Motor Running Lean
Thread Starter
Burning Brakes
Joined: Sep 2013
Posts: 969
Likes: 141
From: Staten island NY
Motor Running Lean
Trying to dyno-tune my 2001 C5 the engine keeps running very lean. The mechanic is un-able to set the fuel reading. I installed a new Airaid air filter and air bridge. He cannot seem to find any vacuum leaks. Going to re-install the stock filter and air bridge to see if it makes a difference. MAF had a hir line cracked but the mechanic patched it.
Does anyone have this type of problem? Are we overlooking something??
Thanks in advance!!
Does anyone have this type of problem? Are we overlooking something??
Thanks in advance!!
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
Is it running lean at P/T ?? or at WOT or both ???----Also the MAF wires are so small they may have been permanently damaged after the cracked housing and won't read accurately anymore--Of course this could make it run lean---OR you have over -oiled the new airaid filter which will foul the MAF and it will read wrong---
Any idea what your LTFT fuel trims are during P/T ?
Any idea what your LTFT fuel trims are during P/T ?
Thread Starter
Burning Brakes
Joined: Sep 2013
Posts: 969
Likes: 141
From: Staten island NY
goes into the MAF, FAS then into intake manifold then the fuel is un adjustable, goes high low on scale no matter what type of adjustment you try to make. Stays too lean. Don't know what ur acronyms mean but it all starts as power is increased. Fog machine showed fog coming out from under intake manifold. I don't think there anything under there that would affect this, unless the manifold gaskets are leaking. I'll get back to it tomorrow
Dry filter installed
Dry filter installed
Drifting
Joined: Sep 2009
Posts: 1,719
Likes: 4
From: cinnaminson n.j.
St. Jude Donor '14
What is the air fuel ratio reading on the Dyno graph? What is he using to tweak the tune?
How much experience does he have with ls engines?
An intake manifold base gasket leak would give you an unstable idle and high idle fuel trim readings. If it's leaking bad enough it would set codes and possibly stall. It would not have a big effect on wot afr readings.
How much experience does he have with ls engines?
An intake manifold base gasket leak would give you an unstable idle and high idle fuel trim readings. If it's leaking bad enough it would set codes and possibly stall. It would not have a big effect on wot afr readings.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
goes into the MAF, FAS then into intake manifold then the fuel is un adjustable, goes high low on scale no matter what type of adjustment you try to make. Stays too lean. Don't know what ur acronyms mean but it all starts as power is increased. Fog machine showed fog coming out from under intake manifold. I don't think there anything under there that would affect this, unless the manifold gaskets are leaking. I'll get back to it tomorrow
Dry filter installed
Dry filter installed
Thread Starter
Burning Brakes
Joined: Sep 2013
Posts: 969
Likes: 141
From: Staten island NY
Not trying to offend anyone. I am an laymen don't do dyno tune. Just trying to relay a message second hand. Hopefully get some sound advice.
Last edited by Clancy209; Apr 9, 2014 at 04:15 PM.
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Le Mans Master
Joined: Aug 2007
Posts: 6,473
Likes: 297
From: Orange Park FL
Check your fuel filter if you haven't. I had a blockage making mine run lean...off and on. I found a piece of rubber in the filter that was partially blocking the hole. It drove me nuts for over 3 months.
Now logging right back at 12.6 - 12.8. It was hitting high 13's to 14.1
Just a thought.
Now logging right back at 12.6 - 12.8. It was hitting high 13's to 14.1
Just a thought.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
Would gladly like to help anyone who needs it----But whoever has given you these terms or words seems to not understand GM tuning at all----Otherwise he would use words that are known by all the LS community---in is diagnoses-----I would take the car so someone who is familiar with the GM LS based platform
Drifting
Joined: Sep 2009
Posts: 1,719
Likes: 4
From: cinnaminson n.j.
St. Jude Donor '14
Would gladly like to help anyone who needs it----But whoever has given you these terms or words seems to not understand GM tuning at all----Otherwise he would use words that are known by all the LS community---in is diagnoses-----I would take the car so someone who is familiar with the GM LS based platform
I have know idea what they are trying to do or how.
