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 > 911 Engine Rebuilding Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Registered
 
safe's Avatar
 
Join Date: Feb 2004
Location: Sweden
Posts: 4,148
Garage
Problem with 993 RS engine

A friend of mine has a 993 RS with engine problems, it doesn't have any power on the top, which we got confirmation on by this:
Torque on the left, crank hp on the right. This engine should have at least 300, maybe 320 since it has better cams and headers.



Lambda:




We have tried a bunch of things:
*Checked cam timing.
*new airflow meter
*removed vario ram
*changed knock sensors
*changed coils
*changed ECU

All cylinders are the same, did 6 identical dyno runs with 1 injector disconnected at a time.

We think that it's an electrical problem and not a mechanical. But we are running out of ideas now...


Here is an older dyno run when the engine ran fine showing 302 crank hp.

__________________
Magnus
911 Silver Targa -77, 3.2 -84 with custom ITBs and EFI.
911T Coupe -69, 3.6, G50, "RSR", track day.
924 -79 Rat Rod EFI/Turbo 375whp@1.85bar.
931 -79 under total restoration.
Old 08-15-2013, 12:26 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered
 
Trophy's Avatar
 
Join Date: Mar 2006
Location: Calgary, Canada
Posts: 164
Garage
Did you check the ignition module (under drivers seat near ecu) Changing the coils won't show if the module is working properly or not. At idle pull the lead from one see if the idle changes at all, then try the other.

Is the Varioram working correctly? is there a vacuum leak at all?

Compression and leak down numbers, what are they?

Do you have a Bosch PST2? I would also check the following:

MAF
Air Temp sensor

Regards,
__________________
Steven
1995 - 993 RS Tribute - 4.0l Engine plus other stuff...
2005 - Touareg V8 Tow Vehicle
Old 08-16-2013, 08:20 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered
 
safe's Avatar
 
Join Date: Feb 2004
Location: Sweden
Posts: 4,148
Garage
Quote:
Originally Posted by Trophy View Post
Did you check the ignition module (under drivers seat near ecu) Changing the coils won't show if the module is working properly or not. At idle pull the lead from one see if the idle changes at all, then try the other.

Is the Varioram working correctly? is there a vacuum leak at all?

Compression and leak down numbers, what are they?

Do you have a Bosch PST2? I would also check the following:

MAF
Air Temp sensor

Regards,
We haven't checked the ignition modules, we ran it on one coil at a time, so both work. Maybe if one module is a little bad and don't work over 4500 rpm.

Varioram is working, also just tried it with it removed (working i high rpm mode).

Compression is good, don't have the numbers, equal over all cylinders. Haven't done a leak down. Engine had a top end rebuild recently after an over rev that bent a few valves.

PST2 is that the "hammer"?
Error codes was checked at the dealer, nothing.
MAF is new
Air temp sensor, I don't remember if we changed or not.
__________________
Magnus
911 Silver Targa -77, 3.2 -84 with custom ITBs and EFI.
911T Coupe -69, 3.6, G50, "RSR", track day.
924 -79 Rat Rod EFI/Turbo 375whp@1.85bar.
931 -79 under total restoration.
Old 08-16-2013, 01:04 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered
 
rsscotty's Avatar
 
Join Date: Mar 2006
Posts: 820
The dyno graph looks like it may be air flow limited. There are two places that the throttle cable can connect to on the throttle body. It has to go to the highest lever towards the center of the engine. The other one is only used if the car has cruise control.
Old 08-16-2013, 03:50 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered
 
safe's Avatar
 
Join Date: Feb 2004
Location: Sweden
Posts: 4,148
Garage
Quote:
Originally Posted by rsscotty View Post
The dyno graph looks like it may be air flow limited. There are two places that the throttle cable can connect to on the throttle body. It has to go to the highest lever towards the center of the engine. The other one is only used if the car has cruise control.
It gets full throttle, no doubt about that. The intake has been apart several times and checked.

The feeling you get is that the engine "wants to go" but is held back.
__________________
Magnus
911 Silver Targa -77, 3.2 -84 with custom ITBs and EFI.
911T Coupe -69, 3.6, G50, "RSR", track day.
924 -79 Rat Rod EFI/Turbo 375whp@1.85bar.
931 -79 under total restoration.
Old 08-17-2013, 12:00 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered
 
Join Date: Feb 2013
Location: Essen, Germany
Posts: 192
Powerless

Hi,

Next step to go is checking the exhaust side.

