Engine revs between shifts

[Onefunranger]

The recall that was talked about a couple coments before

 

[2011GT]

Ok, I cut the vss signal wire directly before the ECU. The rpms don't hang at all anymore it's great. Except now my CEL is on saying the speed sensor is bad. Also Both airbag lights are on. Maybe there is a different wire I can cut so my airbags still work?

 

[jfcasey]

Just wanted to update this thread incase it comes up in someones search.

I thought I read it here but it must have been in another thread, anyways, I ended up taking a sheet of 1/8'' gasket material and cutting a new gasket for the IAC. When I cut the new one, I cut the same size hole as stock on the filter side of the throttle body, and on the intake manifold side of the throttle body, I put a way smaller hole than stock. Its probably about 1/4" in diameter.

This doesn't allow the IAC to control the engine speed, so it will make the motor behave "normal" while driving down the street. The only negative I can say about this, is you don't get the PCM controlled high idle when its cold out so your truck might stall if you try and leave it idling on really really cold morning.

 

[Earl43P]

I toyed with that IAC gasket a while back, read up on it on a Focus forum. I went back to normal gasket after I found the vacuum leak. Mine was the PCV tube elbow (I haven't had that 3.0 truck in a couple years, my son has it).

Restricting how much air the IAC can flow pretty much confirms that you have unmetered air causing it to idle higher than normal. I suspect if that is the case, you could unplug the IAC and the idle will still be somewhat high, since the IAC can't control the unmetered air (vac leak).

Another thing that'll do it is if you continually reset yhe PCM. I'm terribly guilty of that because I have my EGR Valve disconnected (removed and plugged vacuum line to EGR valve - I like how it runs disabled). Every time you reset the codes (I use a ScanGageII) it has to relearn the idle. Unless you idle in Neutral/Park, AC On/Off for like 4 minutes in each condition, it can take a while. Defeats the purpose of its adaptive learning strategy (although that can compensate for crappy sensors, like a lazy O2 sensor).

It's been a LONG day, you've made my head hurt with all this thinking.

But thanks for posting a good alternative that drops the idle, provides engine braking AND keeps the speedo working.