Terrible gas mileage - white slime in valve cover vent hose - Page 2 - AudiWorld Forums

Go Back  AudiWorld Forums > Technical Discussion > Engines > 12v V6 Discussion
Reload this Page >

Terrible gas mileage - white slime in valve cover vent hose

Notices

Terrible gas mileage - white slime in valve cover vent hose

Old 04-16-2012, 05:41 AM
  #11  
AudiWorld Senior Member
Thread Starter
 
vtraudt's Avatar
 
Join Date: Jan 2010
Location: Brighton, MI
Posts: 1,399
Default

Update:

New O2 sensors (no code) did not change a thing.
Gas mileage is still 12 mpg highway (and 10-12 mpg mixed driving).

I pulled the spark plugs out (less than 5k since new) and had an 'expert' take a look. They show NO signs of running rich.

Also cut the catalytic converters out (one was rattling anyway) to rule out 'plugged cat'. Inside of the exhaust pipes looked also 'normal' (no signs of running rich).

Last time I checked the vacuum, it was at -18 (which seem normal, or?) at idle.

I had replaced the fuel pressure regulator, no change.

a) could I still have a vacuum leak that is causing the terrible gas mileage?

b) when I did the timing belt service, I checked compression, which was ok and fairly uniform across the 6 cylinders. I will check again

Key question: what could (any ideas are very welcome) cause such terrible gas mileage?

- dirty injectors?
- leaking injector O rings?
- EGR system (I would expect a code, even on this very basic Hitachi ECU)?
- air pump or other evap stuff?
- resonator or muffler plugged (maybe from cat 'debris'?)?

Without obvious signs (or codes), I am at a loss.
Power seems poor, but it is hard for me to judge (my other cars are 2.7T 6spd stage 2, 1.8T manual stage 3, 1.8T manual stage 2, so yes: this 2.8 A4 with auto trans seems awfully slow, but I have not comparison.

Suggestions, PLEASE!
vtraudt is offline  
Old 04-17-2012, 06:19 AM
  #12  
AudiWorld Senior Member
Thread Starter
 
vtraudt's Avatar
 
Join Date: Jan 2010
Location: Brighton, MI
Posts: 1,399
Default

Does the 2.8 have EGT sensors that could go bad and tellung the ECU to run rich to 'cool', causing the high gas consumption?
vtraudt is offline  
Old 04-19-2012, 06:23 PM
  #13  
AudiWorld Super User
 
Prospeeder's Avatar
 
Join Date: Aug 2011
Location: Washington
Posts: 2,369
Default

pull the injectors out, but leave them attatched to the fuel line and rail, and turn the key on so the fuel pump primes. but dont start! and put paper towels under each injector, and any that get wet, are leaky and bad. also you can use an ohm meter, and check the resistance of each injector. They can electrically short out.

Bosch injectors - 15-17 ohms
Siemens injector - 13.5-14.5 ohms

Anything dramatically less is junk.
Prospeeder is offline  
Old 04-20-2012, 05:06 AM
  #14  
AudiWorld Senior Member
Thread Starter
 
vtraudt's Avatar
 
Join Date: Jan 2010
Location: Brighton, MI
Posts: 1,399
Default

Will do.
Get a set of O-rings (number/specification to order the correct ones? Source?) and change them out while at it?

Originally Posted by Prospeeder View Post
pull the injectors out, but leave them attatched to the fuel line and rail, and turn the key on so the fuel pump primes. but dont start! and put paper towels under each injector, and any that get wet, are leaky and bad. also you can use an ohm meter, and check the resistance of each injector. They can electrically short out.

Bosch injectors - 15-17 ohms
Siemens injector - 13.5-14.5 ohms

Anything dramatically less is junk.
vtraudt is offline  
Old 04-20-2012, 01:54 PM
  #15  
AudiWorld Member
 
Join Date: Apr 2011
Posts: 124
Default

would the injectors make the check engine light come on if bad. got the same white slim on oil cap and in breather hoses. my check engine light will come on if it sits and idles for 10-15 mins. car also wants to die right after starting will rum real rough at around 3-4 hundred rpm for about 5 mins then it seems to come out of it. Then at low rpm wile driving it hesitates. at about 2000 rpm it seems to come out of it but still dont feel like it has full power. and what would symptoms of one clogged cat and the other free flowing. exhaust makes weird high pitched kackle. caused by misfire? or what
goodys90 is offline  
Old 04-20-2012, 02:00 PM
  #16  
AudiWorld Member
 
Join Date: Apr 2011
Posts: 124
Default

I have 2.5" exaust from right behind the cats into a cherry bomb glass pack for resinator then into a pilot dual 3" tipped muffler
Originally Posted by goodys90 View Post
would the injectors make the check engine light come on if bad. got the same white slim on oil cap and in breather hoses. my check engine light will come on if it sits and idles for 10-15 mins. car also wants to die right after starting will rum real rough at around 3-4 hundred rpm for about 5 mins then it seems to come out of it. Then at low rpm wile driving it hesitates. at about 2000 rpm it seems to come out of it but still dont feel like it has full power. and what would symptoms of one clogged cat and the other free flowing. exhaust makes weird high pitched kackle. caused by misfire? or what
goodys90 is offline  
Old 11-28-2018, 02:09 PM
  #17  
Audiworld Junior Member
 
Join Date: Oct 2015
Posts: 10
Default

So I know this is a super old thread but was there any resolution to this problem? I went to do my coolant temp sensor today and when I took off that hose at the rear of the valve cover (1.8T) it was full of that white crap.

Any help would be appreciate, thanks.
Jeffsg605 is offline  
Old 11-28-2018, 02:56 PM
  #18  
AudiWorld Super User
 
uberwgn's Avatar
 
Join Date: Sep 2009
Location: Boston MA
Posts: 6,670
Default

Jeff, is it cold where you are operating the car?
uberwgn is online now  
Old 11-28-2018, 03:33 PM
  #19  
Audiworld Junior Member
 
Join Date: Oct 2015
Posts: 10
Default

Yes, Chicago.

So a little background, at the end of last winter, I changed the thermostat, J-plug, coolant temp sensor, and that weird coolant connection at the rear of the engine. Car ran great until maybe September. Then I realized the temp gauge on the dash took a bit longer to reach operating temperature. Once it started getting cooler, it took a lot longer and now that its been cold, it'll often never reach operating temperature, even after driving 30-40 minutes. I do get heat pretty quickly although it never gets as hot as it usually does in the winter so I'm not sure its the thermostat. I do have a P3081 "Engine temperature too low" and a P2181 "Cooling System Performance".
Jeffsg605 is offline  
Old 11-28-2018, 03:35 PM
  #20  
Audiworld Junior Member
 
Join Date: Oct 2015
Posts: 10
Default

I guess I don't know if any of that is related but the point is that I went to change the Coolant Temp Sensor when I noticed that weird white crap.
Jeffsg605 is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
c6vetteman
2.0T FSI Discussion
30
09-18-2018 07:54 AM
Boosted01tt
1.8T Discussion
5
01-03-2017 06:55 PM
dougpaper
A6 (C7 Platform) Discussion
9
09-28-2015 02:47 PM
mug23
A4 (B5 Platform) Discussion
1
09-27-2015 11:28 AM
Stubborn, but Happy
Audi allroad
2
09-12-2015 01:58 PM


Thread Tools
Search this Thread
Quick Reply: Terrible gas mileage - white slime in valve cover vent hose


Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: