Too much air flow going through MAF Sensor...
Senior Member
Joined: Nov 2005
Posts: 267
Likes: 0
From: Port Orange, FL
Originally Posted by Marc Carpenter
If you have been reading many of the posts here you would know that there has been a problem with many of the '04's running lean from the factory, with many being in the 14/1 to 15/1 range. Mine included. The easiest way to compensate and to keep your truck running safely is to have it custom tuned.
Senior Member
Joined: Feb 2004
Posts: 10,390
Likes: 10
Originally Posted by weaseled
If there is a lean condition from the factory, it's not going to be in the 14.1:1 to 15.1:1 range. With stoich being 14.5:1, then a curve that dips to ~14.1:1 as soon as the PCM senses WOT and slowly crawls to 15.1:1 would be acceptable. If the truck in question had some sort of forced induction that would be a different story... If anything 14.1:1 is getting close to causing a rough idle due to a rich condition.
You forget something. Marc was referring to Open Loop operation, not Closed Loop where the A/f's are determined by feedback from the O2's.
BIG difference. 14-15:1 in open loop (and under high load) is definitely running lean with consequences.
Try Searching - this has been covered exhaustively already...
Cheers
Grog
Senior Member
Joined: Aug 2006
Posts: 1,274
Likes: 6
From: Simi Valley CA
Originally Posted by Marc Carpenter
If you have been reading many of the posts here you would know that there has been a problem with many of the '04's running lean from the factory, with many being in the 14/1 to 15/1 range. Mine included. The easiest way to compensate and to keep your truck running safely is to have it custom tuned.
Senior Member
Joined: Jul 2001
Posts: 2,803
Likes: 1
From: North Canton, Ohio
Originally Posted by MeanGene
When you had your truck tuned to compensate for the lean mixture did the fuel mileage change?
My vehicle has been one of the test mules for Mike Troyer since day one.
When I discuss gas mileage I can only compare "stock" to "present" conditons which include Mikes custom tunes ( I normally run the 93 Perf tune), Air Force1, Magnaflow Lightning Style exhaust, and his electric fans.
Stock 13/15, present 16/18.5.
My truck is an '04 Supercrew 4x4, 5.4, 3:73LS running 285/70/17 Kuhmos on 17x9 Mickey Thompson Classic-2's.And I do drive it like it was stolen...
I removed my AS leveling kit, and lowered my truck 2 1/2"/ 5" and picked up an additional 2 mpg highway which is reflected in the numbers I previously mentioned.