known to man?......and what is the real solution to world hunger?

    TIA

    First, the rain sensor results in the calipers getting a light, constant, precharge, so that shouldn't be the source of the pulsing.

    The "pulsing" you describe is the same feeling I get in our '01 F/awd RX300 when applying the brakes lightly in the wet and on a slight downhill incline. The dealer ascribed it to the EBD, Electronic Brakeforce Distribution, the automatic, dynamic, shifting of braking forces front vs rear to take optimal advantage of braking at both ends.

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