BBI CSI question

84 BBI Federalized and Ca BAR certified. G&K ECU, Frequency valve (1), narrow band O2 sensors (2) spliced together, WURs looped together via vacuum line, cats, MSD 6AL ignition with stock coil. 21K miles Passes CA smog with no problem.
Acquired Jan 25 with 18K miles and it had several "drivability" issues. Have most issues resolved but a couple of things I don't understand about the CSI cold start and hot idle. When I first got it I had to set the hot idle at 1.7 K with air bleeds or it would continually stall when cold snapping (like taking foot off gas to shift) back to idle.
To cure this I adjusted the Aux-air-valves(2) to full open when cold and balanced the system side to side with vacuum gauges and manometer. Also did some work on the distributor as the advance bushings were broken, thanks Eric Sander. Got it to where it idles hot at about 1250. (in car tach) and doesn't stall ever when cold. However it does surge when cold until it warms up.
So thinking it should idle a little slower and not surge I took a long look at the throttle body butterfly stop screws and air bleeds.
Turns out the throttle stop screws were a full 4 turns in and I had adjusted the air bleeds to about 1/2 turn out.
After reading threads, thanks Rifledriver, the suggested settings are the throttle blades set at 3 thou or about 1/4 to 1/2 turn in and the air bleeds about 3 turns out.
So I disconnected the linkage and set the stops at 1/2 turns and air bleeds at three turns.
Hot idle speed increased to 1500 so I backed the stops to 1/3 turns and closed the bleeds to 2 1/4 turns and rebalanced.
Now idles at 1100 (AC off) and doesn't surge or stall. Much better.
So after that lengthily explanation my question is a simple one .

Is the primary purpose of setting the throttle body butterflys open such a small amount is so they won't bind or jam in the throttle body when closed rather than setting idle rpm and the air bleeds are used set idle rpm? The way its currently set it won't idle with the air bleeds closed.
One other thing. Apparently there is no dash pot to slow return to idle?
Thanks for your patience.
Barry

 

It's been a L-O-N-G time since I've fiddled with CIS. Yes...you are correct, the throttle valves are set so no binding or wearing into the the plenum over time. The air bypass screws are for setting idle speed. The mixture adjustments can also play a role in idle speed.

 

Carguy. Thanks so much. That was my conclusion. I haven't messed with the mixture yet as I'm not sure of the interplay between the frequency valve and mixture. In other words would the o2 sensors / ECU / frequency valve override the mixture adjustment. If I get a chance I'll add a couple of wide band O2 sensors so I can monitor the changes.
Thanks again
Barry

 

Hello Barry....the 02 sensors are disconnected when adjusting the fuel mixture. Also the hole to access the mixture screw needs to be plugged after each adjustment (vacuum leak). It also goes without saying that every supporting system has to be in good condition, things like plugs, plug-extenders, wires, etc. I tried using wide-band 02 sensors but had some difficulty as the CO value sort of follows a slow sing wave. I ended up buying a 4-gas analyzer and that did the trick.

 

Hey Carguy. I pretty much understand about having it in "open loop" when adjusting the mixture as well as making sure the plugs are in the mixture adjusting access holes. What I'm wondering is if I adjust the mixture a bit in "open loop" what happens when I plug the O2 sensors back in? Wouldn't the ECU/O2 sensor/Frequency valve override the small mixture adjustment based on O2 voltage? I don't know how much mixture range the electronic monitoring system has. Probably going way down a rabbit hole here as the car runs great after warm. Just would like a stabler idle when cold as well as being able to slow the warm idle down a bit. Manual specifies 1K +- 100 rpm hot idle. Mine is a little higher than that an if I slow it down the cold idle becomes sketchy Anyway I'll keep messing with it and may pick up a 4 or 5 gas analyzer so I can go further down the rabbit hole. .

 

Not true. From Ferrari directly in various schools. Throttle stop screw adjustment with air bleeds totally closed should be 700-750 RPM with correct mixture and banks balanced. Open air bleeds to 1000-1100 with recorrected mixture and banks balanced.

Its important to set mixture with an exhaust analyzer and at every step. At low RPM CIS mixture changes considerably with RPM change and setting without an analyzer is a waste of time.

 

Gray market cars typically had their control pressure modified so getting it good hot and cold may be impossible.
I'd never consider serious tuning or diagnosis without a 4 gas. Also many, if not most of the aftermarket O2 systems I have seen used to federalize cars were junk. On cars I want to run well I typically dispense with them.

 

Rifledriver: 700 -750 rpm hot or cold? I assume this is done with o2 sensors disconnected (open loop)? I will pick up a 4 gas analyzer as I can use it on my carbed 308 also.

 

Is there a good quality one available for under $1000?

 

There are scarcely good quality ones available for shop level use at any price. My old SUN 4 gas died since no one services them any more and a new supposedly high quality electronic cost me thousands. Total POS. I think I finally found someone to fix my old one and I am sending it off.

No market anymore. I had one of the big dealers call and ask how to diagnose a CIS car. I told them to give me gas readings. This monstrously funded big new dealer didn't have one and no one on staff knew it could be used for diagnostics. And Ferrari seems proud of the fact they will work on any Ferrari.

 

Cold exhaust spits out water condensate. If you ever get water in your exhaust analyzer it will be going off for repair, especially the new electronic tinker toys. The wiz kids who design them do not build in water traps.

 

a 4 gas analyzer below 1000 US $? I not think that you will find one what is working fine for this money

you like then to use it only when the car stands or also during driving? because then you would need a hand held with powered by 12 V