Why is my dry-shot lean at lower bottle pressure?
Thread Starter
10 Second Club
Joined: Nov 2002
Posts: 1,471
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From: Berkeley, California
Why is my dry-shot lean at lower bottle pressure? I am spraying a 125-shot downstream from the MAF using an IAT-tricker to pull timing and add fuel. With commanded AFR = 10.6:1, wideband measured AFR is 12.5-12.8:1 I reduced the commanded AFR to 10.4:1 in preparation for stepping up to a 150-shot. The result was a leaner AFR, wideband measured above 13:1 The only difference (other than commanded AFR) was bottle pressure. Bottle pressure for the rich pass was 900 psi. Bottle pressure for the lean pass was 775 psi. May not be related to bottle pressure but I can’t see any other difference. Any ideas?
if you dont hit the MAF with enough N20 it wont richen it up as much.
We used to put the nozzle closer to the MAF to richen it up.
Put a fresh bottle in and try it before you change anything.
We used to put the nozzle closer to the MAF to richen it up.
Put a fresh bottle in and try it before you change anything.
I'm not a big fan of the resistor mod. If going this direction I would just use the Interface to do your fueling. Its much more complicated than a simple resistor to accomplish a post maf dry shot.
Nick
Nick
Thread Starter
10 Second Club
Joined: Nov 2002
Posts: 1,471
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From: Berkeley, California
ATV, Thanks but I am spraying after the MAF - nozzle is in the bellows between MAF and TB.
Nick, the interface is a good suggestion but I would still like to understand why I am seeing an unexpected lean condition. Charts of two passes are attached.
Nick, the interface is a good suggestion but I would still like to understand why I am seeing an unexpected lean condition. Charts of two passes are attached.
Last edited by Gary Z; Oct 9, 2009 at 12:53 PM.
Your fueling will be dictated by your maf and if it is a pressure related issue I wouldn't be surprised if some of the nitrous on the higher pressure pulls were maybe cooling the maf and causing the maf to add more fuel.
Any particular reason you're running your dry setup like this? You have a nice setup in your sig so why run your spray setup like this?
Any particular reason you're running your dry setup like this? You have a nice setup in your sig so why run your spray setup like this?
Thread Starter
10 Second Club
Joined: Nov 2002
Posts: 1,471
Likes: 3
From: Berkeley, California
Any particular reason you're running your dry setup like this? You have a nice setup in your sig so why run your spray setup like this?
