TallTodd67

I just installed Pacesetter long-tubes with their ORY. Now the car is running lousy. It feels like the motor is missing just slightly when it is under a load. It idles ok, but I can feel a bit of hesitation under throttle. It is also popping and backfiring much more than it used to, especially after if heats up. After reading different posts, I thought I might have crossed a plug wire, but I've checked that twice. I replaced all the plugs during the install with the proper gap. I am confident that all the plug wires have a solid "snap" connection except for #2 cylinder, which I can barely reach, but it feels solid. I have felt around the collector connections, the y pipe joint and the other exhaust joints for leaks and nothing seems out of line. I can feel a slight pulsing of air in the y pipe joint, but it is very minor. The header flanges at the head have been tightened after a few heat cycles and they seem ok. The only thing I haven't double checked are the O2 sensors which I lengthened using the butt connectors supplied with the kit. Could they be the problem? I'm not getting any check engine light. The car is a 94 Z28, M6, with CAI and 3" cat back. It also has 150K miles. Thanks for any help you can give!

Injuneer

Faulty O2 sensor extension could cause your problems. Also, is it possible you contaminated the sensors while handling them, used excessive anti-sieze, used rust penetrant to get them out of the old manifiolds, etc.?? Are your Pacesetters cera-metallic coated? The initial burnoff from the coating is believed to contaminate the O2 sensors.

Any chance you have a plug wire or the O2 wires burning on the headers?

jaben2

I would check the header gaskets again. When I did mine they seemed to seal up good. However after a while the passenger side had a leak at the rear of the engine. I couldn't really tell until I pulled them off. Replaced it and all was good.
It could however be the O2's

TallTodd67

Probably all of the above! The O2's were nearly welded into the old manifolds. It took a lot of PB Blaster and a cresent wrench with a cheater bar to get them out. I used a about a pea sized spot of anti-seize on each sensor thread. I just unwrapped the electrical tape that covered the butt connectors and everything appears ok, but who knows? None of the wires seems to have pulled out. Is is worth the effort to remove the connectors and solder them? The routing of the wires looks to be clear of the headers and don't show any evidence of burning. This may have been a dumb move, but while removing one of sensors out of the old manifold, the nut was beginning to round off. I used a pipe wrench on the body of the sensor itself to get it to break free. I guess that could have damaged it. The headers are not coated. I just used high-temp paint.

TallTodd67

I just pulled the O2 sensors and noticed that the tips are black as coal. I could be mistaken, but I thought they were gray when I pulled them. Any thoughts?

TallTodd67

Is it possible to "decontaminate" an O2 sensor, or are they a lost cause?

Injuneer

What you are seeing is only the "shell" that protects the sensing element. The "thimble" that does the sensiing is inside. If the engine was running rich, it would be normal for the shell to be sooty. But that does not contaminate the sensors. It will "burn off" when the A/F ratio problem is corrected, and the sensors will work normally.

Excessive solvent, PB Blaster, etc on the OUTSIDE of the sensors can contaminate them. The sensor works by exposing the outside of the small thimble to the exhaust, and the inside of the thimble to ambient air. The air gets into the thimble through the wire passage. If you load up the outside with anything, it's going to prevent the air from entering the sensor. I had a sensor go bad on my wife's Jeep when the PS pump leaked and PS fluid dripped on the outside of the sensor. Jeep ran really bad.

TallTodd67

Was the Jeep throwing a code? That's one thing that is baffling me about my car. No codes. It really feels like it is running on 7 cylinders. I'm going to start from scratch and pull all the plugs, check for proper gap and for any possible cracks in the plugs. I also bought a new set of plug wires just in case something got pinched in the install that I didn't notice. If that doesn't solve the issue, I will replace the O2 sensors. I really need to get the thing fixed. I'm 6 foot 6 and laying on concrete beneath the car for hours is killing me! Thanks for all your help.

Injuneer

No code on the Jeep. I just put my scanner on it and watched the sensor. It moved but not the way it should. The codes generally set when they stop moving completely, slow down, or read high or low all the time.

TallTodd67

Mystery solved. It never fails that it is the easy basic stuff that trips you up! I decided to start from scratch and pull all the plugs and wires. Long story short, the #5 cylinder spark plug was cracked completely around its base. One trip to Autozone and $5 later, the Camaro is running great. The longtubes are awesome and the difference in power in the upper rpm range is noticeable. I never would have attempted this project if it weren't for the great advice from this forum. Thanks to all who have posted on header installs!