Dialling in Idle Air

Decipha's custom GUFX strategy covers all 89-93 foxbody ecu's including the 88 mass-air california ecus.
auscob07
Posts: 17
Joined: 2021 Feb 27, 06:15
Location: Palm Beach
Vehicle Information: Cobra. 5.0. TFS Heads and cam. MassFlo (ProM) EFI.

Dialling in Idle Air

Unread post by auscob07 »

In the Idle Air write up there are two references to the SPOUT connector for measuring the AM for non mechanical idle:

If you so choose to dial in the airmass and throttle body airflow while custom tuning you must plug in the IAC, TPS, and SPOUT to calculate idle airmass.

... and later:

You must temporarily lock out the ignition timing to get an accurate idle airmass, this can be achieved by either removing the SPOUT CONNECTOR

Given the reference to locking timing at 10*, I am assuming the SPOUT needs to be disconnected, but IAC and TPS would remain. Is that correct?
PaulC-turbo5.0
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Vehicle Information: 1989 fox GT convertible
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Flipped JBA headers, custom SS 2.5" hotside built by me
custom 3" coldside thru On3 intercooler
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Re: Dialling in Idle Air

Unread post by PaulC-turbo5.0 »

If you are running deciphas A9L2 and mechanical idle then disregard that you just pay attention to the logged idle airmass correction.

If you’re still working with stock idle setup then yes spout comes out and iac disconnected. Disconnect tps if you need to open the throttle blade while the engine is running
auscob07
Posts: 17
Joined: 2021 Feb 27, 06:15
Location: Palm Beach
Vehicle Information: Cobra. 5.0. TFS Heads and cam. MassFlo (ProM) EFI.

Re: Dialling in Idle Air

Unread post by auscob07 »

Thanks, PaulC

To clarify, I am banging on the original A9L tune. I am not using mechanical idle (yet).

My query is not actually about the adjusting the idle screw, but measuring airmass at idle to update the FN875N table.

Given the timing lockout is required, reckon I'll just remove the SPOUT and leave the IAC and TPS.
PaulC-turbo5.0
Posts: 104
Joined: 2021 Feb 15, 21:56
Location: Lancaster New York
Vehicle Information: 1989 fox GT convertible
5.0 stock block, E7 heads, stock cam
Explorer GT40 intake flipped to driver side inlet
Single 67mm On3 BB turbo
Flipped JBA headers, custom SS 2.5" hotside built by me
custom 3" coldside thru On3 intercooler
tuning with Moates QH + TPRT
Dechipa's GUFX and supporting files, couldnt have tuned it myself without him!

Re: Dialling in Idle Air

Unread post by PaulC-turbo5.0 »

My bad guess I didn’t read your OP clearly enough.
dleach1407
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Re: Dialling in Idle Air

Unread post by dleach1407 »

You unplug the iac and the spout and then log the maf air flow when the car is at operating temperature. You may even have to do something with the pcv valve since it also is pulling in fresh air which would skew the results of the TB airmass.
auscob07
Posts: 17
Joined: 2021 Feb 27, 06:15
Location: Palm Beach
Vehicle Information: Cobra. 5.0. TFS Heads and cam. MassFlo (ProM) EFI.

Re: Dialling in Idle Air

Unread post by auscob07 »

Thank you both, that makes sense. Much appreciated.
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