MyE28.com

LOL I guess I could join the club and say that I have you you could have ( my price would have been just a ride in the car!)

But getting a new one is better, you know it works....

Um,
Duke is half right, and Greg, the WOT switch is only a small part of the problem if your using a 059 ECU. Even if the car is not seeing the WOT signal, the top load line in the part throttle map will be very close to the WOT map, trust me. It should run pretty close to the desired AFR w/o the WOT signal. Your problems are elsewhere. Im not saying you should not fix the switch, but dont be complacent that its your only problem.

The 059 ECU goes into a open loop condition anytime the AFM flapper is 50% or greater open condtion(2.5V or greater). It stops using O2 feedback and goes into accel enrichment. This gets you to ~13.5:1 AFR from maps in a stock engine. The O59 ECU pressumes with a load greater than 2.5V on the AFM that your needing accel enrighment. Why your car is runing stochio until 4.xk rpm is due to improper tuning of the FMU(you know this now).

Are you using the TCD chip?

RussC

Duke M535ti wrote:

GregATL wrote:Well I found a problem most likely the problem. As Todd suggested TPS. It works fine and all the contacts are good. Except that it won't turn far enough to engage the WOT switch when on the car.

Why would this cause your problem? From what I know, the WOT switch takes the ECU open loop mode and the ECU goes to internal fuel maps. If it does not do this, the ECU will stay closed loop and should not be going rich.

Russ,

PLEASE stop using "Um" to start every post.

There, I feel better.

Uuu,
Im thinking

RussC

Sweeney wrote:Russ,

PLEASE stop using "Um" to start every post.

There, I feel better.

russc wrote:Um,
Duke is half right, and Greg, the WOT switch is only a small part of the problem if your using a 059 ECU. Even if the car is not seeing the WOT signal, the top load line in the part throttle map will be very close to the WOT map, trust me. It should run pretty close to the desired AFR w/o the WOT signal. Your problems are elsewhere. Im not saying you should not fix the switch, but dont be complacent that its your only problem.

The 059 ECU goes into a open loop condition anytime the AFM flapper is 50% or greater open condtion(2.5V or greater). It stops using O2 feedback and goes into accel enrichment. This gets you to ~13.5:1 AFR from maps in a stock engine. The O59 ECU pressumes with a load greater than 2.5V on the AFM that your needing accel enrighment. Why your car is runing stochio until 4.xk rpm is due to improper tuning of the FMU(you know this now).

Are you using the TCD chip?

RussC

Duke M535ti wrote:

GregATL wrote:Well I found a problem most likely the problem. As Todd suggested TPS. It works fine and all the contacts are good. Except that it won't turn far enough to engage the WOT switch when on the car.

Why would this cause your problem? From what I know, the WOT switch takes the ECU open loop mode and the ECU goes to internal fuel maps. If it does not do this, the ECU will stay closed loop and should not be going rich.

Russ,

I mentioned this two days ago, that it was an FMU or AFM tuning problem.

Although you've confirmed the FMU is raising the fuel pressure, it appears you might be getting too much fuel pressure. This is the only adjustment you have other than the AFM which gives you some control over injector pulse width.

Does the WBO2 you're using have a logging capability? Something to consider looking at, tap the AFM signal into the ECU and monitor the voltage to the ECU when you are off boost and when you start to make boost. If you see the AFM voltage swing to quickly towards 5 volts, the injector pulse width could be increasing more quickly than needed. This would mean tightening the spring tension which obviously would impact your idle A/F ratio. To reset the idle A/F ratio would require moving the wiper arm on the shaft to re-establish the idle A/F ratio at stoich.

FWIW: I know of a place you could probably do your pulls and not be bothered by LEs.

Rich

Thanks for posting the additional info regarding the voltage point at which the 059 adds the acceleration enrichment.

Seems to me Greg could still have probelms with either his FMU and AFM adjustments.

