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Ford EEC IV, engine stalls when I turn electric radiator fans on

2K views 8 replies 6 participants last post by  chevotass 
#1 · (Edited)
Background on the motor - It is a 1989 5.8L truck motor, converted to MAF with an aftermarket harness, using an aftermarket MAF, and an A9L computer. It has ran flawless since the first time i started it.

Tonight I reassembled my buggy to the point that I could start it up and test some things out.

Here are the events

1- battery was dead, found my booster. After 3 attempts the buggy finally starts.

2- Idle is crappy, pretty much stalls as soon as it returns to 700 rpm or so. Might be because I had the battery cable disconnected to it lost all adapt table.

3- I clean the MAF and leave the air filter off (air filter was solid mud). This might not have anything to do with the saga, but who knows.

4- Buggy starts fine and idles OK. Within 5 minutes the buggy idles great.

5- I let the coolant temp reach operating temp, then flip on the electric radiator fan, and the engine stumbles for about 1 seconds then stalls. I have 2 radiator fans, the same problem happens regardless of which fan I turn on.

6- repeat 5 numerous times.

7- restart the buggy but use the throttle to keep it running when i turn the electric fan on. Even at 1000-1200 rpm it has a miss.

8- restart buggy with electric fan off and everything is perfect at all RPMs

Pull codes, here is what I have

KOEO
81 Boost control solenoid - Solenoids
AIRD solenoid - Solenoids and Air Injection
3.0L SHO - Inlet Air Solenoid - Solenoids
I don't know what this code is, but everything I read shows it is because smog is removed

82 2.3L TC - Fan Control wire shorted to ground - A/C and Fan Circuits
AIRB solenoid - Solenoids and Air Injection
same as above, it is because smog is removed


84 EGR Vacuum Regulator - Solenoids
EGR cutoff solenoid - Solenoids
EGR Vent solenoid - Solenoids
EGR and smog removed, makes sense....

95 (R) AIR not Diverting (AIRD) - Air Injection
another smog code



Memory Codes
33 ALL - (O, M) EGR did not open/ respond during test or if memory code, did not open intermittently
another smog code, EGR deleted


66 Vane Air Flow (VAF) or Mass Air Flow (MAF) signal low -
This one bothers me. If the MAF is operating correctly until I turn my fans on, then I am suspecting some sort of electrical interference. My fans draw big amps and are about 10 inches away from the top of the motor (and MAF). What confuses me is that I have never had this issue.


Or, there is option C- none of the codes above are causing this issue.

What sensors on the motor would be extremely sensetive to electrical interference?
Why would it just randomly start now? cold weather?

Can someone tell me if code 66 will set a CEL? I did have the CEL come on, and the RPM smooths out. About 5 seconds later the CEL turns off and the RPM stumbles. It does this over and over
 
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#2 ·
How close is your MAF to the fans?? They are real sensitive about the air going in, needs to be un-buffered air, if the fans are blowing air towards the MAF even with an air filter it can cause problems so it would be worse with just an open MAF. If thats not it i would be voltage drop testing the powers and grounds to the ECM and MAF, could be losing something when the fan is turned on.
 
#7 ·
How close is your MAF to the fans?? They are real sensitive about the air going in, needs to be un-buffered air, if the fans are blowing air towards the MAF even with an air filter it can cause problems so it would be worse with just an open MAF.
ding ding ding

I owe you a case of beer when our paths cross. I know I was pretty tired in the garage last night, but I'm surpised I overlooked that. The MAF is outboard of the fans by 10-12", but there is still a lot of airflow the way I have everything plumbed. I put the filter back on and the old junkyard 5.8L is running like a dream.
 
#4 ·
Here's a couple things to try: ( a lot is echoing FRDBOY )

The MAF sends a frequency to the ecu, where it's converted to airflow. It should be on a 5V sensor supply voltage. I would monitor that when the fans come on to make sure it stays at a steady 5V. Could be a chance the fan load is pulling this circuit down.

You have access to an O-scope or any data acquisition equipment? You're deadline is too soon for me to order the proper stuff for my current equipment to help out with programming, but I may be able to get set up to take data so we can see wtf the MAF is doing. (I may be able to borrow an O-scope too)

Check, double-check and triple check the quality of all your grounds.
 
#5 ·
as a last resort i have a scope and we could take it down there to help him if we need to.

i have found the older fords to be real fussy about thier battery/alternator operations. i had a f150 of similar vintage that woudl run great until you wanted to use the plow, then it would idle like crap and pick up a miss. i put a new battery and alt in the vehicle because they were not working 100%. once they were installed it ran great.

no clue if this is your problem just food for thought.
 
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