Second Try

My Brother has a 90 n/a and is having problems with irradic idle, so we are pretty much covering ALL of Chapter 4 in the Hayes manuel.

The car also dies when he stops quickly. We properly adjusted the TPS and reset the idle.

We also checked the position on the primary/secondary throttle valves in the TB. They seemed off so we attempted to adjust the postion if the valves.

This is where we had trouble. The Hayes manuel say to "Bend this Tab" on the back of the TB. We figured we werent supposed to adjust the nut. How do you "bend"? how much force? with what tool? and what will give us the results we need?

If any one has had experience with this proceedure or can send me to a tutorial that is more in depth the the Hayes version, I'd greatly appreciate it.

 

Yes, you can adjust the throttle stop screw.
My quick (alternate) method:
Set the air bypass screw on top of the dynamic chamber about 2 turns from closed.
Idling with no extra loads.
Loosen the lock nut.
Turn the screw until the the idle speed starts to increase (~900 RPM).
Then back it off until it just stops decreasing (~750-800 RPM).
Tighten the lock nut.
The BAC should control idle from there. (If it can't, then it's stuck or has a bad connection.)
Reset the TPC to 1 volt or 1K ohms - whichever method you prefer.

There's more in the on-line factory manual, in the "fuel & emmissions" section..

 

SureShot, I appreciate the reply and the link to the manual.

I'm not actually trying to adjust the idle just yet. We pretty much have that figured out.

What I am trying to do is adjust the Clearence between when the Primary Throttle Valve open comapred to the Secondary Throttle Valve.

On page F1 36 of the Fuel and Emissions Control system chapter for a non turbo, it says "If proper clearence is not within the specification, BEND THE TAB until the proper clearence is obtained."

This is what I am trying to solve. How am I supposed to bend the tab? How much should I bend it and i what direction to get a desired throttle valve relationship?

 

Are you using a stock TB? or modded? Coz if stock, you might want to check the dashpot function. Keeps throttle from slamming shut on decel.

 

That setting is not too critical.
You just want the primary to open a bit before the secondary starts to open.

The only time I think it matters at all is at the end of the warm up, as the fast idle cam is about pushed off.
There is a vac port just behind the primary butterfly that would go a bit high if the primary were closed & the secondary open a little.
I don't recall it's function since all that stuff has been off my TB for years.

 

Is this covered in the Manual? If not, can you give me more info? His Car does die when he stops fast.

Also, might he need a new fuel pump?

 

Is this covered in the Manual? If not, can you give me more info? His Car does die when he stops fast.

Also, might he need a new fuel pump?


PS, Stock TB

 

http://208.62.166.66:82/guest/shop_m...systems_na.pdf Check 4A-50 for info.

Hope this helps, Good luck

 

It does still have the High Rev system when he starts the car... waste IMO,

But we tried to adjust the position of the Primaries when the Secondaries open. Now its backwards, the Secondaries are opening first!!

So thats why I am so determined to get this "TAB" figured out.

 

Thanks, will be sure to look into this as we tune this fuel system.