I was trying to help a buddy with a problem he's having. A little background... 2008 600SCI with Whipple kits. They have had the IAC circuit repaired. Motor ran fine but suddenly after a restart failed to build boost. The motor on cold start will NOT go into high idle/enrichment and sounds weak. It is firing all cylinders, and there are no codes. It will idle all day without issue, albeit it has no "crispness". Boost gauge shows vacuum at idle and when rev'd will get to no vacuum and build absolutely zero boost as it falls on its face. So far my friend has swapped IAC, TPS, MAP, IATs, ECUs, and pretty much anything else that will go motor to motor without help. He has also swapped the boost relief solenoid (not sure if that's the proper term) to no avail. Any ideas?

[QUOTE=Jpzaluski;4177603]I was trying to help a buddy with a problem he's having. A little background... 2008 600SCI with Whipple kits. They have had the IAC circuit repaired. Motor ran fine but suddenly after a restart failed to build boost. The motor on cold start will NOT go into high idle/enrichment and sounds weak. It is firing all cylinders, and there are no codes. It will idle all day without issue, albeit it has no "crispness". Boost gauge shows vacuum at idle and when rev'd will get to no vacuum and build absolutely zero boost as it falls on its face. So far my friend has swapped IAC, TPS, MAP, IATs, ECUs, and pretty much anything else that will go motor to motor without help. He has also swapped the boost relief solenoid (not sure if that's the proper term) to no avail. Any ideas?[/QUO

i believe the whipple that is on the motor has a bypass valve,,now what controls it might be temperature related..

Have you pulled the belt and checked to see if the snout shaft has broke? Just happened to me this weekend on a 4.0 Liter

With no codes and no boost, I'd be looking into the blower. Smartcraft keeps an eye on pretty much everything else.

Ran a 700 one time with the blower belt off ( due to a seized blower ) and it idled low/weak as you have described.

replace the boost control valve

Boost control valve or the fuse that controls it on the back of the engine.

As mentioned, check the snout of the blower and the coupler that drives the snout. They have a tendency to fail.
Eddie

Thanks for all the info guys I appreciate it. I had already changed the boost control valve and other parts exchanged from other motor. Brett I just got done checking fuse. It was bad. I pulled the other motors same fuse and it created the identical problem so I know I am working on the correct circuit. Even with the boost control valve unplugged it still blows the fuse when started. I pulled the fuse and check both fuse plug in terminals with an ohm meter to ground and got no reading. It has 14volt on the red wire side fuse plug when running nothing on the red wire with blue stripe of course with no fuse installed. There must be a short to another wire on the red with blue stripe that goes to the boost control plug or something. Looks like same wire from fuse to boost control plug but travels into wiring harness loom so I am not sure. Do you know if that wire goes through another control or sensor before going to boost control? I guess its time to source a wiring diagram to check circuit route on red with blue stripe wire maybe? Again thanks for everyone's help and Jason for starting this thread. Any other suggestions are welcome. There is no one in my area locally that work on these type of engines. Also I pulled both super charger belts and both blowers spin and feel the same with no noise, no play in shafts or binding etc. Supposedly the only have 100 hrs on them.

you may want to give whipple a call,,they might have a solution for you..

If I cannot get it fixed I will call Dustin sooner or later he and mercury HP put me on the boost control valve. He is a busy guy to try and get a hold of and right now is not the time to be calling him with what happen at LOTO. Now that I know its blowing fuses I can call back Merc HP back and run that by them. Thanks everyone for your help and comments. Any more info is appreciated.