only one problem....

[JayRome]

one problem i cant figure out... could be something really really tiny.....

its a 4g63 N/A close to 11:1 comp, retarded timing etc, its basically a VR4 engine straight up minus the compression....

so the problem... no other problems but this...

under hard boost (6psi ish) when you completely back off say from 50% throttle down 0%.... the engine wont hold idle like it should... should drop to about 1.5k, then when your full stopped, it should go down just past 1k...

but it just shuts off instead....

now this never happened with the SuperCharger, the wiring/ecu has not budged position nor have i changed or added any wires....

i have also noticed while under boost, the A/F ratio gauge reading disappears.... its probably the only thing i have moved since upgrading to a turbo is the Oxy sensor, rather than reading cyl 3's exhaust gasses, its now reading from the dump pipe, where all turbo cars get there reading from.....

its not really a big problem, you just have to be in gear at all times (which i am anyways) but emergency braking needs the booster filled with Vac press to work better and if the engines dead, tis not a good thing....

problem was around from day one, with or with out the plumb back BOV and fluttering. no leaks minus some exhaust gases from a shitty gasket....

i am running a GGSR loom with a Aspec VR4 ECU with 4wire oxy sensor... so it has its own heater and does not need to be ridiculously close to the turbo...

i have checked all wires, connections etc and can't find a fault anywhere... SAFC has been reset and is only running as a gauge not as a controller..

any help would be appreciated...

 

[CLuTZ]

I'd say its a vac issue?

Have you played with the BISS screw?

 

[JayRome]

I'd say its a vac issue?

Have you played with the BISS screw?

the what screw? vac maybe, but idle is perfect.... but it shouldnt just shit it self while the rpm drops rapidly..

 

[MDK87]

The Basic Idle Set Screw (BISS) is the big screw recessed in your throttle body.

I have similar stalling issues with mine every now and then. I've pressure tested my intake as well. I've just learned to live with it.

EDIT: http://www.vfaq.com/mods/BISS-1G.html

 

[JAP63]

under hard boost (6psi ish) when you completely back off say from 50% throttle down 0%.... the engine wont hold idle like it should... should drop to about 1.5k, then when your full stopped, it should go down just past 1k...

but it just shuts off instead....

Im a little confused, are you sayin that if you hit boost, then back off, then put the clutch in..it stalls. ?
Or do you mean that with no throttle the car wont drive itself in gear at low rpm, insted it just turns off?

If its the first, then I'd be looking at either a vac leak, as mentioned earlier, a blow off valve leaking, or an AFM issue...
If its more like the second, id say start looking at throttle positon sensor and Idle stepper motor, idle stepper motors are known to go to shit on these engines..

Also, has it got to do with anything you had setup for the supercharger to bypast at idle? just a thought.

Ps-Your strut tower brace is crazy..haha

 

[JayRome]

Im a little confused, are you sayin that if you hit boost, then back off, then put the clutch in..it stalls. ?
Or do you mean that with no throttle the car wont drive itself in gear at low rpm, insted it just turns off?

If its the first, then I'd be looking at either a vac leak, as mentioned earlier, a blow off valve leaking, or an AFM issue...
If its more like the second, id say start looking at throttle positon sensor and Idle stepper motor, idle stepper motors are known to go to shit on these engines..

Also, has it got to do with anything you had setup for the supercharger to bypast at idle? just a thought.

Ps-Your strut tower brace is crazy..haha

ahh okies let me make it easier...

hit boost, then back off with clutch in = engine stalls

happened even without the bov installed yet...

although S/C was constantly on boost soo couldnt really say if it ever happened..

could be AFM but then the readings on the SAFC never read 000Hz

although without the BOV, on hard boost everytime my car would flutter, and do the same thing....

TPS/ISC all work, still do the usuall 1.5k rpm till you come to a hault then drop to idle speed...

mind you my turbo is literaly less then 10cm away from my AFM, with hard lines, so there could be air pressure getting jammed in that tiny place...


oh i can build anyone a custom strut brace if you really need it, stronger then the alloy ones...

 

[JayRome]

The Basic Idle Set Screw (BISS) is the big screw recessed in your throttle body.

I have similar stalling issues with mine every now and then. I've pressure tested my intake as well. I've just learned to live with it.

EDIT: http://www.vfaq.com/mods/BISS-1G.html

yer thats been adjusted correctly...

 

[Dean]

so have you tried it with the BOV yet?
maybe this will fix things up.

 

[JayRome]

so have you tried it with the BOV yet?
maybe this will fix things up.

yer still doesnt work.... its a freakin odd problem...

 

[to4garret]

i had the exact same symptoms in my old VR4, in my case it was because i had a VTO BOV which the spring was too loose.

 

[JayRome]

i had the exact same symptoms in my old VR4, in my case it was because i had a VTO BOV which the spring was too loose.

hurm..... has a look, my bov seals perfect, and has a stiff spring... but i'll tension is and see how we go...

but i'm thinking its related to the Oxy some how..... gut feelings tells me its in the area...

 

[JayRome]

problem could be fixed..... i'll get back to ya'll after work when i test it..

 

[olly]

yo jay i think i know what it is..
does it happen all the time? it use to happen to my GSR with the SAFC and ITC in it. It's got to do with the AFM. Something about it how it only measures air flow and not pressure. Where as a full stand alone ecu would not have this problem because it doesn't need an AFM .

 

[JayRome]

problem solved, thanks for the input everyone..

 

[JAP63]

problem solved, thanks for the input everyone..

Do enlighten us with the details

 

[JayRome]

ohh, my OXY sensor decided to die.. was wondering why my economy droped heaps.... so on back off, there was no signal going back to the ecu and it would shut off...

lucky i had a spare one that came from the evo 8, so dumped it in this morning before work. engine is a lot smoother now... ...

 

[coop1er]

Interesting. I was thinking the air flow sensor signal was being affected by the airflow when coming off throttle. But if an oxygen sensor fixed it then good luck.

 

[cblancergsr]

its amazing what 1 sensor can doo too make a engine play up

 

[youda]

lol, i had the same prob when my dump pipe came loose, sry couldnt reply ealier dont get on the net as often anymore