shuddering at full boost (cobb stage 3) seeking advice/thoughts on trouble shooting
05-30-2014, 08:22 PM
#1
shuddering at full boost (cobb stage 3) seeking advice/thoughts on trouble shooting
I need some thoughts on this issue.
info on my setup: vf39, pinks, ebay large tmic, walbro fp, accessport v2, full catless 3-inch turboback.
during a pull getting on the high way I heard a noise like a small pebble hitting the exhaust pipe and bouncing down to the end of the pipe, then immediately after that noise the car started to shudder so I let up my foot off the throttle and checked things out.
my finding:
no smoke from exhaust, no power loss until full boost at 16ish psi (when the shuddering starts), no other odd or outstanding sounds from the engine or exhaust, no change in clutch, brakes, electrical, etc. no new CEL code (other than my O2 sensor one that's been on)
looking under the hood:
some fresh-looking oil buildups from the return line near the turbo, no sounds of grinding, or anything odd from the turbo while at idle and at on-throttle.
my biggest concerns:
pistons/rings/cylinders damaged (but then there would be so kind of smoke right?)
turbo damaged (oil buildup) maybe lost a turbine blade on the hot side???
I'm stumped. the car drives and sounds fine, until i hit 16psi...Please help.
I'm going to take the turbo out this weekend for closer inspection. a part of me is really hoping that i can just swap in a dif. turbo and be back on the road. I'm just not at a point where i can easily do an engine rebuild.
info on my setup: vf39, pinks, ebay large tmic, walbro fp, accessport v2, full catless 3-inch turboback.
during a pull getting on the high way I heard a noise like a small pebble hitting the exhaust pipe and bouncing down to the end of the pipe, then immediately after that noise the car started to shudder so I let up my foot off the throttle and checked things out.
my finding:
no smoke from exhaust, no power loss until full boost at 16ish psi (when the shuddering starts), no other odd or outstanding sounds from the engine or exhaust, no change in clutch, brakes, electrical, etc. no new CEL code (other than my O2 sensor one that's been on)
looking under the hood:
some fresh-looking oil buildups from the return line near the turbo, no sounds of grinding, or anything odd from the turbo while at idle and at on-throttle.
my biggest concerns:
pistons/rings/cylinders damaged (but then there would be so kind of smoke right?)
turbo damaged (oil buildup) maybe lost a turbine blade on the hot side???
I'm stumped. the car drives and sounds fine, until i hit 16psi...Please help.
I'm going to take the turbo out this weekend for closer inspection. a part of me is really hoping that i can just swap in a dif. turbo and be back on the road. I'm just not at a point where i can easily do an engine rebuild.
Last edited by ravenlunatic; 05-30-2014 at 08:26 PM.
05-30-2014, 09:08 PM
#7
yeah that's kinda my thinking too. it would be nice to switch up the turbo and get a real tune but I do think that my car may not hold up to the extra abuse....I may be better off saving for a motor rebuild/swap if I can't sort out my current issue with my current funds.
05-30-2014, 10:16 PM
#8
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Location: Santa Cruz, California
Posts: 3,228
Car Info: 2006 obp wrx limited sedan
If you have an extra wideband bung bring it over to my work in foster city and I will look down inside at the turbine with a borescope.
Otherwise just drop the downpipe and look inside. Was the vf39 cracked at the wastegate when you bought it? Maybe it cracked and you heard a micro piece of metal bouncing down and out. Or maybe your o2 sensors tip fell off......
Trying to think of anything else post turbo that could happen......so it will make a noise @ 16psi? Post a video of said noise maybe too
Otherwise just drop the downpipe and look inside. Was the vf39 cracked at the wastegate when you bought it? Maybe it cracked and you heard a micro piece of metal bouncing down and out. Or maybe your o2 sensors tip fell off......
Trying to think of anything else post turbo that could happen......so it will make a noise @ 16psi? Post a video of said noise maybe too
05-31-2014, 03:31 PM
#9
If you have an extra wideband bung bring it over to my work in foster city and I will look down inside at the turbine with a borescope.
Otherwise just drop the downpipe and look inside. Was the vf39 cracked at the wastegate when you bought it? Maybe it cracked and you heard a micro piece of metal bouncing down and out. Or maybe your o2 sensors tip fell off......
Trying to think of anything else post turbo that could happen......so it will make a noise @ 16psi? Post a video of said noise maybe too
Otherwise just drop the downpipe and look inside. Was the vf39 cracked at the wastegate when you bought it? Maybe it cracked and you heard a micro piece of metal bouncing down and out. Or maybe your o2 sensors tip fell off......
Trying to think of anything else post turbo that could happen......so it will make a noise @ 16psi? Post a video of said noise maybe too
I know that the VF39 is prone to crack but with minor to no boost issues. This one, however, is the largest crack I've seen! I'm thinking that this maybe the root of my issue. What you do guys think?
Last edited by ravenlunatic; 05-31-2014 at 03:45 PM.
05-31-2014, 08:48 PM
#14
How did the turbo look when you pulled the downpipe? Was their shaft play or damaged blades? From your description my first thought was that your engine might be pinging at high boost.
06-01-2014, 12:12 PM
#15
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Posts: 7,380
Car Info: 04 impreza wrx R.I.P Daniel Wentz JOEBOBBUCKET
On my setup, my tmic hose blew off on the turbo side and I was still able to drive fine but going onto full boost it would shudder so bad felt like it was misfiring