High RPM Miss

[TheNicky]

I wasnt aware of that jim!
I was told by 3 mechanics one off the ford assembly line who had been there for 28 years and is now the smog tech i have been seeing...

He said those are for idle only... he said hints being called Idle mixture screws...
Me being a kid took that info and applied and looked elsewhere...

I have a miss and its hit and miss which screams something electrical to me anyways...
but a rich or leaned out mixture screws can cause that too im guessing...

I have HORRIBLE gas mileage so maybe its running a little rich...
And i keep failing at 25mph so too much gas could be the result of my richness...

i will check tonight!

 

[Original_Ranger84]

Wait... You didn't mess with the idle mixture screws? I thought you did that awhile ago? A Idle mixture would cause rich running in higher rpms. I thought told you to do that.

My truck has an intermitten miss too... if that helps. Its Durasparked. (eliminating all the vacuum lines and wires associated with the computer) ... or its missing cause I removed the wire or whatever.

 

[TheNicky]

No i didnt lol!
I had intended to.. i made a O2 Voltmeter tester thing too.. or a buddy did for me...
to get it as close as possible but after reading on here and talking to a smog tech i didnt mess with it... shoot if this fixes it im gonna be pissed!

 

[dangerranger83]

They say that you cant adjust the idle and whatnot on those carb. trucks. I could make my dads idle as high or as low as I want it to.

Why would the city be mad that your truck was in your buddies driveway? Are they that mean there in Cali. or what?

 

[TheNicky]

Yea i dont know...
Still i dont think thats my miss problem, rich or lean...

and yea becuase technically its unregistered vehicle...
soooo they can do what they want...

when im bustin my ass to get this thing registered they mock me...
All fees and registration paid for just this pesky smog...

Hmmm Besides the air pump, and mixture screws any of you have any thoughts?

 

[Brypur]

My 1985 has a feedback solenoid that is attached to the rear of the carburator. To the best of my knowledge this is the device that the computer uses to control the fuel mixture. It has no effect at idle (thus the idle mixture screws) but does for the rest of the RPM range. I am still investigating how it works but it appears to meter the air going into the emulsion tubes thus effecting the mixture.

Something else to look at/consider.

Bryan

 

[85_Ranger4x4]

My 1985 has a feedback solenoid that is attached to the rear of the carburator. To the best of my knowledge this is the device that the computer uses to control the fuel mixture. It has no effect at idle (thus the idle mixture screws) but does for the rest of the RPM range. I am still investigating how it works but it appears to meter the air going into the emulsion tubes thus effecting the mixture.

Something else to look at/consider.

Bryan

+1

The computer does more on a computer controlled engine than play with the timing.

If you want to make it so you can tune it 100% with a screwdriver you will need to do the metering block mod... which I highly doubt is legal in California.

 

[TheNicky]

Thanks guys i will look into that!

 

[Brypur]

And of course the O2 sensor would have a heavy impact on how the computer adjusts that solenoid.

Bryan

 

[Brypur]

If you want to make it so you can tune it 100% with a screwdriver you will need to do the metering block mod... which I highly doubt is legal in California.

Metering block mod? Educate me...

Bryan

 

[dangerranger83]

x2 whats that?

Thx, Bryan

Weird I found somebody on here with my name.

 

[RobbieD]

Metering block mod? Educate me...

Bryan

Bryan- see your other post.

 

[Brypur]

Thanks Robbie!

And for others here is the link to my metering question.
Motorcraft 2150 Carb Body Plumbing

As for Nicky's problem I wonder if the smog techs would pick up on that or not. Would leave a disconnected connector back there that might draw extra attention and closer investigation but I would think that in a once quick over it might go undetected. Would be a pretty big risk, not sure I would take it. Once they catch you tampering with things they get pretty cranky.

Bryan

 

[enginepaul]

The guy doing the smog might not be as old as the truck. I USED to get by with a little cheating. For instance, you could run any wire from under the solenoid cluster to any part of the engine and I doubt if they will check. BUT I did get one jerk who flunked me for "tampering" with the system. I had a EGR sensor connection go bad and then just wired three wires without the fitting. It worked, but 'eagle eye' said it was tampering. A referee passed me. So you may get buy with a little visual slight of hand - but if caught, just more time and money.

If that solenoid that admits air (in back of the carb) is bad, that would cause it to run rich. Check it, it may be bad. AND it may throw the computer off.

 

[TheNicky]

Ill be doing this today...
yesterday i had a couple things to get done before the weekend!
My 21st Bday lol...
Sooooo today ill check that solenoid...that and my dizzy one more time...
im wondering if damage had happened with that metal pickup and cap chunks spinning at the bottom did damage...

and the o2 sensor is brand new... got that a month or so ago...