Ever since my Pacesetter LT install the car has ran like crap. Really weak, bucking, kicking, refusing to pull at low RPMs, painfully rich, almost undrivable at times (daily driver must move 80 miles a day). I have had some pretty large exhaust leaks at my header Y-pipe conections, those have recently been fixed. I will soon be getting new 02s as my stock ones have 101k on them. I have been getting the 304 misfire code @ #4. But it may go a day or so without throwing this code. What do you guys think.. Opti?

Since my online time is limited-- if I have over looked other threads that apply please send me those links, and thanks.

 

I assume you mean you have a DTC 300 for a misfire on cylinder #4. Chances are good since you had a bad exhaust leak, it was running rich and fouled that plug. The first thing to do is check the wire real well and change at least that plug. I do not think it is opti related. While you have the plug out, check for spark.

If you continue to have problems with that cylinder, try swapping the plug wire from an adjacent cylinder. If it continues, check the resistance of the injector and use a noid light. If that doesn't help, it's time for a leakdown test.

 

Thanks,

I will look into this later today. Hoping that she gets her act together 5 a.m. Monday comes early. Thanks again for the tips.

 

Removed #4 Plug today. Very black and dirty. Checked for spark after cleaning, looked fine.

Ran a little better with no code between idle - 2500 RPM for about 10 min. Drive to town, the first 20 min. of trip were terrible more bucking, kicking and misfires. Now misfires from #4, then 6, then 8, then 3..I'm thinking WTF !! ??

After about 25 min of driving car runs smooth, no more misfires, no more SES.

FYI, the code puller am using is very basic and only gives me the trouble code.

 

P0300 is "random misfire". But there is a P03X code that corresponds to excessive misfires for each specific cylinder. P0304 would in fact be set by excessive misfires on Cyl #4.

Rich conditions can be caused by exhaust leaks and excessive misfires.... get one cylinder in a bank misfiring, and all 4 of them end up running rich, and then all 4 of them can misfire. An exhaust leak before the O2 sensors will also affect all 4 cylinders in that bank. Did you use extensions for the O2 sensors? That can screw up A/F ratio on that bank. And once you burn a wire, its only going to go downhill. Simply replacing the wire or a messed up plug may still leave the other cylinders in the bank with fouled plugs.

 

Yes,

I used extensions for the 02s. With my 02 sensors being as old as they are I am going to replace them, and hope this helps. Again today it runs great AFTER I have been driving for abotu 25-30 minutes, but before that its horrible.

If I can get them all firing (and no more misfiring) will the plugs clean themselves once up to temp or do I need to remove them all and Clean them?

Will an 02 Sensor "foul out" like a plug where it becomes to old and dirty to do it's job? After I fix the leaks (probably just going to have the connections welded) and add new 02 sensors, should the resolve the issue?

 

A carboned up spark plug will not "self-clean". Best thing to do is replace them.

A carboned up O2 sensor may self-clean.

There are so many possibilities related to the header install that you need to rule all of them out. Burned wires, cracked plugs, bad extensions, contaminated sensors, exhaust leaks.

Did you reuse your "old" sensors after the install? Did you perhaps contaminate them with rust penetrant when you took them out of the manifolds? Did you use anti-sieze when you reinstalled them? Are your headers cera-metallic coated? Have you checked carefully for leaks at the flange to the heads?

A lot of possibilities.

 

I reused old 02 Sensors, and I know for a fact they were both covered in PB Blaster.

I did not use anti sieze on the 02s.

They are ceramic coated headers.

I have been checking for leaks at the head. I am still struggling with leaks at the connections on the y pipe. This weekend they are getting welded.

By welding the headers to the Y pipe will i be able to later change the Header gasket without cutting the weld?

What really blows my mind is for it to run so poorly this morning (untill 25 min pass of driving) and then for me to jump in this afternoon and to have no problems, no codes teh 40 miles home.

 

You may have contaminated the sensors with the solvent. There sensor housing admits outside air to the outer surface of the zirconium membrane, and its the difference in O2 concentration between the exhaust and the outside air that generates the voltage signal. If you got the housing full of solvent, it might explain the probelms.

Many people have also experienced problems with slow responding O2 sensors after a coated header install. We've speculated that something is buring off the header coating on initial use and contaminating the sensors.... just a theory though.

Another thought..... since you put in the headers, its likely the under hood temperatures have increased. Possibly you're getting heat soak on something like the IC Module and its causing the intermittent problems.

Just thinking out loud.

 

Injuneer,

Thanks---really good information. I will keep you posted.

Matt

 

After having the Ypipe connections welded to remove the clamp leaks I installed new O2 sensors. Things have improved greatly. Fuel milage back up. I still get rough running when cold, I am thinking it is the plugs. Will install new plugs as time permits.

 

Update for future searches:

After new plugs issue got a little better, then worse again. Random misfires began across all cylinders but mostly on the even bank. Extremely rich, fuel milage shot to heck.

My patients and time to work on this problem eventually ran out and I took her into a friend of mines shop. Cap and rotor needed and replaced. I went ahead and had him put the whole opti in. Slightly leaking water pump also replaced before it ruined my new opti.

She's running great now.