97 Cutlass Supreme 3.1L Misfire in cylinder 3

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glockgal2010
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Joined: Fri May 24, 2013 7:27 am

97 Cutlass Supreme 3.1L Misfire in cylinder 3

Unread post by glockgal2010 » Fri May 24, 2013 7:40 am

Hello all,

My olds starting running like complete crap yesterday while I was out running errands, flashing service engine light and all. I was hesitant to drive it like it was, but based on what my husband and dad said, I ventured to O'Reilly auto where they pulled code P0303. The guy gave me a list of "reported fixes" including replacing fuel injector wiring, injector o-rings, and fuel pressure regulator. At first I left feeling rather optimistic, but after thinking about it for a while I realized that he suggested we try replacing the most expensive part first. (Well duh, they are a parts store, why wouldn't he tell me that??) SO, I talked to my dad and he suggested checking the distributor cap and/or coil packs. We had this code pop up last summer and changed the plugs which seemed to resolve the issue, so we thought... I just don't know where to even start at this point. The more research I do online the more issues I find that it could be. Any thoughts or suggestions are greatly appreciated.

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ProTech
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Re: 97 Cutlass Supreme 3.1L Misfire in cylinder 3

Unread post by ProTech » Fri May 24, 2013 7:46 pm

Yes, lots of different things that can cause a misfire on cylinder 3.

Coil, ignition wire, spark plug, injector, etc.

Start with the basics, no need to spend money that don't have to. Check for spark. Pull the plug out and see if it's fouled or if it's cracked, etc. With #3 cylinder being in middle on the back side of the engine, it is pretty much impossible to check the fuel injector or the wiring going to it without first removing the upper intake plenum. This isn't difficult, but if you're not experienced it might be a bit much. You can try and ohm the injector with a multimeter, it should be around 12 ohms. If you have a scanner and a fuel pressure gauge you can also try and do a injector balance test, but since you went to a parts store to get your code pulled, I'm doubting you have the equipment. If there's any noise to the engine, there's also a possibility of a rocker arm that has come off due to the bolt pulling out of the head....but this isn't as common as a fuel injector issue or ignition problem.

Basically, if the ignition components check out, replace the injector.
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glockgal2010
Posts: 3
Joined: Fri May 24, 2013 7:27 am

Re: 97 Cutlass Supreme 3.1L misfire in cylinder 3

Unread post by glockgal2010 » Sat May 25, 2013 7:25 am

Excellent! Thank you so much!! Yes, the plugs on the back are a pain in the you know what. Last summer when we replaced them we had to take the dog bones off and use ratchet straps to rock the engine forward.

If it is a bad plug, what could be the reason that particular one keeps going bad?

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ProTech
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Re: 97 Cutlass Supreme 3.1L Misfire in cylinder 3

Unread post by ProTech » Sat May 25, 2013 11:57 am

If it is a fouled spark plug, it's either going to be from fuel or oil. Fuel fouling would be from something like a stuck open fuel injector where it's flooding the cylinder. Oil fouled spark plugs are much more common, especially on older high mileage engines. This can be from blow-by from bad piston rings, or leaking valve guides and/or seals.
GM Dealer Technician For 18+ Years
In the automotive industry for 20+

glockgal2010
Posts: 3
Joined: Fri May 24, 2013 7:27 am

Re: 97 Cutlass Supreme 3.1L Misfire in cylinder 3

Unread post by glockgal2010 » Tue May 28, 2013 5:48 pm

Well over the weekend we replaced the plugs even though they looked fine, wires and the coils were good. We priced injectors, but my husband wanted to try one last thing before we took it to the shop. He put a can of Seafoam in the tank and within a couple hours she was running like new again. We cleared the code and let it run, drove it a bunch, but it didn't have anymore issues. I'm guessing there was junk built up on the injector that just needed to be cleared out. Thank you for all your help with this!!

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