Richen mixture
Thread Starter
Intermediate
Joined: Jan 2013
Posts: 47
Likes: 0
From: Leominster MA
Richen mixture
Well, the Tunercat is here and among other things, I'm wondering how exactly to richen things up a bit. My reasons are:
1. I've got more intake capacity with open element, gutted maf, 52mm, SLP runners, Edelbrock baseplate and 1.6 rockers.
2. I've got a freer-flowing exhaust.
3. I hate running hot.
4. I like to run a bit richer than 14.7 anyway.
On a $32, without trying to reshape the various fuel curves (and probably screwing them up), can I do this by modifying the injector flow rate? Set in stock bin at 23lb/hr, and I'm using stock injectors. Is it all as simple as changing the programmed size to, say, 21lb/hr and expecting the target AFR to go from 14.7 down to 13.4? I'm estimating maybe 10% more air flow capacity, and that would be around 10% richer. Is that a good hack, or is it just too easy to be true?
1. I've got more intake capacity with open element, gutted maf, 52mm, SLP runners, Edelbrock baseplate and 1.6 rockers.
2. I've got a freer-flowing exhaust.
3. I hate running hot.
4. I like to run a bit richer than 14.7 anyway.
On a $32, without trying to reshape the various fuel curves (and probably screwing them up), can I do this by modifying the injector flow rate? Set in stock bin at 23lb/hr, and I'm using stock injectors. Is it all as simple as changing the programmed size to, say, 21lb/hr and expecting the target AFR to go from 14.7 down to 13.4? I'm estimating maybe 10% more air flow capacity, and that would be around 10% richer. Is that a good hack, or is it just too easy to be true?
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Look at the BLMs first. They will tell you how your setup is running. Based on that you can modify and see where things go.
If you're running any ethanol it will result in a richer mixture (about 14.5), so be sure to factor that into your tuning.
If you're running any ethanol it will result in a richer mixture (about 14.5), so be sure to factor that into your tuning.
Safety Car
Joined: Sep 2001
Posts: 4,157
Likes: 554
From: Glenbeulah Wi
You cannot richen the mixture in closed loop nor do you want to. The computer is designed to use the Narrow band O2 sensor to keep the mixture at 14.7 to 1 and the engine will run fine at the mixture. The WOT mixture or AF needs to be around 12.8 to 1 and that is done by adjusting your power enrich factor and WOT change to AFR vs RPM table.
When the car is in closed loop it will try to hold 14.7 to 1 AFR and you need to check your fuel trims (BLM's) to see how close you are to 128. If the BLM's are not close to 128 you need to adjust the MAF sensor readings at the voltages you are operating at.
With real wild engine combinations you may need to run richer then 14.7 to 1 but your combination is not one of those. If you need to force a mixture richer then 14.7 to 1 you can do it but it requires quite a bit of knowledge on engine tuning to really understand what the engine wants and how to make it happen.
When the car is in closed loop it will try to hold 14.7 to 1 AFR and you need to check your fuel trims (BLM's) to see how close you are to 128. If the BLM's are not close to 128 you need to adjust the MAF sensor readings at the voltages you are operating at.
With real wild engine combinations you may need to run richer then 14.7 to 1 but your combination is not one of those. If you need to force a mixture richer then 14.7 to 1 you can do it but it requires quite a bit of knowledge on engine tuning to really understand what the engine wants and how to make it happen.
Thread Starter
Intermediate
Joined: Jan 2013
Posts: 47
Likes: 0
From: Leominster MA
I've seen 142 on blms. That looks pretty close to my 10% guess. So what I should do is run through the MAF tables and increase the g/sec for each 'volts' reading by (e.g.) 10% or whatever value gets the blms close to 128 ?
Last edited by leoman; Apr 18, 2013 at 02:46 PM.
