Idle Speed Control Valve Question

turbojonny

Registered
Do I need this to be active? I switched it off via the ecu. I think it was switched off with the original turbo map. The bike has runnover rich on boost since the rebuilt motor was put in. Perfect until boost, then too rich.

Throws a c40 code when the isc is active (c40 is the isc code). I just dont know if it's relevant to air fuel if it is not being used (sgur off).
 
Hmmm, mines been there since new and through 25k miles of boost. Does it vent to atmosphere ever? Maybe Ive been giving up some hp? It threw a code when I left it turned on via the last ecu flash. I've turned it off again, but it still seems like it's not like it was.
 
Give Richard a call but i was under the impression and was told it needed to be removed because boost would blow it out
 
Could be. I remember using the gen instructions for the install. Maybe gen1s don't have this same sensor. I'll call Richard. I try to leave him alone and not be a pest as much as possible.
 
It can be left on, and active. I've never shut them off or removed them. There's nothing that the iac does that controls fueling specially because the bikes don't meter intake air volume.

You've been having a lot of issues since the rebuild of your engine and it's worth having someone look over it.

What was your set up before this new engine? Stock engine, then went to built?
 
The bike has an rcc ultra mini kit. I discovered that I had already removed and capped the iac (I have NO memory of doing that, lol).
The motor was rebuilt to the same specs as pre rebuild with tho only difference being that the head was milled (APE, unknown mm shave) and I switched to Carillos.
The bike was built and set up in its current configuration years ago and had worked perfectly prior to the rebuild.
The problem statred as an over rich on boost issue, then it started to go full lean on deceleration SOMETIMES, and now has become sputtering and rough running at mid throttle (I got home but it's now not rideable).
I did unhook the AMS from the bike and no change.
Fuel pressue maintains and last time I looked while it began to boost it was rising correclty, so not a kinked or collapsed return line.
 
Let me ask you this. Why was the engine rebuilt in the first place? Melt a piston?

You say it was rebuilt to the same specs as before, but were the same pistons used? Changes in compression will change a tune fast. Another thing that will affect a tune is cam timing. Cam timing can change when you mill heads and deck cylinders. Although if they did that for clean up purposes that's not likely. But anytime you raise the head (with a base spacer) or lower the head (with machine work as mentioned) that affects cam centerline timing. Or, timing could be off a tooth.

Going full lean on decel isn't a problem. In fact on gen 2s, on decel the injectors actually shut off. It's called decel fuel cut off. So I wouldn't worry too much about that unless it's popping real bad once the injectors turn back on.

What's your base fuel pressure?
 
Base is 42.5. It does pop after injectors come back on now.
Same pistons. Had a seeping head gasket leak that was pressurizing the coolant. I was thing about the cam timing. It has what seems like more low end grunt now.
 
I put the stock map.back in, unplugged the tps and the stcv and it revved no differently and threw no codes other than the original c40.
 
Yep. IAC is out and plugged. I put the stock map back in to see if the ecu would give me all the codes it should give me if it thinks its stock.
I was expecting to see a code for the tps, secondary valve, iacv, and maybe one or 2 more.
 
Yeah they won't kick a code unless a sensor or something repeatedly goes out of range. It would of came on eventually for those.
 
Thank you for the reply. I am soooo grateful for your help. Nobody out here wants to tohch it, so if I want to ride this year I am on my own. Ill dig in more this weekend.
 
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