Car stalling when shifting down
03-30-2018, 11:58 PM
#1
Instructor
Thread Starter
Car stalling when shifting down
All,
I'm new posting in the forum even if I read you a lot and thank you for all the information I can find here.
Also apologies if my technical English is not 100% appropriate.
I have a manual 993 C2 Cabrio I've purchased 1 year ago.
Runs great but has an issue; the car idles at no more than 500rpms; and this wouldn't be a big issue per se.
The problem starts when I shift gears down; during the shift (clutch pushed down) RPMs literally fall down until the car stalls if I don't give some quick gas on the accelerator.
When I push the clutch, revs fall so quickly It definitely feels like there's nothing to keep them over the minimum...
I've already cleaned the ISV valve and also replaced it with a new one.
To note: my car has (from previous owner)
- non OEM air cone filter;
- modified exhaust
- Probably (according to Porsche ATLANTA) a lightweight flywheel
Car runs great and sounds better than opera, but driving with this constant risk of stalling is a bit stressful....
Besides being potentially dangerous
The car was PPId before purchase but they didn't find anything at the time (when it was inspected I didn't mention this issue to the Porsche mechanic since I drove it just for 15 minutes before that).
My independent dealer is looking for solutions but wanted to have somebody else's opinion before, eventually go to PORSCHE dealer again (2h away).
thanks
I'm new posting in the forum even if I read you a lot and thank you for all the information I can find here.
Also apologies if my technical English is not 100% appropriate.
I have a manual 993 C2 Cabrio I've purchased 1 year ago.
Runs great but has an issue; the car idles at no more than 500rpms; and this wouldn't be a big issue per se.
The problem starts when I shift gears down; during the shift (clutch pushed down) RPMs literally fall down until the car stalls if I don't give some quick gas on the accelerator.
When I push the clutch, revs fall so quickly It definitely feels like there's nothing to keep them over the minimum...
I've already cleaned the ISV valve and also replaced it with a new one.
To note: my car has (from previous owner)
- non OEM air cone filter;
- modified exhaust
- Probably (according to Porsche ATLANTA) a lightweight flywheel
Car runs great and sounds better than opera, but driving with this constant risk of stalling is a bit stressful....
Besides being potentially dangerous
The car was PPId before purchase but they didn't find anything at the time (when it was inspected I didn't mention this issue to the Porsche mechanic since I drove it just for 15 minutes before that).
My independent dealer is looking for solutions but wanted to have somebody else's opinion before, eventually go to PORSCHE dealer again (2h away).
thanks
03-31-2018, 12:24 PM
#2
Rennlist Member
There is a lot of information here about lightweight flywheels contributing to stalling problems in 993's. Just do an advanced search on keyword "LWF," specify "Search Titles Only" in the preference box below the keyword, then on the right hand side of the page under "Search in Forum(s)," specify "993 Forum," then click "Search Now" at the bottom of the form.
You'll get enough citations to keep you reading for several days.
You'll get enough citations to keep you reading for several days.
03-31-2018, 04:00 PM
#5
Instructor
Thread Starter
There is a lot of information here about lightweight flywheels contributing to stalling problems in 993's. Just do an advanced search on keyword "LWF," specify "Search Titles Only" in the preference box below the keyword, then on the right hand side of the page under "Search in Forum(s)," specify "993 Forum," then click "Search Now" at the bottom of the form.
You'll get enough citations to keep you reading for several days.
You'll get enough citations to keep you reading for several days.
I probably didn't link my issue with the LWF...
03-31-2018, 04:18 PM
#7
Rennlist Member
Trending Topics
03-31-2018, 11:36 PM
#8
RL Community Team
Rennlist Member
Rennlist Member
Have you considered keeping the ignition stock and puttimg back the original flywheel? Smoother quieter, altering the DME may cause other functional issues.
04-01-2018, 12:37 AM
#9
Rennlist Member
You’re entitled to your opinion but have you first hand experience with a Steve Wong or Steve Weiner chip in your 993, Andy?
04-01-2018, 01:26 AM
#10
Instructor
Thread Starter
Saw the procedure in pelican parts... seems pretty easy to do.
To remedy stalling on the 95s with LWFW, you’ll need a chip and problem solved. I’ve had a Steve Wong chip on a previous 90 and 95 Carreras.
Thanks for the suggestion.
As mentioned above I'll do the easy stuff first... I've already saved some pages to read regarding the mod you've mentioned...
I've seen your multi 993 experience... how would this mod work? What is adding? or, better question, what is missing?
