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Discussion Starter #1
2017 FFS 28K miles
GFB Diverter valve
Unleashed 91 tune
Steeda CAI

Boost has fallen off a cliff, no Check Engine Lights
Went from 22psi - 14psi max, wont even go over 14psi now. In sport or Normal nothing. Temperature has dropped from 75-80F to 60-70F on an average day but I don't think that's making the 7+psi loss is it?

I'm freaking out because I cant deal with this thing about to blow up in my face. Any suggestions? or Solutions? PLEASE!
 

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BDX REV-X Tuner from unleashed. So it may be a bit off, but I mean the butt dyno isn't lying to me this time... its much less boost than before
Might have a boost leak. Do you have an upgraded FMIC

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Discussion Starter #5
Might have a boost leak. Do you have an upgraded FMIC
I do not. Just the upgrades I have listed.

Torrie from Unleashed just emailed me saying he would expect that its bad gas ( lower than 91 octane ) which is interesting considering I had just filled up an almost empty tank from a gas station out in the boonies of ND.

Going to go throw in like a quarter gallon of 110 unleaded that we have here in town and see if that does anything.

Hopefully its just bad gas!
 

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You can try adding e85 as well. has around the same octane as 110 race fuel but a lot cheaper. Our cars also are very specific to say not to ever add stabilizer or any other fuel treatments or seafoam or anything like that so stay away from those solutions. You can also try flashing back to stock and seeing if the problem persists.
 

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Discussion Starter #7
You can try adding e85 as well. has around the same octane as 110 race fuel but a lot cheaper. Our cars also are very specific to say not to ever add stabilizer or any other fuel treatments or seafoam or anything like that so stay away from those solutions. You can also try flashing back to stock and seeing if the problem persists.
I had a 87 tune from torrie.

Threw that on and I'm up to 18.5psi again. Ive never run the 87 tune so idk if 18-19max sounds right but it put my worries to rest...
 

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Did you check the GFB? Maybe it is sticking? I would not think so, but 3 bolts it is worth checking.
 
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Does the car feel like its making less power or did you just notice a reduction in boost level? Can you monitor PIDs with your BDX? I'd be interested to know what the desired boost level is vs. the actual boost level. Boost on these cars is not a fixed value, its constantly adjusted by the PCM to hit a target torque, so it could just be needing less boost to hit the desired torque. If you're able to, monitor TCBP_DSD and TCBP to find out what the desired boost pressure is vs. the actual.
 

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If you had hptuners you could monitor torque source and fuel source to see if something was wrong. 14 psi sounds stock. I had issues with hitting this limit when there were certain limiters .
 

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It's the yellow engine cover!

Haha kidding! :)

I'd listen to Torrie. Already sounds like he guessed it. I'd just run out the tank of gas on the 87 tune, fill up with 91/93, run through that tank, then fill up again with 91 and put the tune back on.
 

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Discussion Starter #14
Update, ran the bad gas through.

Have gone back to 91 tune and it’s back to full 22psi.

Bad gas is bad 😅
 

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Amazing what bad gas will do...
 

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Hate to bring up such an old thread but I am having the same problem. I cannot get over 11psi. I have put about 7 gallons of 93 from another gas station just to see but still nothing. Do I need to reflash my tune? No codes, but definitely way less power. Should I check something else like the diverter valve or wait for more gas to run through before jumping to conclusions? Thanks!
 

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Agree with metroplex loose boot or possible crack in FMIC tank weld.
 

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I am leaning toward a crack in the FMIC. I can hear it now. Ugh. Anyone deal with this? Is this warrantied? I really can't afford to go days without my car running and would rather not put the stock one back on. Anyone around Detroit and can aluminum weld? Assuming it is aluminum....
 

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Cold temps will reduce boost happens to me all the time when it goes into sub zero temps up in Canada I'll see 9-12 psi then when it warms up boost go right back to normal 18.9 James tunes or 22.9 unleashed. Maybe bad gas.
 
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