[broncomike]

I've been trying to improve idle and realized that the ISCDC value is stuck on 12.51. Any thoughts has to why this would happen. software, hardware, bad IAC?
Using:
TunerPro RT
GUFB
A9L

[LeadHead]

I could be wrong, but I believe 12.51 is the minimum it will report. It may indicate you have an air leak somewhere.

[85GT]

What is it idling at and what do you have it set for? Did you change the right value?

[broncomike]

Thanks guys for the reply.
Let me back up and start with why I'm needing to make tuning adjustments. I'm having problems with surging idle. Once the motor gets pass the first 10 seconds after starting it seems to be fine...no surging. I'm new to tuning and have read over the MD idle air 101 article several times and decided to give it a shot. When I started working through the steps I noticed that the ISCDC reading was stuck on 12.51. Everything I tried has no affect on the read out. (i.e. rev engine, cold start, hot start, disconnect IAC, adjust throttle stop,etc). The motor idles at around 670-700rpm after surging stops and the NUBASE is still set at 672. I haven't changed any values yet becasue of the apparent issue with the ISCDC reading. Thanks again for any help.

[85GT]

Try closing the throttle some, say 1/2 a turn out and see if it goes up.

[broncomike]

Tried adjusting throttle down still no change from 12.51. Checked voltage at IAC 11.8 and checked IAC with Ohm meter and it appears okay. It really seems to be a software issue with how the dashboard is interpreting the data. Would this be a problem with the GUFB.adx file?

[decipha]

no its a mechanical problem, its not adding air because it can't reach idle speed

if you unplug the iac connector and the engine still idles at the same rpm then the engine is getting too much air

since you have a surging idle too then you have an air leak

[broncomike]

Mechanical problem okay......however the surging only occurs after start up and last for about 10 sec or if I hold the throttle down at about 2000rpm and release slowly it settles to a smooth 670-700rpm. Once it starts idling its very stable. If I unplug the IAC the motor will die so it would appear that some of the required air is coming in through the IAC. What seems strange is that the ISCDC 12.51 value never changes....ever. Start up, shut down, keyon/engineoff.
Thanks for the help!

[TwinSCs]

The problem may be with your ADX file or the way you have your dashboard setup. It's been a while since I've used Tunerpro but I remember not being able to log ISCDC also, the value on the dashboard never changed. IIRC I found a different ADX that worked but it's been a while since I've played with it.

[decipha]

Everything I tried has no affect on the read out. (i.e. rev engine, cold start, hot start, disconnect IAC, adjust throttle stop,etc). The motor idles at around 670-700rpm after surging stops and the NUBASE is still set at 672.

you should choose your wording a little moe betta, I took that as meaning you unplugged the IAC and it stayed idling at 670-700

for your surging startup you need more fuel, go kick up the startup table for the first 5 sec or so at them lower temps where it gives you issues

yea its time you get the updated adx

efidynotuning.com

click on downloads >> tunerpro >> gufb

you can thank me later

[broncomike]

I'll just go ahead and thank you now decipha........any/all help is welcome. I'll head over to your website and download the file.
Thanks

[broncomike]

Finally had some time to work on the motor again today......downloaded the updated .adx file and still no luck. The ISCDC value is still stuck on 12.51 all the time. As for the surging idle...I was able to increase selected values in the fuel start up table and noticed an improvement. At first I thought the surging idle was completely gone and after about 40 minutes of run time the problem presented again after 4 start-ups......

With all the difficulty I've been having I went back and started checking vacuum lines and connections and all looked to be in order. One concern I have is low vacuum. It hovers, fairly steady, at about 12"....is this low for a e303 cam? The motor is fresh with Ford Aluminum GT40 heads, Ford Cobra intake, and Explorer throttle body.
Thanks for opinions....