04-01-2018, 12:21 PM
#11
Rennlist Member
Then if you’re considering a chip, contact either Weiner or Wong to inquire. I personally used the Steve Wong chip. Go to his website as there are different variations available. My first experience was with a 95 that I bought with LWFW and Wong chip installed. Idle was bumped up slightly and a few extra HP- not day/ night difference in power. More importantly it never stalled. A few years later I purchased a 90 964 with a LWFW with stock chip. It would stall on downshifts especially with AC on. Again I went with Wong chip. Installation was quite easy. You remove the DME from under the driver seat, pull out factory chip, and install new chip. Not a huge power gain, but delivery was much better and improved throttle responses. Key here is to remedy stalling, not adding power. You can choose from his basic chip to improve throttle and stalling-fix, 93 octane chip, cat-bypass chip, etc... BTW, Steve is very responsive. I’ve spoken with him over the phone several times. No affiliation, just happy customer. Hope this was helpful to you.
04-02-2018, 11:52 AM
#12
Burning Brakes
Assuming there's no other issue in play (such as a LW flywheel):
Since the car is an ODBI (1995) car, isn't there an idle adjustment he can do as well if the DME reset doesn't work? IIRC, I remember seeing a thread where an allen screw on the ISV(?) could be adjusted to manually increase the idle speed (it bears searching for it on the forum).
If the car has a LW flywheel installed, though, I think you'll need to address this via a chip upgrade for the ODBI (1995) cars.
Since the car is an ODBI (1995) car, isn't there an idle adjustment he can do as well if the DME reset doesn't work? IIRC, I remember seeing a thread where an allen screw on the ISV(?) could be adjusted to manually increase the idle speed (it bears searching for it on the forum).
If the car has a LW flywheel installed, though, I think you'll need to address this via a chip upgrade for the ODBI (1995) cars.
04-02-2018, 11:37 PM
#13
Instructor
Thread Starter
Yes there's a post about this:
https://rennlist.com/forums/993-foru...n-for-lwf.html
I've saved it in my "to read" when I have some free time from work :-)
My "indy" mechanic said there's seem to be nothing to do to "manually" increase the minimum rpms....
in the next week I'll look at different options and I'll make a plan..
My idea would be to:
- Start looking at the DME and eventually replace it;
- Look at the ISV valve (it has been replaced already);
- In the meanwhile study and get more info on the CHIP that P-Daddy is suggesting.
- Air filter? should I give it a clean anyways?
- Other?
I'd like to keep the LWFW for 2 reasons:
- I think I like the effect it has (although I don't remember exactly how a normal FW 993 is to drive);
- I don't want to pull down the transmission for changing something that is currently working
Qurestions:
- what minimum rpm does your 993 has? Mine is 500
- How does the oil pressure fluctuates when you shift gears? Mine goes down to half... is it normal? I have the felling there's nothing that keeps up the revs until it stalls
https://rennlist.com/forums/993-foru...n-for-lwf.html
I've saved it in my "to read" when I have some free time from work :-)
My "indy" mechanic said there's seem to be nothing to do to "manually" increase the minimum rpms....
in the next week I'll look at different options and I'll make a plan..
My idea would be to:
- Start looking at the DME and eventually replace it;
- Look at the ISV valve (it has been replaced already);
- In the meanwhile study and get more info on the CHIP that P-Daddy is suggesting.
- Air filter? should I give it a clean anyways?
- Other?
I'd like to keep the LWFW for 2 reasons:
- I think I like the effect it has (although I don't remember exactly how a normal FW 993 is to drive);
- I don't want to pull down the transmission for changing something that is currently working
Qurestions:
- what minimum rpm does your 993 has? Mine is 500
- How does the oil pressure fluctuates when you shift gears? Mine goes down to half... is it normal? I have the felling there's nothing that keeps up the revs until it stalls
04-02-2018, 11:45 PM
#14
Rennlist Member
Aside from a LWFW related problem, a bad O2 sensor and/or a dirty MAF could cause stalling when off the gas. Good maintenance projects, and they could help, if one or the other is suspect.
04-17-2018, 12:45 AM
#15
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LWFW checks
My 96 has the LWFW installed and it stalled despite being a 96.
1. check for vacuum leaks.
2. Make sure the throttle hits the stop. If the throttle is even a little open the idle circuit won't engage. That's what fixed it for me.
You might be able to "clock" the ISV as an idle adjustment.
1. check for vacuum leaks.
2. Make sure the throttle hits the stop. If the throttle is even a little open the idle circuit won't engage. That's what fixed it for me.
You might be able to "clock" the ISV as an idle adjustment.