Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > Porsche 911 Technical Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered
 
Join Date: Jul 2003
Posts: 23
Loss of power problem - 964 turbo

Hi, all. I have a 1991 turbo that started exhibiting a weird problem.

When either driving or idling (generally idles around 800-900rpm), the car can start sputtering and loses power. If I watch the tach, it drops down to 400-500rpm. If I hit the gas, it sputters and struggles. The car lurches and cannot pick-up consistently. These episodes are intermittent and last anywhere from 5-15 seconds, at which point the car starts idling smoothly and all is well.

It's pretty unsafe to drive it like this, as I could lose power and get rear-ended. I took it to a local Porsche mechanic. He experienced it while driving, could watch it happen occasionally with the car idling in his lot, but it never lasted long enough for him to do any diagnosis. He had the car for 2 weeks and finally gave it back to me, saying "we need for it to fail for longer - I can't diagnose it the way it is and I don't just want to start replacing things without having an idea of what might be wrong."

Has anyone had any similar issue or good theories on how something like this could occur? Thanks in advance.

__________________
Frank - Menlo Park, CA
1991 964 Turbo
Old 04-16-2015, 08:53 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered
 
rsrfan's Avatar
 
Join Date: Jun 2004
Location: Siesta Key, Florida
Posts: 1,240
Check the turbo boards. I seem to recall the ez69 ignition causing intermittent problems like that...
Old 04-16-2015, 10:36 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Straight shooter
 
Lapkritis's Avatar
 
Join Date: Sep 2012
Location: Vilnius
Posts: 3,088
Garage
What mods/engine management?
__________________
“Of the value traps, the most widespread and pernicious is value rigidity. This is an inability to revalue what one sees because of commitment to previous values. In motorcycle maintenance, you MUST rediscover what you do as you go. Rigid values makes this impossible.”
― Robert M. Pirsig, Zen and the Art of Motorcycle Maintenance: An Inquiry Into Values
Old 04-16-2015, 11:31 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered
 
Join Date: Dec 2008
Location: San Antonio, Texas
Posts: 3,590
have him check the coil
__________________
1973 911S (since new) RS MFI specs
1991 C2 Turbo
Old 04-16-2015, 01:07 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered
 
puddy's Avatar
 
Join Date: Sep 2013
Location: Ontario, Canada
Posts: 1,879
Garage
I had similar problems on my 1989 3.3 turbo, was a vacuum leak.
__________________
Cheers, Chris
1986 951

SOLD: 1975 Carrera / 965 tribute w/ 1989 3.3 turbo 8.5:1, custom Evergreen K27 7200, 964 cams, euro CIS, TEC1 dual plug, rarlyL8 headers & hooligan pipe.
Old 04-16-2015, 01:18 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered
 
Join Date: Jul 2003
Posts: 23
Thanks, everyone. So far, I have the following culprits to potentially check

- flywheel sensor/connector
- EZ69 ignition
- ignition coil
- vacuum leak
__________________
Frank - Menlo Park, CA
1991 964 Turbo
Old 04-16-2015, 02:41 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered
 
Join Date: Dec 2008
Location: San Antonio, Texas
Posts: 3,590
you first have to make sure it is not fuel related. are your fuel pump relays ok, clogged fuel filters exhibit similar symptoms. Does your mechanic have a diagnostic tool that plugs in to the engine management? It was originally the hammer, but I think they are using more modern equipment.
When my coil went out, the car would just cut off at 4500, when my ez69 failed, it just wouldn't start. Pray it is not the ez69 as 3 years ago it was 3900.
__________________
1973 911S (since new) RS MFI specs
1991 C2 Turbo
Old 04-16-2015, 03:34 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered
 
Join Date: Jul 2003
Posts: 23
The mechanic had the car for 2 weeks, during which time he experienced the problem during a drive and had the car running numerous times, heard it stumble and stutter, but it wouldn't last long enough for him to identify the cause. I don't know all of the things he might have done while he had the car, but I do believe he looked at the relays, tried to get a fuel pressure reading and other things. I don't recall him mentioning looking for a clogged fuel filter.

Maybe I need to take the car to a more electrically minded shop.
__________________
Frank - Menlo Park, CA
1991 964 Turbo
Old 04-16-2015, 03:48 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Registered
 
Join Date: Jul 2003
Posts: 23
I never got this problem resolved and the car has just been sitting in my garage the past 3 months, unsafe to drive.

I pulled it out and let it idle in my driveway this weekend to see if I could catch the problem and get a video of it. It did happen and I got it on video (the car was already stumbling when the video starts and stumbles until the 54 second point, at which point, it corrects itself).

https://www.youtube.com/watch?v=9A3Xh5MALi8

Any theories on what this could be? Thanks in advance.
__________________
Frank - Menlo Park, CA
1991 964 Turbo
Old 07-13-2015, 11:02 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Insert Tag Line HERE.....
 
rattlsnak's Avatar
 
Join Date: Nov 2000
Location: Atlanta, Ga
Posts: 9,680
Garage
Send a message via AIM to rattlsnak
Sounds like an A/F ratio issue. Have you tried to disconnect the O2 sensor to see if it makes a difference?
Old 07-14-2015, 03:06 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Registered User
 
IMR-Merlin's Avatar
 
Join Date: Oct 2010
Location: Southern NH
Posts: 3,553
Frank, you are much better off in the turbo forums.

911 / 930 Turbo & Super Charging Forum - Pelican Parts Technical BBS
Old 07-14-2015, 03:40 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
RSS RSS is online now
Registered
 
Join Date: Mar 2005
Posts: 158
Have you checked your boost hose from the turbo to the intercooler for leaks? That is a common problem with turbos. Good luck
Old 07-14-2015, 04:44 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
Registered
 
Join Date: Sep 2012
Posts: 388
I doubt it's the EZ69 or coil. My understanding is they work - or don't.
There isn't much electrical on this car - it has CIS just like the 930 - no "engine management" like on Motronic cars.

Did you or anybody do _anything_ to the engine prior to this happening? - obviously check any parts that have been recently touched.

Is this a recent and sudden change? If so I'd look hard at the vacuum/boost hoses. There aren't that many. Make sure the intercooler to throttle body o-ring is good - and yes the turbo to intercooler hose.

If it's been a slow process I'd look at fuel pressure (the WUR).

I also agree - post up on the Pelican 930 board - as well as Rennlist 964 Turbo specific.

My money is on leak or fuel pressure. Personally - I highly recommend the Brian Leask adjustable WUR.

Keep us posted

__________________
Brandon
'91 911 Turbo
'87 325i Convertible
'16 Audi Allroad
Denver, CO
Old 07-15-2015, 02:30 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Reply


 


All times are GMT -8. The time now is 08:43 PM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2025, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2025 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.