Truck wont idle

Troubleshooting an idle issue, any suggestions on where to start?

 

What do you mean "won't idle"? Stalls? Runs rough at idle? Engine rpm's stay too high when it should be idling?

 

Will not idle after engine has warmed up. It starts to run rough then dies. Cannot even keep it running with the throttle.

 

MAF sensor?

 

Maf sensor?? What is that exactly??

 

Gas in the tank? Seriously, we've all done it.

 

yea, when is cold and when i feather the throttle, I can keep it running. I been told to clean the IAV and check the codes for bad O2 sensor? any suggestions??

 

suggestions

when someone names a sensor or term you don't know, google it and learn about it

o2 sensor has nothing whatsoever to do with idle
o2 sensor on these vehicles has one function only and that is test cat effifciency

a/f sensor might have something to do with idle, a/f sensor has everything
to do with amount of fuel pushing through the motor, but not at idle very much

---
MOST LIKELY it is this (and cheapest to check/fix/replace)

MAF needs cleaning
TPS needs replacing

 

well, first I did research terms I didnt recognize. Second, this being a forum about issues someone may have with their vehicle, I thought I would ask. And lastly, read the manual, they sends signals to computer which ref. the voltage signal to air/fuel ratio, which will regulate idle.

 

O2 sensors can cause weird shit.

First thing to do is read any codes off your OBD2. Any auto parts store can read codes for you.

Could be bad gas, bad plug(s), bad sensors, dirty MAF sensor, or a number of other problems. Keep us posted, and we'll try to help.

You'll need to learn to ignore people giving you shit on here. Even the helpful members get in a mood sometimes (myself included), so don't write off the folks giving you shit.

 

dudemanguy

understand how modern fuel injected CA emission vehicles work.

here are FACTS

the exhaust stream sensors, there are TWO types

air fuel sensor

oxygen sensor

in the past is was only one thing, an o2 sensor. but those are not accurate enough
to meet EPA emissions standards, so the wideband o2 [now always called an a/f ] exists which is a 'sophisticated version' of an o2 sensor. but it is not an o2 sensor at all.




they are VERY similar and built almost exactly the same and look the same
but perform very different functions

1) AIR FUEL sends fine (wideband) signals to the ECU about the stoichiometry of the burn

this controls engine power and lean/rich mix

this is the first sensor and it is in front of the cats

yes it does control idle because it controls fuel, but when these go south idle is rarely affected, or it will idle high.

2) O2 sensor, this is a 'rough sensor', basically just high or low voltage that tells
the ECU how well the exhaust is getting cleaned up by the cats, it is behind the cats
and its ONLY function is to trip an engine code and READY emissions status


o2 sensor does not do a damn thing for idle

3) IDLE issues (lacking anything else simply busted) are MOST COMMONLY
a dirty MAF or bad TPS. ALL vehicles driven long enough will have these two things go bad...but not all vehicles will have the a/f or o2 sensor go bad









QUOTED
"You'll need to learn to ignore people giving you shit on here. Even the helpful members get in a mood sometimes (myself included), so don't write off the folks giving you shit."

I am not wrong I am just an asshole

and yes I an tense lately because of the current 2015 MotoGP championship debacle in Sepang and the Valencia final Sunday and how free practice today is fleshing out....Multimillion dollar sponsorship contracts are dropping left and right and this stuff matters to me and my company. If you are unaware, no matter who wins they have already cancelled the Victory celebrations. This is a HUGE deal in motorsport and sponsorship, to be denied the sponsors 'Spoils of Victory' and huge advertising dollars.

 

Do you have check engine light? Codes?

When cold, you are in open loop so AFR sensor is not used. But when warm you switch to closed loop and then the AFR sensor is used.

Have you touched something, work on the truck lately?

Try disconnect the battery for few minutes.

 

Sounds like it's running rich. I would ask about the condition of the air filter for starters.

 

I would thoroughly test ECT sensor or possibly simply replace it.
ECT - Engine Coolant Temperature sensor.
This is the sensor that dictates ECU how much idle to open based on engine current temperature.

 

I recommend going down the list to eliminate variables. Start with easy ones first:

Air filter
Try a tank of high octane gas
Fuel injector cleaner
Spark plugs
Clean MAF

This happened to me on my first car, and it ended up being clogged fuel injectors

 

How many miles are on the truck? Have you done any 'tune ups' if it has higher mileage? Air filter, spark plugs,etc. FYI, there is no fuel filter to worry about on these trucks. MAF will definitley make the truck run horribly if it's disconnected or dirty.

 

check for vacuum leaks first. cheapest repair always first guys