Slow idle after clutch replacement.....

[sorka]

After warming up, idling around 480 which is giving the engine mounts a work out. Short term fuel trend showing -5% or so when I rev between 1000 and 2000 RPMs. This is my moms car so I don't know what it was doing long term but it wasn't idling this slow when I got it last week to bring it home. I suppose it's possible that resetting the long term fuel trend when I pulled the battery is exposing an existing issue but I don't think that's it.

The only thing engine wise I took off when I remove the transmission was the air box and what I'm guessing is the PCV return hose upstream of the throttle body. All that's back together. The bands for the airbox are correctly tightened and there's no obvious hiss from any sort of leak.

I'm stumped.

[WeeYari]

Originally Posted by sorka

I suppose it's possible that resetting the long term fuel trend when I pulled the battery is exposing an existing issue but I don't think that's it.

When was the battery pulled, and how long has it been running since hooked back up?

An extended battery disconnect will reset the ecu and it then needs to relearn fuel trims. Until it has done so, the car will idle extremely low, to the point of nearly stalling.

[sorka]

Originally Posted by WeeYari

When was the battery pulled, and how long has it been running since hooked back up?

An extended battery disconnect will reset the ecu and it then needs to relearn fuel trims. Until it has done so, the car will idle extremely low, to the point of nearly stalling.

The battery had been out for 4 days.

So after another 5 minutes of driving, the idle actually dropped even further to 440 and engine smoothed and I could hear the slight timing chain slap that I'd noticed before and at about the same speed as before I started the clutch, so I guess it's been doing this before but 440 seems low. After about 10 minutes of driving the long term trends are sticking at about -2%. Wouldn't that indicate a very slightly rich condition and it's leaning it out -2% to make it not rich? i.e. not an air leak after the MAF?

[WeeYari]

You need a good 30 minutes of uninterrupted driving to get it settled back in, not a couple minutes here and there.

[bronsin]

Possible the computer needs a little time to configure the engine to your driving input.

[sorka]

Yup, so after my 130 mile drive to work, the idle is sitting at 650 which is the upper limit of the factory spec, so it's all good.