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Idle problem...Need help

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Old Dec 24, 2007 | 05:19 PM
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Default Idle problem...Need help

I posted this in general maintenance section, and didn't get a whole lot of hits. Read on another post that it is better to post here for the most inputs.

Original post:
Ok folks I know someone has probably posted the same issue before, but I just can't find anything relating to my problem. So if you would read my problem and help before I throw tons of money at maybe an easy fix.

The car is a 2002 WS6 A4. It is pretty much stock. The only mods made to the vehicle have been:
1. SLP Lid
2. Magnaflow Catback
3. Electric cutout welded into the magnaflow catback

The problem is this. On a "Cold Start" the vehicle idles decent until the engine temp begins to rise. Once it begins to warm up, the idel gets terrible. It will start bouncing around from the 700-800 RPM range down to 300-400 RPM range. Sometimes it will even completly stall/die. It will restart fine, but the rough idle will remain until the engine has warmed up completly. About 10-15min. After it is warm smooth as butter. I can "Warm Start" all day long without issue. It has not been setting the SES light anymore.

In fact I have been back and forth with the dealership in which I've purchased it for warranty work. Thank god for extended warranties. There isn't an event that I did with the vehicle to cause this. This was the initial reason I took it in for warranty work. They have been able to pull codes before, and ended up replacing the MAF, the passanger side CAT, and Pre 02 sensor on the passenger side. Now according to the dealrship it checks out fine, and they don't see an issue anymore...................Well it seems that nowadays that if there isn't an SES light or check engine light it must be fine. I am not an esxpert, but I know when something just isn't right, and this isn't right. After reading multiple posts here I am going to look for a vacuum leak, and probably replace the IAC valve. Please stop me ahead of time if there is a much easier fix. Thanks for the advice ahead of time.

Since then I have replaced the IAC, all plugs, and wires. It still does not idle well until the dang thing has completely warmed up. After that good as gold. I do get a P0300 code while it is acting up. I would think that sensors are either good or bad, not bad when cold, and good when warm....Those are the days of tubes.

I have an SCT Xcalibrator 2, yes it acts up on the stock tune, and am waiting for my buddy to come back so I can hook it up to his laptop, and monitor the engine while it is running.

In the meantime are their any suggestions?
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