Quad Whipple Acting Up
 

Have a customer with a Quad Whipple that keeps popping or backfiring through one compressor, never the other.

Primarily if the throttle is held in one position or on a reduction of power.

What could be the cause?

Its an EFI set up. Driving him crazy, which is now doing the same to me as my engine never did this and i am not much help!!

is it at around 3500 rpm if it is i heard it could be the fuel damper that on the fuel rail

It seems to be almost anywhere. If you keep increasing throttle it sounds and runs fine. When you stop or bring it back to idle, POOF!!! It blows through the starboard compressor.

Im a 2 stroke person, but dont 4 strokes backfire from a lean condition when you lift?

i had the same problem the boat only ran good at full speed but at low and mid range rpm it pops call whipple and see what they say

Tried...no luck so far.

Someone has had to experience this.

Whipple offers a by pass valve, does your system have one ?

The symptoms you describe is what the by pass is designed to correct.

There are bypass valves on both sides of the superchargers. We tested the diaphrams and the operation, all appears normal.

They rigged it into a different boat, but the componenets are all the same.

Its on a stand and still doing it.

The Whipple was resealed, rotors never were removed, just the intercoooler to manifold resealed. No leaks as they dont see much movement on a vac gauge and sprayed starting fluid around the intake seal to check for leaks...nothing.

Try to send Dustin a PM , he is always on OSO some where I'm sure he would be glad to help . Just my 02 :ernaehrung004:

The guy has been on the phone with Dustin and we sent him email. I'm sure hes busy and we understand.

This cannot be the first time this issue has happened. It only backfires (for a lack of a better term) out of one compressor. If it were common in the manifold it would do it from both compressors right?

What would cause one to respond or act different from the other?

Engine has been thouroughly checked with compression test and leak down - all is well.

Dustin? Anyone?

Obviously,there is a passage which is restricted or not opening.

The internal passage may be restricted or even casting slag blocked.

You may try swapping the valves and controls from one compressor to the other.

You may also look at the inner cooler for fin or otherwise restriction.

check the pully to see if it may be sliping on the end of the drive, it is just a friction drive and can slip, it does happen.

If the pulley is slipping the charger would cause this issue?

Yes, if the blower stops turning the fuel on that side stops flowing and lean pops back, all the fuel has to pass thru the blower and if it does not turn at the right speed for a time it can happen. We have seen it. If the drive inside the snout breaks it will still idle but bang back hard under load.

Getting it straightened out. Plugs were black and very rich.

Relocated the regulator near the fuel rail where it was before customer moved it!!!

Base fuel pressure 50 PSI, new set of plugs and its running great.

Still an issue when bringing back throttle. I think they messed with the bypass valves when installing the exhaust, and the IAC is not responding properly.

Any info in setting them up?

50 psi fuel pressure?? Seems a bit high to me. What size injectors??? I run 60 lb injectors at 38 psi. My old setup was stock injectors at 45 psi.

Actually we did answer, we said its either lean or spark related. First check is the ignition system, cap, rotors, plug wires, coil, etc. After that, which I doubt is a problem, an air fuel meter should be installed to see if it's lean, which I assume it is. Every boat/weight/gear ratio/prop size and type/ are different so the map is probably off from what it needs to be in this boat.

Dustin

Regulator mounting can effect harmonics in the rail, both rails need to drain into both sides of regulator so it helps dampen. If its longer than 12", it may need dampner. But again, it's probably lean under decel, this boat, which I believe is a pontoon boat, probably has considerable load during decel and is in area's that have not been extrapolated in the map.

Dustin

Engine is out of the boat on a stand.

Thanks for the input Dustin.

In no way shape or form is this the Whipples fault!!! Someone evidently messed with something that they didnt understand.

Dustin - where can I get new screens for those injectors? Need 8 of them please. Or a model number of the injector to get the screen kits locally.

This I gotta see. A quadrotor toon!

Ran the engine again today. Ran terribly and fouled plugs.

The only difference was we ran water through the intercooler. I didnt realize the guy installed a two stage pump so it always pumping through the intercooler. We stopped the flow yesterday, but let it run today.

Engine was sooo rich it was terrible.

My boat didnt have a dual stage pump just a water pichkup for the intercooler. Could this be the issue?

The short answer is YES with reference to how it ran with water running through the intercooler at idle and not up to temp.

Don't know about injector screens, never seen anyone sale those. Should be cleaned with standard screens on.

IC on during idle can affect af about 1 full ratio, but what your describing is more than that. If motor is not in boat, then it's just off, whether something changed such as fuel psi regulator, bypass system, linkage, etc., something is different. Check TPS voltage, fuel psi, timing in reference to what ECM is commanding. Then check AF ratio and modify cal accordingly. There's probably not a smoking gun here, its just off, needs to be adjusted. Once you check ignition and IAC, gotta look at AF.

Dustin

Thanks,
Dustin

If it's popping back through only one blower, I would bet you have a broken drive on that blower. Hard to diagnose "over the net" :)

I pulled the flame arrestor off the side it was popping though, throtle blades werent closed all the way!!! So I fixed that.

Rotors turned fine. So nothing appears broken.

Its definatley in the tune with that cold water running through the intercooler at idle. The guy has a choiice - retune or pull the dual stage pump off!!!

I can check all the above with the program.

Thanks Dustin. And you too Richard, I know you know alot about these set ups.

Dustin - Arent they Rochester 95 injectors? Should be able to get screens and orings somewhere. It looks like the took them out when they flowed them in May.