Electronic Balance of Throttle Bodies

[STJIM]

I got the correct ELM327 interface for the TigerTool program and used it to check the throttle balance.

The tool said "Balanced" before doing any adjustment.  All three were very close but not all exactly matched, so I touched them up a bit.

I was surprised how little change I saw when doing the adjustments on #1 and #3 cylinders .  #2 is the reference and isn't adjustable.  #1 and #3 are adjusted to match #2.

Now I'm wondering how accurate the electronic balance is.  I'm not criticizing the TigerTool.  It only reports what the ECU computes.  I expected to see more of a change in the readings when I made the adjustments.  I base this assumption based on experience balancing throttle bodies and carbs on other bikes using vacuum gauges.

I'm tempted to buy a flowmeter type gauge to measure the actual flow into each cylinder.

[STJIM]

I now have one of these on order.  I owned one of these back in high school and used it to balance the carbs on my friends 1964 Corvair, but I can't find it anywhere.

[1675]

I think my mate has the tool you used to balance the Corvair carbs. He still has most of my gear!

[Jeffb]

I experienced the same thing- it seemed like the response was not equal to the amount of adjustment.  This will be interesting to see what you find.

[STJIM]

I received the flow meter today.

To re-cap, when I did the electronic throttle body balance it seemed like making the two adjustments had little effect on the electronic throttle body display horizontal bars.  So, I wanted to be able to measure the actual flow thru each T.B. to see how closely balanced they actually were.

Using the flow meter,  I could see they weren't even close to be balanced, even tho the electronic balance said they were doing just fine.

I'm using TigerTool but this problem has nothing to do with how TigerTool works - it only reports what the ECU is computing.

So, I was able to get the 3 T.B.'s flow to be match almost exactly by using the flow meter.  It's a little tricky because the Trophy has an "electronic" idle speed - the ECU controls the T.B. stepper motor which adjusts the idle speed. So after an adjustment is made, the ECU changes the position of the T.B. valve positions.   But after a few tries,  I was able to get the balance really close, just about perfect, actually.

The electronic T.B. balance is a slick idea, but it looks to me like a more precise balance can be had by using a flow meter.

[Jeffb]

I've never used a flow meter, but they look pretty slick. Do you have a link to yours?

[STJIM]

Jeffb:

I got mine off EBay and this listing was about $10 less than others for the same exact item (??).  Being retired and on a fixed income ( besides being a cheap ( ******* ) I went for it.


https://www.ebay.com/itm/VW-Bug-Beetle-Carburetor-Synchronizer-Carb-Sync-Tool-AC000130-Dual-Carbs/172327264552?hash=item281f816128:g:tWkAAOSwpzdWtQDj

It's simple to use.  It has some foam rubber for sealing when you place it against the opening of the T.B.  After position the tube in a vertical position, then you adjust the opening on the device to get the plastic float to rise to a position in the tube. 

The adjustable opening needs to be almost closed off completelyto get the plastic float to rise but that doesn't effect the running of the engine when you put the device over the T.B. opening.  That was a concern I initially had, but proved not to be an issue.

Start with the center T.B. to get a reference flow reading since the center T.B. has no adjustment.  I'm sure you get the idea.  Then move to #1  & #3  T.B.   It takes a bit of playing around so each T.B. eventually has the same flow, but it took me less than 5 minutes.

The bike had a nice idle when done.

JeffB :  Are you a LD Rider ?  I'm organizing some IBA rides in the U.P. next year, BTW.

[Yaga1973]

Did you check the electronic balance readout when you were done?