V7 STI stuttering at high boost, no fuel pressure in lines when off.

[josephstef]

Ive just got v7 which has been completely rebuilt, It was running fine for a month or so and has now started stuttering out of the blue, usually when boosting over 10 psi. It also likes stalling after driving it hard and being stopped at the lights.

First off I replaced the fuel pressure regulator to a high end aeromotive as the previouss one was reading 43psi even with -20 psi boost through it.

The new reg now reads around 37 psi when at idle which seems more promising. It now seems to stutter a lot less and idle a bit smoother (previously it was hunting all over the show until it stalled).

This hasnt fixed the problem, so now ive put new spark plugs in it, still the same.

What ive noticed is that when setting the pressure on the regulator it only holds pressure for a second. I literally had to get some one to sit in the car to keep priming the fuel pumps so i could set the pressure before it would fall to 0 psi.

So is this a problem? As when i turn off the car Im mmedialtely reading 0 psi fuel pressure on the regulator, is it because im running a surge tank?

[ADIKT]

I would say your hunting/stalling could be maf afm realated... or could very well be a boost leak.

your new reg should be reading same pressure

[josephstef]

Ive checked for boost leaks, and error logs/ limits on the link ecu nothing comming up there. Might get a garage to test the AFR on it.

[Pappu1]

Idle pressure is 43.5

Set it to that with the vac hose pulled off

And needs to be a 1:1 regulator

Next - what all mods on car?

Where u based?

[josephstef]

idle pressure is 43.5 i was meaning when -20psi boost idle.

Its actually a subaru b4, just seemed easier to describe it as a v7.. haha

Im in Wellnigton.

2.5L forged cp pisonts, datrton sleaves, eagles rods.

v7 sti avcs heads with some work done to them

bosch 044 fuel pump with surge tank

walbro 255 in tank pump

id1000 injectors

Holset hx40 turbo

NGK 7 heat spark plugs.

Aeromotive regulator 1:1 ratio

[Pappu1]

Nice

Looks like a lot of work

I assume it\'s tuned

Stock Ecu?

Twisted turbo?

Still running afm?

[josephstef]

Thanks , Its a link G4 Storm with twisted turbo and no afm, and tuned. So the stuttering was random.

There was a problem with the Piston rings letting oil through so they had to be changed, but the problem still started before we changed the piston rings.

[funkytown]

take it back to the tuner for investigation. you have a totally custom machine and its obviously not right.

whether its the tune or something mechanical thats the place you need to start.

you risk killing that built motor if its leaning on boost or worse.

[josephstef]

 funkytown said:

take it back to the tuner for investigation. you have a totally custom machine and its obviously not right.

whether its the tune or something mechanical thats the place you need to start.

you risk killing that built motor if its leaning on boost or worse.

I did it with richard and jason in christchurch, they seem to know you. Jasons comming up in decemeber so will have a chat to him when he comes to welly.

[funkytown]

yer i do know them, and them me.

if its a wellington based car, talk to either shred or STM for a power run.$150 from memory. i put my money on them working it out real quick.

$150 is a massive saving over a ruined performance motor.

waiting and continuing to run it while its not right just risks damage.

ymmv

[Pappu1]

yep agreed...its a very custom piece of setup

best to get the original tuners have a look and they can figure out since they did it

post some pics tho as it does sound real nice

[josephstef]

yeah, im gonna order a afr sensor today aswell. I called up shred, he was thinking it could be the coilpacks but im going to take it in sometime next week.

[Koom]

 josephstef said:

What ive noticed is that when setting the pressure on the regulator it only holds pressure for a second. I literally had to get some one to sit in the car to keep priming the fuel pumps so i could set the pressure before it would fall to 0 psi.

So is this a problem? As when i turn off the car Im mmedialtely reading 0 psi fuel pressure on the regulator, is it because im running a surge tank?

This just sounds like you don\'t have a check valve in the system. From memory the 044\'s don\'t have a built in check valve like the Walbro\'s and factory pumps. I don\'t think thats a major issue?

[hijacka]

 Koom']

[quote name='josephstef said:

What ive noticed is that when setting the pressure on the regulator it only holds pressure for a second. I literally had to get some one to sit in the car to keep priming the fuel pumps so i could set the pressure before it would fall to 0 psi.

So is this a problem? As when i turn off the car Im mmedialtely reading 0 psi fuel pressure on the regulator, is it because im running a surge tank?

/quote]

This just sounds like you don\'t have a check valve in the system. From memory the 044\'s don\'t have a built in check valve like the Walbro\'s and factory pumps. I don\'t think thats a major issue?

Yep! Bang a check valve on the end of the 044 pump

[Guest]

 josephstef said:

idle pressure is 43.5 i was meaning when -20psi boost idle.

Its actually a subaru b4, just seemed easier to describe it as a v7.. haha

Im in Wellnigton.

2.5L forged cp pisonts, datrton sleaves, eagles rods.

v7 sti avcs heads with some work done to them

bosch 044 fuel pump with surge tank

walbro 255 in tank pump

id1000 injectors

Holset hx40 turbo

NGK 7 heat spark plugs.

Aeromotive regulator 1:1 ratio

What ended up happening with this? Any update on this monster?

[gotasuby]

It goes good. Real good.

[Guest]

 gotasuby said:

It goes good. Real good.

ohhh I know exactly how good you mean

kw figure/400m time? not just seatometer lol and what was the issue?

[gotasuby]

He set fuel pressure to high and also tune was out. No idea what power as was road tuned by me. Hasn\'t had 1/4mile time yet