[guarddog]

See previous thread on adjusting idle....

They said they adjusted for a lean condition, but the idle would increase if they did that... So they reset it back to the lean condition and said it was a bad idle control valve.

I'm fairly competent with cars, but this is new to me.

 

[jhodg5ck]

by turning the CO adjusting hex bolt clockwise. It is just in front of your air metering plate. 3 mm hex key..insert, push down till it bottoms, turn in fractions of a flat to adjust.

I would check your voltage @ the air idle valve after adjusting the mixture/CO (btw, this only effects up to 2500 RPM mixture wise).
When was your O2 changed last?

Does the car have a rough idle?

Jonathan

 

[guarddog]

by turning the CO adjusting hex bolt clockwise. It is just in front of your air metering plate. 3 mm hex key..insert, push down till it bottoms, turn in fractions of a flat to adjust.

I would check your voltage @ the air idle valve after adjusting the mixture/CO (btw, this only effects up to 2500 RPM mixture wise).
When was your O2 changed last?

Does the car have a rough idle?

Jonathan

Thanks man, appreciated. No it idles fine, purrs like a kitten. Have no idea when the 02 was last changed. Should I swap them out ya think? Doesn't hurt as far as preventitive maintenance.....


.

 

[jhodg5ck]

If it idles fine why do they think it's lean? Usually when these cars are horribly lean they will surge @ idle.

If you don't know when the O2 was done last it would be wise to swap it out. I'm partial to the 4 wire conversion on our cars.

Jonathan

 

[Nutz 4 Benz]

Connect a voltmeter to the output wire/s of the lambda and ground the other lead.You should see roughly 500 millivolt and if not,turn the 3mm screw.Adjust CO only after the engine is thoroughly warmed up.

 

[jhodg5ck]

I've dropped that method in favour of adding an extra O2 bung and running a wideband O2 sensors/gauge. 3 Wire sensors are mighty slow to respond and w/ the A/F ratio reading out in real time it doesn't get anymore accurate. Also very handy for seeing if your EHA is set properly (about 2500RPM).

Jonathan

 

[guarddog]

So just take the 4th grey wire and clip it and run it to the ground on the battery, correct?

Also, I can use a sensor from a mustang, right? I might have one of those around--I have 95 Mustang GT, so that should work fine, right (last of the 302 5.0 liter engines.)

How do I tap into the lambda and where is it on a 420 SEL 1991. I found an article talking about the emissions, but couldn't find out where the port is for it.

I'd like to install a wideband, but they are still kind of spendy for a one shot calibration of Air/Fuel ratio. I guess I could run it on a dyno for $60 to get an air/fuel reading... Would that be better than reading the millivolts?


.

 

[marlinspike]

A not super Kosher way to set your mixture is to get some carb cleaner, spray it in the intake (take the air cleaner cover off to get it right in there), if the engine picks up you're too lean if it stumbles you're too rich.

 

[jhodg5ck]

So just take the 4th grey wire and clip it and run it to the ground on the battery, correct?

Also, I can use a sensor from a mustang, right? I might have one of those around--I have 95 Mustang GT, so that should work fine, right (last of the 302 5.0 liter engines.)

How do I tap into the lambda and where is it on a 420 SEL 1991. I found an article talking about the emissions, but couldn't find out where the port is for it.

I'd like to install a wideband, but they are still kind of spendy for a one shot calibration of Air/Fuel ratio. I guess I could run it on a dyno for $60 to get an air/fuel reading... Would that be better than reading the millivolts?


.

Here's an article on setting via the lamda/duty cycle:
BOSCH KE3-JETRONIC MIXTURE ADJUSTMENT

Yes, the 4 wire off of a later Mustang should work fine...and you are correct, just run the extra ground to your negative battery terminal.

As for setting w/ a wideband you can have the extra bung installed (should be minimal cost) and then running @ the dyno will let you set things Very accurately..or, ideally if you can find someone w/ an Innovate hand held wideband you'll be Set

Jonathan