i recently went non sequential on my fd because of this crazy boost issue i am experiencing and i know now its not sequential system related. i cannot boost at all until i slowly reach 4500 rpm. any time below 4500 rpm, the car will start to afterfire from exhaust and the engine falls flat on its face(starts bucking). i have three trouble codes:aws,egr,relief 2 and i know these wont cause a boost issue.also, ive checked all of the remaining important senors (tps,knock,boost, intake temp, and 02 sensor )and they work fine.furthermore, i dont believe its wastegate related either.its like i have to give it a light load all the way up to 4500rpm in order to try to get boost in every gear.after 4500 rpm the car will go to around 5-7 psi which is around what non seq boost should be. people on the forums say it might be secondary fuel injectors failing .but i dont know for sure.i applied battery voltage and they do click. im wondering that someone has encountered this boost issue before and might have some helpful troubleshooting tips. thanks plenty....

 

forgot to mention:oh and i am not in limp mode!!!(because ive experienced it before and its different)

 

Did you go "poor man's" non-sequential or did you go full parallel?

 

i went "poor mans" non-sequential

 

I have poor mans non seq and my boost comes on same rpm but i do reach full boost from then on out.

So i would assume its "normal".

Not to mention im still running the stock cat.

 

do you get full boost by 4500 rpms or does it just start building boost by that time? Hesitations and bucking or anything like that shouldnt be happening regardless. You said you checked the map sensor right?

 

thats normal i get boost around 3000 but i ported a lot of crap and i have a huge exhaust.

 

it is not normal. it is nearly impossible to boost with the issue i have. even if i were to hit boost, it doesnt hold it steady.i have to go easy on the pedal even to try get it past 4500rpm. oh and my map sensor works fine...

 

Compression check?

 

If its bucking, you have another issue.

I would first start with the TPS as thats usually the culprit of the bucking situation.

Its easy to get the calibrations and at least with that out of the way, can you narrow down easier, what the problem could be.

If you went non seq, its obvious you had to pull the manifold apart.

Im guessing in the process of removal and installation of everything caused the TPS to go out of range.

It happened to me and when i fixed it, it was a world of difference in teh way the car acts.

 

85 psi on both rotors. = 6 even pulses (dry compression test)

 

oh and i keep on adjusting my tps and the issue is still there . its like the tps is only helping me with my idle and has not much to do with this boost issue..thanks though...

 

ok so i know my stock ECU is good because i swapped out it out with a good one and the problem is sitll there. also, checked the wiring to my secondary injectors and its fine. ----why is it that right when my boost gage reads 0 psi and under 4500rpm , the car will hesitate and wont boost at all untill 4500 rpm is reached. the car shakes violently and bucks when trying to give it a heavy load at low rpms between 2000-4400 rpm.

 

Does the car run fine at idle? Was anything else removed or changed when you went non seq? The fpr line still hooked up? Any check engine codes? Did you remove the solenoids for the sequential system? More detail on the conversion as a whole might help. Sounds like limp mode or map sensor not connected to me. Check that you have spark at all 4 as well though doesn't sound like an ignition issue

 

my turboII had this exact thing happen i would have a huge hesitation or even a buck right when i hit 0 on the boost gauger it turned out to be my map sensor maybe you can try another one to test it you said yours worked fine how did you test it to see if it worked fine.

 

TPS has a idle range and a WOT range.

Did you check both?

 

you may be experiencing a violent misfire situation, check the resistance of your coils, also how new are your plugs, how clean are they? Is your ignition harness (small one that connects that coils to the main harness) in good shape?

It sounds a lot like the misfires most people get when dyno tuning and find out their ignition is bad, car starts bucking under heavy load because the engine is demanding more, stronger spark and isnt getting it so the fuel doesnt combust. it would also explain your backfiring.

kevin.

 

i used my friends fd map sensor(his car boosts fine)so it good.and i checked the narrow and full range and its fine. but that sounds interesting what TEKNICS said to test out , ill give it a try and see how that goes. thanks .........

 

im not in limp mode because ive experienced it before and it was not cool . i still have all the solenoids connected electronically only for resistance on the ecu for the trouble codes. aslo, everything is sealed and blocked properly with no boost leak. my car's rpm can rise even past 6500 rpm with no problem as long as i dont give it a heavy foot(heavy or even medium load). but once i reach 4500rpm and still giving the pedal ease , boost builds up to about 7 psi and holds .but, acts violently and if i upshift under 4500rpm , same thing .....

 

ok , so now i checked to see if any of my primary boost was leaking out my secondary turbo because i have no charge control valve and it is not leaking out. also im only using my stock air bypass valve (blow-off valve) and no charge relief . my air bypass valve tested good so i know for sure i am not loosing any primary boost .i was told by someone that my car runs as if its fuel/ air mixture was rich (improper combustion) so im going to get a wideband installed . but, im wondering how i can be rich all of a sudden from boosting perfect to not being able to boost anymore with a stock ECU..any advice

 

VC311 i think ur car sucks throw it away and get urself an FC straight up *****!!! peace free bump

 

ok so now i am starting to believe that my fd is having some kind of fuel or ignition issue. i recently replaced the fuel filter and pump new.also, i just sent out all 4 injectors to get cleaned and flow tested. they tested great. so now i also tested my high tension leads(spark plug wires) and the resistance tested well. also i have new ngk-R spark plugs .my car still wont boost and actually i cant even get it to slowly boost a little like before after 5000rpm . that's strange.... even more crazy. i disconnected the connector for the throttle position sensor for troubleshooting and my car ran better. it would go into about 5 psi of boost with slight hesitation and very poor idle.well ,not all the time , but im just throwing that out because it might be informative. so anyone have any ideas on what else to test out...thanks

 

Does the boost hit suddenly? you're going, you're going, you're going, boom 10psi?

 

Have you replaced the coil pack harness? Mazda updated the design of the harness a while back, and you could be getting ignition breakup. I worked on a guy's car that had similar problems, new coilpack harness solved it.

This is definitely not a problem with the turbos or anything like that - it's an engine problem, pure and simple, if you're getting bucking and stuff. Other possibility is a fuel pressure issue - I saw you have a Walbro, if something isn't 100% perfect with the fuel pump install, you could have low or too much fuel pressure. Also, make sure the fuel pressure regulator's vacuum line is hooked up to the proper vacuum source so it raises and lowers fuel pressure with boost and vacuum like it should.

Another thing to look at - saw an FD once that replaced the filter that's in-line with the MAP sensor with a check valve, thinking he was upgrading the "bad" check valve in that line. It's a filter, not a check valve . The MAP sensor has to see boost and vacuum.

Dale

 

try your plugs!