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Malibu - Codes P0306 and PO205


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davescountry
New User

Mar 15, 2010, 1:15 PM

Post #1 of 2 (5664 views)
Malibu - Codes P0306 and PO205 Sign In

This is on a -
2000 Chevy Malibu
111,000 mile
3.1 engine

In the last 3 months I have done:
- replace fuel filter
- replace fuel pump
- replace lower intake gaskets
- re-wired IAT plug
- replaced IAT sensor

I am getting OBD codes PO306 and PO205 which I know to be "Cylinder misfire on 6" and 'Injector Malfunction on 5." These are pretty intermitent and when I don't have them, the car runs great. When I do, it runs terrible and skips and bucks horrendously.

Sometimes, if I can get the rpms up, it smoothes out. Also, occaisonaly when it gets really bad, I get two more errors -- PO410 - Secondary Air Injection System Malfunction and PO412 - secondary air injection system switching valve a circuit malfunction. Quite honestly, I am not as concerned about this for a couple reasons. First, I suspect it could be an output of the car running so poorly. I mean, when I get this code, it is skipping and misfiring so bad it feels like the engine is going to fall out. Even if thats not the case, I basically know what I need to do here to fix this.

I took it to a shop first. He said the misfire was due to a vacumn leak on the upper plenum. I then took it to the dealer. Eventually, he gave me the same diagnosis (after I told him what the first guy said) along with that I needed to change the injector on 5.

I did change the upper gaskets, and no improvement. I also checked the injector connections on 5 and made sure it was seated correctly. No improvement there.

I am skeptical on that diagnosis for two reasons. First, I couldn't find any vacumn leak when I sprayed the area with carb cleaner and starter fluid, and clearly replacing the gaskets didn't work. Second, I am hard pressed to believe that two unrelated problems (misfire and injector malfunction) keep happening at the exact same time over and over. I never get one without the other.

Just to remove variables, I did also replace the plug, plug wire, and swapped coils -- no improvement.

I went to my local O'Reilly's today and picked up their noid light kit to try and test, but I did not see where any of the lights in the kit matched my injector plugs.

Any ideas on what could be happening here or what to try and test?


(This post was edited by davescountry on Mar 15, 2010, 2:37 PM)


steve01832
Veteran
steve01832 profile image

Mar 15, 2010, 5:34 PM

Post #2 of 2 (5648 views)
Re: Malibu - Codes P0306 and PO205 Sign In

You could try swapping the injectors to see if the code reflects the cylinder of the suspect injector. That would indicate a bad injector. You will need to get a noid light kit to test for injector pulse.
As for the ignition problem, you may have a bad module. If you swap coils and the problem stays on the same cylinder, the module is most likely not firing that coil.

Steve






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