help!! need advice (hestiation)

[sykko]

so ive been trying to track down a issues with my 2g gst hopefully i can get some info to check and try. the car has a hesitation when i go wot it spikes 15 psi starts to stumble and run poor once boost comes down to 10psi it clears up i put the car on logger confirmed its only running 5* degrees of timing at wot. code came on p0300 random misfire. i cleared it it hasnt came back on. also notice the car is worst in the night then day (colder air). i have so far swapped maf, correct ngk plugs and wires, ignition control module, knock sensor, no change at no check engine light ever came back on. no clutch or flywheel has been installed all stock. any help would be greatly helpful thank you.

 

[noobin it]

What is your boost set at? Does it spool normally before the hesitation occurs? Considering the problem changes with air temperature, my guess would be that the problem is boost/air related. I would start with the simple stuff and check your fuel pressure and vacuum. I'm not an expert though.

 

[sykko]

boost is stock for a t25 spike 15 drops to 10psi im thinking possibly fuel pump dieing cant keep up with the demand for that boost level in the day and when air becomes denser the fuel pump becomes worst on keeping up

 

[interturbo]

You may want to check fuel/air curve as well. If your car is bucking a little or falling flat on its face sometimes then you may want to inspect your tps.. it may be on the frits but not bad enough to trip an engine light or it could have a flat spot on it. Is very common at least with the stock 1G

 

[sykko]

i have tested the tps its all good thanks for the responds. also i have check o2 its .98 volts plug gap is correct for stock

 

[interturbo]

Ok.. dumb question for ya.. have you confirmed your voltage in the daytime vs nighttime when I would guess all your headlights and such would be on? And have you checked or replaced your fuel filter? Only other thing I could say off the top of my head would be to have someone follow you in the daytime and see if anything such as smoke is dumping out your tailpipe and see what color the smoke is. If black smoke you have too much fuel if no smoke then not enough fuel. Hope this kinda helps and home you get her fixed.

 

[sykko]

thanks alot that was my next check could be bad fuel pump them if it cant keep how does that sound?

 

[interturbo]

Yea it could be bad fuel pump.. but don't get me wrong... from what I understand all these cars emit some black smoke at times but not a lot of it as far as when your foot is mashing the gas pedal to the floor. You should only be checking for excessive black smoke when the car is acting up..don't know where you live or how hot or cold it is when your car acts up or what kind of driving is done most of the time such as city or highway or maybe she needs a break .. my talon did similar to that but she would buck and sometimes fall flat on her face but it was my tps and I have a 1G