Quick Q's
 

I got some interesting readings from my SAFC when I finally got it installed into my '88 TII yesterday. When I got it wired in, we were monitoring RPM's, Throttle Position, and Airflow. No chance to take it to the dyno until next week, but I saw some interesting things and wanted to get some feedback from some other FC3S owners.

First, I noted that the RPM's seem to be a lot lower than the tach, by 2-300 rpms at points I was checking. Is this normal?

Second, my TPS readings seemed to be a little bit screwy... I'm hoping this is just an idication that I need to adjust the TPS, but basically when I touched the gas, I went almost instantly to 100% throttle. Voltage reading on the sensor was about .93 at idle once the car warmed up... but would jump to 4 volts almost as soon as I put pressure on the accelerator. Is it possible to set the TPS by this output, or should I just wait until I have my hands on a multi meter tomorrow and do it by reisistance at the plug?

If these subjects have been covered before, some links would be much appreciated, I did a search last night and this morning and didn't find a lot of helpful information on my particular issues.

Thanks

Some additional info... the SAFC is pretty accurate on the revs at idle... it's just when you rev the engine that there is a discrepancy between it and the tachometer.

Okay, I've figured out the TPS issue with a little more research. I've got it set at 1.005 V showing on the sensor input screen on the SAFC and the car is running way better than it's been. We tried setting the TPS by reisistance and it didn't improve brought the voltage down to about 0.745 at the ECU.

It would be nice if we could have a sticky FAQ at the top of this forum with some of the common information, or links to common information like at the top of the 2nd Generation Forum. I've found those links to be very informative, and when searching it took about 4 hours and 3 different searches to learn that the S4 FC3S has a narrowband TPS and that the throttle signal is going to be 100% by a third of the pedal travel.

I'm about to embark on a search for some further details of setting up the SAFC using the boost sensor for the throttle input. Anyone want me to post links to my findings?

http://www.1300cc.com/howto/how2/safc.htm
at the bottom explains how to regulate the safc

Using the Boost Sensor in a S4
 

Thanks, I found that on Thursday, plus I located the setup for running off the Boost Sensor versus the TPS since I have a S4.

For those of you interested, and since I didn't find anything concise existing in this forum, the setup is fairly simple.

Essentially what you need to do, is install the SAFC, with the throttle signal coming from the boost sensor, then go out for a drive and watch your throttle %. You want to have a boost guage that shows vaccuum for this as well, so I'm not sure what the N/A guys might want to do with this.

Essentially when you are at 0 boost (no vaccuum, no boost) then this is the point where the engine starts to load. You want to figure out the percentage throttle that displays at this stage and this percentage will be the crossover point from the low throttle to the high throttle map. To play it safe, I would probably actually pick a few percent lower to actually switch over to the high map.

Tune your low throttle map for fuel economy, tune the high throttle map for 11.5:1 AFR for safety. Should see a huge improvement.

We ran out of dyno time on Thursday, so I didn't get a chance to actually make the changes. If tonight is slow then I may be able to change the throttle input over from the TPS to the boost sensor. I'll add any additonal notes as I encounter them.

tps vs pessure sensor.
 

did you use the pressure sensor signal from the ecu or did you tap straight in the engine compartment. have you done any testing to see if this is safe ? if so how were your reults ? and can you explain how you did them. im in the procces of soldering my safc so if its better doing it your way let me know now ! thanks

Doriftwolf any new updates as far as the boost sensor hook up on the S-afc ?