Strange idle when Cold?

[jaybird1741]

1997 Q45 220,000 miles, has a bad Surging Idle when cold, when the car warms up runs perfectly fine. Car has Codes for Knock Sensor Bank 1&2, Lean Code Bank 1. I think I have a vacuum leak somewhere causing the lean code, possibly causing the Surging? Can anyone can help me with Idea's? Thanks

[94Q45Beast]

Does it only happen on cold start ups? if so, it could be the coolant temp sensor.

[jaybird1741]

Yes, just when Cold. My MASS AIR Sensor is bad(I just ordered a New one) I cleaned it, now it doesn't run good and stalls when plugged in, when Cold unplugged runs fine but cuts out when you give it gas. It must have been on its way out, it was the original for the car. But I did get a code one time for the Air Temp Sensor, the one that's before the MASS AIR SENSOR. But I will give your idea a try with the Coolant Temp Sensor! Thanks Man...

[Q451990]

I'd wait to see if replacing the MAF cures it... if you're getting bad MAF readings, everything else will be off.

[xFastZ28x]

Yes, just when Cold. My MASS AIR Sensor is bad(I just ordered a New one) I cleaned it, now it doesn't run good and stalls when plugged in, when Cold unplugged runs fine but cuts out when you give it gas. It must have been on its way out, it was the original for the car. But I did get a code one time for the Air Temp Sensor, the one that's before the MASS AIR SENSOR. But I will give your idea a try with the Coolant Temp Sensor! Thanks Man...

Did the MAF replacement fix it? I have the same issue.

[bslyth]

Yeah I had the same issue. Stalling and lurching when cold and slight power losses during medium acceleration. I had codes thrown for the MAF and both Knock Sensors L&R. Replaced MAF and got a new air filter and she drives happy now. Knocks will be later ($1000 job).