Bought a jag last week, need to get it smogged, but it keeps popping this code.
i've looked around and checked the intake for leaks and it looks ok.

it only seems to happen after driving on the freeway for a little while, not sure if it's something getting warm or if it's just something that the computer only checks under certain conditions. when it comes on it triggers the restricted performance, which goes away after 60 seconds or so.

the PCV valve (is it a PCV valve? round thing on the right hand valve cover, hose goes to intake) makes a hissing sound, and lets air through both ways, i'm suspicious of it, but i would've thought a vacuum leak would trip both banks.

not sure if it's related, but the throttle response is pretty poor IMO. revving at idle with the hood open you can distinctly here the woosh of the extra air before the engine revs, but again i would expect this to trip both banks.

thinking i'll run some techron concentrate through it, and throw an O2 and MAF at it to be sure, but any suggestions would be welcome

 

For best help, please clarify the Model Year. Best is to edit your signature so it is there going forward...

 

Sorry, it's a 2006

 

See threads about fuel trims for how to check.

Hissing is usually a bad sign, though. The whole system needs to be 100% air (vacuum) tight.

 

Definitely focus on the source of the hissing. Probably needs a few o-rings to seal again. Harbor Freight has great kits for this.

Also, get a code reader capable of getting fuel trims. eBay has cheap ELM327 wireless adapters that you pair up with a phone app like TorquePro. Your long term trims should be in the (ideally low) single digits. A code trips up at 25. Keep in mind that this code trips because of the sum total of all leaks is too large, so there can be multiple causes. Check all hoses to the head, pretty much all of them need o-rings. Replace the VVT seals if you see any oil. Replace the o-ring for the dip stick. The EGR pipe bellows also leaks sometimes. Hopefully as you fix these leaks, you can see the short term trims going negative, contributing to reducing the long term trims.

Best of luck, keep us posted.

 

Just got done correcting a similar code issue on my car. In my case there were multiple small leaks but, for some reason, it would only throw a code on one bank. Found a leak on the connection to the right bank (plastic hose), the oil dip stick o-ring and both VVT seals. Made a huge improvement in throttle response, and now the short and long-term fuel trims are in single digits. I also took fmertz's advice and purchased a box of metric o-rings at Harbor Freight. Trying to buy them individually is a pain, and a lot more expensive.