Is there a catalysator ?

If yes find out if it is flowing correctly.

What kind od header / silencer configuration are you running ?

My dyno can check torque / power / lambda / and the real ignition timing simultaniuously.

This could help in those cases a lot - talk to your dyno shop or simply find a dyno dynamics digital system in your region.

Best regards from Krautland

Dirk
Old 08-17-2013, 12:37 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
Registered
 
safe's Avatar
 
Join Date: Feb 2004
Location: Sweden
Posts: 4,148
Garage
Quote:
Originally Posted by Edelweiss View Post
Hi,

Next step to go is checking the exhaust side.

Is there a catalysator ?

If yes find out if it is flowing correctly.

What kind od header / silencer configuration are you running ?

My dyno can check torque / power / lambda / and the real ignition timing simultaniuously.

This could help in those cases a lot - talk to your dyno shop or simply find a dyno dynamics digital system in your region.

Best regards from Krautland

Dirk
Yes, we thought about the cat, it had the original RS exhaust, so we changed it. It now has a complete system from a 993 RSR that we know works.

Yes, I agree that we need to know what happens to the ignition timing, haven't found a dyno yet around here that can.
__________________
Magnus
911 Silver Targa -77, 3.2 -84 with custom ITBs and EFI.
911T Coupe -69, 3.6, G50, "RSR", track day.
924 -79 Rat Rod EFI/Turbo 375whp@1.85bar.
931 -79 under total restoration.
Old 08-17-2013, 01:01 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Straight shooter
 
Lapkritis's Avatar
 
Join Date: Sep 2012
Location: Vilnius
Posts: 3,088
Garage
You should be able to data log through the obd port if you have one.

I use http://WWW.ross-tech.com as I bought it primarily for use on my daily driver audi. Pays for itself in no time as the dealer charges an hour of labor to pull codes. Used it on our dodge truck to trouble shoot a bad throttle position sensor that wouldn't throw a code. You might find the same just data logging while driving.
__________________
“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 08-17-2013, 02:41 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Registered
 
safe's Avatar
 
Join Date: Feb 2004
Location: Sweden
Posts: 4,148
Garage
Is it possible to log ignition timing through the ODB??
I think I can borrow a Duratec.
__________________
Magnus
911 Silver Targa -77, 3.2 -84 with custom ITBs and EFI.
911T Coupe -69, 3.6, G50, "RSR", track day.
924 -79 Rat Rod EFI/Turbo 375whp@1.85bar.
931 -79 under total restoration.
Old 08-17-2013, 11:09 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Straight shooter
 
Lapkritis's Avatar
 
Join Date: Sep 2012
Location: Vilnius
Posts: 3,088
Garage
Yes, you can with Rosstech vagcom as it interfaces with your laptop and saves to your computer hard drive. You can then view the data in an easy to read excel spreadsheet.
__________________
“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 08-18-2013, 05:24 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Registered
 
geolab's Avatar
 
Join Date: Dec 2007
Location: Paris
Posts: 48
not on a 993 RS, no timing log
Moist probably ou have a vacuum problem as said before.
Remove the auxiliary blower on the left of engine, plastic all out.
Behind on top, you will notice there is a rubber vacuum hose coming from the left body panel.
It connects with a T connection with two legs. Like the Phi letter in greek.
It is from rubber, and three more vacuum hoses connect to this piece.
Grab it from middle and press it. If rubber is soft and you can press it, you should change this piece.
This piece becomes soft, and your vacuum varioram at 4500 rpm will not function if it is soft and clogs with high vacuum
Old 08-19-2013, 03:14 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Registered
 
safe's Avatar
 
Join Date: Feb 2004
Location: Sweden
Posts: 4,148
Garage
Quote:
Originally Posted by geolab View Post
not on a 993 RS, no timing log
I was afraid of that. To make it further complicated this is a club sport, which differs more than you would think from an normal RS. An ECU from a normal RS won't work, must be from another club sport.
For those who don't know, there was only 200 CS produced.... Luckily we could borrow an ECU from another CS in sweden.

