SR20 Stumbling between 2.5k and 4k

[TheSquidd]

Just bought an S13 with a red top SR20, completely bone stock (has stock air box!).

Driving on the freeway it is now stumbling pretty hard when I hit 2500 rpm - 4000 rpm. Shuttering / stumbling, struggles to get up to boost. When it hits boost the problem seems to go away, around 4-4500 rpm.

Just wondering where I should start looking? Coilpacks? Air Filter? MAF?

Thanks everyone! Glad to be back in a 240.

[Om1kron]

could be maf, could be knock sensor what codes is the ecu throwing?

[TheSquidd]

I will check for codes in the morning. I'm starting to think it's the coilpacks or the coilpack ground wire.

[Chriscooke]

When the coil pack fails the missfire normally gets worse when you hit boost in my experience.

Mine revved fine with no load right up to the redline but missed massively at around 3k revs upwards when in gear.

Could be worth checking the plugs.

[TheSquidd]

No codes from the ecu. Car now feels like it has 100hp max and isn't blowing any smoke or running very rough. Just no power at all. Coilpack ground is secure, coil packs all seem to be in good condition.

Bad turbo ? Plugs were fine.

[Chaluska]

seems to be a problem alot of people are having lately (including myself)

no power from 3000-3500 rpms ..

i suspect a few things..

fuel pump
knock sensor defective/broken
MAF dirty

[boms]

I would clean the maf.. but a "bad" maf wont let it rev past 3000 ish
I would do a fuel pressure test as well.. get that out of the way. as well as replace the fuel filter.

[TheSquidd]

K, took off the coilpacks and reseated them, seems to have added a bit of power but still stumbles very hard 2.5-4k.

I have a Z32 fuel filter to install, but I would assume a clogged filter would make it run rough throughout the powerband/idle, not just those rpms.

I'll clean the MAF and check the knock sensor (should throw codes right?)

Pressure test soon too.

Thanks for the help gents!

[G-z]

injector clips
check the ignition fuse also

[TheSquidd]

Got it! Apparently a dirty MAF. Running like a champ now! Thanks everyone for the help.

[joeapple8]

How do you clean the maf? I was thinking about using Maf cleaner and q tips... I'm scared though. LOL

[Jesse SR20]

How do you clean the maf? I was thinking about using Maf cleaner and q tips... I'm scared though. LOL

Noooo !

Don't touch the resistor with anything. It's delicate, and the maf cleaner will do it's job fine by itself. Just let it all evaporate before sending voltage to the sensor.