The surge is most likely in the transmission, especially if it idles smooth. The CVTs have a torque converter and this may be the problem. Any modern car with an auto trans that is surging makes the torque converter lock up clutch the immediate suspect. there is very little in a fuel injected engine that will cause a surge when the idle is smooth. You need to get it in for a diagnosis of this problem. The CVT is a special animal.

 

Had same issue. In order to properly diagnose it I needed to fix all vacuum leaks & clean my MAF sensor. Then I got the dreaded TCC stuck open code. A simple test for this is to get the car to 45mph +, when the RPM's are at like 3k or so take your foot of the gas suddenly. If your RPM's drop suddenly your TCC is going. It's a common problem & Audi is a bunch of assho*es for not recalling it.

TCC is you Torque Converter Clutch (the "clutch" for an automatic transmission). Audi's engineers missed that this internal seal was horribly designed and it disintegrates eventually. The stuck open is a fail safe in an attempt to prevent further transmission damage. You have to go under the transmission section in the VAG COM control module 2 I believe to scan the trans computer's codes for this.

Your MAF talks to your trans computer too though so make sure the TCC is your last resort. $1,500 + for the job.

 

If it was a transmission problem why would it run smooth once it hits 1800RPM...also runs smooth under acceleration all the way to 1800 also....only surges 100-200 when cruising between 1000 and 1800 RPM...gets worse once engine gets warm.
I have cleaned MAF, cleaned and readapted throttle plate, checked all vacuum lines... two items I am going after now is...I have a CEL for camshaft sensor which I will check and replace...if still surging I have been told next stop should be MAF...make sense?

 

oooo one more thing...you got to love the 2002 3.0 Audi dont ya!!! mechanics challenge on a daily basis,

 

You either need a timing belt service or a new sensor. I've been working on Audi's for a long time. It's one thing after another ALWAYS! Weekly VAG COM scans lol.

 

I did the 3K 45MPH transmission test that was mensioned....rpms went down very slowly so does not seem like thats an issue (I hope)

 

You would probably have the TCC Solenoid Stuck Open Code if it was the TCC. There are two sensors that are worth cleaning/replacing.

Start by doing this, Make sure all vacuum lines aren't damaged, if they are replace them. Clean your MAF sensor. You can buy the cleaner from an auto parts store or just use 91-100% iso alchool. Clean your ICM sensors as well too (located on top of the air box with four wires attached to the two sensors) These are solid state so if they are either good or bad, cleaning may not do too much.

That crank shaft position sensor code can be extremely detrimental. If your overdue for a timing belt service get that done asap.

 

whats an ICM sensor...does a 2002 3.0 have them on air box? ...never noticed them. What do they do?

 

OK so far I have done the following to try to solve my surging issue.-
-replaced bad cam shaft sensor
-cleaned and re-adapted throttle plate-
- Checked, checked and rechecked vacuum lines
- Installed a new MAF sensor
- checked transmission as mentioned earlier as a potential cause.
all CEL faults are clear now except for a CAT issue that I have had for years.

Still surges between 1000 and 1800 RPM - (138,000 miles, 2002 3.0)

- Idles smooth most of time...every once in awhile surges
-accelerating to cruising speed, runs fine
- smooth as glass the minute rpms hits 1800 and above
- really only surges again beween 1000 and 1800RPM when at cruising speed
- In park reving engine its totally smooth
- problem is only slight when engine is cold...gets worse when at normal op temp.

I'm lost at what should be next step.

 

Audi claims it's "lifetime" fluid. Lifetime fluid my ***. Have the trans pan cleaned, and put a new trans filter in & of course have the fluid changed.

When they (or you) change the fluid, investigate it for metal shavings or anything besides trans fluid. Metal pieces are a sign of something wrong with the trans.

When I changed the TCC in my car, the seal that had failed actually melted to the bottom of the trans pan. Luckily I caught it in time before it caused any mechanical damage thus no metal shavings were present. But that trans fluid was filthy.

Your car has to have a set Ignition Control Module (ICM) sensors located on or near the air box. You have to remove the plastic cover to see them. Try changing those.