Rennlist Discussion Forums   classifieds | membership | rennlist | photo album    
sponsors | upload photo | chat    
 



Go Back   Rennlist Discussion Forums > Water Cooled Technical Discussion Areas > 928 Forum
Sign in using an external account
Register Forgot Password?
Search


This Rennlist Forum is sponsored by      ....dedicated to Your Porsche 928

Reply
 
Thread Tools Search this Thread
Old 06-12-2007, 12:57 AM   #1
edco
User
 
edco's Avatar
 
Join Date: Feb 2006
Location: Castro Valley, CA
Posts: 330
Send a message via Yahoo to edco
Default One side of my exhaust is running hotter than the other

Hey Guys,

One side of my exhaust is running hotter than the other. Difference at idle on a warm engine is 50 degrees. I had the car on a lift today and both cats are good and no obstructions in the mufflers. So my driver side is much hotter at idle.

Bill Ball asked me to check for a loose spark plug or plugs and everything was good. We are thinking that the previous owner might have the timing belt off a tooth. Any thoughts on what might cause the difference in temperature from one side to the other?
To remove this ad, register today or login if you already are registered!

edco is offline   Reply With Quote
Old 06-12-2007, 01:07 AM   #2
atb
Addict
Rennlist Member
 
atb's Avatar
 
Join Date: May 2001
Location: Puyallup, WA
Posts: 4,370
Default

Where are you taking your measurement?
__________________
Adam Birnbaum
'88 S4 A/T Schwartz
'79 5 speed Primer (Track car project)
PacNW 928
Proud Member of 928 Owner's Club
atb is offline   Reply With Quote
Old 06-12-2007, 04:09 AM   #3
edco
User
 
edco's Avatar
 
Join Date: Feb 2006
Location: Castro Valley, CA
Posts: 330
Send a message via Yahoo to edco
Default

We checked it from front to back but measured the heat right at the h-pipe where it bolts to the manifolds
edco is offline   Reply With Quote
Old 06-12-2007, 04:11 AM   #4
IcemanG17
Addict
Rennlist Member
 
IcemanG17's Avatar
 
Join Date: Sep 2004
Location: Stockton, CA
Posts: 15,757
Default

Matt
What adam said.....is it right at the header-cat or further back (tailpipe area).....

Hot typically means lean....but cam timing could be a factor...but thats a BIG difference....hopefully its the passenger side bank, since its easier to check.....I would say bad injectors...but you just had them fixed along with the fuel pressure reg too.....
__________________
"think all cops are bad....try living in a world without them!"
Brian
Co-founding member of the "Stockton Sharks Society"
79 racer "Casper" 5spd, 5.0 Euro ???hp, ??? torque 2624lbs
10 Silverado (tow rig)
13 Scion FR-S FUN commuter!!
----------------------
84 auto "Estate" racer 215whp 256torque, 2800lbs
08 M3....gone but not forgotten
88 S4 Guards Red/Champagne Leather (gone to a new home)
89 S4 5 speed track beast!!!! BLACK WIDOW (gone..dead)
IcemanG17 is offline   Reply With Quote
Old 06-12-2007, 04:12 AM   #5
IcemanG17
Addict
Rennlist Member
 
IcemanG17's Avatar
 
Join Date: Sep 2004
Location: Stockton, CA
Posts: 15,757
Default

One more thing.....how is the engine running...smooth with good power....seemed like it in the ORR?
__________________
"think all cops are bad....try living in a world without them!"
Brian
Co-founding member of the "Stockton Sharks Society"
79 racer "Casper" 5spd, 5.0 Euro ???hp, ??? torque 2624lbs
10 Silverado (tow rig)
13 Scion FR-S FUN commuter!!
----------------------
84 auto "Estate" racer 215whp 256torque, 2800lbs
08 M3....gone but not forgotten
88 S4 Guards Red/Champagne Leather (gone to a new home)
89 S4 5 speed track beast!!!! BLACK WIDOW (gone..dead)
IcemanG17 is offline   Reply With Quote
Old 06-12-2007, 04:18 AM   #6
edco
User
 
edco's Avatar
 
Join Date: Feb 2006
Location: Castro Valley, CA
Posts: 330
Send a message via Yahoo to edco
Default

