fstrnyou

Sometimes at high rpms (5k+), I feel a hesitation. Boost is at 12psi. There are times that it doesn't do it tho.

A little background info: When I had my custom intake, and exhaust on, I could boost close to 20psi. When I did that, I got the same hesitation but was told that I was running lean with the stock injectors. So, I put the stock intake back on and now I'm running no more than 12psi. When it starts hesitating, I ease off the throttle to get rid of it but it continues until about 1/2 throttle.

I have a 255lph fuel pump, about 5k miles on the fuel filter, Magnecor wires, relatively new plugs, and a 4GA ground wire running from a water pump bolt to the strut tower where the boost sensor is at. All factory grounds are also connected.

Not trying to be a dick or anything, but I don't want to hear any posts about my 20psi on this thread. I just want the 12psi hesitation gone.

Also, I know my sig says 550/850, but I'm currently running all 550's, stock intake with OEM filter, custom exhaust w/ RB DP, and streetport.

OneOfFew

I doubt if it is going lean but it is not hard to check, just use an AFR gauge. They are cheap and can answer the too lean or is it rich question.


Few Questions.
1. About the boost. Is it holding 12psi during the hesitation at wot or does it dip?
2. Also do you have an aftermarket boost controller?
3. Can you push through the hesitation if you keep it wot and if you can how long does it last?
4. Does it feel like it is mis-firing?

It sounds like a waste-gate problem because I have seen a similar problem on a fd. But I'm not saying thats what it is. Just trying to get an idea.

fstrnyou

1:nah, the boost creeps to 12 until about 5.5k and then begins to fall off again, usually ending up at 7-8psi by the time i shift.
2:no boost controller
3: most of the time, it hesitates to redline, sometimes it doesn't hesitate at all.
4:i consider hesitation and mis-firing as the same thing.

oh, i have an AFR guage but it's a gay one. it never goes to lean unless i'm off the gas. the damn thing is not an led AFR but a needle guage. and it shows 14.7 from .18volts to .85 volts. that is very stupid. the only reason i got it is because it seems to match the factory guages pretty nicely.

OneOfFew

I still think it might be the wastegate. Pressure test the it with something that can put out 12-15 psi, not 90 like an air compressor. See when it is opening. If it feels stiff or tight replace it. It could be sticking open sometimes, even just a little will kill power ALOT. You could even try spraying a lubricant into it although It might not help.

fstrnyou

well, i know the actual wastegate isn't sticking but i'm not sure of the actuator. although when i'm not a full throttle, by boost does pause near 5.5psi, which leads me to believe that my wastegate is operating properly. still doesn't explain the miss/hesitation.

OneOfFew

The wastegate should open ONLY at the designated boost, 12 psi or so. If it is opening before or or not till 3 or more psi after then the actuater is bad. Thats why I sudjested testing it with compressed air to see at what psi it opens. The wastegate will almost never open at part throttle if it is working properly, WOT only at high rpm. The purpose of it is to reduce boost supply to the engine, at part throttle the turbo is not producing enough pressure to need the wastegate to open.

Also. Miss and hesitation are 2 diffferent problems. A miss is caused when the engine does not fire (a complete loss of power in that particular combustion cycle). A hesitation is when the engine looses power BUT is still firing (you have power but not what it should).

fstrnyou

well, like i said, the wastegate opens at 5.5psi no matter what throttle i'm at because that's what mazda set it to open at.

and if you're gonna word it that way, then i have a miss. i can feel each miss when it happens. like a fast stuttering of sorts.

OneOfFew

Sorry, My mestake. I was thinking if the 13Btt. Don't I feel like an ***. Ok. If your AFR Gauge stays rich you shouldn't be hitting fuel cut. Check over the ignition. It sounds like a odd consern consitering your engine is not combusting. I'm sorry I'm at a loss. I have not had that kind of problem before. Sorry for the lack of help, originaly sounded like a problem I dealt with.

fstrnyou

oh, that's ok, i thought your advice was a little misplaced but wasn't sure. well, the only time my Defi' AF guage went rich is when i had 850's in the secondaries. only that was flooding the motor out so i put my stock ones back in. there is another guy on here doing a wideband install right now. i'm seriously thinking about looking that direction to see what my motor is really doing.

EDIT: i was thinking ingnition as well, but everything seems to run fine normally. and i know the factory coils are stong (when new). i don't know, it only messes up at that particular rpm range and even so, sometimes it runs fine there. i'll see if i can poke around the coils and CAS. maybe timing is off a bit, i'll check it and see.