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bit of a flat spot til bbm activates 

 

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 Post subject: bit of a flat spot til bbm activates
Posted: Fri Dec 09, 2011 9:29 pm 
Parts Gopher
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Ride: fairlane ute

Location: wodonga
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Hi
Hooked up my BBM properly today with EL ecu, idles beautiful now but reckon its a bit flat mid way through the revs until the BBM kicks in. This sound like timing? i set base idle to 0 degrees. Might it take a while for the ECU to figure it all out?
cheers
car is EF motor ED dizzy in XF ute.
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 Post subject: Re: bit of a flat spot til bbm activates
Posted: Sun Dec 11, 2011 5:45 am 
Stock as a Rock
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Ride: EF xr6 AU3 220kw xr8

Location: frankston
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Is the vacuum actuator on the end of the manifold in the closed position under idle upto about 3400-3500RPM. If its open all the time that would explain the lagging as the computer has been programmed to correct A/F before BBM opens and when its opened. Check the vacuum line hasnt been pinched also, as this would cause the valve to be in the open position all the time.

Food for thought

Cheers Joel

 

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 Post subject: Re: bit of a flat spot til bbm activates
Posted: Sun Dec 11, 2011 8:51 am 
Technical Contributor
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+1 for checking the Vac hoses and lines. The hard plastic line could have been crushed or pinched.

Proplem is that you have confused it, EF Motor, ED Dizzy, EL ECU in an XF. It doesn't know what it's supposed to do. :D
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 Post subject: Re: bit of a flat spot til bbm activates
Posted: Mon Dec 12, 2011 6:04 pm 
Parts Gopher
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Ride: fairlane ute

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the actuator is all the way up at idle with vacuum , actuator drops down with car off and at 3500ish rpm, thats right isnt it? ECU cuts vacuum at 3500 or so?
cheers
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 Post subject: Re: bit of a flat spot til bbm activates
Posted: Sat Dec 17, 2011 6:33 pm 
Stock as a Rock
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Ride: EF xr6 AU3 220kw xr8

Location: frankston
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No the ecu doesnt cut out the vacuum, it happens naturally as the engine revs and the throttle body butterfly opens more causing less vacuum in the intake side. The vacuum in the intake side holds the actuator closed until about 3500rpm and as vacuum drops at about these revs the actuator releases and opens the manifold up completely to allow full air flow for high revs.

Have you found the problem yet?, If not maybe try disconnecting the battery for 1/2hr to reset to factory settings and let the ECU do some learning.

Just for kicks check your plugs in case they may becoming fouled up with carbon. Is the car running straight petrol of dual fuel?

Cheers Joel

 

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 Post subject: Re: bit of a flat spot til bbm activates
Posted: Sat Dec 17, 2011 7:24 pm 
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yes it does...
the engine has vacuum at idle which activates the diaphragm putting the manifold on long runners, there is a one way check valve that holds the vacuum in the diaphragm untill the ecu cuts voltage to the bbm solinoid releasing the stored vacuum from the diaphragm at 3800rpm, switching the manifold to short runners...
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 Post subject: Re: bit of a flat spot til bbm activates
Posted: Sat Dec 17, 2011 8:51 pm 
Parts Gopher
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Ride: fairlane ute

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thanks troyman, confirmed what i figured was right, i was seriously starting to doubt myself. I utilised a vac tank inside the plenum, off a ZL Fairlane, and a check valve so no chance of BBM vacuum upsetting anything else. Any way as it turns out i wasnt waiting long enough to allow ecu to go into timing mode ( bit different on EEC4 ecu's) and it was fair bit retarded, reset and advanced a couple degrees, all seems good now. Thanks again
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 Post subject: Re: bit of a flat spot til bbm activates
Posted: Sat Dec 17, 2011 9:41 pm 
Stock as a Rock
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I stand corrected Troyman.

I didn't realise it was electronically switched.
I was under the assumption that there was a pre tensioned spring in the diaphragm that was compressed under vacuum and released when the vacuum dropped in the manifold. Anyway i learnt something today.

Cheers Joel

 

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