Surging under light throttle?

[caminperth]

Hey all,

Quick question that's been bugging me for a while. I get a sudden drop off of power under light throttle. Can happen in any gear, mostly in 5th gear when accelerating lightly from 100+km/h and backing off the throttle slowly.

Now I know this is due to the fact that the boost is dropping off sharply, but I can't pinpoint why. I've tried adjusting my BOV and it didn't seem to make a difference and it's really starting to bug me.

Ideas? Comments? Help?

[G0DF4Th3R]

i get the same problem at times.. but it went away i dunno why :S

[itbmils]

i get the same problem at times.. but it went away i dunno why :S

have you checked your fuel presure (regulator) ?

I have a malpassi (spelling) that has been playing up - and I get the same problem

[caminperth]

Nope - didn't think that would do it. Have got the std one. How do you check it?

[itbmils]

I didn't - my mechanic did it - I can ask if u like

[USRB25S13]

I have the same problem with my car expect the surging happens when I am at a constant throttle trying to hold a fixed speed. I have an FPC and I turned off the O2 control and the problem goes away. But my gas milage suffers. I guess in my case a new O2 sensor may fix the problem.

[Cake]

cam mine does the same, only if i back off under low boost and get flutter, then it surges for a second, did loosen the bov and it improved a little, but still does it.

[GunMetalR33]

It could be your boost controllers, I have the same problem.

[caminperth]

I don't think it's anything to do with fuel regs or O2 sensors as I have no other problems with the car.

Boost controller - not sure about this one. I run a HKS EVC4 and it works a treat. Haven't had any problems with it getting the set amount of boost happening..

boo5t - I tend to agree that it's a BOV problem.. just not sure how to fix it.. perhaps SK has an answer? He usually does..

[pnblight]

Hey all,

Quick question that's been bugging me for a while. I get a sudden drop off of power under light throttle. Can happen in any gear, mostly in 5th gear when accelerating lightly from 100+km/h and backing off the throttle slowly.

Now I know this is due to the fact that the boost is dropping off sharply, but I can't pinpoint why. I've tried adjusting my BOV and it didn't seem to make a difference and it's really starting to bug me.

Ideas? Comments? Help?

wot ecu you using is it std?

[caminperth]

yep std...

[pnblight]

has the car had many mods done to ie upgraded turbo etc

[pnblight]

I have the same problem with my car expect the surging happens when I am at a constant throttle trying to hold a fixed speed. I have an FPC and I turned off the O2 control and the problem goes away. But my gas milage suffers. I guess in my case a new O2 sensor may fix the problem.

this is definity o2 sensor (not like the problem descrided in this thread) as you hold fixed throddle position the ecu switches from map to closed loop control on the fuel system and with the pfc as you have done you can disable this closed loop function and uses the map only with cause the heavy fuel use , so buy new o2 and save some $$ on fuel.

[600hp]

Simple don't use light throttle!! ha ha

My o2 sensors are stuffed and the fuel milage sucks arse!

I have ordered new ones .

[caminperth]

pnblight - std turbo, cooler, exhaust, piggy backs, evc, bov and intake.. nothing special.. 270rwhp and runs well, cept under light throttle!

[pnblight]

Piggy Backs? well what my thinking was , was basically tune around light throddle was out or out because other facts. As most dyno tunes will not even look at parts of tune off the std power pull path (ie light throddle etc).

my surgestion would be most like check all or analog input (throddle sensor,o2 sensors etc)

and if no luck buy apex pfc and get a good tune to ozzy condition and fuel.

sorry cant be of more help.

[GTR-Ben]

My friend gets this trouble in his S13 at times.. under full throttle and only sometimes.

With the Boost Controller off (EVC III) it doesn't do it.. odd

[caminperth]

still don't think it's the tuning.. definitely feels like the bleeding off of boost.. anyone know how a bov should REALLY be adjusted?

[benl1981]

Cam,

Did you get to the bottom of this. If so what was the issue?

I know its old