496 whipple loading up on idle
 

I have a 2005 496 HO with a whipple. Runs great at high speed and high rpm. However when I idle for any length of time and try to take off it chuggs and puffs black like crazy. Once it is cleared out, It seems to run better. It has below water exhaust so I had whipple put a custom tune in which has not fixed it. I also routed the exhaust above water with a secondary 3 inch pipe that taps into the main 4 inch exhaust to try to help it breath. Not sure I am even on the right track. Any thoughts? Anyone have a used scan tool they wanna sell? I can't take this to a dealer. I am afraid they won't know where to start with the whipple installed. I have confirmed fuel pressure. Tps voltage and replaced the iac because it was cheap. Still has the same problem. Advice appreciated.

maybe the injectors need to be cleaned,they can be checked and cleaned fairly cheap.

Take it to someone that knows how to tune it.

If the fuel pressure is fine chances are the fueling at idle is too rich.

I take it the blower was just installed? If it was, the tune needs some work.

Is there a procedure for adjusting the blow off valve on a Whipple. There is an adjustable stop and a linkage but I have not messed with that _ (set at the factory) Just curios if it is opening and closing when it should. Any ideas?

Do you have a vacuum/boost gauge in the boat?

If so and the engine has vacuum at idle and its making boost then the valve is working fine.

If not, you can get a gauge cheap at the parts store and stick on there to check the vacuum, but I don't think that's your problem.

What really needs to be done it hook a wideband o2 to it and see what the AFR is at idle.

What kind of regulator is on it? Maybe you have the vacuum line for that in the wrong place and its causing the regulator to open at idle, raising the FP and causing it to load up?

I had too much water going thru the intercooler at idle...it made the intake run too cold, telling the computer to run richer...i put a restrictor pipe in the intercooler feed line....voila!

Agree with pqjack had the same issue after long idle times!

Thanks for all the help guys. Latest info. I changed plugs and confirmed one was actually fouled. It runs better but still really rich on idle. I am going to tap into the risers with O2 sensors. I can weld the stainless bung ports on no problem but I am a little green on the use of the fuel air reading tools. I have found many wide band kits for automotive but do I need something special for Wet exhaust? Anyone have a brand or part number they would reccomend. Also, I don't really need it all the time. Just looking for something to provide data for my tune. It looks like roughly $150 per side but let me know if you have a less expensive option

Also, PQJACK, I've heard the same things about cold water through the intercooler at idle. That makes sense as I am in WI and the water is much colder than many of you have to deal with. DId you use a low pressure valve that opens once the RPM builds or just a reducer in line. I'd like to try that first but have concerns restricting flow at high RPM. Let me know what you used. Thanks for all the help guys. Greatly appreciated.

We will force feed the intercooler with a transom mounted pickup. That way, it only gets water to it once the boat is on plane. There is really no need to put water through the intercooler at idle. That Cupro-Nickel intercooler is very efficient, so it will really cool the intake charge. This is especially true this time of year up north, where the water is still really cold. You can cool the charge so much that the fuel wants to come out of suspension and form droplets that will puddle in the intake.

Is this a new install? Has this been a problem since it was installed or is this a new problem on a previously installed supercharger?
Eddie

I installed it last year and have been struggling to fix the rich idle ever since. It runs great everywhere else in the RPM range. However, I literally leave a huge cloud of black smoke after going through a slow no wake zone. The engine coughs and sputters until it clears out and then runs fine. Originally I thought it was just the below water exhaust which probably did not help the situation. Now I have branched off the exhaust to let it breath above water. However, this did not really help my rich idle problem. The cold water issue makes sense. I ran it up in Eagle River WI last weekend (2 weeks after ice went out) and it ran terrible. Even if I slowed down for 30 seconds it acted up. I'll play with it more this week to see if this fixes it. I tapped into the main water cooling line right after the sea water pump for the intercooler. I might try putting the tee later in the system - i.e. after fuel cooler, oil cooler and power steering cooler. This might help slow the flow to the intercooler at idle.

I think you can eliminate your issue by force feeding the intercooler. You will pull the water away from it at idle. I imagine it's even worse this year since it was so cold.

You have to be careful by changing the point at which you pull water. That engine will not tolerate any detonation. By getting the water from a place farther down the line, you may help the idle and low speed but you could cause a rise in intake air temps at higher rpms. That is something that you don't want to do. Those Hyper-U-crack-it pistons will not take any detonation, so you don't want to raise the IAT's under boost.
Eddie

duplicate

Group, just wanted to follow up. Finally fixed my issue. It was the intercooler working too well at idle causing a cold engine situation. I installed a low crack pressure stainless check valve in line. It opens at 4.5 psi so it prevents flow at idle. It opens and flow well after 1500 rpms. Completely eliminated my issue.

part available on amazon
Duda's 3/4" NPT Check Valve In-line Low Cracking Pressure 304 Stainless Steel WOG1000

Thanks for the help.

Low crack pressure valve
 

Did you find your sea pump getting to hot while at idle before getting water pressure above 4.5 psi? Think of adding flow restrictions to the inner cooler to my 500efi whipple motor.