Rpeck

I am thinking I might give it a shot. With the S4 TPS, I am thinking at the very least I will get better fuel economy, I look at the throttle level at 85MPH on the freeway and it is running %100 (I.E. my high map) and I am not even boosting.

Who is currently running there S-AFC on the boost sensor (as opposed to the TPS), and how do you like it? Was it a bitch to tune? Thanks for the input.

Also, how do you have yours set, I plan to tune, but I would like a baseline to start from.


Thanks,

-Robert

RETed

The Zenki cars run a "narrow range" TPS, which goes full open at around 1/3rd throttle input.  Live with it, else go stand-alone EMS.

Trying to use the boost sensor as the primary load sensor for your car, with the stock ECU, will possibly cause you to blow your engine.  The boost sensor is only used to adjust ignition timing - it does not affect fuel delivery.



-Ted

Rpeck

but the AFM does affect the fuel flow, and there is a pretty direct corolation between boost and aif flow right? I have been readign where the DSM guys swear by setting it up via the boost sensor even though that have a full range TPS.

Bambam7

I tried.. I couldn't get it to work well, maybe because of my turbo lag.
It doesn't matter that the stock boost sensor reading doesn't have an effect on fuel delivery, it delevering a reading to the S-AFC in place of the TPS to increase fuel.
By just using the TPS, you have to do a lot of estimating as to what certain boost levels will be at given throttle positions. By using the boost sensor, you don't. The advantage is that you won't run lean by getting more boost at a given throttle level than expected, therefore saving your engine from detonation!
I might try it again, with a different tuning approach.

Aaron Cake

iTrader: (1)

Use an aftermarket 0-5V boost sensor (even though the stock sensor is a 0-5V unit). You'll get a much better result. I am currently unsure as to why this is, because it should be a "6 of 1, half a dozen of the other" type situation. I have not put a lot of effort into it since I am going Microtech...

Rpeck

Hmm interesting. Do you have a recomendation Aaron?

I might give it a shot, just keep the boost at stock levels so I don't risk fuggin anything up, until i decide how I like it.

Aaron Cake

iTrader: (1)

MSD and Crane both make sensors that are designed to be used with their retard boxes (that sounds so funny taken out of context). They seem to work alright (or at least did when I tried). But I only ran like that for a few days because I was borrowing the sensor.

gsracer

When I bought my safc last summer I wired it into the pressure sensor. It gives off 0-5 volts just like the TPS sensor. I have all stock injectors for now, but a pair of 720's are sitting on my desk and should be going in soon. I haven't been back to the dyno since last march, but hopefully I can get it all together soon. As it is I have the safc cross over from lo-thrtle map to hi-thrtle map at around .5bar. I trust the primary injectors to handle up to this point, at which point I'd want to start adding more fuel. Since the secondaries don't fire until 3800, I'm actually going to put the 720's in to replace my 550 primaries. Under .5bar I'll dial back the primary injectors till they are at the stock values again, and that will be my low thrtl map. After I get on the dyno, I'll get some values i like for my hi thrtle map, plug them in and I'm done.

Rpeck

Well, I have dual stage boost controller. And my thought was to have the low settings set for more or less ~8 PSI, (stage one on my boost controller) and have the high settings set to common a boost level just a hair above what my max of stage one would be... so it therefore will go to the high map only when I click into the 2nd stage of my boost controller.


will it work? How's it sound? I just sounds more logical to me .. I mean if it's based on boost (thats when you really need the fuel) it sounds safer than based on where your foot is on the pedal. I.E going up a steep incline Etc. I mean it has to be better than the current `%30 throttle and the S-AFC thinks I am WOT

RETed

The relation of MAP sensor output to fuel delivery requirements are not typical linear - this complicates things.

So what you're saying is you're trying to eliminate the stock AFM, use some other MAP sensor, and plug the S-AFC in to mod the signal going back to the stock ECU into the AFM input?

This is going to get interesting...


-Ted