PCM Diagnostics & Tuning HP Tuners | Holley | Diablo
Sponsored by:
Sponsored by:

A/F way off.

Old 12-18-2009, 04:12 PM
  #1  
Teching In
Thread Starter
iTrader: (1)
 
boysiner's Avatar
 
Join Date: Jan 2008
Location: Wichita,KS
Posts: 34
Likes: 0
Received 0 Likes on 0 Posts

Default A/F way off.

Wasnt sure which section to put this in but I took my car(details in sig) to my tuner the other day and my a/f is at 16.1 and as high as 16.9. what would cause this to get that out of wack. i replaced o2 sensors but have not replaced the maf. Could the maf throw it off that bad or is it just in the mods and the ecu? Im confused. Any thoughts or opinions are most appreciated. Thanks.
Old 12-18-2009, 09:00 PM
  #2  
TECH Senior Member
iTrader: (25)
 
2xLS1's Avatar
 
Join Date: Nov 2001
Location: Warr Acres, OK
Posts: 5,649
Likes: 0
Received 8 Likes on 8 Posts

Default

1. Check fuel pressure
2. Clean MAF
3. Make sure the short hose between the pcv valve and the manifold is not torn and leaking. I'm seeing this more and more lately.
Old 12-18-2009, 11:33 PM
  #3  
Teching In
Thread Starter
iTrader: (1)
 
boysiner's Avatar
 
Join Date: Jan 2008
Location: Wichita,KS
Posts: 34
Likes: 0
Received 0 Likes on 0 Posts

Default

I have done the first two items myself. I checked the fuel pressure at idle only tho and it read somewhere around 60 if i remember right. it was where is should have been. the guy i took my car didnt say anything about low fuel pressure at idle. im not sure if he is telling me everything. And I cleaned the heck out of the maf. Sprayed it down several times with maf cleaner. I will look at the third suggestion.
Old 12-19-2009, 12:41 AM
  #4  
FormerVendor
iTrader: (45)
 
Frost's Avatar
 
Join Date: Jul 2005
Location: Richmond VA
Posts: 5,913
Likes: 0
Received 2 Likes on 2 Posts
Default

You will know it's the MAF failing if your LTFTs are excessively high...
Old 12-19-2009, 10:17 AM
  #5  
TECH Senior Member
iTrader: (25)
 
2xLS1's Avatar
 
Join Date: Nov 2001
Location: Warr Acres, OK
Posts: 5,649
Likes: 0
Received 8 Likes on 8 Posts

Default

Steve, I've seen +25 ltfts with a clean working MAF and only the hose leaking.
Old 12-19-2009, 12:39 PM
  #6  
Teching In
 
copson20's Avatar
 
Join Date: Sep 2008
Posts: 3
Likes: 0
Received 0 Likes on 0 Posts
Default

Did you tune after the headers were installed?
Old 12-19-2009, 06:41 PM
  #7  
Teching In
Thread Starter
iTrader: (1)
 
boysiner's Avatar
 
Join Date: Jan 2008
Location: Wichita,KS
Posts: 34
Likes: 0
Received 0 Likes on 0 Posts

Default

No tune after headers were installed but the car acted like a turd before i did that. i put headers on it and off road y originally thinking the cats were clogged and that was the problem. but it was not.
Old 12-20-2009, 09:37 PM
  #8  
11 Second Club
iTrader: (14)
 
NSSANE02's Avatar
 
Join Date: Mar 2008
Location: Houston
Posts: 1,434
Likes: 0
Received 0 Likes on 0 Posts

Default

Is that the reading at idle or wot? Might want to disconnect the maf next time you have a wideband on it and see what happens. Also if you're talking about wot afr then you need to test your fuel pressure at wot.
Old 12-21-2009, 08:42 AM
  #9  
Moderator
iTrader: (11)
 
jimmyblue's Avatar
 
Join Date: Mar 2002
Location: East Central Florida
Posts: 12,605
Likes: 0
Received 6 Likes on 6 Posts

Default

Question #1 - sensor in the tailpipe, or what? You
can get all wrapped around the axle if you believe
the wrong thing.

Bad O2 sensors almost always result in a rich-actual
closed loop operation.
Old 12-21-2009, 11:12 AM
  #10  
FormerVendor
iTrader: (45)
 
Frost's Avatar
 
Join Date: Jul 2005
Location: Richmond VA
Posts: 5,913
Likes: 0
Received 2 Likes on 2 Posts
Default

Originally Posted by 2xLS1
Steve, I've seen +25 ltfts with a clean working MAF and only the hose leaking.
me too, but air leaks like that with large trimming usually result in fat WOT AFRs
Old 12-21-2009, 11:33 AM
  #11  
Banned
iTrader: (1)
 
CalEditor's Avatar
 
Join Date: Feb 2008
Location: Rock Hill SC
Posts: 514
Likes: 0
Received 1 Like on 1 Post
Default

I am aware of a glitch in a Tuning Software package that has the Target AFR Stoich formulated backwards. If it was set for 14.1 to 1 (E10) with the software I am refering to the Actual AFR would be 15.1

What Software use to tune it?


Thread Tools
Search this Thread

All times are GMT -5. The time now is 12:17 PM.