car stutters/jerks when hitting full boost

[Thomas91169]

symptoms.

will accellerate and hit full boost(around 16 psi) and as soon as full boost is reached the car will be stutter/jerf once for a split second. if i keep on the gas itll stop then do it maybe 1000rpm later. the first stutter is usually at 3k then another at maybe 5k, then fine afterwards.

possible causes
i installed a dejon tool dual MBC, low side set at 11 and high was 18lbs. was fine the first few days of max boosting, but one morning i was playing with a civic and hit full boost and got what i thought was FUEL CUT.



i have turned the boost down to 15psi and i still get it when i go WOT and hit full boost. i thought it to be fuel cut cause the air is much colder and denser now causing the ecu to read more air coming into the engine than before. though now with it set at stock boost levels i still have it. plugs were iridium crappies, but swapped to NGK bpr7es.

any ideas? mods in profile. yes i searched but come up with lots of fuel cut, which i know about but i cant tell if this really is the infamous fuel cut or just a sputter/jerking motion. its violent but id expect more and longer shutoff if it was fuel cut.

 

[Thomas91169]

nevermind, i remembered how much my gauge is off(3-4psi) so i turned it down till it says 14psi which is around 17-18 and all is fine. guess it was fuel cut.

 

[Thomas91169]

whoa guess what i just did. i did a boost leak test using my friends boost leak tester. one of my couplers had a 1" slice in it from rubbing with the hose clamp. after putting a new one on i tested more and no leaks. went out, and my low side boost was now 15psi which in my 5lbs off boost gauge is 20psi, and my high side said 20 which is about 25psi. turned the low side all the way down to 9(14) and high to 15(20).

i also retuned my greddy BOV cause i was ecperiencing compressor surge(car jerked violently during a high boost low rpm shift) and fixed that problem as well.



unfortunately though after i turn the car on after retuning everything in the garage the CEL comes on. ill take it to autozone to get the code pulled tomorrow, hope its something stupid and easy.

 

[johnk]

I'd get a new boost gauge or tap it in somewhere else if you think that's causing the low readings on it. Boost leaks and a bad gauge don't help you know what your really running.