JeTexas

I knew a bunch of guys who put them on Mustangs to supposedly reduce the load of the alternator, A/C & smog pump. They don't do much except make it hard for your car to idle because the alternator isn't putting out enough juice. You'd be better off just removing the A/C.

I believe the door latches are mechanical in nature (except for the microswitch which makes the window drop), so the chances that they both broke are slim to none. I think the issue is that the doors are not unlocking. The interior door handles actuate the lock mechanism and unlock the door if it is locked. That's all I can figure.

Well, continuing to monitor and track the problem for the last few days has blown my theory that it only happens when the coolant temp is below 90 degrees C. Last night it continued to idle high long after the car warmed up even after several "zero speed" stops, which drop the idle to 800 and usually make it quit running that way. One interesting thing I noticed is that after slowing down for a toll booth, the idle began dropping, and I thought the problem was over for the evening, but then as the idle was dropping, it felt like something kicked back on and the idle shot back up. It was like the cruise control kicked on or something suddenly started injecting more air/fuel into the engine. I don't know. It was strange. Of course, it didn't do it at all this morning. Still waiting on the temperature sensor.

I use the Porsche Roof Transport System (RTS) on my Carrera to transport my bike. Until now I had a Yakima bike rack with universal mounts that clamped over the bar. However, I just picked up a used Porsche rack that actually slides into the groove of the RTS. My question is, what do you do with the windlace? Do you just leave it out? Does Porsche expect you to cut it to fit around the attachments you put on your racks? I guess it really doesn't matter if I cut it because it's not like I'm really going to be putting other attachments on the bar once this bike rack is installed, but I just wanted to be sure there wasn't something I was missing before I started hacking it up.

They have spark plug reading charts in most automotive manuals. Here's a link to one online. http://www.aa1car.com/library/reading_spark_plugs.jpg Yours looks pretty normal as far as I can tell.

This morning I hooked the Durametric up just to record some live numbers for another forum member, and I was surprosed to get the P0446. No CEL, just the code in the reader: P0446 Fault Code 95 - shutoff valve activated Charcoal filter (function) I cleared it, and it didn't immediately come back on, but is it telling me that the charcoal element in my EVAP canister is pretty much done?

I can run a diagnostic with the fields you need to compare and send it to you, but I have a 3.4 996, so it won't be an exact match.

I believe that with the MAF unplugged the DME is reading the oxygen sensor values and adjusting the fuel/air mixture solely by that. If your new MAF is under warranty, I'd try exchanging it.

That's what I started thinking too -- that somehow the cold idle speed, which is supposed to be 850 rpm got adjusted to 2200 rpm. However, it's intermittent, so some days it does it, some days it works correctly. Also, I can't find any physical way to adjust the idle speed. I think it's all computerized. All I can figure is that some compenent is throwing wacky voltage to the DME and it's locking the Idle Speed Sensor wide open and not shutting off the fuel injection when I clutch instead of keeping everything where it should be.

The guys at Porsche North Houston took pity on me. Apparently the service techs have these briefcases full of all the plugs on the wiring harnesses, so they can replace them if they accidentally break one. They hooked me up with both a new Idle Speed Sensor plug and a new Temperature Sensor plug along with some pigtail repair leads in case I can't get the wiring out of the old plug. I still have to wait a week to see if changing the temp sensor makes any difference though.

Nothing's ever easy. I think we've got 5 Porsche dealerships in the greater Houston area, but the closest dealership with a temp sensor in stock is in Plano. So it's on order, but I'm not going to be able to test the theory this weekend. (Not keeping parts in stock is probably a great business model, but sucks for the customers and for your service techs.) However, to make things worse, I was messing with the car again after visiting the dealership, and when I went to pull the plug on the coolant system the little tab on the bottom just fell off in my hand. Now I need a new plug for sure. The question is, can I buy just the plug or am I stuck ordering new wiring?

I'll try to find a temp sensor today to swap that out -- just to be sure. It seems to be sending the correct temps to the Durametric though and the DME kicks into the correct program at 80 C.

I've been poring through service manuals for days now, and I've finally come across this. 2452 • Idle Speed Air Control Valve A compact twin-coil control valve (A) is used. It is directly mounted onto the throttle housing without additional air ducting hoses. In conjunction with the DME control unit, the basic quantity of air required for the corresponding operating condition of the engine is supplied via the control valve bypass. Deviation from a programmed basic quantity of air when the engine is at idle speed is adaptively corrected by the DME control unit under the following conditions: • Idle speed • Zero vehicle speed • Engine temperature> 79,5° e In conjunction with the DME control unit, the idle speed air control valve also regulates the idle speeds required for the different operating conditions of the engine. Idle Speed The idle speed for all transmission variants (manual transmission and Tiptronic) is 700 rpm (warm engine/coolant temperature > 60° e), with air-conditioning system switched on: 820 rpm. However, if the engine oil temperature exceeds 143° e or less than 11.03 V is applied to terminal 15 (power supply) of the control unit, the idle speed is increased to 850 rpm by the control unit. Downward adjustment of the increased speed after undervoltage is performed after the next transition from partial load to idle speed if the supply voltage was higher than 11.03 V. So upon further inspection of my pages upon pages of Durametric Excel charts, the problem, while intermittent, only occurs at temperatures below 80 degrees C. It also never happens when the car is at "zero speed." This tells me that something crazy is going on with either the DME or the IACV when it's running the Idle Speed program, and I've replaced the IACV and gotten the same problem. So is the DME throwing some wacky voltage? The cable cable between the DME and the IACV shorting out? Is the DME just not running the Idle loop half the time? I'm not quite sure how to test the voltage from the aforementioned terminal 15 since the DME runs the "zero speed" program, not the "idle" program when sitting in the driveway. Another thought is could the resonance flap be sticking open? This is driving me crazy.

