Scan results on our 94 aerostar 4.0:

koeo... 111 passed koer...111passed memory codes.....181...fuel sys at rich adaptive limit at part throttle: system lean bank 1. 185...mass air flow lower than expected. 186... injector pluse width higher than expected. 187... injector pluse width lower than expected.


Dcl data (at idle) test #1-19: #01= engine rpm 828. #2= spark advance
19.7*. #3= intake air temp. 2.1 volts. #4= engine coolant temp. 190*.
#05= egr feedback volts 0.0. #06= throttle position sensor 0.9 volts.
#07= vehicle power 14.3 volts. #08= injector pluse width 2.3 ms. #09
egr vaccum reg. 1 0.0%. #10= idle air contol 47.9%. #11= vehicle speed
sensor 0 mph. #12= oxy. sensor 0.72 volts. #13= brake (boo) off. #14=park neutral yes. #15= low speed fan n/a. #16= high speed fan n/a. #17= wot a/c throttle cut off yes. #18= loop status closed. #19= p/s psi. high yes.


Dsl data real-time ( l=idle rpm/ h= high rpm) test #1-19: #01= engine rpm. (l) 860 (h) 4800+. #02= spark advance (l)19.7* (h) 38.7* #03=
intake air temp. (l) 2.1 volrs (h)2.1 volts . #04= engine coolant temp. (l)
188.2* (h) 198.8*. #05= egr feedback (l) 0.0 volts (h) 0.0. #06=
throttle position sensor (l) 0.9 volts (h) 1.9 volts. #07= vechile power (l) 14.3 (h) 14.6. #08= injector pluse width (l)2.2 ms (h)varied from 4.8 ms at mid throttle to 2.4 at (h). #09= erg vaccum reg 1 (l) 0.0% (h) 0.0%
#10= idle air control (l)43% (h) varied 65%. #11= vehicle speed (l) 0 (h) 0. #13= brake (boo) off. #14= park/ neutral yes. #15= low speed
fan n/a. #16= high speed fan n/a. #17= wot a/c cutoff yes. #18= loop status closed. #19= p/s psi. high.


In addition to the memory codes I have a slight surge at idle. The van runs good, I just installed Motor-craft reman. engine about three moths ago.
I replaced the injectors, new wires and plugs and oxy. sensor. Resued the remaining sensors due to cash shortage. The CEL started coming on a month ago, only once in a while at first then more often later. It also developed a
ping when going up a grade.


After retriveing the codes I have cleaned the maf installed new plugs (autolight d/platinum) gapped at .051 and wires (borg warners high end)
from Kragan. Cleared the codes re ran the scan the same codes re appeared

Can anyone help with a solution? Do you think the maf could be bad? My next step is to clean the IAC and new oxy. sensor. Should I be looking at other sensors? I'm at a loss as what to do next!

 

Ping indicates carbon buildup in combustion chamber. Pre-ignition sensors and PCM will control pre-ignition to a certain point, then loses control. Ping is then heard and felt.
I would start with a carbon cleaning with 1 pint of water into the throttle body slowly to a operating temp. engine at half throttle, inject slowly over 5 minutes so as to not kill.
Also Berryman's 12 or Seafoam is supposed to work well into throttle body, same conditions.
If no improvement, pull 1 plug on each side and check color, lt. gray with no black carbon buildup.
Can try cleaning the IAC with electrical cleaner, but success not guarenteed. Read a Ford service bulletin some time back covering IAC cleaning with disassembly and using a fine hair brush with cleaner but have lost info so don't have details. Replacement with real Motorcraft IAC may be only solution if IAC contaminated or damaged. Try pulling the electrical plug from the IAC to see if idle becomes worse. MAF may also have to be replaced, too contaminated, sounds like hi mileage Aero.

Try a bottle of Chevron Tech concentrated 20 oz. injection cleaner, the good stuff, about $10 a bottle in a half tank of fuel.

These PCM computer systems sometimes create their own problems. Some carbon buildup with light pre ignition, so PCM compensates by cutting back spark timing and increases fuel injection. Both also create more carbon buildup. So one can now actually hear pings. Vicious hysterisis loop.
Disconnect the batt. neg lead for 10 minutes after each step to clear last run memory in PCM, then run for 5-10 miles so PCM can relearn sensors.

From Ford Aerostar service manual:
Idle Air Control Valve

The Idle Air Control (IAC) valve assembly (Figures 24 and 25) controls engine idle speed and provides a dashpot function. The IAC valve assembly meters inlet air around the throttle plate through a bypass within the IAC valve assembly and throttle body. The PCM determines the desired idle speed or air bypass and signals the IAC valve assembly through a specified duty cycle. The IAC solenoid responds by positioning the IAC valve to control the amount of bypassed air. The PCM monitors engine rpm and increases or decreases the IAC duty cycle in order to achieve the desired rpm.

The IAC valve assembly is NOT ADJUSTABLE and CANNOT BE CLEANED.

The IAC solenoid (part of throttle body assembly) has an internal diode on some applications. If the internal diode is measured in crossed terminal position with a DVOM, there will be an incorrect or negative reading. It is important that the mating component and harness connectors be in the proper orientation. Diagnostic procedures verify this importance.

The PCM uses the IAC Valve Assembly to control:

l No touch start

l Cold engine fast idle for rapid warm-up

l Idle (corrects for engine load)

l Stumble or stalling on deceleration (provides a dashpot function)

l Over temperature idle boost.