Quote:
Originally Posted by geolab View Post
Moist probably ou have a vacuum problem as said before.
Remove the auxiliary blower on the left of engine, plastic all out.
Behind on top, you will notice there is a rubber vacuum hose coming from the left body panel.
It connects with a T connection with two legs. Like the Phi letter in greek.
It is from rubber, and three more vacuum hoses connect to this piece.
Grab it from middle and press it. If rubber is soft and you can press it, you should change this piece.
This piece becomes soft, and your vacuum varioram at 4500 rpm will not function if it is soft and clogs with high vacuum
I'll check the T connection, but it's not varioram related. In the dyno above the varioram was gutted completely to remove it from the equation.
__________________
Magnus
911 Silver Targa -77, 3.2 -84 with custom ITBs and EFI.
911T Coupe -69, 3.6, G50, "RSR", track day.
924 -79 Rat Rod EFI/Turbo 375whp@1.85bar.
931 -79 under total restoration.
Old 08-19-2013, 03:59 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
PFM PFM is offline
PFM
 
PFM's Avatar
 
Join Date: Dec 2009
Location: Southern California
Posts: 290
Magnus,

Above you say the variorum was gutted completely, what do you mean? The controls were removed? As mentioned if the butter fly valves are in place they need controls. If not then ignition is my next guess,
__________________
Stay Tuned,

PFM
Old 08-19-2013, 05:14 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Registered
 
safe's Avatar
 
Join Date: Feb 2004
Location: Sweden
Posts: 4,148
Garage
Quote:
Originally Posted by PFM View Post
Magnus,

Above you say the variorum was gutted completely, what do you mean? The controls were removed? As mentioned if the butter fly valves are in place they need controls. If not then ignition is my next guess,
Intake disassembled and inside all flaps removed.
__________________
Magnus
911 Silver Targa -77, 3.2 -84 with custom ITBs and EFI.
911T Coupe -69, 3.6, G50, "RSR", track day.
924 -79 Rat Rod EFI/Turbo 375whp@1.85bar.
931 -79 under total restoration.
Old 08-19-2013, 05:18 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Registered
 
geolab's Avatar
 
Join Date: Dec 2007
Location: Paris
Posts: 48
Quote:
Originally Posted by safe View Post
Intake disassembled and inside all flaps removed.
there are two operational throttle bodies, the top one for low rpm, and the bottom one for high rpm. If you remove the flaps in the varioram, the trumpets would not open in the intake tubes, thus it is like air is limited to half gas pedal push.
You know that air intake is vacuum driven. the longer the intake tubes, the more air goes in and colder it is.
Old 08-19-2013, 06:33 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #15 (permalink)
Registered
 
safe's Avatar
 
Join Date: Feb 2004
Location: Sweden
Posts: 4,148
Garage
Quote:
Originally Posted by geolab View Post
there are two operational throttle bodies, the top one for low rpm, and the bottom one for high rpm. If you remove the flaps in the varioram, the trumpets would not open in the intake tubes, thus it is like air is limited to half gas pedal push.
You know that air intake is vacuum driven. the longer the intake tubes, the more air goes in and colder it is.
The trumpets where also removed.
This is how it was raced when it was new, they did't believe in varioram.... The varioram was later put back in.
__________________
Magnus
911 Silver Targa -77, 3.2 -84 with custom ITBs and EFI.
911T Coupe -69, 3.6, G50, "RSR", track day.
924 -79 Rat Rod EFI/Turbo 375whp@1.85bar.
931 -79 under total restoration.
Old 08-19-2013, 06:44 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)
Moderator
 
Bill Verburg's Avatar
 
Join Date: Dec 2000
Posts: 26,411
Garage
Mine was down 50hp at the top end because of a vacuum leak up under the dash board w/ a contribution by a failing check valve.

all of the vrams use the same vacuum controller for the fresh air flap in the dash area , the 2 vram actuators under the intake and the resonance flap, there are also 2 check valves on the tree on the left and several vacuum fittings that are prone to collapse


__________________
Bill Verburg
'76 Carrera 3.6RS(nee C3/hotrod), '95 993RS/CS(clone)
| Pelican Home |Rennlist Wheels |Rennlist Brakes |
Old 08-20-2013, 04:16 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #17 (permalink)
Reply


 


All times are GMT -8. The time now is 08:02 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.