Low Idle

[BeavisTheMighty]

Having a weird idle problem with my 05 Expy right now... Idles fine at ~750rpm in park. Drop it into gear and it falls to 400-500. It was throwing a P0506 Code (IAC - Idle Lower Than Expected). Checked the vacuum lines (no easily visible cracks or breaks). On a different (and I suspect unrelated) note, occasionally when starting out from a stop, the whole truck shudders very hard. When driving at speed, everything works fine. After resetting the code, it hasn't come back even with a sub 500rpm idle in gear...

 

[toms89]

The IAC valve is primarily responsible for controlling the idle speed so I would look there first. Check the valve and hose feeding it and make sure there is no obstructions maybe a good time to clean it. Also check and make sure the electrical connection is good.

 

[BeavisTheMighty]

The IAC valve is primarily responsible for controlling the idle speed so I would look there first. Check the valve and hose feeding it and make sure there is no obstructions maybe a good time to clean it. Also check and make sure the electrical connection is good.

Looks like the "IAC" on an 05 isn't user servicable much less cleanable.

 

[toms89]

Looks like the "IAC" on an 05 isn't user servicable much less cleanable.

Sorry. Not familiar with the 05's. Its throttle by wire correct?! Maybe it just controls the throttle for idle. Can you check/clean the throttle body?

 

[BeavisTheMighty]

Sorry. Not familiar with the 05's. Its throttle by wire correct?! Maybe it just controls the throttle for idle. Can you check/clean the throttle body?

Pulled it all apart... no visible sensors and the manual specifically states not to run any cleaner through the TB. Are these thing speed density? If not, they did a really good job of hiding the MAF.

 

[toms89]

Pulled it all apart... no visible sensors and the manual specifically states not to run any cleaner through the TB. Are these thing speed density? If not, they did a really good job of hiding the MAF.

What sensor are you looking for??

From what I recall Ford says not to run chemical cleaner through the throttle body because they coat it with something that is suppose to prevent any buildup of oil deposits or carbon and any chemical cleaners could remove this coating. If its clean I would agree but if there is buildup the coating is not working correct?! You also do not necessarily have to use chemical cleaners.

Again I am not familiar with the 05 expy but assume the MAF sensor is located somewhere in the intake tubing between the air filter and throttle body. Hopefully someone with an 05 will chime in.

 

[BeavisTheMighty]

What sensor are you looking for??

From what I recall Ford says not to run chemical cleaner through the throttle body because they coat it with something that is suppose to prevent any buildup of oil deposits or carbon and any chemical cleaners could remove this coating. If its clean I would agree but if there is buildup the coating is not working correct?! You also do not necessarily have to use chemical cleaners.

Again I am not familiar with the 05 expy but assume the MAF sensor is located somewhere in the intake tubing between the air filter and throttle body. Hopefully someone with an 05 will chime in.

Yeah, the TB was FILTHY on the back side. Cleaned it with some TB cleaner and it works like a CHAMP now. Accidentally broke the locking mechanism for the connector that attached to the TB motor. Have it zip tied for now, hopefully I can pick up a new one from the Ford dealership.