sputtering

Reply Subscribe

Thread Tools

Search this Thread

Mar 16, 2009 | 11:16 PM

gregm

Thread Starter

Cruiser

Joined: Jun 2007

Posts: 213

Likes: 2

From: Port Orchard, Washington

sputtering

I just had a local independant HD shop convert my '05 EGC (TC88 35000 mi) to a set of gear driven cams. The cams are a small upgrade but mild enough not to have to change the valve springs (Head Quarters 034G), I also added a Power Commander III and K&N air cleaner. After the conversion the engine sputters when MAINTAINING speed/rpm on level roads, but not under the slightest load or when decelerating. The sputtering only happens above 2000 rpm, not below, and the throttle position is less than 10%. The plugs & wires were replaced with new, the wires made a difference but the sputter was still there. The Power Commander was adjusted to six different settings with no noticable change (we were in contact with Dynojet during all this). We finally disconnected it & reconnected the factory ECM but there was no difference, the sputter was still there (now thinking a pre-existing condition, possibly masked by the chain drive). A compression check showed less than 10% difference in pressure between the cylinders. I pulled the plugs out after 70 miles and the rear cylinder plug had a fluffy black deposit all over while the front plug had a nice tan/grey color like you'd expect from a well running cylinder. I also replaced the "cored" HD mufflers with stock mufflers but ther ewas still no change in the sputtering. Anyone have any suggestions?

Mar 16, 2009 | 11:51 PM

LilBudyWizer

Road Warrior

Joined: Mar 2008

Posts: 1,691

Likes: 3

Maybe you're scavenging more on the rear cylinder from the front one. Maybe lower the fuel on the rear cylinder and up the fuel on the front one. Maybe use a stethoscope to get a better idea just what you're hearing and where it is coming from.

Mar 17, 2009 | 09:29 AM

Old Gunny

Road Warrior

Joined: Nov 2007

Posts: 1,984

Likes: 7

What Lil Budy said.

Mar 17, 2009 | 10:36 PM

gregm

Thread Starter

Cruiser

Joined: Jun 2007

Posts: 213

Likes: 2

From: Port Orchard, Washington

Sputtering

Quote:

Originally Posted by LilBudyWizer

First, thanks for the input. Second, how do you do that on an injected model?
Gregm

Mar 17, 2009 | 11:33 PM

LilBudyWizer

Road Warrior

Joined: Mar 2008

Posts: 1,691

Likes: 3

You use the cylinder trim tool in the software.

Mar 18, 2009 | 10:23 PM

gregm

Thread Starter

Cruiser

Joined: Jun 2007

Posts: 213

Likes: 2

From: Port Orchard, Washington

Sputtering

Thanks LilBudyWizer, I'll check that when I take it back to the indy.
Gregm

Mar 19, 2009 | 07:38 PM

gregm

Thread Starter

Cruiser

Joined: Jun 2007

Posts: 213

Likes: 2

From: Port Orchard, Washington

Sputtering

I put the stock slip-ons back on and the plugs evened out as far as the black fluffy coating goes. I decreased the Power Commander midrange fuel setting by 5% and some of the fluffy plug coating went away but I still smell the over fueling, and it still sputters. I decreased the low RPM range by 5% and the idle went up by 100-150 RPM like it was running too lean, so I set it back to where it was. I'm going to ride it for a couple of days before I tweak it any more.
Gregm