Summarized/Corrected Base Idle Reset Procedure

[Guest]

[Joel5.0]

Summarized/Corrected Base Idle Reset version

1. Clean TB with carb cleaner and nylon brush (toothbrush size). Engine off, fully open TB blade and spray/brush TB until all gunk and oil residue is cleaned.

2. Allow to dry, or close TB blade and start engine until it clears all carb cleaner fumes/liquid.

3. Let engine idle...if it doesn't, increase idle speed via TB stop screw until engine stays idling on its own.

4. Disconnect IAC valve, if engine dies repeat 3 with IAC disconnected.

5. Set idle speed to the lowest setting possible between 600-800 rpms with IAC disconnected. It is key to use the lowest possible to prevent idle surge, rolling, etc once the IAC is connected as follows.

6. Turn engine off, and reconnect IAC

7. With Ign On Eng Off, check TPS voltage output....if it's between .7vdc - 1.0vdc, it's OK. This voltage check should be done between the Green and Black wires at the TPS side connector as shown in the pic below....(-) terminal of the DVOM on the Black wire and (+) terminal on the Green wire.

8. Disconnect battery (-) for 3-5 minutes.

9. Reconnect battery, start engine, allow it to idle for 2-4 minutes to confirm setup,

10. If idle speed falls too low or stalls, increase idle speed via the TB set screw a little at a time.

11. Turn engine off for 20 seconds, re-start engine and repeat 9 - 11 if required.

12. Reconfirm TPS output is within the .7vdc - 1.0vdc range.......you're done!...

..no need to reset ECM KAM (reset computer) b/c the TPS minimum value used for idle control, is automatically reset by the EEC-IV every time the ign is cycled on-off for 20 seconds-on, and as explained in the next post

13. Allow a 10-20 minute "relearning" period under normal driving conditions (drive cycle).....now you're done.

 


The procedure described above is based on Ford's TSB 91-7-4 regarding the installation of an Idle Air Bypass Plate + the revised EFI Throttle Body Idle Adjust Procedure.

[Joel5.0]

Adjusting the TPS......a case in Mythology

Summarized EEC-IV logic for the TPS......

The following is a very short explanation of the EEC-IV Idle/TPS Strategy as contained in the EEC-IV Strategy Book - GUFB. Every time the Ign Switch is turned to the ON position.....the EEC-IV will do the following for the TPS signal:

• Minimum voltage at closed throttle over .49 vdc. , less than .49 and codes 23 and 63 will set as failures. 
• Max voltage closed throttle should not exceed 1.2 vdc, or codes 23 & 53 will set as failures. 
• TPS voltage between .5vdc and 1.19 = no codes, TPS  ...then EEC-IV system is  (TPS wise)

►Closed throttle TPS value is reset by the system to the lowest value read when ignition is turned on every time. Or as explained by the EEC-IV RATCH algorithm:

The variable RATCH is the output of a ratchet algorithm which continuously seeks the minimum throttle angle corresponding to a CLOSED THROTTLE position. This alleviates the necessity to set the throttle position sensor at an absolute position and compensates for system changes and differences between vehicles. The ratchet algorithm uses filtered throttle position for the determination of RATCH.

► A voltage increase of .04 vdc from the minimum registered will id part throttle status.
► Minimum WOT value of 3.21 vdc (.5 + 2.71) and not higher than actual Voltage REFerence (VREF) generated by the ECM to access WOT strategy.

 ....This does not include the other registers and functions, the system uses to id acceleration, deceleration, cruise...etc, like:

  APT = At Part Throttle flag

The value of APT is determined by a logic. Briefly, throttle angle breakpoints, in terms of counts, are used to define the CLOSED/PART_THROTTLE and PART/WIDE_OPEN_THROTTLE transitions.

OLDTP = Previous TP sensor value, counts.
TAR = Throttle Angle Rate of change, deg/sec.
TP = Throttle position sensor.
FN331B = A multiplier as a function of the present throttle angle minus the lowest measured throttle angle (TP - RATCH)
Etc, etc, etc

Adjusting the TPS is a MYTH....or more proof is needed?

