BB4 keeps cutting out

lewie fraser · Post by **lewie fraser** » Sat May 07, 2016 9:40 pm

so my bb4 keeps cutting out and its mostly when the car is slowly heating up.been driving for around 5 mins then its dying at junctions and roundabouts.its getting to the stage where its dangerous.

so I have cleaned the iacv,throttle body,fast idle control value.changed the plugs aswell.

am sure this has been covered a lot but if anyone has more ideas and tips to narrow down the problem then please throw them my way

Post by **NafemanNathan** » Sat May 07, 2016 10:51 pm

Is it when you slow and come to a halt that the revs drop so low it cuts out?

lewie fraser · Post by **lewie fraser** » Sun May 08, 2016 7:48 am

yeah exactly that

Post by **NafemanNathan** » Sun May 08, 2016 8:59 am

I had that and it was significantly worse when lights and other electrical items were switched on due to the additional power drain. My idle dropped down considerably even when I wasn't driving. I tried various things including a replacement alternator. It turned out a good blast of carb cleaner directly into the mouth of the throttle body whilst the engine was running sorted out it. I imagine the IACV port hole in the throttle body was all carboned up. I've not had the issue since.

http://www.ludegeneration.co.uk/post288767.html#p288767

Post by **vanzep** » Sun May 08, 2016 10:48 am

check the connections at the alternator - one time i found the actual terminal on the earth strap had snapped but was still attached

the other time i replaced the alternator and that fixed the problem

and check earth strap from battery and all other grounds for a good connection

Post by **Greg-SiR** » Sun May 08, 2016 1:05 pm

It could be electrical but does any of the instrument/dash act up too or is it mostly mechanical?
Smothering,does the rev hold good at idle?
Fuel pump or filter maybe a bad dose of dodgy petrol..

lewie fraser · Post by **lewie fraser** » Sun May 08, 2016 10:05 pm

I removed the AICV and cleaned it with brake cleaner.same with FICV.I changed the fuel filter for a genuine Honda one a few weeks ago too so fueling must be good.I used a video merlin posted up a while back on how to check your AICV and FICV.I removed the air Intake piping and there is 2 holes on the throttle body that you can now see.one near the bottom and one near the top.when I block the bottom hole my car is fine.when I block the top hole my car is dying.i am guessing it has to be the AICV now.There looks like an adjusting screw on it so I will give that a slight adjustment and see what happens.if not I will just replace the AICV.

Post by **vanzep** » Sun May 08, 2016 10:39 pm

didnt know the iacv was adjustable but i see there is small countersunk screw on the side with a hex drive..never noticed that before

lewie fraser · Post by **lewie fraser** » Sun May 08, 2016 11:01 pm

yeah I noticed it tonight mate,it must turn so it must adjust the idle.I ll soon find out tomorrow

Post by **NafemanNathan** » Sun May 08, 2016 11:35 pm

Your engine is behaving as it should do when blocking those holes.

The bottom one is for the FITV (Fast Idle Thermo Value), so when the car is warm and the FITV is working this valve should be closed anyway as it no longer needs air to bypass the throttle body.

The top one is for the IACV (Idle Air Control Valve) and again if it's working properly your car should be idling fine normally but when blocking the top hole in the throttle body thus starving the IACV of air it can no longer control the idle and the car will stall.

So I wouldn't go tweaking that screw as it wouldn't have shifted itself and you will likely screw it setting, but do try blasting carb cleaner down the top hole whilst revving the car at the throttle body.