BCDD removal

[siteunseen]

Could somebody that has taken their BCDD off tell me whether they like not having it or wish they hadn't removed it. Thanks for any replies.

[Jeff G 78]

If it's working properly, leave it alone, but if you can't get it to work right with adjustments and you can't find a good replacement, take it off. I plugged mine and all is fine.

[deadflo]

I had to remove mine when I put on the larger throttle body. Didn't seem to affect anything.

[280~Master]

Its no bid deal to remove. Mine has been off for sometime and have not noticed a difference.

[siteunseen]

I am slowly putting everything back together and would like to eliminate any future headaches. It did keep a high RPM for about 5 seconds when I came to a stop. So it's going in the "extra parts box". Reading old post from SEARCH is nothing like 1st hand experience. Thank you all for your replies.

[TomoHawk]

I was able to remove the BCDD from my throttle. I made a cover plate and screwed it on, with a little RTV sealer. I needed to verify which of the vacuum tubes went to the little hole in the throttle throat for the distributor vacuum advance. I haven't been able to tell what effect having the BCDD solenoid unplugged has on the engine's operation.

[Wade Nelson]

Only remove the BCCD or other emissions control devices if you have SOLID evidence they have failed and/or negatively impacting the operation of your vehicle. Theoretically all the BCCD is going to do is cut fuel while your engine returns to idle as you coast or engine brake down, also preventing backfires. That's a good thing, a single backfire can destroy your AFM. And cutting fuel when the engine isn't supplying power saves fuel. There's simply no real benefit to removing it unless it has failed in some way. Instead learn how it works, test it, read the Datsun fuel injection manual on adjusting it IF you think it's misbehaving, (manual available online as a .pdf) and in general LEAVE IT ALONE unless you have a valid reason to remove it.

[TomoHawk]

I disagree:

Per the FSM, it doesn't affect the fuel delivery.

There is nothing "theoretical" about the device.

The purpose of the BCDD is to let a little extra air into the intake manifold when you let off the gas, while coasting, to keep the mixture a little more even, so the engine doesn't pass a puff of unconsumed fuel out the tailpipe.

See attached. Page EC-5

[240260280z]

BCCD also reduces high vaccum that will draw oil into the cylinders. (when throttle valve closes at high RPM's)

[siteunseen]

Is that bad? Oil in cylinders. Or I guess your saying on the tops of the pistons where there shouldn't be oil.

[TomoHawk]

So far, the removal of the BCDD hasn't affected the engine's operation in any bad way. We still need to check how the vacuum advance is working, as it gets the vacuum through the BCDD. Otherwise, there aren't any vacuum leaks.

[siteunseen]

FWIW I turned mine clockwise until it smoothed out comng to a stop. Seems to be working fine.