Random misfire concern

[FireFight]

I had a customer buy a set of new factory style NGK plugs and out of the box he had a misfire, I didn't believe him that that was the problem, but low and behold I warrentied them and gave him a new set and problem fixed. Not saying for sure that's the reason but with plugs so cheap maybe toss in another set and check the gap?

[peterman]

I had this exact problem. The CEL is most likely an excessively rich code. Get the CEL to come on - ideally in your driveway when the car is idling - then shut it down. You can peform the stomp test to read what the CEL was crying about.
I replaced o2 sensor, fpr, injectors, cleaned grounds, tried dofferent wires, new plugs... i. The end it was the cap and rotor I got from autozone. Get a Bosch cap and rotor. That fixed it for me.

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[Bggdnssnguy]

Hmm I'll try new plugs. I mean it can't hurt, my buddy works at the oriellys I got them from.

If it was rich, wouldn't the CEL stay on when put into drive or reverse. Cause it's putting the engine under a load. But instead the light goes off as it riches the lean mixture.

[peterman]

Hmm I'll try new plugs. I mean it can't hurt, my buddy works at the oriellys I got them from.

If it was rich, wouldn't the CEL stay on when put into drive or reverse. Cause it's putting the engine under a load. But instead the light goes off as it riches the lean mixture.

The light only goes on once it notices a rich mixture for more than 8 seconds I believe. If the misfire goes away when the car is under load then youre not running (as) rich. Potentially still running rich, but stoich enough to pass the o2 sensor as correct.

[Bggdnssnguy]

Well then it's either a temp sensor I replaced or the maf if it's running rich. I'll change the plugs and start from there. I'm warranting the maf out for another new one. And will test the sensor. Idk what to do after that. It ran great before this shit.

[Bggdnssnguy]

Also. If it was running said "rich". On hot start up and it was sputtering like it does after I restart it. Wouldn't it cut out from to much fuel when revving while it's in its sputtering spell? Cause if it's running soo rich that's it's sputtering to clear up the fuel, adding more fuel would or should make the sputtering worse. At least you would think.

[peterman]

Your thinking its running rich because of too much fuel but in fact its running rich because its not burning fuel tricking the 02 sensor to think too much fuel is being injected. If theres a weak sparkand not all the fuel is burned then it o2 will see it. (Cap and rotor) Perform the stomp test. You have had the light come on. It should be in the ecus memory. That will tell you what the problem is.
Also if you listen to the sputter around the cap, you may hear the arc thats occurring in the cap in time with the sputter.
Pull the code thats the easiest starting point.

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[Bggdnssnguy]

Okay. Performed stomp test today.
1222- 02 sensor lean/rich control stop.

I just replaced intake gaskets, throttle body gaskets, intake boot, iacv hose, breather hose for valve cover.
O2 sensor was just replaced maybe 3k miles ago with a new Bosch one.

Could my wires/cap and rotor be bad and bnever showed up till I put new plugs in?

[Bggdnssnguy]

Also while inspecting my car for stuff I might of forgotten to plug up or tighten up. I noticed a Allen head screw in the maf sensor towards the intake boot. Is that some sort of adjustment screw?? It's the only thing that hasn't been painted.

[peterman]

When the car is idling crappy, go down the line and pull each wire 1 by 1. Pull one see if the idle changes. Put it back, pull another. Do the same for the rest. If the idle doesnt change with one of the wires pulled you have found the arc in either the cap or the wires. I bet cap and rotor solve your problem.

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[Bggdnssnguy]

The idle does change not huge change. But it did a small bit.. I did this test when it first did it.

[peterman]

The idle does change not huge change. But it did a small bit.. I did this test when it first did it.

It should almost die then recover. If its not doing that then your ignition is off in some form. Cap, rotor, wires, ect... Also if one of the wires bites you with a shock the insulation is comprimised and that would indicate that you need new wires.

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