Bronco Forum - Full Size Ford Bronco Forum banner
1 - 15 of 15 Posts

·
Registered
Joined
·
37 Posts
Discussion Starter · #1 ·
I was told by my mechanic that my IAT may be bad. Since it's pretty cheap, I'll replace it. The problem is that it stalls or sputters until it reaches operating temperature. Then it runs great and has plenty of power. When re-starting hot, it still runs great. Only when starting cold and a few minutes until it gets warmed-up, it'll intermittantly run crappy and/or surge while driving. No codes to read either. Is there any other sensor that'll cause this?

Just remembered, he told me my O2 sensor needs to be replaced but that it was likely my IAT... could the O2 sensor have anything to do with it?
 

·
The Anti Yam!
Joined
·
22,674 Posts
pre-Prerunner said:
No codes to read either.
You ran the test and came up with all 11's?

Also the year and size engine would help us diagnose it a little better :toothless
 

·
Registered
Joined
·
37 Posts
Discussion Starter · #3 ·
Gacknar said:
You ran the test and came up with all 11's?

Also the year and size engine would help us diagnose it a little better :toothless
Yes, sorry! 94, 5.8

Well, my code reader came up with a 332 and that has been fixed. No other codes. I was told that there are two "sensors" for engine temperature. One is the IAT which controls fuel mixture for a given engine temp which is on the manifold just next to the fuelrails (schreader valve) and another to send a signal to the temp gauge which is under the air intake tubes etc.
 

·
Registered
Joined
·
867 Posts
pre-Prerunner said:
Yes, sorry! 94, 5.8

Well, my code reader came up with a 332 and that has been fixed. No other codes. I was told that there are two "sensors" for engine temperature. One is the IAT which controls fuel mixture for a given engine temp which is on the manifold just next to the fuelrails (schreader valve) and another to send a signal to the temp gauge which is under the air intake tubes etc.
When you first start it up do you get 3 flashing check engine lights, then revs hi till it come in temp range.
I did a search on this because my bronco has been doing this for a bit.
And what it came out to be was a loose clamp on the hose coming off the oil breather to the intake hose.
In the search thread the other guy had a crack in the intake tube, he taped it up and fixed his.
 

·
Registered
Joined
·
37 Posts
Discussion Starter · #5 ·
hipropos said:
When you first start it up do you get 3 flashing check engine lights, then revs hi till it come in temp range.
I did a search on this because my bronco has been doing this for a bit.
And what it came out to be was a loose clamp on the hose coming off the oil breather to the intake hose.
In the search thread the other guy had a crack in the intake tube, he taped it up and fixed his.


No, it idles just fine then creeps into a stalling period then back to normal. It'll do this until it's warm. If I drive it, it feels like I'm almost on empty. When I tap the gas to keep up speed, it'll stumble and surge and make me look like an A-hole (I'm not an a-hole by the way!). I just look like I'm driving like a jerk
 

·
The Anti Yam!
Joined
·
22,674 Posts
pre-Prerunner said:
Yes, sorry! 94, 5.8

Well, my code reader came up with a 332 and that has been fixed. No other codes. I was told that there are two "sensors" for engine temperature. One is the IAT which controls fuel mixture for a given engine temp which is on the manifold just next to the fuelrails (schreader valve) and another to send a signal to the temp gauge which is under the air intake tubes etc.
There are three.
ECT
http://fordfuelinjection.com/index.php?p=28

ACT
http://fordfuelinjection.com/index.php?p=29

and the sending unit for the gauge.



I am not familure with an IAT
 

·
Registered
Joined
·
37 Posts
Discussion Starter · #7 ·
ACT
http://fordfuelinjection.com/index.php?p=29

and the sending unit for the gauge.



I am not familure with an IAT[/QUOTE]


It's the ACT by the looks of that picture (thanks!) My Haynes has an IAT section and when I asked for one at the parts store, he came back with what looked like the ACT in your picture. When I removed mine (just now) the thread depth on the new one was about 40% deeper than MY sensor as well as the ACT in your pic. Could I have been given the wrong part?
 

·
Registered
Joined
·
77 Posts
The O2 sensor shouldn't cause your problem. The pcm ignores the sensor until it reaches operating temperature and the truck will run in open-loop. It usually takes the sensor a cpl minutes to warm up.
 

·
Registered
Joined
·
37 Posts
Discussion Starter · #10 ·
Gacknar said:
Take a pic of it.
The manual says the IAT is synonomous with the ACT. And you said it is in my airbox? I may sound stupid here but isn't the airbox where my air filter is? If so, there aint no ACT in there. WHat I was directed to replace was in the manifold just in back and below the Schrader valve. I'm getting confused.
 

·
CheeseBurger Milkshake!!
Joined
·
3,760 Posts
Also check for vacuum leaks, my Mustang did the same thing, w/no codes. I replaced some marginal vacuum lines when I replaced the valve cover gaskets, and the problem went away.
 

·
Registered
Joined
·
76 Posts
I have the same problem. The new o2 sensor helped a little but gacknar and yak told me to check the fuel pressure and the iat & ect.
 

·
Registered
Joined
·
37 Posts
Discussion Starter · #15 ·
Thanks, everyone for all the help! I solved it... it was the O2 sensor! I'm sure I will need your help again soon :^( but I wanted to let you guys know what happened in case it helps others...

Look in "It's the O2, stupid" thread for a SHORT rundown.
 
1 - 15 of 15 Posts
Top