I changed the TPS sensor & IACV with absolutely no change in symptoms.

Something about your story doesn't add up. Why were you in a store for a couple hours? Are you sure it wasn't a pub? As for the car, when my 996 gave me those exact symptoms, it was a bad MAF. Try unplugging it and see if it starts.

Mine is. 99 C2. The front hood takes a very firm press to latch it. I'm sure the latch can be adjusted, but I haven't bothered.

The chart above is from last night's drive home with the last time the rpms hung and then the first time the car started running normally. Notice the trigger to the change was my speed dropping to 5km/h. Looking at the Actual Values logs from the past few days it looks like when the problem is there, the voltage on the 02 sensors ahead of the cats fails to drop to zero when I clutch. Once I hit less than 10 mph, the voltage drops to zero and the idle returns to 800 rpm or when the car is behaving correctly and I clutch at any speed with my foot off the gas, the O2 voltage will go to zero and the engine returns to 800 rpm. Along with the O2 sensors dropping to zero, I've also noticed that when the car is behaving correctly the MAF will drop into the 1.3 - 1.5 range, but I'm guessing that reading is dependent on the air flow, not the cause. So my question is, what sensor or switch creates the fuel cut off or new programming loop that leans the mix and makes the 02 sensors blip to zero when I clutch, so I can fix it?

I logged more data yesterday evening, but I haven't had time to go over it yet. A few more pieces of info ... When the idle is hanging and I'm at speed, but take my foot off the gas without clutching, instead of slowing the engine the car continues at speed like it's on cruise control, but with some surging. The surging is much more pronounced when the temperature is under 50 degrees F outside. I really hadn't noticed it when the weather was warm. The problem starts and ends only when the car comes to a stop. (Well, basically a stop. It has to drop under 10 mph, which seems to reset the computer to the idle circuit and drops the rpms to 800.) If I'm on the freeway, and the car isn't doing it, it won't randomly start doing it unless I either come to a stop in heavy traffic or get off the freeway and come to a stop. Then if it does start, it will keep doing it until the next time I come to a stop. No variance in speed (aside from dropping below 10 mph) or amount of clutching will get it to start doing this or to stop doing this once it starts. The only consistent factor is that everytime I come to a stop sign or stoplight, it's a crapshoot whether or not the engine will do this until I stop at the next stop sign or stoplight. This problem started about a week after I had my spark plugs and oil changed back in July. I didn't think it was related at the time, but going back over my receipt I saw that after "Spark plugs" they mention "Slight tuning." I'm wondering if this isn't completely computer related due to Firestone's attempt at "Slight tuning" and if I should go have a Porsche specialty shop re-tune it. Anyone know a good shop in the Houston area and how much a tuning would cost?

There's a difference between limiting and clipping. Limiting keeps certain tones at a certain volume while clipping cuts the information of those tones out altogether. The loudness button limits the highs and lows while bringing up the mids to create a sound profile more appealing to your ear. It's like playing with an equalizer. And I was always told to make sure the amp was double the wattage of the speakers as well - just remember to match ohms. I don't know if it's as much an issue with car speakers as it is with PA and stage speakers, but the double the wattage rules only works if it's an 8 ohm amp with 8 ohm speakers or with a 4 ohm amp with 4 ohm speakers, etc.

I think Porsche restricts a lot of the alarm-related and key-programming functions for the security of the cars. If the cables and software were cheap and readily available, you know there would be people reprogramming stolen cars and rolling back odometers like it was going out of style.

Sounds like a good test mule for that electric conversion idea somebody was posting about.

I think you should write an open-source diagnostic program and share it with us. Or even better, an App for my iPhone with a wireless interface.

I'm embarrassed I didn't realize that was the power steering reservoir. Thanks so much.

1999 996 C2 Cab 6-speed First, can anyone tell me what this bracket is supposed to be secured to? It's just hanging loose on this hose, and I can't figure out where it was supposed to be secured. Second, does this hose coming out of what I believe is part of the idle-run-on system supposed to connect to anything or is it just a vent hose? It's just hanging there, and I can't find anything that looks like it would attach to it. And last, but not least, does anyone know a source for the little metal retaining clip that hold the IAC wiring on? I lost mine, and my Porsche dealer cannot figure out a part number to order one. I've been using a twist tie, but my searching has led me nowhere. The closest thing I can find are retaining clips for old car door handle and window regulators.

I'm at 103,000 -- still running like a champ. If only I could sort out my vacuum leak/hanging idle problem.