Thread: Erratic misfire under boost, PO134 code

Hey everyone.
I just randomly started misfiring under boost, it's very erratic. I'm also throwing a PO134 code. I tried replacing the O2 sensor and no avail. Not sure if this is related, but my boost gauge also stopped working and now won't read over 3.5psi when it was reading 10psi, just gets stuck there. It has all new spark plugs and wires. Am I missing something? The car runs perfectly fine when not under load, no misfiring. I can go up slowly through the RPM range but as soon as it hits boost it starts the misfires.

Originally Posted by Scottydoggs

you have any mods? 10 psi is higher then stock.

and theres a fuse in the under hood fuse box, #21 iirc. see if thats blown. it powers the maf and the o2.

also check for damaged wires on the cars plug side.

Just bolt ons and a tune by Reptile. I'm still on the stock pulley. I'll go check that fuse right now.

Originally Posted by Scottydoggs

you have headers? if so make sure your o2 extension is not melted to the header.

No, no headers, my bad. I have CAI, Tune, NGK TR6, ZZP 3" DP, 180 thermostat, basics.

Originally Posted by Scottydoggs

you have headers? if so make sure your o2 extension is not melted to the header.

also the fuse looks fine.

Originally Posted by Fivefingerdeathpunch

If it's missing it should still either spit out a code or maybe even start flashing the SES light.

I'd try and get it to flash the SES just to help give you an idea if it's a certain cylinder or a P0300 for a random misfire. WOuld help steer you towards a coil pack or even a ICM issue.

The only code it's throwing is the po134.

The Bosch. Cheapest at autozone lol

Okay so I got some more information,
I'm really starting to think it's vacuum or even exhaust related, semi-clogged cat? After playing around with it a bit more, i figured out that the car runs, and pulls completely normal up to 2psi. As soon as it goes over 2psi it'll start the miss/jerk thing. It also idles at about 900rpm and is at 20in.Hg at idle. Is that normal? Here's a really short video of what it's doing, i hope you can hear it. I can take a longer one tomorrow if needed, sorry it's filmed with a potato.

https://www.youtube.com/watch?v=wrf0...ature=youtu.be

Well I fixed it with a new set of spark plugs and wires. I took it to a local shop for a tune up 3 weeks ago and they supposedly put in new NGK tr6 plugs for me, there weren't any. There was 4 AC Delco plugs and 2 NGK plugs. NONE of them were gapped properly. One was gapped at .74 lmao