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Discussion Starter #1
so have been trying to figure out my low idle problem and ran KOEO with pass code 111...when it came to the KOER test it is supposed to advance ignition timing by 20 deg right? well it wouldnt do that and i got code 411 and 412 (cannot control RPM during KOER high/low).
My 93 f250 with 7.5l passed both tests as was able to advance timing etc so i know i was doing the test right.
any thoughts? I might also tell you that i have no rpm change when i unplug the IAC...even after cleaning. would this be what is giving me the codes and low rpm?

Thanks in advance
 

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yo Franco,

DTC 411 Idle speed system not controlling idle properly (generally idle too high); "...DTC 411 indicates a dirty/ bad or connector issue w/ Idle Air Control valve (IAC). inspect it for crapola. Some can be cleaned. But our's shouldn't since the TSB says; "...Cleaning is not required on sludge tolerant throttle body designs released for 1991 and newer model years...." in Idle Air Control (IAC) Sludge; Poor Idle TSB 91-25-07 for 85-92 Bronco & F Series & many others; "...Hard cold starts, hesitation and stalls on initial start-up or during idle or decel may be caused by sludge in the throttle body and/or idle by-pass valve. Sludge deposits or oil film on the throttle body bore and plate or the idle air by-pass valve may cause one or more of the following conditions. Hard Cold Start, Stall On Initial Start-Up, Stall During Idle, Stall During Decel, Rough Idle, Rolling Idle, Hesitation During Acceleration. A new idle air by-pass service kit (F2PZ-9F939-A) is now available for service use to correct sludge contamination concerns of the throttle bore and plate only. It eliminates the need to clean the majority of past model throttle body applications. Cleaning is not required on sludge tolerant throttle body designs released for 1991 and newer model years..."


DTC 412 Cannot control RPM during KOER self-test high RPM check. \"...indicates that during the Engine Running Self-Test, engine rpm could not be controlled within the Self-Test upper limit band. Possible causes: Open or shorted circuit. Throttle linkage binding. Improper idle airflow set. Idle Air Control (IAC) solenoid contamination. Items external to Idle Air Control system that could affect engine rpm. Damaged IAC solenoid. Damaged Powertrain Control Module (PCM). Turn the key \"OFF\", connect a tachometer. Then start the engine and disconnect the Idle Air Control (IAC) harness connector. Does the rpm drop or engine stall? If it does, turn the key \"OFF\" and disconnect the IAC. With an Digital Volt/Ohm Meter (DVOM) check the resistance of the IAC solenoid. It should be between 6.0 and 13.0 ohms. Due to diode in the solenoid, place the DVOM (+) lead on the VPWR pin and the (-) lead on the IAC pin. If it is not within specification, replace the IAC solenoid...\" miesk5 Note; Ford says the range is 7-13 ohms Source: by Vincent C
 

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yo,

Nelbur is the person here that re-worked the IAC Gasket
@ http://broncozone.co...t-idle-problem/
here it is; "I checked on the Idle Air Service Kit that Miesk5 mentioned. Ford has them for $89, and an outfit named TOMCO has "one" for $64. It is just a spacer with set screws that allow air to bypass the IAC. I'm too cheap to pay that kind of money to solve my stall on hot start problem. I've grown used to catching it with a bit of accelerator when it starts up. I think I will try cutting away some of the gasket between the air holes, to allow air to bypass the IAC. It could be adjusted by trial and error by cutting away more gasket, and the gasket could even be doubled up if more bypass is needed. ?"


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Code readers often have the ability to adv timing as part of the diagnostics; see page 30 and on @ https://www.scribd.com/doc/14081160/13/

ENGINE-TIMING-CHECK-EEC-IV-SYSTEMS

Before performing the KOER Self Test, the vehicle’s Ignition Base Timing and the computer’s ability to electronically control timing advance must be checked for proper operation. Maladjustment of ignition timing, or a problem in the advance circuit, might generate false fault codes when performing the KOER Self Test that would cause the test to be invalid. Use the following procedures to check for proper ignition timing and to verify the computer’s ability to electronically advance ignition timing.

