Whenever the fan is turned on it makes quite a racket in the intake.  When we unplug this plug the noise goes away.  The engine seems to run fine without it plugged in.  Anyone know what this is for and why the heater fan is affecting it?  Vehicle used to have AC.

on my 90 5sp 8v that plug runs my 4x4 light, 5 gear switch and back up lights

It is on bottom front of the 8v fuel injection.  I think it may be an electronic EGR, sounds like a burned intake valve when actuated.  Now the issue is that it now engages with the heater fan on, in any speed.  With the plug disconnected no sound, no apparent issues.  What does it do?  And any ideas as to why the heater fan actuates it?
(No trick questions, just trying to fix it.)

You must really suck at tracing wires.   If you would have followed the wires for about 6" (or less) you'd see they go the the TPS and the IAT sensor.  The TPS is that round black thing on the front of the TB that has 4 wires running into the top of it.  The IAT sensor is a tube like thing that is screwed to the passengers side of the TB.  I would suspect the IAT is where you are getting the noise from.
Why the heater fan is affecting it?  No idea, other than maybe some fu....messed up wiring.

Is that the Throttle Position Sensor on the 8 vavle?  I figured it would stop running correctly when we unplugged that...

How would putting voltage on an air sensor cause noise?  Might be a bad ground and voltage going down the wrong line putting voltage to the intake and opening up something it should be...  Time to break out a volt meter I guess.

You must really suck at tracing wires.   If you would have followed the wires for about 6" (or less) you'd see they go the the TPS and the IAT sensor.  The TPS is that round black thing on the front of the TB that has 4 wires running into the top of it.  The IAT sensor is a tube like thing that is screwed to the passengers side of the TB.  I would suspect the IAT is where you are getting the noise from.
Why the heater fan is affecting it?  No idea, other than maybe some fu....messed up wiring.

Thanks for the information, and stating the obvious.   Tracing wires is not that hard, identifying what is at the ends is more challenging.  Knowing what the problem is in helps in where to look for the solution.  

You must really suck at tracing wires.   If you would have followed the wires for about 6" (or less) you'd see they go the the TPS and the IAT sensor.  The TPS is that round black thing on the front of the TB that has 4 wires running into the top of it.  The IAT sensor is a tube like thing that is screwed to the passengers side of the TB.  I would suspect the IAT is where you are getting the noise from.
Why the heater fan is affecting it?  No idea, other than maybe some fu....messed up wiring.

The IAT is on the manifold not the TB, you can see it in the top picture. Do you mean the ISC (Idle Speed Controller)? that would be the most likely culprit for the noise. The ECU uses the ISC to compensate for additional electrical loads  so the ISC duty cycle will increase to maintain idle. You should check that all the pipework around it is OK and check all the grounds.

Is that the Throttle Position Sensor on the 8 vavle?  I figured it would stop running correctly when we unplugged that...

How would putting voltage on an air sensor cause noise?  Might be a bad ground and voltage going down the wrong line putting voltage to the intake and opening up something it should be...  Time to break out a volt meter I guess.

Yes, that is a TPS.  It will still run with it unplugged.  Did you actually drive it with it unplugged, or just run it at idle?  It will likely idle ok with it unplugged, but generally it will run crappy when you actually drive it.

The IAT is on the manifold not the TB, you can see it in the top picture. Do you mean the ISC (Idle Speed Controller)? that would be the most likely culprit for the noise. The ECU uses the ISC to compensate for additional electrical loads  so the ISC duty cycle will increase to maintain idle. You should check that all the pipework around it is OK and check all the grounds.

Oops, yeah, I think you are right on the ISC (at least I knew where the wires went, was just wrong on the name ).  After thinking about it some more, I think the ISC is basically a little motor that adjusts depending on the electrical load, to adjust the idle speed.  So it would make sense that when the heater/AC blower is turned on that it would try to compensate for the load by increasing the idle speed and it can make a lot of noise.  I don't know if making a lot of noise is normal, but if the idle speed increases (or stays steady), I would say it is functioning properly.

Idle Air Control Valve huh, we'll pull that and clean it up next.  As for driving with the TPS unplugged, it runs fine.  Not sure on the mileage though.  BRD HNTR will have to chime in with that. 

http://carfix.stufftoread.com/

why guess at all. 

3rd link on my kick pages.

http://carfix.stufftoread.com/

eee schematics link,   ( nice if you say year of car, why have us guess?)

on the 8v the TPS and Injector is shared. IN ONE CONNECTOR (just look)

if you unplug this conn. it kills the injector (gee you can trace it 6 inches no?)
and if unplugging it does NOT kill injection ,   BAD !
that means the main O-rings on injector are leaking horrible or
injector is leaking
or the ECU drivers are shorted.  ( i have schematics of the actual drivers , I made them) ask.

keyon,no start, look down air horn.   bingo , LEAKING !


BTW: if you pull any (1 at time)
sensor
the ECU will drop to limphome mode, (rich an retarded timing, (FSM))
the CEL will glow, and DTC will store in memory.

i have a vast amount of data  on the 8v.

Especially the EFI electronics.

hope that helps.

quoted and copied from another thread (he posted in the wrong thread)

Wrong.  On the early trackicks the TPS and injector was not wired in the same plug.  In Drone's pics, the injector wiring is the white plug that has the red and yellow wires in it.  So there is no wiring issues, the ECU drivers are not shorted.....I would say it is just the ISC chattering (probably needs replaced).

Quote from: jtgh on March 25, 2009, 10:39:51 AM

http://carfix.stufftoread.com/

why guess at all. 

3rd link on my kick pages.

http://carfix.stufftoread.com/

eee schematics link,   ( nice if you say year of car, why have us guess?)

on the 8v the TPS and Injector is shared. IN ONE CONNECTOR (just look)

if you unplug this conn. it kills the injector (gee you can trace it 6 inches no?)
and if unplugging it does NOT kill injection ,   BAD !
that means the main O-rings on injector are leaking horrible or
injector is leaking
or the ECU drivers are shorted.  ( i have schematics of the actual drivers , I made them) ask.

keyon,no start, look down air horn.   bingo , LEAKING !


BTW: if you pull any (1 at time)
sensor
the ECU will drop to limphome mode, (rich an retarded timing, (FSM))
the CEL will glow, and DTC will store in memory.

i have a vast amount of data  on the 8v.

Especially the EFI electronics.

hope that helps.

quoted and copied from another thread (he posted in the wrong thread)

Wrong.  On the early trackicks the TPS and injector was not wired in the same plug.  In Drone's pics, the injector wiring is the white plug that has the red and yellow wires in it.  So there is no wiring issues, the ECU drivers are not shorted.....I would say it is just the ISC chattering (probably needs replaced).

And I have no idea what this has to do with the rear seat of a Sami.

Seems to be running fine with the wiring plug off.  Idle is at 400 rpm.  Tomorrow I will adjust the low idle with the plug on and the fan off.  Then see where/how it runs.  I removed the little noise maker and did not seem to change any whether I plugged the vacuum leak, or let it race the motor.  There are two other intake/tbi's here and all are different,so finding another idle speed controller that is the same may not be that easy.

93 Tracker 2 door 8v.
Another question:  On the 4 pin plug for freezing the timing (among other things), does the D pin wire (lower right corner) go to a connector just a few inches away.  My plug is missing the D pin & wire, but there is a open slip in connecter just inches away.  (Not going to try grounding it until someone knows that is it for sure.)