Okay I have a 2004 SC Monte carlo ss, I have a 3" catless zzp dp, CAi and a tuned pcm from Reptile, I was recommended to buy replacement autolite 606 copper spark plugs, I went today to change them, started driving down the road for a test and the car started sputtering, came back to the garage took the plugs out and 3 of them cracked , okay so then i went to the auto shop and bought a set of NGK iridium spark plugs instead, replaced those and same thing still sputtering and misfiring, then i went and bought a set of duralast wires replaced those and same outcome but this time i had some smoke coming out and i dont know wtf is going on, at autozone i had the chick there read me the codes hat got thrown out. they are

p1664 skip shift 1-4 upshift lamp control circuit fault. probable cause open or short circuit condition in the driver circuit, failed or missing bulb.

p0140 ho2s12 circuit condition heated oxygen sensor bank sensor 2, probable cause engine misfire condition-repair, oxygen sensor defective, fuel system running very rich or lean check other codes first, fuel pressure very high or low fuel pump or pressure regulator

p0654 engine speed output control circuit fault, probable cause failed tachometer or instrument cluster error, open or short circuit condition on output speed circuit, driver circuit ecm defective.....

 

So you already had all the other mods, and the car ran perfectly fine with no codes; then as soon as you did the plugs, the car wouldn't run right and threw 3 engine codes at once?

Also- how did the plugs get cracked? I assume you're talking about the white insulator- did you use a spark plug socket, and were you careful putting them in? That stuff shouldn't crack unless the plug gets some decent force on that area; but if you use a plug socket and are careful, you should never have any force on that area. That's a good reason for it running poorly though- I'm sure once the cracks spread when it heated up- the electricity was able to jump from the plug base in the head straight to the core through the crack.

Is it possible that the new plugs are cracked too- maybe you're doing something wrong installing them?

I also wouldn't worry about the 0140 code; once you get the engine to stop misfiring, you'll stop having all that unburned air/fuel dumping into the exhaust, and it should go away.

As for the other 2 codes, and the smoke pouring out- I have no idea. The smoke should be fairly easy to track down I'd think? But the other 2 codes have nothing to do with plugs/wires unless something else (a wiring harness or something) got damaged during the install.

 

Idk, they are offset at .60 idk if that matters, i was pretty carefull on putting them in.... i just dont understand why its happening, it only does it when i boost

the codes have been there since i installed the tuned PCM they did not just pop up

 

Ok, I'm getting more confused.

When you still had your original plugs in, did you have this misfire issue? I'm trying to understand if this misfire just started when you switched plugs, or if this is a problem you've had and were trying to cure by doing new plugs.

Offset- you mean gapped? Also, I hope you mean 0.060", and not 0.600" (over half an inch, lol). Could be spark blowout- maybe trying knocking them down to 0.050 or 0.045 and see if that makes a difference?

The bad thing is, I've never seen plug insulators just crack on their own- especially brand new plugs. It is possible they had hairline cracks from a faulty manufacturing process and the heat from the engine popped them- but just check the new set before you put them in.

Also, if this misfire just started happening since the plug change, and is still happening- I'd definitely pull the new plugs you put in and check them for cracking. I'm still thinking a possible install problem.

That's a pretty important detail that you didn't mention- so the car normally runs and drives just fine; but starts to misfire when you get into boost? That makes me lean even more towards spark blowout, although with just minor mods, I wouldn't think it would be an issue. Do you have access to a scan tool? Easiest way to tell would be to take the car for a WOT run while recording all the major sensors and post that up- maybe it has a fueling problem (although that wouldn't have started magically the day you did plugs); or maybe its not getting a good spark- leaking electricity somewhere between the pack, wire, or plug before it jumps the gap under heavy load?

Why 606's anyways? I'd rather go with a 605 since its one heat level colder than stock; especially if you're modding. If you have intentions on dropping pulley size, I'd definitely go back to the copper plugs though.

What about the sputtering/misfiring? Did you ever find out what was wrong with the pcm from "reptile" since its throwing codes? Sounds like something wasn't done correctly.

I looked up that 0140 code, and that's for the rear O2, looks like it shows its not responding- I see you've got a catless DP- what did you do with the rear O2? Sounds like you just left it out, and needed this code turned off? I didn't see anywhere else that said anything about this meaning the engine was running bad, other than in your description above.

 

Hey there man thanks for the feedback, the misfiring happened after i installed the DP and before i had the tuned PCM so t still missfires it has been ever since it was installed, i actually fixed it after 2 more cracked plugs..... I gapped them to .35 instead and they seem to be firing just fine now, but i still dont know where the misfiring is coming from

 

Confused again- you said it has been misfiring ever since the DP install; but you regapped the plugs and replaced more cracked plugs, but you don't know where the misfiring is coming from.

Is it misfiring now or not?

You say 2 of the new iridium plugs were also cracked? That must be installer error- no way 2 totally different plugs would be defective like that. Where are the cracks at in them?

IMO, I'd just get 6 new autolite 605 coppers; a correct spark plug socket- and be careful installing them. Also, you really shouldn't need to be running a .035 gap to get it igniting- that's a nitrous gap; even heavily modded SC cars don't usually run near that small of a gap, and you're on stock boost. If it takes that small of a gap to get the plugs to reliably fire at WOT- I'd think you're losing your spark energy somewhere- cracked plug boot/wire- another plug with cracked insulation (even minor).

Even if you don't go out and buy all new plugs again- I'd definitely get a proper plug socket and inspect the 6 you have in there now. If you have a cylinder that's misfiring because of that, you're going to be wasting lots of fuel and robbing yourself of power.

 

No idea where the misfire is coming from, nor do i know what the problem with the plugs was, but all i know is that its working fine now, i am very concerned about the gas mileage i am down to 18 now after the tuned pcm, let me rephrase 1 autolite and 1 ngk busted probably at install but i dont know for sure

 

i would check the soil packs as well as in the conection where the boot of the spark plug wires go to see if there is any oxidation on them. oh i forgot to mention did you use dielectric greace on the boots to make sure you are getting the corect voltage to the plugs. my second question do you have a volt ohm meter if you do you can get the resestance reading from the wires as well as making sure you are getting the corect voltage to the coil packs.

 

Who is this 'reptile' anyways? Why not just go with a regular ZZP or similar pcm? The tune has a lot to do with fuel mileage, and performance oriented pcm doesn't have to kill gas mileage. That combined with the new pcm throwing a bunch of codes would make me either drop a stock one in, or just get a vendor's tune in there.

May be a good idea to pull all of the plugs and recheck everything. Plugs don't normally just break like that- something was going wrong during the install- and I'd be worried more might be cracked?

 

ok from knowledge I would've gone with OE AC Delco plugs for your car, it sounds to me like your having RFI interference which is causing the tranny shift issue and misfire and copper plugs for an 04 monte I believe they were Platinum plugs from the factory but it is a SC car and has been tuned so maybe I am missing something too