[8950lx]

Why do I see adjustable type and non-adjustable type TPS's on 5.0L mustangs? If you were to take the tps off for some reason, can you just put it back on and set it to b/w .8 - 1.0vdc and be done with it? Someone told me there is a spring inside that unwinds if you take the TPS off, and that you should somehow wind it back to be able to put it back on. 

Oh yeah, I'm guilty of trying to set the TPS to EXACTLY .98vdc before, but only because I was told the car wasn't going to run right if it wasn't at .980000000000vdc 

[Joel5.0]

 .....

 ...it doesn't unwind....if it does the TPS is FUBAR. Mustang and Ford TPS (very few exceptions come to mind, like some CFI's)...are not adjustable...besides, why would you want to adjust a sensor the logic takes care of.... ...... as far as the EEC-IV logic goes, a TPS set @.5vdc = 0...one set @.8vdc = 0, @1.1vdc = 0......@.98000000000000vdc = 0... . Why would you need a computer that cannot compensate?.....

[Lumpen]

Adjusting the TPS is a MYTH....or more proof is needed?

Sorry for the thread mining (sigh newbie etc etc etc) but that just re-enforces my dim view on australian knowledge of these engines.... 


Cheers,
Lumpy

[Jdubes]

I've always thought this too, that it doesn't need to be set at a specific voltage, but I've noticed that SCT tuning software tries to have you target .98v too. Don't know why.

[Joel5.0]

I've always thought this too, that it doesn't need to be set at a specific voltage, but I've noticed that SCT tuning software tries to have you target .98v too. Don't know why.

It's a byproduct of the myth, unless the SCT tune cancels the TPS filtering (I call it re-zero) function logic (which can't be done AFAIK)...... it doesn't make sense.

[machstang23]

I am a little confused on checking the TPS voltage.. do I disconnect the TPS sensor from the wiring harness and check it by pushing the needles from my voltmeter into the sensor plug, or do I have to try and push those needles down past the insulation on the outside of the connector while leaving the sensor hooked up?

[Joel5.0]

Nope.... you check it with the TPS connected, and probe into the wires insulation. Just make sure it falls within its window range of .8 - 1.0 vdc....... or .7 - 1.1 vdc.... or .6 - 1.1 vdc....... no need to adjust the TPS, it will work fine. The .8 - 1.1 vdc window is the "middle ground" to allow for any voltage variations.

[tx90vertgt]

When trying to correct a surging idle on cold start only, should I warm the car first before doing the base idle reset?  I would think if I attempted to do it while it is surging (ie the first 1 1/2 minutes after a cold start) I would have to set the idle way to high.

I would have started a new thread but this seemed like a good addition to this topic.

[Joel5.0]

Base idle needs to be done at op temp........ then the cause for the cold start symptom worked separately.

[1trickponie]

 so i've done all of those step's and i've got a crappy multi meter from wally world!!HAHA ithe tps was showing no voltage with the ignition off? what do i do now?buy a new t.p.s?:wtf:i beat the f++++ out the black and green wire's looking for voltage,even checked the voltage on the a/c volt reg on house plug's and it's working fine!!!?i'm not getting voltage to tps? any one got any input would be greatly appreciated!!! thank's, wes

[Haystack]

car should be on or running. Otherwise. whats the point in checking how open the throttle is?

[Joel5.0]

so i've done all of those step's and i've got a crappy multi meter from wally world!!HAHA ithe tps was showing no voltage with the ignition off? what do i do now?buy a new t.p.s?:wtf:i beat the f++++ out the black and green wire's looking for voltage,even checked the voltage on the a/c volt reg on house plug's and it's working fine!!!?i'm not getting voltage to tps? any one got any input would be greatly appreciated!!! thank's, wes

Key should be in IGN ON.....

[1trickponie]

car should be on or running. Otherwise. whats the point in checking how open the throttle is?

well if you read the top post it say's WITH THE IGNITION OFF CHECK THE TPS,thats a little misleading,