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Discussion Starter · #1 · (Edited)
today while driving, i noticed that i was getting a "flat spot" in my boost. like clockwork, between 4200 - 4800 rpm, i am getting a significant decrease in boost, (approx. 0.015 mpa or .15 bar). this happens at the same spot in 1st - 4th, and a soon as i am out of that rpm range, the boost jumps back up to where it was before. let me give you a brief history:

i added a joe p mbc running at about 16psi, and got a slight hesitiation in that range. then i tried adding a "t" with a restrictor that vented to the atmosphere after the mbc, before the wastegate. i did this in hopes that it would alevaite the decrease in boost at 5500+ rpm. it didn't seem to work so i went back to the original/standard mbc setup. it seemed ok the day i did it. i put the car up for a day or so in order to do brakes and add k&n filter. when i took it out for a test drive, (earlier today, described above), that's when i really started to notice the problem. does anyone have any ideas at all? should i reset the ecu?
 

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I would reset the ECU and see what happens. It only takes 5 min. and is worth a try. Perhaps the ECU has seen a problem in that RPM range in the past and is trying to correct for it.
 

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Discussion Starter · #3 ·
thanks jmussetter. i reset the ecu, and that seems to have done the trick. no big drops in boost level i still have a slight hesitation around 4000 rpm, but i guess i will have to learn to live with it. thanks for the help.
 

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Glad your boost is up to par. If your still having hesitation, then you might want to look at some of the threads reguarding the "Grounding mod". Basically you run extra ground wires from certain locations in the engine bay back to the neg. terminal on the battery. This seems to help a lot of rexx's that have this hesitation problem, it has something to do with the sensors working more accurately after the mod I think.

I had a slight hesitation on mine for awhile after I installed my MBC, but after I got the unichip, I havn't noticed it anymore. I'll have to see if it comes back with time, if it does, I will be doing the grounding mod as well.

Good luck.
 

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Discussion Starter · #5 ·
i have already done the grounding mod. i don't think it did anything for me. i wonder if 12 gauge wire was enough. i read in another thread that it was. i haven't seen much difference. thanks again.
 
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