Closed-loop fuel enrichment
07-08-2010, 02:37 PM
#1
Closed-loop fuel enrichment
As some of you may or may not know, even though we can use something like the AEM F/IC to adjust fuel and ignition under open-loop conditions (wide open throttle), we still have no way to compensate for closed-loop operation (part throttle). Because of this, it's possible for us F/I guys to spend 50% or more of our drive time in conditions MUCH too lean for the engine.
I've been in contact with a company over the past few weeks trying to find a solution to be able to adjust my A/F trims while in closed-loop mode. One of their units arrived on my doorstep earlier this morning and I spent a couple of hours troubleshooting and experimenting with it... So far the results have been very positive! I've been able to successfully trick the ECU into thinking that the car is running too lean and therefore dump more fuel in to the engine.
Prior to adding the unit:
A/F at idle: 14.6 - 15.1 with engine fully warmed up
Short term fuel trim: -1.00 - 0.88 with engine fully warmed up
After adding the unit:
A/F at idle: 13.8 - 14.1 with engine fully warmed up
Short term fuel trim: 2.10 - 2.85
That's nearly 1 full point of adjustment!
I still need to do some more real-world testing and work with the guys to get some more adjustment out of the unit, but things are looking good for those of us who've been waiting for some sort of solution for this! I'm hoping that I can get them to produce some custom units that are capable of tying in to the F/IC for better adjustment across the board.
Stay tuned for more info!
I've been in contact with a company over the past few weeks trying to find a solution to be able to adjust my A/F trims while in closed-loop mode. One of their units arrived on my doorstep earlier this morning and I spent a couple of hours troubleshooting and experimenting with it... So far the results have been very positive! I've been able to successfully trick the ECU into thinking that the car is running too lean and therefore dump more fuel in to the engine.
Prior to adding the unit:
A/F at idle: 14.6 - 15.1 with engine fully warmed up
Short term fuel trim: -1.00 - 0.88 with engine fully warmed up
After adding the unit:
A/F at idle: 13.8 - 14.1 with engine fully warmed up
Short term fuel trim: 2.10 - 2.85
That's nearly 1 full point of adjustment!
I still need to do some more real-world testing and work with the guys to get some more adjustment out of the unit, but things are looking good for those of us who've been waiting for some sort of solution for this! I'm hoping that I can get them to produce some custom units that are capable of tying in to the F/IC for better adjustment across the board.
Stay tuned for more info!
07-08-2010, 04:43 PM
#5
J36Twingt28r's,nextgt30r
^^very true i haven't run into this problem yet cause of not being boosted but will soon be 
. and anything to help the j-series community is greatly appreciated by all, so i say goodluck my friend and 
.
. and anything to help the j-series community is greatly appreciated by all, so i say goodluck my friend and .
07-08-2010, 07:31 PM
#6
One minor update... I spoke with the guys again this afternoon and they're going to send me a new unit with some adjusted values to hopefully give me a little larger tuning range. I asked them to send a unit that wasn't covered in epoxy so that I could maybe fiddle with it myself (think digital potentiometer for use with the F/IC). We'll see what shows up.
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07-16-2010, 02:17 PM
#12
One more quick update. They are building one more custom unit for me with certain points on the board exposed so that I can add a piggy-back unit in order to control it from the F/IC.
Also, I'm going to do some more experimenting over the next couple of weeks and try to build a unit from scratch. That should keep costs to a minimum. If I can successfully build and test the unit, I'll post schematics and a parts list for everyone. I can also offer to build them myself (for a fee) and send them out for anyone afraid of starting their house on fire.
If all else fails, the piggy-back unit will be cheap enough to build and add on to the existing units.
Also, I'm going to do some more experimenting over the next couple of weeks and try to build a unit from scratch. That should keep costs to a minimum. If I can successfully build and test the unit, I'll post schematics and a parts list for everyone. I can also offer to build them myself (for a fee) and send them out for anyone afraid of starting their house on fire.
If all else fails, the piggy-back unit will be cheap enough to build and add on to the existing units.
Last edited by bmeyer; 07-16-2010 at 02:24 PM.
07-17-2010, 06:21 PM
#17
Team Owner
Very interesting. What about people that are running larger injectors and need to go the other way, will it be able to lean it out under part throttle?
07-18-2010, 12:14 PM
#18
The old unit that I had used an analog potentiometer which would change the O2 values across the board by a static percentage. The new units though will connect to the F/IC via its O2 skew wires. They will feed a digital potentiometer in place of the analog potentiometer and allow for continuously variable settings on the module based on the values in the F/IC's O2 tables.
In order to DIY, you will need some sort of ability to program PIC chips. If you're unable to do that, I can probably buy a bunch of chips, program them and send them out. Everything else should be relatively simple to wire up though.
