Boost Jumps At High Rpm??

[1994talontsiawd]

I HAVE A DEJON TOOL MBC. AND WHEN I GET ABOUT 5000+ RPM, MY BOOST STARTS TO JUMP FROM 15 TO 10, AND BACK AGAIN NON-STOP. MY CAR HAD A CRACKED TUBE HEADER ON IT, SO I CHANGED IT TO A EVO III, IT HELPED SOME WITH BOOSTING FASTER, BUT NOT WITH THE SPIKING. I KNOW ITS NOT FUEL CUT, CAUSE IT DOES IT AT HALF THROTTLE, AND IT JUST JUMPS AROUND. ANY IDEAS???

 

[winterftbl]

Does it do the same at wide open throttle?

 

[1994talontsiawd]

Yes, it seems like it gets worse the higher it gets in rpm.

 

[turbobird14]

have you disconnected the MBC to see if it will hold steady boost with just wastegate pressure? what kind of turbo are you running?

 

[1994talontsiawd]

I'm running a 16g turbo. And yes I hooked the factory one back up, and it goes to 10, then up to around 11, then back and holds at 10. I figure thats just boost spike. Think the dejon mbc is bad?