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Catalytic Converter Questions!!!

So far so good with the ZZP downpipe & cat setup, no codes have been thrown so far. Gotta check out the misfire soon, figured I'd give it a bit of time to see if it works itself out. I did replace the upstream O2 sensor but that seems to have just helped with MPGs not misfire.
 


I'm gonna bring it into the shop soon and have him run a scanner on it to see which cylinder it is. I'll let you know what the problem is since you seem so interested
 
I understand, i'll let you know. If these plugs end up causing trouble i'll probably just go back to the Stock Plugs cause I don't want to have to replace plugs all the time.
 


For the record, Autolite's last a lot longer than what people tend to think...I tested this in the blue one.

Still a golden brown, the AL103's that are super cold and are only supposed to last 6-8k miles...had them in at 14k, still going strong...now amplify that for the hotter range and I'm sure they will last 25K+...I think Rynoman had close to 30k on his plugs when he changed his AL104's...since your stock...AL606's gapped at .050" should have no problem lasting 30K+ miles IMO. Especially on the stock pulley.

Give it a shot...why not? The plugs are like a dollar a piece. Plus, having MSD's...you won't ahve to change wires...I had mine off a trillion times.
 
My car starts misfiring at idle after 2000 miles on TR6's or autolite 104's.

Never burn brown. White with a small patch of brown on the insulator. Probably too cold it seems.
 


they're good to go then.

Just make sure they're still at 60 thou.

They're supposed to ship at 59 thou, but its still worth checking.
 
Did start getting the codes for the O2 Sensor and all. Bought a scanner for now to erase them when they come up, will probably get the car tuned soon. Hopefully that will fix that issue. Replaced the Pulstar Plugs and the company gave me a 100% refund, went back to Stock GM Plugs since they worked well before and have a long life.
 
So I haven't gotten the car tuned yet. Haven't had the money. All plugs were replaced with Stock Plugs and I tend to get misfires above 3000 RPMs when accelerating hard if I was already in motion. It will also misfire at around 4000 RPMs if I push the accelerator down too far if I was starting from a stationary position. I've been driving it very carefully to minimize misfires since I haven't had the money to tune the engine. The O2 Sensor Error Codes are P0420 (Catalyst System Efficiency Below Threshold Bank 1) & P0036 (Heated Oxygen Sensor Heater Control Circuit Bank 1 Sensor 2). I've found a local HP Tuner shop, but that costs around $500 to inspect for the cause of the problems and tune. Any ideas on other shops in the Central Florida Area that tune vehicles at a good price? Any ideas for how else to help fix the misfires and O2 Sensor error codes? I know several people will say "copper plugs" but I like the stock plugs, they last 100,000 miles and so far work well, other than the misfires which seems to be cause by a combination of aftermarket parts installed on the car without a tune to compensate for it. Thanks for the help!!
 


All plugs, wires & coils are new and seem to be operating well from what my mechanic has been able to tell. He isn't the shop with the HP Tuner so he doesn't have that type of system to look into the computer. But he has another system that we drove around with to look at misfires and we replaced the plugs that were misfiring consistenly at low RPMs. The high RPM misfires are random so he suggested the tuning of the engine to compensate for the variation in engine operation with all the aftermarket parts.

The downpipe is a ZZP 3'' Downpipe with magnaflow cat. This downpipe moved the O2 sensor further back since the cat placement changed with the new downpipe setup.
 
Fivefingerdeathpunch said:
You might have a ICM problem causing the misfires if all the plugs and wires are new.
Click to expand...

ICM? Do you mean PCM? if not, what is the ICM? If you meant PCM, that was the reasoning for getting the car tuned through the HP Tuner setup since I don't trust buying a new PCM and hoping that will work. I trust a true custom tune alot more.
 
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