My bronco idles at 2500 rpms in park!!!

[Chuck Norris Battle Wagon]

I have a 1990 Ford Bronco eddie bauer ed. 4X4 and it idles at 2500 rpms in park. When i shift it to drive it drops to about 14-1500. I dont know where to start and could really use some help!!!!

 

[BroncoJoe19]

There are a few things that come to mind.

Vacuum leak (s)

IAC Idle Air Control Valve

http://www.fordfuelinjection.com/?p=39

Timing

and TSP throttle position sensor.

What I would do would be to rule out vacuum leaks, and then pull DTCs diagnostic codes from your computer.

With a 1990 all you need is a 4 inch piece of wire

Please read this thread for instructions on how to pull codes.

http://broncozone.com/forums/index.php?s=&...ost&p=74581

 

[Chuck Norris Battle Wagon]

There are a few things that come to mind.Vacuum leak (s)

IAC Idle Air Control Valve

http://www.fordfuelinjection.com/?p=39

Timing

and TSP throttle position sensor.

What I would do would be to rule out vacuum leaks, and then pull DTCs diagnostic codes from your computer.

With a 1990 all you need is a 4 inch piece of wire

Please read this thread for instructions on how to pull codes.

http://broncozone.com/forums/index.php?s=&...ost&p=74581

I just got off work and am going to look up in my haynes manual about the vacuum system to check the lines. Ill get a wire too and check for codes and get back to you. I just replaced the TPS and the ECT sensors about two weeks ago. Just replaced the EGR valve last week. I went off roading and after i got back it started idleing real high like it is. Thanks for your helping me out man, I really appreciate it. Ill post what i find later tonight with some pics of the truck.

Mike

 

[BroncoJoe19]

Great!

I doubt that Haynes will very helpful regarding any type of vacuum diagram.

Here are some tips

Look at your rubber vacuum hoses (they are about 1/4 - 3/8 inches in diameter, if they are dry rotted or cracked, replace them. IF they slip on/off of their connectors too easily, they may have stretched out a little bit, cut the ends off, and put them back on.

You may listen for a leak. Sometimes using a cut off piece of garden hose is a good aid to listen with. Sometimes a cardboard tube (like from gift wrapping paper) is helpful. Just remember that whenever you stick your head inside a running engine compartment, that you are not wearing any loose clothing or jewelry that can get caught.

 

[Chuck Norris Battle Wagon]

Checked vacuum lines and they were good. Did a KOEO test and got code 23. Did a KOER test and got codes 13, 21, 23, and 44. I just replaced the Idle Air Control Valve a few hours ago because the solenoid was bad on the old one. The test codes in the book said that the TPS was out of range to be tested, the EEC same thing and i forget the other ones. One good thing about the Haynes manual is that it has the code descriptions!!! I think that I need to adjust the TPS but i dont know how to do it. Should that be the next step. Im stuck man please help!!!

Mike

 

[BroncoJoe19]

Mike,

Code 21 Engine Coolant Temperature Sensor (ECT)

Did you preheat the engine before you did the self test?

Check your coolent level also.

Then see... http://fordfuelinjection.com/?p=28

CODE 23 Closed throttle TPS voltage higher or lower than expected.

I also suspect that you need to adjust your TPS.

I wrote a thread of how I did mine, and pasted the pertanent part below.

There are instructions in Haynes.

Just to round this out a little bit so that it is instructional.

The Haynes manual states that Adjsutment of the TPS is not necessary on the 4.9L All other models must be adjusted. If you are working on a 1990 or earlier model connect the negative probe of a digital voltmeter to the terminal of the TP sensor with the black/white wire, and the positive probe to the dark green/light green wire. Note: You may have to insert stick pins into the back of the connector where the wires go in, and connect the probes to the pins. If you are working on a 1991 or later negative to grey/red and psotive to grey/white.

WIth the ignition key turned ON rotate the TPS until the output voltage is 1.0 volt. Tighten and recheck your voltage.

NB: Earlier in the chapter when trouble shooting is states that the output voltage should be between 0.5 and 1.0 volts.

Even though my TPS had round holes, there was enough play that an adjustment was possible.

As a side not on my '90 the TPS I pulled off, and the new one I put on had different color wires.

Black was Sig Rtn

Orange was TP Sig

Green was V reference

With the throttle closed should get 1.0 volts between the orange and black and

with the throttle fully open 5 volts.

You should also get 5 volts From the computer to the TPS by checking Vref (Green) and ground SIg Rtn Black.

You will need a digital voltmeter.

I needed to use a third hand the first time I did it, later I used some push pins, and aligator clamps. I stuck the pins through the insulation of the wires, and the aligator clamps to connect them to my voltmeter leads. A little sloppy but it worked /emoticons/[email protected] 2x" width="20" height="20" />

Note:

in my edition of the book on page 4-22 it states to check it, it should be between 0.50 volts and 1.0 volts at idle. Later on page 4-23 it states when replacing it "rotate the sensor until the output voltage is 1.0 volt."

Well I couldn't get it exactly at 1.0 volt! A little above or below, but NOT just 1.0

So I opted to set it between 0.5 and 1.0 as close to 1.0 as possible, I think I am at .96

I think that I found the diagrams on this page helpful http://fordfuelinjection.com/?p=30

BTW: I used a little high temp silicone sealant with my throttle body gasket when I put the throttle body back on to help insure no vacuum leaks occured there.

Overall... make sure all of your electrical contacts to your sensors and actuators are clean and tight. I used a little dielectric grease on them to add a little future protection.

Regarding CODE 44... THERMATOR AIR INJECTOR SYSTEM RIGHT SIDE I don't know about that