Starter Valve Synchronization

TearlessTom

Well I caught myself alooking at my service manual instead of my required reading late last night and I've managed to confuse myself again.


  • What is the point of doing this? Ive read that it improves fuel economy.
  • Do I need 4 gauges as in the picture or can I use one gauge and do one line at a time?
  • What is the need for the tach? Am I adjusting for equal idle speed or for equal vacumn?

Thanks as always,
Tom
 
You're beatin' a dead horse! Oh, sorry... that's your avatar!

You need at least 2 guages so that you can adjust the vacuum of all the cylinders to match #1 at a certain RPM, as I understand it. I've never done it on the ST yet, but I will soon. Next time I'm under the hood. You won't need to buy a tach as there is one in the dash.

Oh and the connection point is a 5 way T under in between the throttle bodies. ( that is of coarse if we are talking about the ST1300)
 
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TearlessTom said:
What is the point of doing this?
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It assures that the fuel/air mixure going into each cylinder is even. If you have one cylinder that's firing more or less strongly than the others (or they're all uneven), the engine will be a bit "lumpy." I saw a 3-4 MPG improvement on my first tank after doing it. Shifts, especially downshifts, are a lot smoother and the throttle response was a lot smoother.

Do I need 4 gauges as in the picture or can I use one gauge and do one line at a time?
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You should have at least two. Cylinder 1 is non-adjustable, and the other three have to be adjusted to match it. It's better to use a full set, because sometimes adjustments to one will have an effect on the others. You'll also be doing a lot of hose switching, and if you plan to restart the engine between swaps, you're going to have to clear the error codes from the ECM and then re-force a MAP sensor error each time.

What is the need for the tach?
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It's just to set the idle speed against something more accurate than the tach on the dash.

--Mark
 
Blrfl said:
if you plan to restart the engine between swaps, you're going to have to clear the error codes from the ECM and then re-force a MAP sensor error each time.



It's just to set the idle speed against something more accurate than the tach on the dash.

--Mark
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I gess harbor freight is going to get some more of my money now!

But wait.......Another question!

Why do we have to force a ECM or MAP sensor error when doing this?

Tom
 
TearlessTom said:
I gess harbor freight is going to get some more of my money now!
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I didn't bother with it. Mine has settled in to pretty much the same RPM when warm since the day I bought it.

Why do we have to force a ECM or MAP sensor error when doing this?
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The obvious answer is "because that's what Honda says to do."

Without understanding the firmware in the ECM, it's hard to say what the less obvious answer is. If I had to make an educated guess, it would be that the manifold pressure isn't quite the same with the airbox off as it is with it on. Inducing the error may force the computer to ignore the MAP sensor and substitute known, nominal values, making the engine more or less correctly under average conditions.

--Mark
 
You get a MAP sensor error because you have to disconnect it to fit the vacuum lines from the balancer. The MAP sensor fails to see the vacuum it expects so sets an error code in the ECM.

I've wondered if directly giving the sensor a couple of pumps from my Miti Vac and then holding it at specified manifold vacuum during the adjustment, would avoid the error being set?
 
wjbertrand said:
You get a MAP sensor error because you have to disconnect it to fit the vacuum lines from the balancer. The MAP sensor fails to see the vacuum it expects so sets an error code in the ECM.

I've wondered if directly giving the sensor a couple of pumps from my Miti Vac and then holding it at specified manifold vacuum during the adjustment, would avoid the error being set?
Click to expand...

There was a post once about how to avoid the MAP error while doing the Sync. Cannot find it anymore. Maybe it was posted before the crash. Maybe the poster is still here and will repost?
 
wjbertrand said:
You get a MAP sensor error because you have to disconnect it to fit the vacuum lines from the balancer. The MAP sensor fails to see the vacuum it expects so sets an error code in the ECM.
Click to expand...

When I did mine, I didn't get the error until the engine was warmed up and I had run it above 2,000 RPM for five seconds using the throttle per the instructions. (In other words, cold idle alone didn't do it.)

I've wondered if directly giving the sensor a couple of pumps from my Miti Vac and then holding it at specified manifold vacuum during the adjustment, would avoid the error being set?
Click to expand...

I don't see what that would accomplish since Honda explicitly says to force the condition as part of the procedure. That may put the ECM in a state that results in smooth idle even with all of the other things that have been disconnected.

The ideal way to make the adjustment would be with the airbox on and the MAP sensor happy, but Snap-On never seems to have that 7mm wrench that can pass through other solid matter in stock. :)

--Mark
 
TearlessTom said:
Well I caught myself alooking at my service manual instead of my required reading late last night and I've managed to confuse myself again.
Click to expand...

I wouldn't read too much into it, the worst parts are getting to the vacuum tubes, and removing the gas tank.

TearlessTom said:
  • Do I need 4 gauges as in the picture or can I use one gauge and do one line at a time?
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No you don't need 4, and you could go cheap and try my "mad scientist" method :D :D:D

https://www.st-owners.com/forums/showthread.php?t=36596

EDIT- I've noticed smoother revs throughout the range.

Don't worry it's easy job,

Tom de
 
MidLife said:
There was a post once about how to avoid the MAP error while doing the Sync. Cannot find it anymore. Maybe it was posted before the crash. Maybe the poster is still here and will repost?
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You disconnect the vac hoses for #2,#3 and #4 cylinders at the throttle bodies and leave the MAP sensor connected to #1 cyl. You use one of the hoses at the 4-way connector for the #1 cyl vac and plug the other two. This way you avoid the error code and still get all 4 vac readings. It is a bit tight getting those tiny hoses back on though. As a bonus, you dont risk breaking that plastic 4 way connector. I just did mine that way and it went well as the idle is now noticibly smoother.
 
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