Thread Starter
Burning Brakes
Joined: Sep 2013
Posts: 969
Likes: 141
From: Staten island NY
Would gladly like to help anyone who needs it----But whoever has given you these terms or words seems to not understand GM tuning at all----Otherwise he would use words that are known by all the LS community---in is diagnoses-----I would take the car so someone who is familiar with the GM LS based platform
Last edited by Clancy209; Apr 10, 2014 at 07:48 PM.
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
It's not the bridge that is causing lean codes----Your problem of lean codes is directly related to the Granatelli MAF-----Go to any speed shop that works on Silverado's Corvettes or Camaro's and you see a garbage can full of aftermarket MAF'S taken off of customers cars----
Unless you have EFILIVE or HP tuners to correct the leaness--- the P/T fuel will never be right---And it takes hours and hours of data logging to dial in an aftermarket MAF -and the net results are minimal maybe 3-4 RWHP---
The stock MAF (screen and all if it came with one) is good for 500 HP---No reason to change it in most cases---
PLUS More importantly IF your car is an A4 the trans uses the MAF signal as one tool to set the line pressure--Eventually the tranny will grenade ---The aftermarket MAF's--untuned sends erroneous data to your ECM which in turn sets the line pressure to LOW
Unless you have EFILIVE or HP tuners to correct the leaness--- the P/T fuel will never be right---And it takes hours and hours of data logging to dial in an aftermarket MAF -and the net results are minimal maybe 3-4 RWHP---
The stock MAF (screen and all if it came with one) is good for 500 HP---No reason to change it in most cases---
PLUS More importantly IF your car is an A4 the trans uses the MAF signal as one tool to set the line pressure--Eventually the tranny will grenade ---The aftermarket MAF's--untuned sends erroneous data to your ECM which in turn sets the line pressure to LOW
Last edited by tblu92; Apr 18, 2014 at 11:35 PM.
Melting Slicks
Joined: Jul 2012
Posts: 2,507
Likes: 9
It's not the bridge that is casing lean codes----Your problem of lean codes is directly related to the Granatelli MAF-----Go to any speed shop that works on Silverado's Corvettes or Camaro's and you see a garbage can full of aftermarket MAFS taken off of customers cars----
Unless you have EFILIVE or HP tuners to correct the leaness the P/T fuel will never be right---And it takes hors and hours of data logging to dial in an aftermarket MAF -and the net results are minimal maybe 3-4 RWHP---
The stock MAF screen and all if it came with one is good for 500 HP---No reason to change it in most cases---
PLUS More importantly IF your car is an A4 the trans uses the MAF signal as one tool to set the line pressure--Eventually the tranny will grenade The aftermarket MAF's--unturned sends erroneous data to your ECM which in turn sets the line pressure to LOW
Unless you have EFILIVE or HP tuners to correct the leaness the P/T fuel will never be right---And it takes hors and hours of data logging to dial in an aftermarket MAF -and the net results are minimal maybe 3-4 RWHP---
The stock MAF screen and all if it came with one is good for 500 HP---No reason to change it in most cases---
PLUS More importantly IF your car is an A4 the trans uses the MAF signal as one tool to set the line pressure--Eventually the tranny will grenade The aftermarket MAF's--unturned sends erroneous data to your ECM which in turn sets the line pressure to LOW
Instructor
Joined: Feb 2014
Posts: 194
Likes: 1
From: Moon, VA
What was the baseline HP and torque before tuning? How involved was tuning the car? how much did it cost you?
Thread Starter
Burning Brakes
Joined: Sep 2013
Posts: 969
Likes: 141
From: Staten island NY
It took about 2 full days including installing gaskets, also had a hair line crack in MAF patched with a 24hr cure time. Lock stock and barrel close to $500.00 including parts and labor, and several dyno runs.
Last edited by Clancy209; Apr 15, 2014 at 05:45 PM.