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If you have a RoW 96'-98' 993 with a lightweight flywheel installed, please let me know if you have experienced stalling issues. I have a suspicion that there may have been a hardware change to the ECU (DME) on post-95' 993s that enables those ECUs to "catch" rapidly falling revs in a way that 95' and earlier ECUs could not. I've been told otherwise, but I'm hoping for some verification here. Thoughts?
And I'm only interested in RoW 993s from these years because, during this period, USA 96'-98' 993s ran 88-pin OBD2 ECUs (DMEs) which apparently do not have stalling issues and, in any case, are not OBD1 like what I run in my car.
The only 993's to come stock with the lightweight flywheel were 95'-96' 993 RS Clubsport models (I think). And, even given the track-oriented nature of those cars, I would like to believe that Porsche would never sell a car that stalls as readily as my car seems to with this flywheel.
And it also seems that all of the 993 LWF stalling issues reported on this forum are 95' models.
This is a battle I'm fighting right now and I'd rather not resort to finding/buying a mid-weight flywheel or switching to Motec. Getting around to doing a smoke test for vacuum leaks. And I've already tried biasing the Idle Control Valve, which helps, but doesn't solve the stalling problem...and it's made my car difficult to cold start.
I found your post a little confusing. How are you running obd1 on a 96-98 993?
Perhaps you could post your cars specs. That would be helpful.
I spoke with Steve Wong about this because I updated the chip in my 95 993. He said that the new chip gets past the problem of stalling. With the new chip I noticed a significant difference in how the engine comes down from high rpm. If I bring it up to 6000 rpm and take my foot off quickly it now has a wee throttle blip at 2500 rpm. I came to think that that little blip gives the ecu time to respond to a sudden decrease in throttle down to idle.
You cant just swap chips if your running obd2, but you can if you are running an obd1 ecu. So what are you running? Maybe you need a new chip?
Thank you all for the feedback, I apologize for bringing up such a well-worn topic.
Originally Posted by knorrena
I found your post a little confusing. How are you running obd1 on a 96-98 993?
Perhaps you could post your cars specs. That would be helpful
Suffice it to say that my car is a Frankenstein (details here if interested), but is definitely running a 95' obd1 ECU that's custom chipped by Steve W for varioram and my other mods.
Cupcar - your mention of adjusting the "coast down injection turn on point" in the ECU software sounds promising. "Coast down injection turn on point" was never a term Steve threw out there when we discussed this problem, but (assuming that's a thing) it certainly sounds like what's set too low on my car at the moment.
I'm hoping to figure out how to smoke test for vacuum leaks this weekend. I'll post an update if I get results from that and/or some Steve W harassment.
Here is my experience. LWF on my 95 has some stalling. Steve Weiner chip took care 99% of this.
I then put on a vram (like you), and ran a 95 stock Euro Chip from Steve Wong. And it never stalled. Ran solid and never a hiccup once. My theory is both the vram and (maybe) software made the diff. I had to run stock chip b/c the performance chip timing is too aggressive for the car.
Help - LWF on RoW 993's
