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Fuel cut and lean cruise 

 

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 Post subject: Re: Fuel cut and lean cruise
Posted: Fri Apr 18, 2014 8:58 pm 
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SWC wrote:
Ford quote 470mm of Hg at idle in neutral. This equals 18.5in of Hg. This converts to 9 psi of Vacuum. Are you sure you are measuring inches of mercury or psi.

If you are pulling 11in of Hg at idle, then that is only 5.5psi of vacuum.

If this is the case then this will explain your fuel issue and lack of closed loop. If this is so then you have a vacuum leak and not necessarily on the intake, it could be through your exhaust valves.

Is the cam and head stock?


Yeah, even with a long duration cam I still get around 15-16inHg at idle.
If you have less than that you definitely have either a bad vacuum leak or valve/cam timing problem.

 

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 Post subject: Re: Fuel cut and lean cruise
Posted: Fri Apr 18, 2014 9:08 pm 
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SWC wrote:
Ford quote 470mm of Hg at idle in neutral. This equals 18.5in of Hg. This converts to 9 psi of Vacuum. Are you sure you are measuring inches of mercury or psi.

If you are pulling 11in of Hg at idle, then that is only 5.5psi of vacuum.

If this is the case then this will explain your fuel issue and lack of closed loop. If this is so then you have a vacuum leak and not necessarily on the intake, it could be through your exhaust valves.

Is the cam and head stock?

unless he is measuring in in/hgA, then 11in/hga is equal to about 19in/hg

 

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 Post subject: Re: Fuel cut and lean cruise
Posted: Fri Apr 18, 2014 9:12 pm 
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I'm measuring MAP, not vacuum, I think that's where the confusion is. I get 11 MAP at idle which is equal to 18 vacuum since atmospheric is 29 today.

 

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 Post subject: Re: Fuel cut and lean cruise
Posted: Fri Apr 18, 2014 9:26 pm 
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shyun wrote:
I'm measuring MAP, not vacuum, I think that's where the confusion is. I get 11 MAP at idle which is equal to 18 vacuum since atmospheric is 29 today.


If that is the case, then yes you are around 18inhg

barometric pressure - (minus) MAP = intake manifold vacuum.

Can I ask how you are measuring MAP.
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 Post subject: Re: Fuel cut and lean cruise
Posted: Fri Apr 18, 2014 9:31 pm 
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SWC wrote:
shyun wrote:
I'm measuring MAP, not vacuum, I think that's where the confusion is. I get 11 MAP at idle which is equal to 18 vacuum since atmospheric is 29 today.


If that is the case, then yes you are around 18inhg

barometric pressure - (minus) MAP = intake manifold vacuum.

Can I ask how you are measuring MAP.


Got a crappy GM 1-bar map sensor hooked upto a datalogger and the laptop.

 

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 Post subject: Re: Fuel cut and lean cruise
Posted: Fri Apr 18, 2014 9:39 pm 
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shyun wrote:
SWC wrote:
shyun wrote:
I'm measuring MAP, not vacuum, I think that's where the confusion is. I get 11 MAP at idle which is equal to 18 vacuum since atmospheric is 29 today.


If that is the case, then yes you are around 18inhg

barometric pressure - (minus) MAP = intake manifold vacuum.

Can I ask how you are measuring MAP.


Got a crappy GM 1-bar map sensor hooked upto a datalogger and the laptop.


Fair enough :D .

So with your Vacuum basicly spot on, that throws the vacuum issue out.

Have you checked your O2 sensor in relation to your fuel issues?

Last edited by SWC on Fri Apr 18, 2014 10:16 pm, edited 1 time in total.

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 Post subject: Re: Fuel cut and lean cruise
Posted: Fri Apr 18, 2014 10:05 pm 
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SWC wrote:
Ford quote 470mm of Hg at idle in neutral. This equals 18.5in of Hg. This converts to 9 psi of Vacuum. Are you sure you are measuring inches of mercury or psi.

If you are pulling 11in of Hg at idle, then that is only 5.5psi of vacuum.

If this is the case then this will explain your fuel issue and lack of closed loop. If this is so then you have a vacuum leak and not necessarily on the intake, it could be through your exhaust valves.

