Surge Under Boost At Around 4500rpm And Upwards? Why Why Why

[DuFFR32]

Hey all just have a problem thats kinda annoying me atm with the three two, the car has been starting to surge under boost a bit lately at around 4500rpm and upwards on 14psi and when I turn the boost up to 18 It gets worse. I know its not the plugs and the car is not missfiring at all Ive gapped the plugs to 0.8mm and cleaned the coil packs and all connections. the car has a HKS GT2530 turbo, front mount, GTR resistor pack n injectors, Z32 Air Flow Meter, pod, turbosmart dual stage boost controller and full 3 inch exhaust cat back but legal DB so not that loud.

Just would like to know why car surges under boost and if anyone else has the problem?

[The Dan]

fuel pump or fuel filter

[DuFFR32]

the car has an upgraded in tank fuel pump not sure about filter tho i will change that n see how i go... should I earth the fuel pump to the chassis to prevent the low rpm stalling?

[The Dan]

What pump? When was it fitted? How was it installed?

[DuFFR32]

Bosch 040 in tank installed around 2 years ago

[The Dan]

Bosch 040 in tank installed around 2 years ago

Ok then you'll need to check flow on that if the filter doesn't turn up results

[DuFFR32]

Cheers will do Providing tune is ok boosting 18psi is ok yeah? whats the limit for the 2530?

[Moodles2]

Find someone with a wideband oxygen sensor and check your AFRs, especially 14psi and beyond

[STATUS]

what ecu?

[DuFFR32]

Well by the looks of the fuel filter its got some age to it I guess i will have to de-pressurise the fuel system prior to taking the old one out but cant read jap on the fuse cover so unsure which relay to take out? and anyone know what the fuel filter model number is by chance?

URAS - ECU was nistuned by PITS a fair while ago ive made a few changes since then so might be time for a new tune, im thinking of taking it to mercury motorsports after I buy a different exhaust thats not so restrictive

Cheers for the wisdom

[blind_elk]

I reckon you have compressor surge, because the ECU can't properly control the combustion process at 14 and 18 psi. Either back the boost off a bit, or get a retune for the boost levels you are running.

[STATUS]

or the guys have set a TP load limit in the remap, i do it to customers i know have fiddly fingers so they cant up the boost.

[STATUS]

or the guys have set a TP load limit in the remap, i do it to customers i know have fiddly fingers so they cant up the boost.

[esky_mad]

if its only just recently starting doing it i would assume its the filter, pop the fuel filler out to loose some of the pressure and take out the filter.

had similar issues on a trust turbo kitted CA, changed the filter and made a suprisingly big difference. filters are so cheap you may aswell give it a shot.

Edited November 18, 2009 by esky_mad

[DuFFR32]

Well im going to change the fuel filter today and leave boost at 14 and see how I go. Dont think its compressor surge ive seen a video of that on youtube its pretty hectic, my power curve is just bumpy under boost How do i de pressurise the fuel system?

URAS whats a TP load limit?

[The Dan]

Well im going to change the fuel filter today and leave boost at 14 and see how I go. Dont think its compressor surge ive seen a video of that on youtube its pretty hectic, my power curve is just bumpy under boost How do i de pressurise the fuel system?

URAS whats a TP load limit?

De-pressurise?

You pull the hose off the filter and make sure it's pointing down

Or, you can pull the fuel pump relay, or you can disconnect the plug for the fuel pump at the tank and crank it over.....either way, fuel if going to get on your floor so you might as well save yourself some work.

Just unscrew the fuel cap before you do otherwise the tank pressure will cause the fuel to just keep flowing out the hose.