Cruising Misfire?

[Bcoy]

I know that people have posted similar problems and have searched a lot for a solution, although mine seems to be a little different and others never really seemed to post it if was resolved or not.

First, my engine setup:

6 bolt block
Eagle Rods
Wiseco pistons
Stock 2G head
Big 16
Injen intake
SSAC front mount

Fresh build, engine is about 200 miles old.

Everything else is basically stock.

Now what's happening is that when I'm cruising (usually between 10 and 20 inches of vacuum) my car suddenly has no power and sounds like it's running on 3 cylinders. Usually if I downshift and bring the revs up, it goes away for a while, but it always comes back eventually. Sometimes I can't even get it to stop, and have to shut my car off and restart it.

It does NOT run bad at idle. Idles great. Appears to have no vacuum leaks. Runs great when I'm pushing it, pulls hard on wastegate boost.

I've already tried swapping out the MAF, any other ideas?

I also linked a video of the symptoms.

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[psiaddict]

Well, it definitely sounds like a misfire… The first things that come to mind would be:
Spark (plugs/wires/coil)
Fuel (injectors) or drivers (ECU)
Mas (going bad, wiring?)
Trigger signal (CAS)

Are you getting any CEL’s? That might help narrow it down...

 

[And_44]

Well, I just got through a bad bought of misfiring. I swapped my ignition coil/module, replaced my wires and plugs. Swapped my CAS, throttle body with new seals and good TPS/ISC, and even my ECU and those didn't help.

Turned out to be my Alternator. It wasn't putting out enough charge to my coil to ignite the plugs. When the misfiring started the only way the car would run is either at idle with a stutter/misfire (still would die if left running at idle to long), or while under heavy load. At an idle the car barely ran but didn't need much spark to keep it running and while under load the Alternator would work harder to pump out the voltage to the coil, and misfire went away.

But out of the items listed above I'd test those and do a Boost leak test.

 

[4gGs-t]

So did u find out what was causing this? i have a very similar problem

 

[Bcoy]

It was because I was using a 2G ecu with the 1G cam angle sensor.

I turned off the cylinder misfire detection function of the ecu using ECMLink and it went away. Problem solved.