so I have about 50K on my 06 XB. It suffers from a lot of engine detonation at the 1600-1900 RPM range when on light throttle. it seems to get worse as the air temps warm up. it's still noticeable when the engine is at operating temperature.

I sound like a VW beetle when i start to drive away from a stop light.

any ideas? or things I should ask the dealership to look at?

MAF sensor... Or possibly a bad fuel filter..

thanks. I suffers from no performance issues and never throws a code. wouldn't a fuel filter issue cause problems throughout the RPM range?

So.. basically.. you have a crap idle?

nope. idles fine and smooth. it's only detonation in low RPM's under load.

almost seems like a timing issue.

That is odd. I believe the timing is computer controlled on these, but if you've messed with the timing belt.. I suppose it could be off. Definitely would take it to the dealership..

nope. never even touched the timing belt.

im thinking something might be telling the timing to advance to much.

Same problem here on my '05, started soon after dealer replaced cam sensor under warranty, either they messed something up or it's the knock sensor. Too late to take back to the dealer as it only started when the weather started to warm up.

Switch to premium gas to see if it makes any difference. Take a look at the spark plugs, if it's time to change try a step colder. Run a can of good FI cleaner through the tank.
Best way to see what's happening is to connect the scanner and monitor outputs from MAF, TPS, Knock, O2 sensors and timing advance, but that will have to be done by the shop.

Got one heat range colder NGK's in it already, 93 octane gas did not help. Does not throw any codes which makes me hesitant to drop $140 on a new knock sensor.

Try seafoam or some other top engine treatment along with FI cleaning.

Got one heat range colder NGK's in it already, 93 octane gas did not help. Does not throw any codes which makes me hesitant to drop $140 on a new knock sensor.

same results here. It does improve once the engine warms up but it never completely goes away.

I've got to get it to the shop soon but it might be a few more weeks.

carbon build up

mine was doing this, I just cleaned my K&N air filter and it seems to have gone away.....

I had a similar situation. I was using the Bosch IR fusion plugs. It didn't hit me for little while that the two coincided. After checking everything else, I went back to the stock plugs and the problem disappeared immediately.
The cheapy stock plugs really do seem to make this engine happy.