91 ford f150 5l rebuilt 3000 miles ago.

Has very bad idle. if I plug the MAP sensor and the vacuum line it idles but(fast) and I'm unable to adjust the idle speed. Also unpluged the fuel pressure regulator and there is no difference. I put a vacuum hose on the FPR and tried pulling some vacuum, no change.

With everything hooked back up the KOEO test is 11. KOER tests I get codes 13 (just because it won't idle), 41 (No HEGO switching) and 81 (Air management 2 circuit failure).

Questions, What the heck is the HEGO system? and What's air management 2 circuit 2?

Help, I really need to get my truck running for this weekend!!!!

PS, New stuff with rebuild.
TPS
EGR
EVP
EGR solenoid
knock sensor
IAC
oil pressure switch
engine temp switch
And so much more.....

Jim C

 

hego is the heated oxygen sensor or O2 sensor, its on the exhaust behind the passanger side front tire.iHaynes says you can get a code 41. Just dont replace these parts could be the wiring is bad. When was the last time you changed the Oxygen sensor? See the list of codes at http://fordfuelinjection.com/index.htm

 

I replaced it with the engine rebuild. I don't think that is it. I have a feeling it's the TAD?? or I think it's called the AIRD solenoid. There is a TAB and TAD next to the coil on the manifold.

Has anyone had a problem with this before?

jim

 

Code 81 is for the Map, test that too. I was just told TAB and TAD are just for emmisions, and should not effect the truck much. You could pull the vacuum hoses off them to see though.

 

Is there a way to test the MAP?

JIm

 

You need a tachometer (mhz) for later model fords, and a vacuum pump. The orange wire should have 4 to 6 volts to battery ground, key on , not running. If that doesn't work then have it tested with a Tachmeter. You should check the wiring first for OHMS. I'm no expert, if you unhook the vacuum hose and it runs different i was told its bad, dont quote me. What does it do when you pull the hose, goes from running fast to running faster? When the search option above comes back type in MAP SENSOR and it should tell you more. Could be a vacuum leak to???

 

This is all i could find without the SEARCH option on FTE. This is some more info i found on one of my old posts. Quotes about MAP sensors. "I found out yesterday that my multimeter has a frequency tester on it, which can be used to test the MAP sensor (I did it yesterday myself just to see if the multimeter worked for that). You don't need a scope. The map voltage on the blue wire should be a steady 2.5V with the sensor plugged in." Maps on Fords 1987 to 1989???<!-- / message -->

 

Thanks for all your help.

I tested the SIG and SIG/RTN wire and got 2.5v then I applied vacuum to the MAP sensor; no change in voltage. That's not good, it should vary in voltage as vacuum is applied. I went to the parts store and got one for $65. She's running like a champ....

Jim

 

great!!!!!!

 

It's great to hear that it is running good now... but the voltage should not change when vac is applied to the MAP. It should stay a constant 2.5V, but change in frequency (measurable only by a tachometer)

-Chris

 

Sounds like you got the correct part replaced. You could read the codes again. You may have to disconnect the battery for ten minutes and then go for a drive then read the codes.

 

Having other problems. See thread Nominal Temp....