MFI - Can't set idle

[NorthernThrux]

The thermostat heats up pretty fast, so if this problem takes 25 minutes to appear, it is something else.

[RSTarga]

If the car ran well before storage the pump or distributor may have been sticking. If you know how to get back to your starting point that would be my suggestion. Adjusting mixtures before checking everything else before is to be avoided. MFI pumps tend to get gummed up during storage if they aren't put up with some sort of fuel preservative beforehand.

[chris belyea]

I found an article on Pelican Parts about MFI Troubleshooting and Adjustments. In the article it seems to talk about idle in two different ways. Here are the two paragraphs.

The adjustment of the idling speed is not performed at the injection pump, but rather with the air correction screws. To change the idle speed, evenly turn each of the six air-correction screws. Be careful to turn each one the same amount. Adjust the screws until the idle reaches 900 ( 50 RPM.)

There are two different mixture adjustments on the MFI system. One adjusts for idle and low rpm, and the other for higher rpm when the engine is under load. You should not adjust these unless you have a CO meter handy and hooked up to the car. Make sure that the car is warm when performing the adjustments, and also make sure that the engine is off when you turn any of the adjustment screws, or you can damage the pump.

What is the difference between adjusting the idle speed at the air correction screws and adjusting the idle at the mixture adjustment on the pump itself?

Thanks

Chris

[RSTarga]

Have you received a copy of CMA, Check, Measure, Adjust?

[edmayo]

I was going to ask,,what is this idle stop screw you keep refering to ?

[chris belyea]

David,

I do. I have to admit, I'm a little lost through it. It seems without the ability to check CO, I'm stuck. I was told that checking the CO was only for emissions and is not necessary. So I really don't know how to approach getting the high idle resolved. The car runs great! Just idles high. Based on what I can tell, I should be able to adjust the idle in 3 ways: 1) idle stop screw, 2) idle mixture 3) air correction screw.

Wouldn't adjusting the air correction screw affect top end as well? Seems like if you make an adjustment with the air correction screw, you should recheck everything.

Sorry..my head is spinning.

Chris

[chris belyea]

Ed,

Isn't the idle stop screw the screw on the pump.

[Jeff Higgins]

Somebody added that stop screw, Chris. It should not be there. You should remove it so you are not tempted to "adjust" the idle speed with it. Idle speed is set with the air bleed screws on each stack - Check, Measure, Adjust (CMA) outlines how to do this. They will not affect air/fuel ratio on the top end.

You really, really need to get a copy of CMA and run through it beginning to end. There is no other way to properly adjust these systems. I mean no offense, but it sounds like you might not have a full understanding of how these systems work and how to set them up properly. CMA will help tremendously. That's how the rest of us learned. Again, there is no other way to go about this.

[chris belyea]

Jeff,

No offense at all. I received a copy of the CMA and I've looked through it. I'm still trying to wrap my head around things but I don't think I have the correct tools to do the work. CO machine seems to be the biggest obstacle.

Chris

[Richy]

I was thinking you were adjusting the throttle plate stop screws on the throttle bodies , there's usually no stop on the MFI pump lever , lose it ! You will be starting from first base , maybe the pump needs to be calibrated .