realcanuk

After my recent repairs for the eforce oil leak I had an issue with bank 1 missing and running lean due to a defective coil pack harness. In all I would say the car was run for maybe an hour at or near idle while trouble shooting the problem. With the new harness it is running perfectly but throwing codes P0420 and P0430. I know what these codes are but my question is could it be that the car running while missing would damage the 02 sensors or cats? Its strange because only one bank was missing but I now have the codes on both. Any ideas ? Thanks

realcanuk

Anyone ? Thoughts on missfiring effecting cats and/or 02 sensors ?

Motorhead-47

Stock manifolds and cats?

realcanuk

Yup. Totally stock exhaust.

Motorhead-47

Something other than the canned Edelbrock tune?

realcanuk

Yes. Tuned by Chuck CoW but no codes since install. Codes only started since the valley plate change and nothing in the tune was changed. Numbers were only checked to see that all was normal after the missing troubles fixed.

Motorhead-47

So you cleared these codes and they come back or could they be relics of the missfire?

The last E-Force bad wire harness I saw (recent) was because the harness was crushed under the coil pack bracket. You need to check the other side also.

realcanuk

I changed both sides for new. The CEL never came on before. It came on about an hour after this fix. I cleared the codes and light and they came back the next day. I cleared them again. So far not back but I haven't driven much.

Motorhead-47

You'll want to give your tuner a call and chat with him.

realcanuk

Source of codes found...........and fixed. Racing cats.... car runs great like it did before..

Motorhead-47

Misfires killed the cats?

realcanuk

Seems that way. Both my guy here ( who is amazing) and the mechanic at Cow (also amazing) both were suprised that just running at idle and low rpm with no load (while troubleshooting) would do this. Much more understandable if the car was actually driven hard while misfiring. They never threw a code before and the car only has 15000 miles on it. Oh well, learn something new everyday day.

eboch

Hi;

I'm new to this site. I've been looking for some help in understanding my P0420/430 codes ... .came across your thread. Very interesting. I have had a similar issue.

I have an '05 Z51 with a 10psi A&A supercharger kit. The kit has been in the car and worked flawlessly for going on 3 years now. The rest of the engine is stock, stock exhaust manifolds & cats, coupled with Magnaflow cat-back. I drive the car daily and track (roadracing) it 2 - 3times a year. Last time I was on the track I had fuel delivery problems at high boost & rpm, where the fuel pump booster needed to kick in to deliver the needed fuel. The pressure switch wasnt workig reliably and the engine got fuel starved on several occasions, I could feel it hesitating.

Anyway, about a week later .... up pops P0420 & P0430 at the same time. The upstream O2 sensors seem to be working fine (i.e. jumping around between .1 and .9V .... I looked at them with HPtuners (but I cant see the downstream O2's with HPtuners). I've had my CATs off and they dont appear to be blocked (at least by visual inspection of the inlet side honeycomb .... which is about all you can see) and there isnt any sign of them falling apart in any way.

For now I've blocked the 0420/0430 DTCs & SES. Before I replace the stock cats, or move to a header/cat combo .... i'd like to better understand what might be wrong. Can a few seconds of fuel starvation destroy the CATs or O2's? would both sides die at virtually the same time (seems tough to believe)

I plan to check the voltage stability of the downstream O2's and measure the inlet/outlet temp of the CATs to get a better idea of what failed.

Any thoughts/guidance would be useful.

Cheers
eboch

HOTMESS

Just bought my wife a stock C5 convertible with 94k. Did a Stock KnN Air Filter for now(Going with the VARARAM).
N BORLA Cat Back Exhaust. In my infinte wisdom, I told the MUF SHOP to cut out the two Big Cats for (INCREASED FLOW). Im guessing this is whats causing the PO420/ PO430 codes..

Can anyone confirm this and how do I get rid off them?


Also, have 100 questions on how to increase power and not blow it up. Not trying to out run a C7, but "TO HELL WITH THESE SRTs & 5.0s)

schpenxel

Few changes to tune is the sure fire way.

Some have had good luck installing spark plug extenders to the rear o2 sensors.

Most decent high flow cats these days aren't costing you much hp, they aren't nearly as bad as they used to be

eboch

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Without the cats , the codes will come up because the o2 sensor tests that are running continuously will fail. You can suppress them with some tuning SW packages .... but i don't beleive that's legal.... and may cause you grief at your next etest.

Cheers
eboch

schpenxel

With "proper" tune changes it will pass inspection no problem.

Some have also had luck using spark plug extenders if there is room. I can't explain how it works, but several people have told me it worked for them.. so it's something easy to try IF you have room

Dude_man

We sell mini cat O2 extensions at work