Is the cam and head stock?


my DOHC read around the minus 20 area in PSI when at idle

 

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 Post subject: Re: Fuel cut and lean cruise
Posted: Fri Apr 18, 2014 10:12 pm 
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mitchell g wrote:
SWC wrote:
Ford quote 470mm of Hg at idle in neutral. This equals 18.5in of Hg. This converts to 9 psi of Vacuum. Are you sure you are measuring inches of mercury or psi.

If you are pulling 11in of Hg at idle, then that is only 5.5psi of vacuum.

If this is the case then this will explain your fuel issue and lack of closed loop. If this is so then you have a vacuum leak and not necessarily on the intake, it could be through your exhaust valves.

Is the cam and head stock?


my DOHC read around the minus 20 area in PSI when at idle


That is 40in of hg.

Is your gauge reading PSI or Inches Hg?

If it is reading PSI, then your gauge is stuffed Mitch.
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 Post subject: Re: Fuel cut and lean cruise
Posted: Fri Apr 18, 2014 10:35 pm 
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psi but was a boost guage, so might read diffrently?

 

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 Post subject: Re: Fuel cut and lean cruise
Posted: Fri Apr 18, 2014 10:39 pm 
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No, Boost gauge works just like a Vacuum Gauge.

Mechanical or electronic gauge?
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 Post subject: Re: Fuel cut and lean cruise
Posted: Fri Apr 18, 2014 10:40 pm 
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Do you know what your dashpot gain is set to?
I got much better engine braking and much faster return to idle by changing dashpot gain and modifying dashpot decay rate. I've managed to get it to the point where it performs similar to having isc unplugged above 1200rpm.
I don't think I've ever seen less than 4l/100km in my EF on decel.
I'm pretty sure my fuel cut is working though because there is a noticeable difference in engine braking if neutral switch is connected to ecu or not.

 

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 Post subject: Re: Fuel cut and lean cruise
Posted: Fri Apr 18, 2014 10:51 pm 
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SWC wrote:

Fair enough :D .

So with your Vacuum basicly spot on, that throughs the vacuum issue out.

Have you checked your O2 sensor in relation to your fuel issues?


Yeah got a wideband with the datalogger (not currently connected)... I've ran both the narrowband sim off that, and now run a separate bung with the narrowband. No problems there always circles around 14.7.

Did a bit of a search and saw a quote on fiends thread that the neutral switch on the gearbox will disable lean cruise and decal fuel cut...so going to try look into that. It seems to work fine like I said before 5V in gear, 0V in neutral. Although the same quote about it says it should be the opposite?

the-garage-f53/futurlane-ultimate-budget-stories-t69180.html?hilit=lean&start=1680




roughredXR6 wrote:
Do you know what your dashpot gain is set to?
I got much better engine braking and much faster return to idle by changing dashpot gain and modifying dashpot decay rate. I've managed to get it to the point where it performs similar to having isc unplugged above 1200rpm.
I don't think I've ever seen less than 4l/100km in my EF on decel.
I'm pretty sure my fuel cut is working though because there is a noticeable difference in engine braking if neutral switch is connected to ecu or not.


I tried unplugging it but drove the same? I noticed unplugged it reads 5v on the neutral wire to the ECU (pin 30), which doesn't really make sense since there's no circuit unplugged according to the wiring I've seen. Do you know what voltage you get on pin30?

 

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Last edited by shyun on Fri Apr 18, 2014 10:54 pm, edited 1 time in total.

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 Post subject: Re: Fuel cut and lean cruise
Posted: Fri Apr 18, 2014 10:53 pm 
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roughredXR6 wrote:
Do you have the neutral switch wired to the ecu? If so check that it's working. If the ecu thinks it's in neutral fuel cut won't work.

neutral switch was mentioned in this thread on the first page

 

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 Post subject: Re: Fuel cut and lean cruise
Posted: Sat Apr 19, 2014 12:34 am 
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SWC wrote:
No, Boost gauge works just like a Vacuum Gauge.

Mechanical or electronic gauge?

electric

 

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 Post subject: Re: Fuel cut and lean cruise
Posted: Sat Apr 19, 2014 6:41 am 
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mitchell g wrote:
SWC wrote:
No, Boost gauge works just like a Vacuum Gauge.

Mechanical or electronic gauge?

electric

Senders f**k.
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