P0299 Turbocharger/Supercharger A Underboost Condition

[JakeEL]

Has anyone seen this code on their expy with the 3.5L V6? I was up in the mountains at about 6000 feet over the weekend and the code came on. I reset the code and it hasn't come back yet. I'm hoping it was just the altitude. Please post what the problem was if found. Thanks.

 

[drewactual]

altitude could have played a role, but your MAF ought to have recognized that.

how dirty is your air filter? restrictive flow is most often cause for this code in my understanding... not 'just' with this engine, but others. it takes five full seconds of the engine requesting the boost (at least 4psi delta) and not getting it to set this code.... that is a pretty solid demand/load on the engine. there are a handful of other issues that can cause it from a leaking boot to a bad VGT- all of which are not nearly as likely as a dirty/restrictive air filter.

 

[JakeEL]

Shoot I didn't even think about that. Leads me to my next question. Is it worth upgrading to a Cold air or a higher flow intake? Since I am in wonderful Cali it would have to be something smog legal. Thanks.

 

[drewactual]

that's your call my man...
most often i figure cold air intakes to be snake oil, but....... you'd not have that issue anymore (if that is in fact what caused it). some say these engines like to breath, and that is true but is something of a misnomer, too- they DO like to breathe, but that is better said that they DON'T like to be restricted.

 

[JakeEL]

Thanks for the input. Ill check that filter and report back. Its getting driven today so well see if the code comes back.

 

[drewactual]

dive into it hard at some point.... request the boost and see if it produces it (NOT resulting in a code)... it'll mean a pretty stiff dive into the throttle for at least five seconds, so.... be as careful as you can speed wise.

 

[JakeEL]

Alright I ordered the KN high flow filter and haven't seen the code since. I'm usually on it so I think the problem is solved. Thanks!

 

[jeff kushner]

Prob was just an intermittent code....the ECM deals with a lot of info and can run into a conflict resulting in a code in "odd" conditions it doesn't "recognize".

jeff

 

[drewactual]

it was probably exactly what i said it was- restricted air due to fouled filter.

OP: if it is something you are interested in, you can install a 'filter minder' which is a spring loaded gadget that holds the highest reading of the vacuum in the air box, post filter. it's likely not needed/required, but it is a nice to have to see if your engine is demanding more air than the filter can pass through comfortably.