Rb20Det Idle Issue

[who's next]

Good evening,

I need some help, About 1yr ago i did a complete conversion on my cefiro using a gtst front cut. from the start i had an idle issue but only when mashing the brakes to slow down, this would become worse when the ac was on, to the point where it would cut off. lately (march) it started to get worse even when the ac was not on. i did searches and i have cleaned the idle control valve, the maf sensor, plugs are approximately 1yr old. in April i changed the turbo and installed a t3/t4 with a top-mount manifold and also a front mount intercooler. the original problem was never solved but i have seen a steady progression and it is getting worse, even with no AC.

here are the new symptoms.

Starts up good, when the car gets warm the engine starts to search, drops to 3k rpms and lower and then pick back up and so it goes until it would cut off. under acceleration the car works perfect, plus real hard at 12psi, air/fuel shows up as 12 to 13, no sputtering etc. when it is back down to idle it feels like it is going to cut off and then it does, only way to avoid it is if i mash the gas and then it catches itself and idles at 800 rpm until it start to search again. i have noticed that on the wide band that i have it goes from 18 to 22.4 when it searches. i changed the idle control valve (the original one had a spring in it the used one i bought does not) but i got the same issue. idle nice when it starts and as soon as it gets warm it starts to search.

any help would be greatly appreciated.

thanks

Roger

[Ben C34]

With the afr's going so lean I would be looking at the plenum area for a vacuum leak.

Edited August 15, 2014 by Ben C34

[who's next]

Still searching would keep you guys posted

[CEF33Y]

Do you have a blow off valve? plumback or vent to atmosphere?

[who's next]

I have a blitz bov vented to the atmosphere.

[daisu]

BOV could be sucking in air, could be a gasket or seal on the inlet manifolds, throttle body shaft seal, could be the exhaust oxygen sensor.

[Ben C34]

I have a blitz bov vented to the atmosphere.

That's your problem. It creates a vacuum leak.

[who's next]

Thanks i would try blanking it and see if it helps, also changed the AFM and it really did not help that much i would work on it next weekend. would update. thanks again

[who's next]

well i mean replacing the pipe with the bov

[who's next]

update changed out the pipe with the bov and same issue. :-( would keep at it

[who's next]

update, i changed the o2 sensor with one i had from a RB20 non-turbo and guess what she runs really good, so it looks like it was a bad o2 sensor was at the heart of my problem. i would look for a new one to replace it. thanks for all your help i really appreciated it.

Roger