High Idle After Installing Electric Fan and Fixing Intake Leak

[tcbaklash]

Not sure if this is the right place...

I just installed a Flex-A-Lite Direct Fit electric fan in my truck and it works AWESOME, but I'm experiencing high idle now. I also patched a hole in my intake hose while I was at it...

Engine: 4.0L OHV ('94 Explorer)
Alternator: 95A

I fear that my alternator is not powerful enough to run the fan, but the truck idles high even when the fan is not running which leads me to believe that my truck runs better with an intake leak? I'm really stumped. Tomorrow I'm going to see if it idles high if I pull the fan relay and then if I re-open the hole in the intake. I just don't know what to do if one or the other is the problem...

 

[RonD]

After engine is warmed up, unplug the wires on the IAC(idle air control) Valve
Idle should drop down to 500rpm or engine may even stall, either is good it means no vacuum leak.

If idle stays higher than 700rpm then you do have a vacuum leak, leave IAC valve unplugged and start checking hoses, something got unplugged during e-fan work.

E-fan won't effect idle, alternator will be fine, assuming it was working before.
If your head light now dim a little at idle then you may want to go with more amps on alternator, if they dimmed at idle BEFORE adding the e-fan then current alternator has one failed field so only has 60amps now.

Hole in the air tube from air cleaner to intake won't change idle but can cause lean code

 

[tcbaklash]

I should've been more descriptive. When I hit the throttle, idle stays high for several seconds and then calms down to normal idle RPM. The more I push the throttle, the higher RPM my motor stays during that period. Unfortunately I do not have a functional tach at the moment, so I'm not able to give specific numbers.

I've checked everything I can think of. My IAC doesn't make any difference when I unplug it, it's a brand new unit too. I cleaned out my throttle body. I replaced my intake hose with one that has no leaks and I checked elsewhere for anything disconnected. My MAF sensor is good, but I have a spare I can drop in after this weekend just in case. Throttle position sensor was replaced last year.

The only things I can think of that may have affected my truck is that I unplugged the battery for an extended period of time while working on the truck and did not idle my truck for very long after I re-connected it, AND I accidentally sparked a wire connected to my positive battery post against my alternator.

 

[tcbaklash]

Bump...

Still unsure what's going wrong.

 

[tcbaklash]

I put in another alternator and it didn't solve the issue.

I also have been experimenting with a 2.9L MAF sensor and it slightly helps, but then the truck idles rough.

Still not sure what's going on. I checked all vacuum hoses, I checked my fuses, I have left the truck sitting with the battery unplugged to "reset" the ECU several times with different MAF sensors. I REALLY don't want to send it off to a mechanic because I'm short on funds. Can anyone help?

 

[RonD]

Engine off
Open throttle manually and release it, see if it snap closed as it should.
Then, if possible, have someone push the gas pedal down all the way and then release it quickly to make sure throttle snaps closed as it should.
Throttle plate needs a pretty strong spring to close it when engine is running, or air flow will hold it open.
So make sure it or the throttle cable isn't sticking.

With IAC valve unplugged engine should barely run, if this is not the case then you have a vacuum leak OR someone has messed with the "anti-diesel" screw on the throttle linkage.
It "looks like" an idle screw, but fuel injected engines do not have Jets so can have no idle screw.
If this seems to be holding throttle plate open too much causing the high idle then you need to back it out until engine barely runs.

 

[tcbaklash]

Throttle closes shut as it should. The screw you mentioned seems fine as it is. My engine nearly stalls when I unplug the IAC.

 

[tcbaklash]

Been a while since I last worked on the truck, but I put in a new fuel regulator in and it seems that it solves the idle problem when the engine is at low temperatures, but operating temperatures will make the problem persist which leads me to believe that i need new O2 sensors. Any thoughts?

Also, my O2 sensors are from the 2.9L, will that be a problem?