[cstmx_ryder]

Yes, that's what I'm leaning towards....the silicone elbow between CP and FMIC on driver side.

But the thing I can't wrap my head around is, the ONLY thing we slightly moved was the Manifold when replacing the oil filter housing gasket (had to move the manifold a tad bit to access the bolt underneath the oil filter housing). Even then, all we did was loosen the manifold bolts and nudged it over a inch or two, it didn't even come off. The CP stayed on the TB and FMIC this whole time.

But, based on what Jeff said, and what I suspect, I'm thinking it's either the CP to FMIC silicone elbow, or the vacuum lines.

Will update when I find something.

[cstmx_ryder]

Could it also be a bad vacuum canister?

IDK

[cstmx_ryder]

If it were the FMIC / CP connection leak (driver-side), wouldn't the car throw an under-boost code? Or does that NOT happen all the time?

TIA

[tc535i]

Originally Posted by cstmx_ryder

If it were the FMIC / CP connection leak (driver-side), wouldn't the car throw an under-boost code? Or does that NOT happen all the time?

TIA

I don't think so, I completely blew my elbow off last week. Car felt sluggish and my gauge jacking was only showing a pound or two of boost even under full throttle. Car actually ran fine, I assume because it's MAP based instead of MAF etc. No light whatsoever.

[cstmx_ryder]

Checked the FMIC silicone elbows (passenger and driver side), no leaks.

Next is:

replace vacuum lines
datalog

I kept thinking about this over the weekend. Although I thought it would be either the DVs or the FMIC silicone elbows, at first. After checking those, they were eliminated from the possible causes. So now I'm thinking that it may be the wastegate(s) not sealing properly when under full load?

I've read somewhere during my research, that, some member was experiencing slow to no boost in low to mid ranges, but after WOT, it was boosting at target. Which is similar to what I'm experiencing. Sounds reasonable? Or totally outta the question?

please chime in.

TIA

[AK 335i]

Mine is around -20 to -24

[Dmacc]

Originally Posted by cstmx_ryder

Checked the FMIC silicone elbows (passenger and driver side), no leaks.

Next is:

replace vacuum lines
datalog

I kept thinking about this over the weekend. Although I thought it would be either the DVs or the FMIC silicone elbows, at first. After checking those, they were eliminated from the possible causes. So now I'm thinking that it may be the wastegate(s) not sealing properly when under full load?

I've read somewhere during my research, that, some member was experiencing slow to no boost in low to mid ranges, but after WOT, it was boosting at target. Which is similar to what I'm experiencing. Sounds reasonable? Or totally outta the question?

please chime in.

TIA

Just went through your issues the past 3-4 months. My remedy was replacing all vacuum lines, as well as replacing both boost solenoids. Wastegates now close properly, no more rattle on accel or decel, my sloppy gas pedal is gone, it's extremely fast to build boost now, and my logs show I'm finally meeting boost target.

If your solenoids have never been replaced, I would recommend it as there are multiple part numbers for that part, so it might be a good idea to get the new revision. I did not test my solenoids, I just came across a thread on n54tech where robC was dealing with a similar issue, and his before log matched mine. I'll see if I can find his thread, but chances are changing the vac lines and solenoids will fix your problem

[cstmx_ryder]

Originally Posted by Dmacc

Just went through your issues the past 3-4 months. My remedy was replacing all vacuum lines, as well as replacing both boost solenoids. Wastegates now close properly, no more rattle on accel or decel, my sloppy gas pedal is gone, it's extremely fast to build boost now, and my logs show I'm finally meeting boost target.

If your solenoids have never been replaced, I would recommend it as there are multiple part numbers for that part, so it might be a good idea to get the new revision. I did not test my solenoids, I just came across a thread on n54tech where robC was dealing with a similar issue, and his before log matched mine. I'll see if I can find his thread, but chances are changing the vac lines and solenoids will fix your problem

To change the boost solenoids, do I need to get to the turbos? Aren't those those two things connected to the turbos that looks like 'lollipop'? Sorry, that's the best way I can describe it, lol.

