Alright had to track you guys down, need some opinions and help. I recently picked up a 94 fd, and im new to the turbo/rotary world. car background info: 3 inch greddy ehaust w cat,basic K&N,Greddy BOV, motor and tranny rebuilt 20 k ago, ceramic seals?(better than your standard apex seals?) supposedly the Japanese motor(not sure, you guys know where I can check the nuumbers?) was original owner, 20 years head tech at mazda. weekend driver, all original. about 116 k. the common occasional pop at idle

drove the car every other day for about 3 weeks then I began to notice every once and a while erratic power output at almost 3k on the dot,(whehn the second turbo spools right?) fall for a split second and then catch itself. completely random, couldnt duplicate it in my driving. about another week after noticing it, took it out for a ride, caught the power in first, but into second nothing at the 3 grand mark, felt like an NA. looked at it again today, it felt like on every 4th rev only that there was 25% of the normal power, other than that, nothing. Im not sure if its my imagination but somtimes it sounds like a constant hiss under the hood like a pressure leak, but you can only hear it inside the car.guys, please tell me im not buying a turbo.oh, a bit of light oil residue on one of the turbo housings and some of the piping fittings.

my plan of attack was to put in a front mount intercooler, Ive heard the stock ones have a problem blowing due to heat/ plastic/pressure, that and the piping would get rid of all the plastic, rubber, and free up some space.any help would be greatly appreciated, this is my first turbo, and first rotary, and im in love.

just hooked up a boost gauge, its showing - 8 at idle and 5-6 psi at WOT. gauge sits at 0 till around 5000

any help or information at all is greatly appreciated

 

boost leak - check the y-pipe coupling and intercooler hosing and the hoses to your blowoff valve and charge releif valve - if the blowoff valve isn't showing anything to 5,000rpm check that hose too as it may have split coming into the cabin. the hole you are looking for will be around 3-5mm otherwise your pressure would likely fall lower than 5-6psi.
check the hose clamps around the system also and visually inspect the secondary intake for signs of collapse.

i had one of these and found the vacuum line from the upper intake manifold to the blowoff valve was rubbed through on the air-pump pulley.

PS: secondary turbo comes online at 4,500rpm - transition starts around 3,000rpm - check the FAQ's under turbo.

 

Sounds more like the 3k hesitation not a boost problem at that rpm. your low pressure indicates a leak some where. the oil/dirt around the couplings may be pointing to the problem areas. primary boost should come on between 2500 and 4500 with a slight drop at 4500 then primary and secondary boost to redline. Check your couplings for leaks and then check your boost patern in third gear from around 35 mph to redline if you feel comfortable.

 

im having very similar problems... i suspect a boost leak also.

 

alright guys, I did the 3rd gear boost test and did a few runs. from 35 mph in third the boost pushes up to 11 psi just before 5000, soon as i hit 5, it rapidly drops, by 5500 its reading out 0 pounds. does this mean there is still a leak? or is the charge actuator not opening the second turbo? this worries me a bit more, still praying i dont need to rebuild the turbo.

 

Well I'm reading alot of these threads and I got the same thing going on. I can hear it hissing under the hood around 3000rpm and I'm getting about 7psi of boost. Stock intake

 

Find the boost leak.

 

That is one nasty boost leak. Check the whole intake tract from the exit of the turbos all the way around to where the UIM and LIM connect.

Most probably its at the y-pipe coupler, or from a missing gasket somewhere along the UIM/TB.