CB gen1 4 knob ECU

[j1mmy2420]

I have not synced the throttle bodies. That and the linkage I did not touch. I was able to do the engine swap without removing carbs, alternator, fan shroud etc. I am going to pickup that vacuum set on amazon, just to see where i am at. I do have the old school single carb sync tool.
update.
I installed new injectors, went ahead and put another new set of plugs and wires. The car ran like a beast. I ran the car for about 45 minutes pulling 12-15lbs of boost in 3rd gear. then all of a sudden the popping started again and the car stumbled and died. Started back up, but ran like poop.
One of the new injectors was spraying out at the fuel rail. I immediately shut it down and pushed it back in the garage. I will tear it down today to check for the cause of the leak.

[Lo Cash John]

Sounds like junk in the fuel system. It ran good with fresh clean injectors then they became contaminated is my theory.

[j1mmy2420]

I can agree,
But I just replaced all the fuel lines from tank back to the tank. including new filters and pump and now injectors.
still seems like its running on 3 cylinders

[Lo Cash John]

Any updates?

[j1mmy2420]

Update 11/18/21
still not running. I bought the cheap amazon dual vacuum gauges to sync the throttle bodies. But.. The needles were bouncing around very violently readings were from 5-20in. SO fast that you cant see the needle. So I bought a good vacuum gauge, but same results. I ended up changing the intake manifold gaskets and found that both were leaking. left side was cracked pretty bad, right side had 2 gaskets which were the wrong size and were leaking in between them. hooked up the vaccum guage and got better results, but still irratic needle fluctuating from 15-20in at idle. car still does not run right. I checked my MAP sensor with a multimeter with the ignition on engine off and the readings are normal. but as soon as I start the car the voltage goes crazy just like the vacuum guages. So these 2 are obviously related.
I have read that the Compufire DIS ignition system sometimes causes problems with the CB FI setup. I am seeing irratic spark as well. Very hard to time the car even with the new Timing light. I am ready to dump the ignition and go back to a regular distributor just to rule that out.
Upcoming dune trip next week, but I may have to go without the sandrail. go figure .....

[Lo Cash John]

In my years of riding and wrenching on 4 cylinder sport bikes I learned how to dampen the needle bounce.
In each vacuum hose (I think you said you have a dual so that means 2 gauges and 2 hoses) you need to place a small restrictor to dampen the pulses.

Go to a hobby store and buy some brass tubing that's a snug fit into the vacuum hoses.
Cut a 1 inch piece of tubing for each vacuum hose. Sand or file the ends so there are no rough edges.
Solder shut one end of each piece tube. There's no need to do both ends.
Using a 1/16" drill bit (or smaller if you have letter & number drills) drill through the solder. You're basically making yourself a jet, like a carb fuel jet.
On the end of each vacuum hose, cut off a 3" piece of hose.
Now, using your home made "jets" splice the 3" pieces of hose back onto the main lengths of hose. You want the "jets" to be about 3" from the source of the vacuum (manifold nipples).

With this mod, the manifold of the engine will pull vacuum on the gauges when on an intake stoke, but the air being pulled out of the gauge and hose must pass through the orifice. This will slow down the needed moving towards vacuum. Then when the cylinder is not on an intake stroke the vacuum drops away, but once again the air must pass through the tiny orifice and that slows the needle from bouncing right back to zero.

That SHOULD solve the bouncing needle problem.

MAP sensor: Generally MAP sensors do not work well with individual runner engines. This is because most folks tie all the vacuum hoses together with a collection of T fittings, then connect the MAP sensor. The sensor is seeing these pulses and the ECU probably has a tough time developing a clear "image" of the data.

Here's an idea:
Make a small vacuum plenum out of the small tubing. I'm thinking like 3/4" or 1" PVC, maybe 4"-5" long with a cap on each end.
Install 5 small hose barbs on the body. I would place 4 of the barbs down near on end and the 5th one at the very opposite end.
Connect 1 hose from each intake runner to 1 of each of the 4 barbs.
Connect the MAP to the 5th barb.

