Boost Fluctuations
 

Coming back from Thanksgiving in Cali on Saturday over the 80 my car started to have some strange boost fluctuations. It was in 4th and 5 gear - it could hold steady boost to about 7 psi and then after that it would vary rapidly from about 6 to about 18 psi when at partial throttle. At WOT, it varied from about 14 to 18 psi. I was near Squaw and put some gas in (taking it from below 1/4 tank to a bit over 1/2 of a tank); after I added the gas, the problem nearly went away. It was still not holding completely stable boost, but it was much better.

I had a similar problem before when my original turbo went out, but having a more full tank did not help it...

I was thinking fuel filter or pump, but before I start replacing things I wanted to see if anyone had some advise.

As for the car's setup: Cobb stage 2 (ACN 91 OTC map), catless uppipe/dp, Borla Hush exhaust, stock turbo, intercooler, and injectors - and a cobb intake (I know, I know... the whole intake deal, but I haven't gotten around to piecing together a stock snorkus setup since I ditched my FMIC setup)

I don't know how a clogged fuel filter would effect boost unless the car was bucking all over the place because the fuel was cutting in and out. I also don't know how topping off the tank would help the issue if it were a fuel filter or pump.

I would guess the problem is that your map doesn't match your mods, exacerbated by driving at high elevation.

What doesn't match? I thought Cobb says you can use their intake on their canned maps?

your ap map is fine for your mods I have the same thing but CAI.My car started running funny coming to SLT but id say do a boost leak test if your boost is jumping like that...Elevation does play a big part in our cars,everytime i go to so cal at 0 elevation my cars runs like shit and takes a few hours for it to fix itself..

you can use any intake on there maps and yeah yeah i know some of you are like no thats wrong but im correct I asked cobb when i saw them at subiefest

Sucks. My car runs perfect at every elevation. It's been documented with data logging including AFR. I guess that's the difference between a custom map and a canned one.

Yeah, I checked their site and on the map notes it says specifically that the SF intake and an uppipe are "still within acceptable parameters of this mapping."

How exactly would I go about doing a boost leak test?

Thanks