need help diagonosing 4.0 problem after a day of cold weather

[beauknowz]

i dont know where to start on this but i have a feeling its an efi sensor.

ok i had a slight problem a while back but only when first starting motor. started whn i cleaned the intake where the plastic meets the metal, where it said not to use any cleaner in it. i used cleaner in it. hte problem only existed at start up.

yesterday it was real cold and actually snowed in houston texas!
the problem was very bad at start up and did not want to go away as usual.
(sputters and wont idle right)
after warming up it went away. on the way home while stopped at a light it came back. if it happens while driving i can give it gas, and let off suddenly it sometimes goes away immediately.

i hate to sound like a moron for asking, but thats the best way to narrow it down. im thinking this is the best place to find the right answer.

i have to drive a little today, but hope i can mess with it tomorrow.

thinking the sensor i cleaned may be the problem, not sure the name of it, MAF maybe?

need help on this, please reply if you know how to go about solving.

thanks

 

[Nhaz]

I would start by looking for a vacuum leak. Some plastics start to break down when some chemical cleaners are applied to them. One of the things that can happen is the plastic can get brittle.

little flex+ cold weather = small crack and you have a vacuum leak where you didn't have one before.

wave a UNLIT propane torch around anything that looks like it has vacuum in the engine compartment while the engine is running. If you can't get it to run at a stable idle get a friend to Hold the engine at a steady low rpm.

If there's a leak it will rev up some as the propane is sucked into the engine through the leak and is burned.

Don't wave it around the air intake since it'll do the same there.


That's where i would start anyways =>

 

[Bob Ayers]

Sounds like a problem with the IAC valve. You may have gotten some trash into it when you where cleaing the throttle body. Try removing it, and cleaning it.

 

[beauknowz]

.

ok, before i do anything ill check for vacum leak. dont have propane but have learned that method using wd40, carb cleaner , or brake clean.
if nothing there ill check what i think is the IAC.
to the best of my knowledge, there is no way to repair or service this type of sensor.

is there a method to verify they are bad?

i know on some electronics you can look for a constant resistance value at device contacts, and if the value fluctuates, it is bad. is this true for these type of sensors?

 

[beauknowz]

.

an update,
i skipped the vac leak test and went to oreillys to pull codes.
this is what i got:

111 system pass
KOEO
157 , 158 MAF- below min and above max range.

181 fuel system rich adaptive limit at part throttle system lean bank
185 MAF lower than expected
186 injector pulse bandwidth higher than expected
187 injector pulse bandwidth lower than expected


KOER
172 lack of heated oxygen sensor switches indicates lean bank
411 cannot control rpm during KOER low rpm check
412 cannot control rpm during KOER high rpm check


ok so i got some MAF cleaner and cleaned MAF. it had gunk on it so surely that will make a difference

the rubber air tube just past MAF had a hole in it so it was taking in cold, dirty air.

i took some silicone and rubber from an old bike tube to patch it up.

ill see what that does. still gotta see about a vac leak tho.

any unput on those codes?

 

[beauknowz]

.

update:
do we have a darwin arard here for mistakes like this?


ok so i did the carb spray to look for vac leak. found a vacant port on the vacum tree! what a dumbass i was. i now remember my ex wifes exploder did same thing a coulple of times. seems when it starts real cold it backfires and shoots the rubber nubby off. i couldnt find any extra vac lines laying loose in back of motor. my brakes had become squooshy too.

ok so i went back to pull codes after finding this, truck runs much better but still a little off.

all other codes seem cleared and the engine light is NOT on, however, i got a code that says" fuel pump relay circuit failure"

any input what this means or what i should do. i didnt know it had one or where its at.