yeah your TPS settings are fine they are within the correct ranges. Do you have a way to monitor the fuel pressure while it bucks/hesitates?
It really does sound like some sort of fuel cut problem. Not from the ecu cutting fuel, but maybe the fuel pump intermittently shutting off or failing? an injector sticking? How are the wires on your injectors? somtimes they can get baked and then the shielding will fall off and the two wires can rub.. I can't remember if the power FC commander shows injector duty cycle.. if it does could he monitor each injector individually? then watch to see if one of them shows the duty cycle drop off as it hesitates?
Just ideas

 

bad O2 sensor maybe? thats what caused the same symptoms in my FC (ls1, I know I know, blah blah blah) and it was a hard one to diagnose but a new O2 sensor fixed the problem.

good luck.

 

under full throttle the ecu doesnt use the o2 sensor for the fuel maps... most guys running the PFC turn o2 feedback off anyway..

 

This may be a ballpark suggestion, but I had a very similar thing happen on my 300zx when I replaced the radiator. I figured, why the hell am I getting violent bucking after changing a radiator? It turns out that I ever so gently knocked the CAS connector and caused it to get a poor enough connection that the ECU occasionally went into panic mode (I guess as the connector intermitantly made/lost connection) cutting my ignition and fuel. It was a horrible feeling. Pulled the connector, cleaned it, and reinstalled with great results.

 

I have this same problem! but only when my gas is almost at E

 

That is called fuel starvation. Do a search on it. Good way to blow a motor also.

 

To the OP, what boost are you seeing and at what RPM? Does it start bucking at a specific Boost level or RPM level?

Also, what mods was the PFC tuned for? Installing a used one can be a dangerous proposition (i.e. blown motor) if you don't know what the map was tuned for.

 

^ it is a used PFC, and im running the base mod map.(i have intakes,and DP) BUT this problem was happening before the PFC.


quick re-cap ,as it seems a lot of posts have not read the whole thread.

It violently bucks/hesitates in FIRST gear only. it was happening BEFORE the PFC. and as far as i know, nothing has changed to cause it.



i did some testing tonight.

it did it over and over, until i decided to smoothly accerlate past the transition to the second turbo in first gear, THEN i WOT around 4600rpm, and it was smooth, and pulled hard. I re-did this test a couple times, with same results.

then i tried it again from a slow roll, in first turbo range. and it was smooth! i tried many times again, including launches from a dead stop, and it was smooth.


so, confused as to what happened, i did some more pulls while watching my commander and my boost gauge more closely. I didnt notice anything that jumped off the screen of my commander,....grant-it, i may not notice anything even if it was off, as i am just learning all this.

My boost gauge in 1st never exceeds about 8 psi. it will run to about 8,drop to 5(a problem im having in all gears) and by the time it has a chance to get boost back up to around 8, its time to switch gears.


so as of this second, the car works again. and i still have no idea whats really going on. when it works....it works GREAT! when it doesnt...well...



is there a way to see fuel pump voltage from the commander?

 

install a wideband and see what the AFR's are when the hesitation occurs.

 

well your boost pattern is off then... you should have a 10-8-10 boost pattern with the stock turbos. Probably a vacuum hose somewhere. Or a bad boost leak. After numerous problems with my whole vacuum nest crap i went non sequential and now single turbo. it's so much simpler.

It's hard to say what your original problem was. Especially without having more way to monitor vital parameters.

 

^ yes, boost is off. and its been off since i bought the car. Its a mazda reman with new turbos, and they hooked all kinds of things up wrong.

ive just recently got it to 10-5-10, after 6 months of owning it. im pretty sure the boost pattern has little to nothing to do with the bucking. it didnt do it when i bought it....it just developed it out of no where? and then it dissapears just as quickly. ...."there have always been ghosts in the machines"

my boost pattern is pretty good in all other gears, except for the drop to near 5psi, instead of 8.

 

No but you can check sensors in the etc menu iirc.

Next time it starts happening, repeat the test procedure and isolate the RPM, boost etc where this happens.

The FAQ thread has a good link to turbo troubleshooting if you want to start researching your boost pattern. Judging by the boost levels, I'd probably suggest first checking if the restrictor pill in the wastegate line was replaced by a silicon hose that doesn't have a restrictor. That limits boost to 7 PSI but sometimes shows up as 8 PSI on diff boost gauges.

 

ok, thanks. ill try to isolate everything as best as i can.

and as fa as troubleshooting the turbo system......im unfortunatly, reasonable versed in the subject lol. Im currently running a blitz sbc id EBC, using version 2 of the wastegate diagrams. i suspect i may have to try version one instead and install a pill in the prespool line. see, my car, since ive owned it, has never had the pills. Mazda never reinstalled them when they replaced everything, and they also hooked up a lot of vacuum lines wrong. and when i bought it, it was making 4-0-0

slowly but surely ive been correcting all the issues, and making minor upgrades along the way. ill update if i isolate it or if it returns and i have more info.

thanks

 

update please...what become of the issue?

 

its still doing it. and it appears now to definitly only be related to the first turbo, in FIRST gear. Same as before, if i accelerate gently through the 1st turbo range, and THEN WOT, everythings fine.

also, i was adjusting my blitz EBC last night. i turned down my gain settings and the car is decidedly quicker. but as i was testing, i developed a NEW problem! alright! ........i guess it could be related.

after some hard runs, i would slow down to acceptable speeds, even have the car in neutral for a while. then, when i would go to boost again, theres no first turbo! it happened many times but after playing with the throttle and changing gears a few times, it would come back online.

im aware of the turbos being parrallel after 4500rpm and back down to low(is it 3000rpm), but this was not that. i was at idle for a while! somehtings sticking. sounds like to me, they could be related.

whatcha got for me degeeseman!