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Surging under light throttle?

caminperth

By caminperth,
in Engines & Forced Induction

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caminperth Grand Master

caminperth

Posted
Posted

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?

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USRB25S13 Enthusiast

USRB25S13

Posted
Posted

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.

caminperth Grand Master

caminperth

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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.. :rant:

pnblight Mentor

pnblight

Posted
Posted
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?

pnblight Mentor

pnblight

Posted
Posted
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. :rant:

pnblight Mentor

pnblight

Posted
Posted

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.

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