Ok ill try my best to explain this odd situation going on. 2006 evo ix
mods:
Sh***y Turbosmart boost controller at 19-20.5ish psi
JMF Open Dump o2 housing
AEM Intake Pipe
Megan 3" downpipe
Exedy hd stage 2 cerametallic clutch
boost gauge-autometer pro, analog
Everything else completely stock.
76,xxx miles

Car was running COMPLETELY great.no issues at all. i purchased a buschur mini battery kit to get ready to run new intercooler pipes. installed the odyssey pc680. went to do a 3rd gear pull after about 25 minutes of letting the car run. thump thump-wtf? feels like fuel cut. happens a couple more times when laying into the boost-still only at 20ish. turn it down. still cutting out even at 17ish psi. now im scratching my head. ok, maybe i got a badly timed boost leak and i was thinking the battery switch caused it.SES light with overboost code. performed boost leak test, my stupid self left the boost controller in on the first check (its been a while since i have done one) and it was leaking out of the bleed hole fitting. which i know is supposed to happen. got a Hallman Pro MBC and went out and drove again. boost was definitly more consistent, but was still hitting the "fuel cut" anywhere from 15-20 psi i tried was still bucking and setting the overboost code. knowing what fuel cut feels like from previous evo experiences i did two more boost leak tests, retightned couplers and whatnot that were bubbling soapy water. held 25 psi with no visible or audible leaks, slowly dropping about 1 psi every 2-3 seconds. ok cool got that taken care of i thought. went out and drove, hitting fuel cut still. checked all my battery connections, all fuses, grounds, body ground off negative cable. everything is good even with a multimeter everything electrically seems very good. The thing is you can go drive without boosting over 5 psi and you would never know the car has an issue, its only when stepping deeper into boost. Noticable symptoms are:

Noticably Poor spool response
slow spool
slow acceleration
bucking, fuel cut, etc
ses light after about 5 fuel cuts with a turbo overboost code.


I really tried to take care of all the basics, but in the back of my head im thinking, the battery is all i changed..did some parameters reset or something? ive had my battery disconnected before without any issues after reconnecting. is this odyssey battery screwing something up? sorry for my long story but i researched and couldnt find anything. I try to be as thorough as possible with my issues, not sure what to do after this. Thanks for any info ahead of time, this issue is really starting to annoy me.

 

When you said you checked your grounds, you made sure that there is no resistance in the ground side circuit? If you have a bad ground it can cause this issue, thats exactly what happened to me. Mine did it in the trunk mount setup and just happened really intermittenly. For whatever reason all of a sudden it just didnt like that ground I used. IIRC how I figured it out was when I measured voltage at the power cable I had ~14v, but at the terminal post of the battery I had ~7v.

My guess is that your just not getting clean voltage and at higher electrical loads your system isnt able to keep up. double check the positive and ground connections. G/L

 

Yes, i will double check the grounds tomorrow, thank you. i thought about this as a possibilty, just trying to think of things that would have to do with changing the battery.