Solved: Typical CA misfire

[Nategreat923]

So I'm having a misfire just like this:

http://m.youtube.com/watch?v=xJ1GS55lgn ... J1GS55lgns

Has a hard time starting, and doesn't change at all even when warm.

Things I've changed/ tried:

Swapping coil packs
Coil packs are grounded
Cleaned MAF
Changed spark plug gap .044- .028
Timing at 10btdc
AFR is 11.7-13.5 (any closer to 14.7 and miss gets worse)

I was able to get it to rev fine with no miss at 11.0 AFR but under a load it wouldn't go above 4,000 rpms.

Mods:
Port, polish, gasket match
Butterfly's removed
T28R
Tubular manifold
3" downpipe
HMIC
Stock ECU
Tomei FPR
Walbro 255

Could it be fuel hitting fuel cut because of the stock ECU? It's only running 6-7psi

[float_6969]

codes?

[Nategreat923]

Hey Dee, so I swapped in some BCP6's, instead of 7's and did more swapping of coil packs and boom, runs perfect.

But, now I rev to 5,300 rpms and it leans out completely for a second causing a misfire. Every single time. Idles at 14.5-7 now.

[float_6969]

That sounds like a failing fuel pump or a bad FPR... I suppose it could be a dirty MAFS, but you said you cleaned it. The stock ECU will hit the cut out before it leans out, so that shouldn't be the issue.

[Nategreat923]

Interesting. It's a walbro 255 that works fine (it did with my last motor) and a new tomei adjustable so I don't think that's the issue.

[Nategreat923]

Here's a video for you:

http://www.youtube.com/watch?v=8XWhSN6VI7c


Sent from my iPhone

[float_6969]

Yea, that's lean everywhere. You're getting a nasty little lean out when the tip the throttle in that shouldn't be there, and even after it recovers, it's still pretty lean until the mis-fire. What do you have the fuel pressure set at?

[Nategreat923]

Sorry for the late reply, took a hiatus from working on it. I don't have a gauge, but I riches it to 11:1 at idle and and the same issue. Lower RPMs weren't at lean but still the misfire and complete lean out at 5200

[Nategreat923]

Bump, any ideas?

[float_6969]

how are you tuning?

[Nategreat923]

Right now stock ECU. I'm buying nistune Friday.

I'm trying to figure this out before I tune it, because it ran great for a day before doing this.

[float_6969]

Have you tried replacing/testing the ignition amplifier?

[Nategreat923]

Problem solved:

[float_6969]

"There's your problem!", LOL. Well I'm glad you got it figured out. It looks like the CAS itself is still OK. Jim Wolf Technologies has just the little splined part so you don't have to replace the whole cam.

[Nategreat923]

I actually have a few sets sitting in the garage, so that's not an issue. Would you mind adding "Solved:" to the title of this, for people searching?

[float_6969]

done!