sputter/missing after long idle

[Hoople]

Can someone tell me how the Idle Air controll works? What is its status when bike is at higher rpms etc.

Rather than set the idle by slightly cracking the butterfly vane (as they did with carbs years ago), now with ECM's on board there is a better way. Keep the vane butterfly closed at idle and achieve the desired idle speed with a variable bypass valve which is the IAC. It only comes into play when the TPS sees that the butterfly is closed. The ECM always knows what the RPM of the engine is and it also knows what the target idle setpoint should be. The IAC is a little stepper motor that the ECM can step in or out thus allowing a "calibrated leak" to get past the closed butterfly. It also performs cold engine "choke" RPM which is a higher than normal RPM and can step down the RPM in levels until the proper engine temp has been reached. Changing your idle target set point is now easier by just telling the ECM what you want it to be. Best of all the target speed will be right on regardless of air temp, humidity, garbage fuel etc. The ECM will do what is necessary (within limits of IAC) to achieve desired setpoint. It's a Great little gadget that made the world a better place to live.

 

[67hat34c]

Did not ck for vacuum leak yet. However I picked up on friday after retune and it made no difference, checked codes and it was throwing PO152 which is rear o2 sensor reading rich. so i brought it back saturday. They took it into Dyno booth at about 1130am and it was done by about 430pm that day. He spent some real time with it and smoothed out curve and raised #s some.


Saturday tune made no difference still throwing PO152 and still having same issue when sitting a long light and proceeding it sputters, misses. NO SMOKE however.

Now I went to line of used bikes and checked codes on sporties with upgraded exhaust and 2 had PO132, Front O2 sensor reading high. So it may be possible that the richer MAP is causing this code and it is not an issue.

I think it is a vacuum leak, MAP sensor or O2 sensor, What do you guys think. Remember they had the top end apart on this bike.

Orlando HD wants me to bring it back and meet with the tech. He is the head tech in the shop and has the most experience, not known if he did the engine tear down before but I did see him do the tuning on Saturday, I watched him for 3 hours then I left and came back when he finished. I know he did everthing possible to tune it and I believe tune is not the issue. Something else is doing it.

 

[Jack Klarich]

f it was a vacum leak they should have found it pretty easy I would think. Guess they should call tech support at the mothership on this one JMO, and stop waisting time and throwing parts at it in hopes of getting lucky. Usually by back tracking to the last thing done to the bike should give them the answer they need, thats how I diagnose a vehicle in my shop, get all the info and start at a baseline, Jack

 

[NEWHD74FAN]

Jack has some sound advice there, cannot troubleshoot on a bowl of jello and throwing hardware at the problem. As I said before, testing for only what you "did" is turning a blind eye to actually basic troubleshooting, start with the basics, identify symptoms, localize root cause and resolve. Simple to describe, not easy to do when in the "heat" of battle.

 

[67hat34c]

Shop is wanting me to bring it back and discuss directly with the tech. The tech is their most experienced and one of the older guys. He is the one that did the dyno tune on saturday. So when I have time in next couple of weeks I will bring it back to them.

 

[Jack Klarich]

Jack has some sound advice there, cannot troubleshoot on a bowl of jello and throwing hardware at the problem. As I said before, testing for only what you "did" is turning a blind eye to actually basic troubleshooting, start with the basics, identify symptoms, localize root cause and resolve. Simple to describe, not easy to do when in the "heat" of battle.

We seem to agree, if the Tech backtracks what he has done last probably going to find the problem and make you a lot happier maybe throw in some thing nice for waisting your time. Time is money,Jack