We took the reading where the exhaust manifold enters the H-Pipe, before the cats, before the two sides mix in the H section. At idle on a warm engine Drivers side 260 degrees / Passenger side 217 degrees

Engine is running fine, almost got 21mpg on the trip up and back, 11mpg on race day
edco is offline   Reply With Quote
Old 06-12-2007, 05:04 AM   #7
IcemanG17
Addict
Rennlist Member
 
IcemanG17's Avatar
 
Join Date: Sep 2004
Location: Stockton, CA
Posts: 15,757
Default

your mileage is fine....not running rough....about the only other thing that would tell if you truely are running lean is a smog check....when is your next one?

I know that the headers are not quite the same length....one side is slightly longer than the other (don't know which one)...its not much...but might explain it a little bit.....

I would test someone elses 928 (bills)....maybe its normal?
__________________
"think all cops are bad....try living in a world without them!"
Brian
Co-founding member of the "Stockton Sharks Society"
79 racer "Casper" 5spd, 5.0 Euro ???hp, ??? torque 2624lbs
10 Silverado (tow rig)
13 Scion FR-S FUN commuter!!
----------------------
84 auto "Estate" racer 215whp 256torque, 2800lbs
08 M3....gone but not forgotten
88 S4 Guards Red/Champagne Leather (gone to a new home)
89 S4 5 speed track beast!!!! BLACK WIDOW (gone..dead)
IcemanG17 is offline   Reply With Quote
Old 06-12-2007, 05:30 AM   #8
edco
User
 
edco's Avatar
 
Join Date: Feb 2006
Location: Castro Valley, CA
Posts: 330
Send a message via Yahoo to edco
Default

Brian,

There is a problem it's hot enough that it is discoloring the bumper cover at the RMB on the same side that is hot at the manifold. So it's not if it's to hot or not but what would cause it to be 45 degrees hotter than the other side at idle. Who knows what that temp difference might be at freeway speed? I took it to a shop today to have a look on the rack thinking it could be a bad cat or blocked muffler they all checked out ok. The tech is not a 928 guy but said it was not the norm to have such extreme difference in temps before the cats
edco is offline   Reply With Quote
Old 06-12-2007, 05:46 AM   #9
John Speake

Rennlist
Small Business Partner

 
John Speake's Avatar
 
Join Date: Feb 2002
Location: Cambridge England
Posts: 6,191
Default

I have known a GT where the cam timing was off about a tooth, and that caused a temp differential sufficient to trigger the "ignition protection relay".
__________________
John '86 Euro S2 16v
SharkTuned LH & EZ-F

www.jdsporsche.com
Home of the SharkTuner
Rebuilt LH, EZK ECUs & MAFs available from agents worldwide.
USA agent for LH and MAF checking and repair is Louie Ott :-
http://www.performance928.com
Diagnostic testers for all models of Porsche 1987 >
John Speake is offline   Reply With Quote
Old 06-12-2007, 08:22 AM   #10
SwayBar
Addict
Rennlist Member
 
SwayBar's Avatar
 
Join Date: Feb 2006
Location: Chicago Bears
Posts: 1,226
Default

If all of the tubes on one bank are cooler than the other bank, then it must be the cam timing.
SwayBar is offline   Reply With Quote
Old 06-12-2007, 09:25 AM   #11
IcemanG17
Addict
Rennlist Member
 
IcemanG17's Avatar
 
Join Date: Sep 2004
Location: Stockton, CA
Posts: 15,757
Default

Quote:
Originally Posted by John Speake
I have known a GT where the cam timing was off about a tooth, and that caused a temp differential sufficient to trigger the "ignition protection relay".
Hmm
Since matts is an 88 it doesn't have that circuit...could be dumping fuel which is burning in the header?? Just a little bit anyway?

time to check the cams
__________________
"think all cops are bad....try living in a world without them!"
Brian
Co-founding member of the "Stockton Sharks Society"
79 racer "Casper" 5spd, 5.0 Euro ???hp, ??? torque 2624lbs
10 Silverado (tow rig)
13 Scion FR-S FUN commuter!!
----------------------
84 auto "Estate" racer 215whp 256torque, 2800lbs
08 M3....gone but not forgotten
88 S4 Guards Red/Champagne Leather (gone to a new home)
89 S4 5 speed track beast!!!! BLACK WIDOW (gone..dead)
IcemanG17 is offline   Reply With Quote
Old 06-12-2007, 10:44 AM   #12
John Speake

Rennlist
Small Business Partner

 
John Speake's Avatar
 
Join Date: Feb 2002
Location: Cambridge England
Posts: 6,191
Default

I appreciate that Matt's S4 doesn't have that circuit, but I was making the point that incorrect cam timing can make a significant difference to exhaust temps.

