Is it the LWFW that stalls my engine?

Since I installed an AASCO LWFW on my MY00 C2 (e-gas), I experience that the quick drop in RPM sometimes stalls the engine. Usually when I press the clutch pedal, the engine electronic catches the dropping RPM and corrects them to approx. 750. However, especially when I come to a red traffic light and put the car in neutral from e.g. 4th gear to roll for the remaining distance, the RPM drop to 400 which (sometimes) stalls the engine (sometimes the electronic corrects it). Fortunately I always caught it in the past and just restart the engine when I see all the lights on the dash; however, I don't think that's perfectly normal. I recently had some O2 error codes that I cleared with my OBD II reader (P1128, P1137); could a defect O2 sensor be the source of this or is it something I've to live with using a LWFW?

I had similar codes when my MAF needed to be replaced. I ignored the issue until it my car started to stall in a similar manor to yours. New MAF and all is now good. The LWFW may just be magnifying the problem that's already there. I've never heard of it being the sole cause of a stalling issue as such. Andy

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I don't have that issue but I also have the GIAC so I'm not sure if that's helping me avoid your scenerio.

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Oh yeah, he's right. That happened to me too I just didn't think the LWFW was the culprit.

this is a side effect of the LWFW. the rpm drops so fast that the engine electronics can not keep up. For those who have the computer modified by a tuner can contact them and see if they can modify the program to take this into account. i guess this is the main reason why i have not seriously considered this mod.

As Manny says...I had my tuner compensate for the rpm drops due to the LWFW.

LWFW = light weight fly wheel?

The LWFW shouldn't cause any issues, I agree with Audion19s, the LWFW is probably magnifying another issue. My LWFW doesn't cause any issues running the stock program. This is an issue with the earlier 993 and 964 cars, in the later cars the software can easily keep up. Todd

try unplugging your MAF to see if the problem goes away. if it does, replace your MAF.

Thanks for all the replies! I briefly thought about the MAF but got it replaced with the latest model MAF about 15 months ago after I installed my K&N CAI - ups the K&N again?! I'll take the MAF out, clean it and see if the problem still occurs. I've a GIAC flash since about one week* and although the problem happened once before the flash, it happened already 5 times since I got the ECU flashed so I'll also contact the dealer who installed it. Thanks again for the quick help! * GIAC flash: I'm unsure if I've any performance gains but I love the improved throttle response up to 3k RPM! This makes it much more fun to drive around town!

hwk, how do you like the LWFW?

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You sure do have alot of mods for someone who isn't sure about its performance.

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LOL! I just didn't want to bring the discussion to the point that we argue once again about the great Porsche engineers that have squeezed out everything of the stock set-up and everyone who spends money on performance mods is a fool. But you want to hear it? My 996 is light, strong and fast and I've at least 350hp now but never dynoed it! Hahahahahahahaha ...

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There are pros and cons and I think it's the only "performance" mod that really let you feel the cons. On the one side I like the quick revving engine and heel and toe is now so much easier; it's really just a blip on the throttle to rev match downshifts. On the other side it can be quite annoying when you drive around town because as soon as you're not accelerating and the engine (I more the guess transmission oil) reaches operating temp, you hear the clatter of the gears. It's not bad when you stand but driving without pull at 3k RPM got really noisy.

Harold, I am experiencing the same issue with my car going from highway speeds and stopping quickly without down shifting. The issue came after installing a racing throttle body when my stock unit gave out (ECU parameters had to be reprogrammed for the larger throttle body.) RPM would fall quickly and bounce at around 450RPM and struggle to stay running. For the time being, I just pop the clutch to restart if it stalls (crappy fix.) It does not happen when traveling slower than 45MPH and I don't think I have LWFW. Hope you find a fix for it. I am getting it looked at when I take it in for the spring tune up and will update accordingly.

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Sounds like a similar issue which brings me to the point to believe that it's an air intake (air volume) thing (MAF). I'll bring my car to the shop where they did the GIAC ECU flash and they'll put the car back to stock to see if the issue goes away. GIAC has one extra module for the flash which is related to the EVO CAI. They installed this module on my car although I've a K&N CAI and not an EVO but I don't think that's the reason for the problem. I'll keep you posted.

hmm. I have the 1st gen EVO CAI. I just have a cone filter so the air volume should not be less. It would be more. Perhaps I should return it to stock and see what happens. I love hearing the engine scream over 5K RPM though.. If the CAI is the issue, I will miss it.

LWFW should not be an issue on a 996

Its true some LWFW can cause the stall, If you get the car flashed make sure you tell the tuner. I recall when ppl first started doing this mod lots of ppl has this same complaint.Now in my 04 C2 i installed a LWFW and did not have the issue, while my friend with an 02 did the same flywheel and it had the stalling problem. He ended up getting repaired by getting a flash..I think it was a EVO or GIAC.