P420 code

**Bluemagic** · 04-25-2012

Well I'm finally getting the cat changed tomoro. Noticed while driving on slow acceleration rpms drop at like 50mph or so then just drags. Just want be sure it's the cat and not the sensor. Well I changed the sensor and the damn light came back so... I'm guessing it's the cat lol. Any thoughts about the rpms dying at 50 miles per hour? Sound like a typical cat issue?

**BillBoost37** · 04-25-2012

Looks, smells and sounds

**Rico** · 04-25-2012

The downstream sensor just monitors catalytic convertor efficiency...I don't think it has anything to do with the way the motor runs.
Get the convertor replaced before you do anything else. This is hell on the engine.

**Bluemagic** · 04-25-2012

Sounds awful. Took it in to check for leaks and they found none. So cat goes bye bye

gotta get a confirmed price though. The exhaust shop charged my friend 160 then tried to charge me 225 for the same Job. Wtf.

**Rico** · 04-25-2012

Originally Posted by Bluemagic

Sounds awful. Took it in to check for leaks and they found none. So cat goes bye bye

gotta get a confirmed price though. The exhaust shop charged my friend 160 then tried to charge me 225 for the same Job. Wtf.

They may have welded his in...and you may be getting an entire downpipe?

**Bluemagic** · 04-25-2012

Naw I have a downpipe and yea they weld everything. They are known to fluctuate in prices when different people are there but when i show them my club logo they give me a discount. Smh.

**Bluemagic** · 04-27-2012

Cat done

car feels a lot more responsive and doesn't drag at all anymore. Now let's hunt down this misfire from cylinders 1 and 4 lol

**BillBoost37** · 04-27-2012

Check again...Likely they were from the cat.

**Bluemagic** · 04-27-2012

I wish. This happened after the cat lol

**BillBoost37** · 04-27-2012

1/4 you say.. odd how they are both on the same coil. Bet if you swapped that with the 2/5 right above it..that 2/5 would probably start messing up, leading you to replacing that coil

**Bluemagic** · 04-27-2012

Ok I'll try that, my car started throwing a p300 code. Which said multiple misfire. So I fired up my torque app and brought up each cylinder and found out that the 1st and 4th cylinder was the culprits. Is removing and switching the coils easy?

**BillBoost37** · 04-27-2012

Each of our three coils fires two cylinders. it fires both posts at the same time, which is why our system is called a waste spark system. It fires the coil to ignite 1, and throws away a spark during the exhaust of 4.

Swap the 1/4 and 2/5 coils and likely the misfires will move to the 2/5 cylinders instead of 1/4. If that happens, replace the bad coil.