This procedure is used to check for proper ignition timing, and to verify the computer's ability to electronically advance ignition timing
For 1992 and older vehicles, the Code Reader can be used in combination with a timing light to check ignition timing and the vehicle's computer ability to advance ignition timing. Follow the procedures in paragraph "A
For 1993 and newer vehicles, follow procedures in paragraph "B"


A.Timing Procedures for 1992 and Older Vehicles (excludingdiesel engines)



Always observe safety precautions before and during Self-Test.



ALWAYS check Code Reader battery before retrievingfault codes.



A timing light is required to perform this test.



The vehicle must pass the KOEO test before performingthis test.

1.

Turn ignition off.

2.

Turn the Code Reader off (press the

ON/OFF

button, asnecessary), then connect the Code Reader to the vehicle'stest connectors.

s

Both the large and small connectors must beconnected.

3.

Start the engine.

4.

Press and release the

ON/OFF

button to turn the CodeReader "ON".

4

5.

Press and release the

TEST/HOLD

button to put theCode Reader in test mode. The vehicle's computer willperform a Key On Engine Running Self test.

s

A square icon (on the right-hand side of the screen)displays and flashes each time the Code Readerreceives a code. The code is then shown on the CodeReader's display.

6.

Wait until all codes have been sent (the flashing squareicon no longer appears) and, without disconnecting orturning the Code Reader off, proceed to step 7.

NOTE:

Do not concern yourself with the KOER test resultsor any fault codes received at this time. The purpose of briefly performing the KOER test is to put the computerinto an "Ignition Timing Check mode". This mode allows you to test the ability of the vehicle's computer to electronically control/advance ignition timing. Once thetiming check confirms that ignition timing is functioningcorrectly, you can properly perform the KOER Self Test.

7.

The vehicle's computer is programmed to advance ignitiontiming 20° (+/- 3°) above the vehicle's “base timing” value,and to freeze this setting for two minutes from the timethe last KOER code is received by the Code Reader. Thisallows the user to check the computer's ability to advanceignition timing.

s

Within this two-minute period, (remember, timingdegrees will remain fixed for only two minutes afterthe last KOER code is received by the Code Reader),check the ignition timing with a timing light andensure that it is 20° above the specified base timing value (+/- 3° ).

Example:

If base timing specification is 10° BTDC,the acceptable timing light reading should be in therange of 27° to 33° BTDC.

NOTE:

Base timing specifications can be found on theVehicle Emission Control Information (VECI) decal. Thedecal is located under the hood or near the radiator. If theVECI decal is missing or damaged, refer to your vehicle'sservice manual for specifications.

8.

If timing light readings are not within the acceptable range,base timing may be out of adjustment, or the computer mayhave problems with the timing advance circuit.
Turn the engine off and disconnect the Code Reader from the test connectors. Refer to the vehicle's service manual for instructions on adjusting and/or repairing ignition timing.

9.

If timing light readings are within the acceptable range, base timing and the vehicle's computer ability to advance timing are working properly.

s

Turn engine off and disconnect the Code Reader from test connectors. Proceed to page 32 and perform the KOER Self Test.

B.Timing Procedures for 1993 And Newer Vehicles (excluding diesel engines)

Due to the complexity and large variation of Ford 1993 and newer models with computer-controlled ignition timing systems, timing adjustment and/or checking procedures vary widely from one model to the next. Refer to the vehicle’s service manual for procedures to check and adjust timing. DO NOT ATTEMPT TO ADJUST TIMING WITHOUT MANUFAC-TURER’S SPECIFICATIONS AND PROCEDURES
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Discussion Starter #4
THANKS MIESK!!!! My code reader has the ability and that is why i was suprised it didnt do it ? like i mentioned i perform the test on my f250 with 460 and it did it there?
anyway i removed iac again and cleaned again to no avail....gonna get a new one on this week as will report findings
 

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Discussion Starter #5
so just wanted to report back on this that a new IAC valve fixed low idle condition and when reran KOER test it passed with no codes
 

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so just wanted to report back on this that a new IAC valve fixed low idle condition and when reran KOER test it passed with no codes
yo,
Good DIY work!
GL with your Bronco!
 
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