Name that backfire..

[ttgtomr]

Hello all. I have an ongoing problem with my blacktop sr20. Under acceleration if I give my car more than 1/5th throttle the car will stutter and if I give it more throttle it will backfire really badly. Mods: sr20 blacktop vmount setup intake catless exhaust evc4 boost controller (stock boost) here are two videos of what the car is doing.. IMG_0642.MOV - YouTube (http://www.youtube.com/watch?v=GwrprJRmxV8) IMG 0641 - YouTube (http://www.youtube.com/watch?v=seyaUkm31Yc) thank you!

[ChinkyChris]

Do you have a wideband? If so how does the AFR look?
Does it smell rich?
How do the plugs look?
Did you check for boost leaks?
Plug Gap?
Whats your fuel pressure?
Does it do this at all temps? (Coolant) not ambient temp

[ttgtomr]

Unfortunately I dont have my wideband installed. It definitely smells rich. I replaced the plugs yesterday. The old ones were greyish mat finish. I don't have a fuel pressure gauge either :/ Yes cold start up and when it is hot too/

[ChinkyChris]

Have you always had this issue? or is this something new?
Do you have any codes?
What did you gap the plugs to?
Assuming you have a boost gauge, what does it show at idle?
Does this only happen at specific RPM? or boost pressure?
Does it run better with MAF unplugged?

Double check your ground for the coil pack harness too

[ka-titties]

i had the exact same problems with my old ka-t when i would get a boost leak somewhere on the intake manifold. pressure test your charge piping and intake manifold is my suggestion.

[ChinkyChris]

Sorry only watched the first video, now that I have watched the second video it sounds like you are dropping spark.

I would say more than likely you have a weak coilpack or maybe the ground is bad.
But i'm sure others will chime in on this one.

[vas570sx]

ive seen high spark plug gaps cause this issue. you said you just changed the plugs? set the gap at like 0.025 and try again.

[ttgtomr]

I have had this issue for a few days. The car was running really well beforehand. I don't have anything to read the codes either. I threw the plugs in there just to make sure it wasn't a spark issue. My old plugs were doing the same thing the new ones are and the old one were fine until 2 days ago. I am showing -22psi at idle. It happens at any rpm but the car is more controllable at 1k-3k that is assuming I am not giving the car more than 1/5th throttle. It is hard to say if it is boost related because the car spools so fast. The car runs better with the MAF plugged in. I have checked out all of the vacuum sources for frays and cuts. They all seem fine.

[ttgtomr]

I just cleaned the MAS looked clean to begin with. No noticeable damage to it either.

[ttgtomr]

Problem solved. The ecu had a loose connection. Thanks all!