Vee2 DIY ISC Sync...
The Vee2 maintenance schedule calls for a periodic throttle body sync (which is actually just an idle air sync). Problem is that the local shops all quoted me about the same price as just buying the required HealTech SDS tool. So I decided to buy the tool and do it myself.
A few pointers and recommendations...(and questions too)
The ISC must be performed at full operating temperature. This requires that you remove the tank and airbox to gain access to the adjustment screws. Then once hooked up, you have to run the engine to full operating temp. So you either have disassemble a hot bike, run the engine for quite a bit with no air filters, or do a dance with the placing and removing the airbox and tank. I would prefer to disassemble a cold bike and get some single stack air filters that can be fitted onto the throttle bodies during warm up, but I forgot to measure the TB / airbox boot diameter when I had it all apart. Does anyone have a pair of exposed Vee2 throttle bodies or an airbox hanging around their shop that they can caliper for the ID/OD of the filter side?
I did the homemade vacuum balancer (long piece of tube zip tied to a stick with some motor oil in it -- just in case of severe imbalance and ingestion of the fluid, I prefer to not use water). Each end of the tube attached to their respective TB vacuum port and the vacuum will pull to one side or the other until balanced. Once the engine reached the operating temp, I activated the ISC adjustment mode on the HealTech software. BTW, it will not activate (and will auto shut off) if the engine temp exits the prescribed range... so be sure that the engine is well within the range and/or you can see the computer screen while adjusting or you may not realize that the ISC mode has turned itself off.
Prior to the adjustment, my hot engine idle had dropped below the designated target of 1229 rpm, which I can only surmise meant that the ISC had reached its limit and could no longer open up more to restore the higher idle. My idle was down around 850rpm. A small adjustment to one TB screw easily balanced them out, but the RPM was still too low. After that I was increasing both of them to achieve the target idle and balance.
After getting the 1229rpm (which such precision is kind of ridiculous since the reported idle speed bounces around (+/- 50rpm or more) faster than you can read it and can only average it out to about 1220.
After completing the adjustment and balance, I turned off the ISC lockout mode and executed the "reset learned position" test with the HealTech tool as directed in the service manual.
I then checked the Throttle Position Sensor position. Mine was off (too low), so I corrected it. In the future, I'll probably do that TPS adjustment before the ISC adjustment.
Here's where the questions come in...
The bike's idle speed was back to normal, and all was well for the test run around the block a few times. In fact, after a few hot / cold cycles and commutes, it seems that the engine runs smoother and has more grunt. Most likely due to increasing the TPS position back to center where it belongs. However, twice since all of these shenanigans my engine has done the infamous Vee2 idle backfire, both times when the engine was cold and part throttle for just starting to take off from a stop. Did not stall. I have had the ECU recall completed and never really had any notable problems with the backfire before or after the ECU replacement. Perhaps those backfires were just a part of the ECU relearning the "reset learned position" and it won't continue. But it got me thinking about how the ISC was tapped out before my adjustment. As I understand it, the ECU has no feedback from the ISC's actual position (maybe I'm wrong on that...?). So if mine were tapped out, then locked into position during the ISC adjustment, wouldn't that mean that they are still near the end of their throw? I thought about setting the ISC adjustment idle speed a bit higher than 1229 rpm so that they can move back toward middle when the ISC lockout is released by the HealTech SDS; however, I do not know how much throw they have and could easily overshoot and end up tapping them out near the bottom of their throw.
Does anyone know how much throw the ISC circuit has to adjust the idle speed?
Is there any way to determine where they are currently at within their range of operation?
Or perhaps a procedure to center them up again?
If the backfire doesn't recur, then it is all just academic... But I would like to maximize the range of correction available to the ISC circuit so that it can deal with the widest range of environmental changes.
Last edited by Grimmer; 11-05-2018 at 08:09 PM.
Reason: typing and proofreading skills could use some remediation...