I'm working off memory, have no pic representation, sorry.

TIA

[tc535i]

no, boost solenoids are the two black "eggs" sitting on the passenger side fender under the hood

[tc535i]

http://www.n54tech.com/forums/attach...0&d=1310932129

the big black can in that pic, and you can see the second one to the left of it

[Dmacc]

Originally Posted by cstmx_ryder

To change the boost solenoids, do I need to get to the turbos? Aren't those those two things connected to the turbos that looks like 'lollipop'? Sorry, that's the best way I can describe it, lol.

I'm working off memory, have no pic representation, sorry.

TIA

They can be unbolted from up top. Only two bolts holding each solenoid. They're on the hot side of your engine, where your vacuum lines all tie into. I'll grab a picture off google when I'm home but just search "n54 pressure converter".

[cstmx_ryder]

Originally Posted by tc535i

http://www.n54tech.com/forums/attach...0&d=1310932129

the big black can in that pic, and you can see the second one to the left of it

Oh okay, the vacuum canisters! I didn't know they were the sam thing, lol.

[Dmacc]

Originally Posted by cstmx_ryder

Oh okay, the vacuum canisters! I didn't know they were the sam thing, lol.

No! They are not! I'm referring to the boost solenoids which are not the canisters, follow the line from the top of each canister and see where they end. THAT will be your boost solenoid (pressure converter). They are literally bolted on the side of your engine. Those are what I'm referring to, I still have my original vacuum canisters, haven't touched them.

[Sfvalley135i]

Here's what dmacc replaced...
$120

http://www.ecstuning.com/BMW-E82-135...oid/ES2498186/

[tc535i]

So is there a way to test this, or are people just guessing at the problem?

[Dmacc]

Originally Posted by tc535i

So is there a way to test this, or are people just guessing at the problem?

For myself, it was a guess.

[cwarren]

go to PRE and get the lines in bulk and replace them . buy 2 new solenoids and your good . if you dont want to spend money on the solenoids i have 2 at the shop you can install them to test out the theory

[cstmx_ryder]

cwarren,

Yes, I'll get the vacuum lines for sure. As for the boost solenoids, can I test them out to see if they are the problem? It shouldn't take long to swap them out, right?

[cstmx_ryder]

Originally Posted by Sfvalley135i

Here's what dmacc replaced...
$120

http://www.ecstuning.com/BMW-E82-135...oid/ES2498186/

Gotcha! Thanks!

[cstmx_ryder]

Originally Posted by Dmacc

No! They are not! I'm referring to the boost solenoids which are not the canisters, follow the line from the top of each canister and see where they end. THAT will be your boost solenoid (pressure converter). They are literally bolted on the side of your engine. Those are what I'm referring to, I still have my original vacuum canisters, haven't touched them.

Glad I saw this post before I ordered anything.....lol.

[cstmx_ryder]

Now I'm back to no boost at ALL.....ugh!

She's such a b*&^%....sometimes.

[C.Pop]

Originally Posted by cstmx_ryder

Now I'm back to no boost at ALL.....ugh!

She's such a b*&^%....sometimes.

Assuming that you've correctly traced out vacuum lines and replaced/checked/etc, then I'd bet you a grape soda it's your Forge diverter valves.

They need to be rebuilt from time to time. The piston can show signs of galling, which leads to both a vacuum/boost leak as well as sticking diverter valves. You won't make much boost at all when the valves are stuck open.

IMO pick up a rebuild kit, ($20ish from Forge) and carefully rebuild. During reassembly remember that less is more with respect to greasing o-rings/pistons. It's easy to put too much grease on things and screw yourself after a few hundred heat cycles. Since Forge tends to be super slow to respond or ship things (I waited over a month to get my rebuild kits), you can certainly take it apart and clean things or just inspect. I wonder if blow-by contamination plays a role in this.

FWIW I found I needed a shim on the yellow spring for correct operation.