Yes, this unit will work with both auto and manual trans vehicles. There are no differences in the operation of their O2 modules.
Right now, I'm just focused on phase one which will only enrich the fuel mixture. As I begin developing my own module, I will look into the possibility of leaning out the A/F as well.
In order to DIY, you will need some sort of ability to program PIC chips. If you're unable to do that, I can probably buy a bunch of chips, program them and send them out. Everything else should be relatively simple to wire up though.
Yes, this unit will work with both auto and manual trans vehicles. There are no differences in the operation of their O2 modules.
Right now, I'm just focused on phase one which will only enrich the fuel mixture. As I begin developing my own module, I will look into the possibility of leaning out the A/F as well.
Last edited by bmeyer; 07-18-2010 at 12:17 PM.
08-11-2010, 09:28 AM
#34
Update: 8/11/10
I worked on the controller unit a little this past weekend, but had some problems with the micrcontroller I was using so I ordered a new one. It should be here by the weekend. I'll need to write a new program for the new chip, but that shouldn't take too long.
Hoping to run a few more tests this weekend - time permitting.
I worked on the controller unit a little this past weekend, but had some problems with the micrcontroller I was using so I ordered a new one. It should be here by the weekend. I'll need to write a new program for the new chip, but that shouldn't take too long.
Hoping to run a few more tests this weekend - time permitting.
Last edited by bmeyer; 08-11-2010 at 09:32 AM.
08-12-2010, 11:59 PM
#35
Good work man
In your first post you said "nearly 1 full point of adjustment"
Does that mean that you will see that much of an adjustment throughout the entire range of normal driving minus wot?
For example, I know with my 5at turbo that if im cruising in 5th gear at 70mph and I hit the throttle a little bit to drop to 4th and build some boost, I will have the rpms around 3500 with the a/f around 14.0-15.0 give or take. Wayyyy to lean even for a few psi. This unit will take that a/f of 14-15 to roughly 13-14 instead?
In your first post you said "nearly 1 full point of adjustment"
Does that mean that you will see that much of an adjustment throughout the entire range of normal driving minus wot?
For example, I know with my 5at turbo that if im cruising in 5th gear at 70mph and I hit the throttle a little bit to drop to 4th and build some boost, I will have the rpms around 3500 with the a/f around 14.0-15.0 give or take. Wayyyy to lean even for a few psi. This unit will take that a/f of 14-15 to roughly 13-14 instead?
08-13-2010, 12:05 AM
#36
Also, with use of the F/IC you can make a 0-2pt. adjustment at any point in the RPM range - real-time! So for example, at idle, you don't need the additional fuel so you'll have the F/IC set this unit at 0, but at 1/2 throttle cruising down the freeway you can tell it to add .5% more fuel (etc...).
08-13-2010, 12:27 AM
#38
Yeah, it will connect to one of the two pink O2 lines coming off of the F/IC that are currently unused. The other end of the unit will tie into the ECU extension harness that the F/IC plugs in to.
There is a table in the F/IC similar to the fuel table that, with a little work, you can basically set your target A/F for a given RPM and load and then fine tune it with your fuel table.
As far as fuel trims under part throttle, it all depends on how much boost you're pushing at a given point. 12:1 might be a little rich for low-mid boost, but your tuner could probably give you a better idea of where you should be.
In your case, I'd probably contact Rodney and see what sort of information he can give you.
There is a table in the F/IC similar to the fuel table that, with a little work, you can basically set your target A/F for a given RPM and load and then fine tune it with your fuel table.
As far as fuel trims under part throttle, it all depends on how much boost you're pushing at a given point. 12:1 might be a little rich for low-mid boost, but your tuner could probably give you a better idea of where you should be.
In your case, I'd probably contact Rodney and see what sort of information he can give you.
08-13-2010, 07:08 AM
#39
As much as i HATE to post this. im going to because i need/want to know since i have the s/c...
So, will this work in conjunction with the ACM or independently OR FI/C only? If FI/C only, could it be modified to work with the ACM or by itself? Also, will this help with the "surge"?
If any of the above then id def want!
So, will this work in conjunction with the ACM or independently OR FI/C only? If FI/C only, could it be modified to work with the ACM or by itself? Also, will this help with the "surge"?
If any of the above then id def want!
08-13-2010, 08:50 AM
#40
No efforts are being made to support the ACM for one primary reason... The ACM does not have a programmable output on it.
It would probably take me several hundred hours to build a unit capable of that and would cost as much as or more than an F/IC. :/
It would probably take me several hundred hours to build a unit capable of that and would cost as much as or more than an F/IC. :/