Boost Cutting Out above ~3200 rmp under load, CEL

**PorscheAG** · 10-17-2016 04:25 PM

Men, (and possibly a few sprinkles of women)

I need some help in here... We have an unmodded 2004 Allroad 6MT with 125,xxx. When accelerating the boost cuts out hard above 3200ish rmp in 3rd and 4th gear(assuming 3rd and 4th are the higher constant boost gears). At first it didn't happen all the time but now its about every time. At first there were no codes or CEL and now there are. First set of codes were random misfire plus cyl 4,5 and 6 misfire. Cleared codes and ran car again. Most recent codes are p0300, p0305 and p0306 random and 5 and 6 misfire. Normally, I work on my own cars but I am super busy lately and dont have time. I took it to a good indie euro shop and they somehow couldnt get it to do it even though I gave them an excuse to flog the turbos. Now I have it in my garage. I pulled a few plugs and they dont look great but in my experience plugs work until there is almost nothing left. I pulled the intake and when I did there was oil in it. I pulled the lower passenger rubber intercooler boot and found a little oil in the boot and some down in the intercooler. I noticed some dry rot on some of the boots so thought maybe one is doing okay until the pressure builds.

Anybody had this problem? Are there any other common parts like coil packs, 02 sensors or hoses to replace.

Thanks!

**V1nny** · 10-17-2016 07:42 PM

very likely some of that rotted rubber does not hold the boost, loosing metered air under boost would create everything else you described. Also check diverter valves, unless replaced recently.
plugs and O2 sensors would foul very quickly under these conditions.

**Club Cheetah** · 10-18-2016 10:46 AM

I just fixed a similar issue, it was a boost leak. I got another over the weekend so this morning I went through and tightened and reseated every one of the hose clamps. It started with a 3-4" tear under my TBB.