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This car has undergone many upgrades and repairs lately. Somewhere in the mix, it's developed a large idle surge once warmed up, rough cold start idle (like a partially fouled plug), increased fuel consumption (vacuum gauge reads low and AFR seems off), and decreased performance (throttle response and boost building). The list of most recent work is:

-Turbo rebuild (Garrett 60-1)
-spark plugs (LFR6A11 NGK) and coils
-new valve cover and pcv valve (aftermarket Dorman probably) (pcv was drilled out)
-1000w amp with new speakers and tweeters all the way around
-new-er alternator
-fog lights modified around intercooler piping and hid kits installed in headlights and fogs
-battery was previously relocated to the trunk from another owner, I moved the ground to a sanded spot in the truck from where it was grounded
-new maf and maf housing
-bov taken off and cleaned/inspected
-air filter cleaned and oiled

There is probably more that I am forgetting...

The car functioned great until the turbo needed to be rebuilt. I had a cheap ebay turbo on it for a couple months while waiting for the rebuild. Most the work was done in that time. I feel like it has to be something I have done. The car felt like it was breathing through a straw and didn't have throttle response or boost building capability. Eventually decided to try unhooking the 1000w amp to see what happened. Immediately better! Night and day difference but still had other issues at play. I have performed multiple boost leak tests and fixed very minor leaks and replaced vacuum lines and clamps where needed. The battery and alternator test great. I have done the idle relearn multiple times. Boost gauge reads -17psi vacuum at idle. AFR reads 14-15.5ish at idle and driving. I know these are off, I'm sure it's leading back to my main issue. The bov flutters nicely under acceleration but does not give the small flutters for less acceleration as it used to when it was more responsive. I am inclined to think that I must have some sort of vacuum leak I haven't been able to track down. It doesn't burn or leak oil anywhere. Could this possibly be related to something electrical and not mechanical since I've learned from my experience with the amp? Maybe bad grounds? I do know of an exhaust leak at the turbo manifold, one of the nuts backed off the stud a bit. I also have an exhaust leak/muffler suicide post turbo. I can't imagine these would be the culprits though. I don't know which symptoms could be related anymore.

I have used the search button for weeks and frankly I don't where to go now. HAYLP!!!

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3,010 Posts
Use a better ground.
I grounded mine the same way and worked for many months but then had serious issues all of a sudden where the car wouldn't even start.
Best to just leave the battery up front unless you need the space
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