Weird P0300 check engine light but two are coming up.

[97prizm]

Hi all,
My dad and I worked on my 1997 Chevrolet Cavalier to get it to pass emissions which it failed a couple of weeks back, ( which I posted). We replaced the plugs with the exact same Denso Iridium spark plugs that were in it ( same part numbers.) I noticed on the firewall that it recommends a spark plug gap of .060 which seems like alot. The new Densos were .030 but was told not to gap those. New wires, new radiator as the original was leaking, new overflow bottle and hoses. It seemed to run smooth early on. I went up to the gas station to fill up and add Cataclean to the tank. It started to sputter at idle and had a mis while driving setting two P0300 which are random misfires. Usually after a tune up your vehicle runs great. I did check the wplug wire order and that was correct. I'm wondering if I got a bad plug or wires?

 

[Oldwolf]

I think I would be installing only factory recommended parts in my old 1997 Cavalier. I'm guessing it has the 2.2 L engine?

 

[Jetronic]

1997, so that's likely a wasted spark setup? makes sense that 2 cylinders are affected by misfires then.. could be anything though, plugs, wires or coil.

 

[SC Maintenance]

Those old engines had much lower compression. Too small a gap may not be a fat enough or long enough spark.

I also would try to find plugs as close as possible to OEM in this case.

Also, inspect all your wires and boots - possibly you have a crack or loose fit.

 

[Lubener]

P0300 doesn't specify a particilar cylinder. I would have used OEM plugs which I believe would be AC, gapped at .060 which is the real spec.

 

[atikovi]

I noticed on the firewall that it recommends a spark plug gap of .060 which seems like alot. The new Densos were .030 but was told not to gap those.

There's your problem. Who told you not to gap them? If so, and they are at .030, they are the wrong plugs for that car.

 

[97prizm]

There's your problem. Who told you not to gap them? If so, and they are at .030, they are the wrong plugs for that car.

Ahh I've been told by many automotive mechanics that due to the fine tip of Iridium Spark Plugs that you shouldn't gap them. This makes alot of sense now. Thanks.

 

[ka9mnx]

Waste gate plug firing will eat iridium spark plugs. Happened to me. Yea, OEM plugs and proper gap.

 

[BAJA_05]

Why didnt you just go with ACDelcos from the get go? I dated a girl who bought a brand new black 1998 2 door Cavalier with the 5 speed and the 2.2L. That little car ran great and had good gas mileage with a kick arse AC.

 

[97prizm]

So I put in NGK platinum plugs after removing the Denso Iridium. The weird thing is that it idled and ran fine two weeks ago but failed the emission testing. Now it has a real bouncy rough idle and wants to die while in drive. The check engine light hasn't come on but with it this rough it most likely will. The right two were really sooty with very little driving. Usually new plugs, wires, And two new fuel, injectors are
Night and day difference.

 

[97prizm]

They are gapped to the correct gap.

 

[Marcozi]

"Now it has a real bouncy rough idle and wants to die while in drive." That sounds like a vacuum leak. Scan, clear the codes, see what happens.

 

[Nukeman7]

Based upon the information provided, I see two things that might correlate with your situation.

(1) Did the rough running/poor idle start right after you added the Cataclean? Perhaps the additive will cause it to run rough while cleaning out the carbon from the catalytic converter matrix substrate.

(2) Did the two sooty plugs come from the cylinders with the two new fuel injectors? If so, the injectors may be improperly sized resulting in a rich fuel mixture.

Also, why does the photo in Post #10 show Autolite plugs when you said they were Denso Iridium? You need to go with AC Delco plugs which were OEM on that Cavalier.

 

[97prizm]

Based upon the information provided, I see two things that might correlate with your situation.

(1) Did the rough running/poor idle start right after you added the Cataclean? Perhaps the additive will cause it to run rough while cleaning out the carbon from the catalytic converter matrix substrate.

(2) Did the two sooty plugs come from the cylinders with the two new fuel injectors? If so, the injectors may be improperly sized resulting in a rich fuel mixture.

Also, why does the photo in Post #10 show Autolite plugs when you said they were Denso Iridium? You need to go with AC Delco plugs which were OEM on that Cavalier.

Sorry the parts guy said Denso but the ones that I installed were in fact Autolite Iridium plugs. I swapped in NGK Platinum with the required .060 gap. How do you know that you're getting the correct fuel Injector size? My dad bought those brand new and they were specified for the GM 2.2 in the Cavalier.

 

[Nukeman7]

Sorry the parts guy said Denso but the ones that I installed were in fact Autolite Iridium plugs. I swapped in NGK Platinum with the required .060 gap. How do you know that you're getting the correct fuel Injector size? My dad bought those brand new and they were specified for the GM 2.2 in the Cavalier.

I don't know enough about injectors other than how your Dad sourced them. However, if they are the ones in the two cylinders with the sooty plugs, I'd be very suspect. This appears to be the OEM ACDelco part:

'97 Cavalier 2.2L Fuel Injector

@Trav is the BITOG subject matter expert on fuel injectors, so maybe he can chime in with some advice.

 

[97prizm]

I don't know enough about injectors other than how your Dad sourced them. However, if they are the ones in the two cylinders with the sooty plugs, I'd be very suspect. This appears to be the OEM ACDelco part:

'97 Cavalier 2.2L Fuel Injector

@Trav is the BITOG subject matter expert on fuel injectors, so maybe he can chime in with some advice.

Would it be worthwhile to have them rebuilt if thats possible? Two of the injectors had the O ring gaskets go bad allowing them to leak. There is a guy not too far from me that does fuel injector service.