The incorrect timing may also mess up the mixture on the correctly timed head because the O2 loop will be fooled by possible incomplete combusition from the faulty side.
__________________
John '86 Euro S2 16v
SharkTuned LH & EZ-F

www.jdsporsche.com
Home of the SharkTuner
Rebuilt LH, EZK ECUs & MAFs available from agents worldwide.
USA agent for LH and MAF checking and repair is Louie Ott :-
http://www.performance928.com
Diagnostic testers for all models of Porsche 1987 >
John Speake is offline   Reply With Quote
Old 06-12-2007, 10:51 AM   #13
edco
User
 
edco's Avatar
 
Join Date: Feb 2006
Location: Castro Valley, CA
Posts: 330
Send a message via Yahoo to edco
Default

Thanks John,

That is what Bill Ball suspected, I just thought it never hurts to see what the group thinks as well. Well check it out today and report back.
edco is offline   Reply With Quote
Old 06-12-2007, 11:55 AM   #14
Bill Ball
Under the Lift
Lifetime Rennlist
Member
 
Bill Ball's Avatar
 
Join Date: Mar 2002
Location: Alamo, CA
Posts: 18,018
Default

Quote:
Originally Posted by SwayBar
If all of the tubes on one bank are cooler than the other bank, then it must be the cam timing.
I asked Matt to shoot the temps for each cylinder to see if it is one cylinder or the whole bank. Also, I asked him to look through the inspection hole at the timing notch on each cam gear per chance it is that simple. It is real easy to be a tooth off on a TB job if you aren't careful. If the temp difference is the whole bank but the gears are right on, then we need to pull the cam covers and do a factory cam timing job.

Matt, if you need help with this, I am free today.
__________________
Bill

GP White '89 S4 - 265K carefree (well, almost) miles, creeping up slowly on 300K. Motor unopened and original TT bearings.
'87 rear resonators; '83 LSD; PKlamp on TT, Bilsteins, 2002 996 wheels; Momo Club 4 steering wheel; H4 Hi/Lo HID headlights; HID driving lights.

Sharks in the Park XIII, May 4, 2013 - Tilden Park, Berkeley, CA.

If you live in North or Central CA, join our group at Norcal928.org
Bill Ball is offline   Reply With Quote
Old 06-12-2007, 01:08 PM   #15
PorKen
Inventor
Rennlist Member

 
PorKen's Avatar
 
Join Date: Sep 2002
Location: Portland, OR
Posts: 8,392
PKProducts
Default

Quote:
Originally Posted by Bill Ball
It is real easy to be a tooth off on a TB job if you aren't careful. If the temp difference is the whole bank but the gears are right on, then we need to pull the cam covers and do a factory cam timing job.
I've seen where someone (dealer?) has installed the belt a tooth off, then adjusted the gear as far as it could go in the slot to try and match up to the follower lift specs, but gave up and left it.




I've heard there is a less invasive way to check/set the cam timing.

Quote:
Originally Posted by Obi-Wan
You must do what you feel is right, of course.
Quote:
Originally Posted by Darth Vader
I find your lack of faith disturbing.
PorKen is offline   Reply With Quote
Old 06-12-2007, 01:08 PM
Rennlist



Paid Advertisement
Reply

Tags
1991, 928, bank, burning, cyliner, engine, exhaust, hotter, lean, leftmanifoldhotterthanright, manifold, pipe, porsche, running, side

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Forum Jump


All times are GMT -3. The time now is 10:02 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO 3.5.2
Copyright ę 1998 - 2007 Rennlist.com

Advertise on Rennlist - Privacy Statement - Terms of Service - Jobs
Emails & Contact Details