Rich

As far as tuning the FMU goes, there really isn't w whole lot to do. By putting in the restrictor and opening the bleed off valve all the way you are limiting yourself to adjusting the static pressure.
I also swapped out the check valve on the bleed off line with the BMW one from the EVAP system. It flows much more air. This was in an attempt to reduce fuel pressure rise on boost and help with the richness issue. I also ran it with the bleed off valve vented directly to the atmosphere to see how that affected fuel pressure rise. Still too rich up top.

IMO the only way to make the FMU more tunable (which I feel it needs) is to provide a larger bleed off system. Then you would have much more tunability. Having one variable maxed out limits what can be accomplished through pressure rise combined with varying bleed rates.

It still wouldn't be perfect but definitely better.

Russ, I appreciate the feedback. So you think my AFM is too tight. Just where should it be set at?

It is currently set this way;

Tightened AFM until ECU had trouble maintaining stoich. bouncing around 14.9-15.6:1.

Backed it off 2 clicks from there.

What did I do wrong if anything?

I ask because I claim to be a newb to AFM tuning.

I turned mine about 27 clicks tighter from stock. I have an AFR gauge to see how stoich I am at idle and cruise.

I turned mine about 27 clicks tighter from stock. I have an AFR gauge to see how stoich I am at idle and cruise.

Tightened AFM until ECU had trouble maintaining stoich. bouncing around 14.9-15.6:1.

Backed it off 2 clicks from there.

What did I do wrong if anything?

Greg,

There are three independent adjustments that can be made to the AFM and they interact with each other.

You know about the spring tension adjustment, however the other two are CO, which is bleed air and used to fine adjust the CO at idle only. The other adjustment allows you to reposition the wiper on the shaft.

When you did the spring tension adjustment was this only at idle or did you also check your A/F ratios at higher RPM and on boost ?

If this is at idle only and you haven't checked what's happening at the point at which boost starts to build, you probably need to do some additional adjusting of the AFM.

Before you do anything else, you need to rig up a test configuration that allows you to monitor the AFM output voltage, A/F ratio and the boost, if you're not doing the tuning on a Dyno. What you want to fully understand is when is the AFM dropping below the 2.5V trip point for acceleration enrichment. If the spring tension isn't high enough, this could be occurring too quickly leading to your rich A/F ratios at mid RPM when you are starting to make boost.

As an example lets say you find the AFM output voltage dropping below 2.5 volts at 3000 RPM due to boost starting to build with the A/F ratio following this and going rich during a gradual pull (no WOT stuff we want to avoid the TPS causing the ECU to go to default maps for WOT). This would indicate the AFM spring tension is too light and the boost which is starting to develop is opening the flap too quickly. Therefore you should tighten the spring, but tightening the spring causes the idle A/F ratio to go lean as you've already seen. What you need to do to correct this is reposition the AFM wiper on the shaft at idle to re-establish just rich of stoichiometric A/F ratio at idle. Once you 've done this then you can retest the AFM output at the higher RPM value and see what happens. Hopefully you should see the AFM output voltage track better and not swing below 2.5 volts, with A/F ratios staying slightly rich of stoich in open loop mode. You'll need to work slowly a couple of notches of spring tension at a time. Once you have something that you fell happy with using gradual partial throttle pulls to mid RPM levels, start pulling to higher RPM levels, again avoiding WOT. If you're happy with the AFM adjustment at higher RPM then do a WOT pull and check the A/F ratio.

BTW, do all the AFM tuning in open loop mode, also clear any adaptations in the ECU by disconnecting the battery before starting your initial checks. Also record EVERY change you make in a note book as you do the adjustments. At a minimum, I'd record the AFM output voltage, RPM at which you see the acceleration enrichment, A/F ratios, and boost values.

HTH

Rich

Thanks for the in depth explanation about the AFM Rich. When I get a chance in a few weeks I will go through those steps thoroughly. Until then I'll drive it like it is. It's not too bad now. I just know it could be better.

Also I have run out of free time for now so it'll have to wait. There are more pressing things to deal with currently.