Now there's a small chamber or plenum for these pulses to balance out and the MAP sensor should see a fairly clean average.
I know of a few people with normally aspirated EFI engines that have done this with success.
If this helps solve your problem you can always make a nice "finished" version with aluminum or stainless tubing and make it all pretty.

As for gaskets, well you should already know to go over ever last little detail when dealing with old engines, especially ones that have been run hard or off-road. The dumb stuff like that can cause you to waste a lot of time looking for a "big" problem when it's just as simple as an intake leak.

[j1mmy2420]

Thank you.... That is great advise. I basically have both intake manifolds going to a Tee and then to the MAP. The pulsing is indeed causing irregular MAP readings. The throttle bodies have 1 outlet in between both cylinders.
Let me see if I understand this correctly. Using a Plenum instead of the T would smoothen out the pulses.
Also since you mentioned the plenum would have 5 outlets. I would run a short hose from one to the other on the outlets not used?
or simply use 3 outlets?

[Lo Cash John]

I did not realize your throttle bodies only have one vacuum nipple each. The ones I've dealt with had 1 per barrel. Anyway, make a small vacuum manifold like I described but it only needs 3 hose barbs (vacuum nipples). Place 2 barbs/nipples down at one end and the 3rd place at the very tip of the opposite end. Basically you're making a "T" with a plenum chamber. Make sense?

Now keep in mind, these things will NOT make the engine run perfect if there is something else wrong. These are just solutions to problems you seem to be having.

Keep posting details and I'm happy to help as much as I can.

[j1mmy2420]

Thank you! That's what I figured, but just wanted to make sure. I feel the irregular or surging vacuum is caused by one cylinder pulling and the other pushing since the vacuum is drawn from the center of the throttle body.
I also have been reading about the wasted spark ignition causing irregular or surging vacuum.
I will build this plenum today and post my results. I have also read about inserting a fuel filter in the vacuum line before the Map to help.
any thoughts on that?

[Lo Cash John]

I've never heard of the fuel filter trick. Probably the extra volume of the filter chamber does the same thing as the vacuum plenum you're going to build. The extra volume helps dampen the pulses.

Please keep updating and add pics too.

[j1mmy2420]

will do thank you again! I am so close now.

[j1mmy2420]

Update again lol...
I added a plenum to the vacuum line which did help absorb some of the pulse vacuum. I resynced the carbs, checked timing again, and bolted all the turbo manifolds back on. Took her for a ride. She runs hard and idles really well, but...... still some popping here and there. Also around 4k rpm's she drops off. feels like i took my foot off the throttle. This is around 5lbs of boost. So I took a video and listened to it and sure enough I dont think all 4 cylinders are firing correctly. This is fight I keep struggling through. I have spark on all 4 and all 4 injectors are spraying. and valves are set to 002 and compression is good all across the board. I am going to pull plugs today since I ran a few hot laps while testing this weekend. My next guess is to ditch the compufire distributerless ignition and go with a simple setup to rule that out.

[j1mmy2420]

https://youtube.com/shorts/HEqHUbxqbM8?feature=share

[Lo Cash John]

Compufire is wasted spark design. I wonder if that's screwing with the CB ECU? It very well might be and that could explain the loss of power as RPM's build. But it sure looks like you are moving in the right direction.

Did you add the restrictors to the vacuum hoses on your dual vacuum gauge tool?

[j1mmy2420]

I read somewhere that the wasted spark does not work well with the Early CB Gen 1 ECU. I have a feeling that is my issue. No I did not add any restrictors. The dual gauges are my tools to balance the throttle bodies. I do not run them on the car. The Autometer vacuum gauge in the dash does not bounce. The plenum did help enough for the car to be driveable. But I am afraid that it might not be running on all 4 all the time. Just by the way it sounds and lack of power here and there. I do have a spare 009 Dizzy with points and Bosch Blue coil. I wonder if that is enough to power this big motor? I was thinking I could add a pertronix ignition to it and ditch the points. Or just bite the bullet and get the magnaspark.