Rb20 Problem

[black_32]

just recently i put a new engine in my 32 it was an rb20 with bout 70,000 k and it was a weird idle in the mornin it will sit on bout 2,000rpm then when it gets warm it fluctuates between bout 1,100 and 2,000rpm a mate said it was a sensor and i hve replaced teh o2 sensor, throttle position sensor, water temp sensor, afm, and teh 1 under the throttle body and its still does it and its really startin to get to me ne help would be great thanks

[blind_elk]

Have you cleaned out the AAC valve (back of the plenum)? Have you set the TPS correctly? Are you sure there are no air leaks?

[black_32]

what do u mean back of the plenum is it closest to teh firewall or opposite teh throttle body and how do u clean it thanks for ur help

[blind_elk]

Yes, next to the firewall.

Undo 4 bolts to remove it from the plenum, then 2 screws to disassemble. Clean with Car-B-Kleen or similar.

[Col-GTSX]

It will be the AFM... with out doubt....

Clean the aac valve works 2% of the time...

[fReak32]

had the same prob with mine the other day. f*kcin afm.

[wheels_24]

I have a AFM air flow meter at home if you need one i don't run one anymore so you canmake a offer if you want

[black_32]

afm has been swapped with a mates and didnt make ne difference but his car is runnin fine

[Col-GTSX]

I would take the aac valve off and spray it with degreaser then bath in petrol.... let is dry and put it back on.... Also take the throttle body breather pipe off and spray contact cleaner down the tube.... Maby even pull the hose from the throttle body and clean with contact cleaner... dont worry is flamable and will combust if you get some down the plenoium.... if none of this helps.... Then you need to look at consulting an auto electrican...

[B0oStEr]

just recently i put a new engine in my 32 it was an rb20 with bout 70,000 k and it was a weird idle in the mornin it will sit on bout 2,000rpm then when it gets warm it fluctuates between bout 1,100 and 2,000rpm a mate said it was a sensor and i hve replaced teh o2 sensor, throttle position sensor, water temp sensor, afm, and teh 1 under the throttle body and its still does it and its really startin to get to me ne help would be great thanks

<{POST_SNAPBACK}>

Have you adjusted the AAC valve? When the motor warms up remove the maroon plug from the AAC valve. Screw in the adjustment screw to set idle at 675rpm. If it screws all the way in and the revs are still above this then you have an inlet leak.

Is this "1 under the throttle body" you refer to the 'air regulator' that is mounted on the manifold runners below the throttle body.

It's job is to increase idle speed until the motor warms up.

I would have thought this a likely cause of the fast idle as these often stick open and allow too much air to bypass the throttle butterfly.

When it warms up try to pinch the hose going to it and see if the idle slows.