Keithr726

What would cause a rich cold idle condition? Upon start up the car idles with AFRs in 10-11. I've heard this is normal but not too sure. Initially the car only makes 10 in. HG in vacuum but this goes up to 14in if I just slightly rev, not to mention the little blip to 400rpm(feeling about to stall) returning to idle and then quickly returning to 800-1000 RPM.

I just don't understand whats causing this....

New parts:
3 bar FPR and dampner
55# injectors with maxx chips
TPS and throttle body reseal (car averages 20-21 in. HG when warm)

I removed the ISV and put epoxy on the seams, could a bad one cause these problems?

Also, normally under boost it maintains a AFR in the 11s but I still see 10s sometimes. Also my gauge records lows and highs and it recorded 8.5.

Tom M'Guinn

How are you managing the extra fuel from the big injectors and 3 bar FPR? MAF? Fuel computer?

Loquat15

i see 15hg when warm and idle... usually around 10hg when cold (when cold the ICV is open more which allows more air to flow through which creates a decrease in vacuum)

I think rich at cold idle is normal as well.

Im not sure about your idle stabilization, someone's gotta know how to fix that :-)

mortymower

You will run rich 10-13 until the car is warmed up, once the needly moves close to the first mark, then you should start to lean out. As long as you are running normal after temp is reached then you should be fine. This is what I understand as a mechanic friend told me, can anyone confirm this?

ausgeflippt951

At startup i run high 11-13 AFRs until warm. Cold, I also will see 13-15 in Hg.

Once warm, my AFRs will be at stoich and I see 18 in Hg.

brad-cam

Rich and 10 inHg at cold startup, 16-18 inHg and stoich when warm.

billthe3

That is normal. The car runs rich until the O2 gets up to the 600F that is required for the computer to go into closed loop.

adrial

Bingo.

adrial

8.5 is pig rich, I would check if that was recorded during wideband sensor warmup or if that's a real value.