ok. after inspecting the engine for a good time, we determined the idle air control valve needed to be replaced. we replaced this, and that solved the idle problem.

had the codes cleared, and now i get these:

P0302 (misfire on cylinder #2)

Causes

A code P0302 may mean that one or more of the following has happened:

• Faulty spark plug or wire
• Faulty coil (pack)
• Faulty oxygen sensor(s)
• Faulty fuel injector
• Burned
  
• Faulty catalytic converter(s)
• Running out of fuel
• Poor compression
• Defective computer

everything is ruled out except the fuel injector, and the oxygen sensor. we tested the electronics of the injector, but not the fuel flow. it seemed to be getting the correct electric current. (i don't know much about that)

i remember changing the oxygen sensor a good awhile ago, and maybe with the new motor it could have made it go bad but i don't know how to tell if the sensor is good or bad.

this is where it gets more interesting..

I now get a code P0420, which means the following:

A code P0420 may mean that one or more of the following has happened:

• Leaded fuel was used where unleaded was called for
• An oxygen sensor is not reading (functioning) properly
• The temperature sensor is not working properly
• Damaged or leaking exhaust manifold / catalytic converter / exhaust pipe
• Retarded spark timing
• The oxygen sensors in front and behind the converter are reporting too similar of readings

which makes me thing the O2 sensor needs to be replaced. but i'm not sure..

we had to replace the coolant that day, or most of it which maybe could have tripped the coolant temp sensor? i'm not sure..either way I just need to know what to start from and go from there...although the spark could have tripped it due to testing.

any input would be appreciated!

thanks

 

help?

 

IDK....When I read the first symptoms, I was sure it was the ignition coil, but you ruled that out....So now all I can think of is either the cat (which is kinda wierd your only getting misfire on cylinder#2) or I guess it could be the Oxygen sensor...

Sorry, I am at a loss of what to tell you, you've already done everything I would have done!

Good luck, and keep us posted if you do figure out the problem.

 

im sry infineON i wasnt on for a few days and didnt remember when i came back. since you have narrowed it down pretty far lets take a look at what you know is wrong. you know that you have an exhaust leak at the exhaust manifold (i think thats what u meant by one of the donut shapes) since that is a possible cause of the p0420 i would suggest tryin to repair that exhaust leak and cing what happens. dont go replacing the exhaust manifold but make sure everything is properly tightened and seated.

the p0420 and the p0302 share 2 common causes. it is logical to replace components that are shared causes. by fixing the exhaust leak you eliminate the possibility that is has thrown the p0420. c if u can properly seat and tighten the manifold and ill talk to another tech at work 2moro and talk to him bout a test to determine a cat vs a o2 sensor. good luck

 

thanks guys! i appreciate it.

so, what i need to do is buy a new doughnut for the exhaust manifold, take it apart, put a new one in, and put it back together? i'm just guessing on that, since i've never dealt with exhaust before.

i agree it is strange how only misfire on cyl #2....car is not sluggish either. like, when i first start it sometimes it is, other than that it runs pretty good.

 

Ok. I am pretty sure it is the catalytic converter, so I am going to replace it. I want to do it myself, and I do not have a welder. Where can I find a direct bolt on for cheap? Can it be a universal (if I decide the bolt on is too expensive), or will it throw codes and make the car run like crap without a tune?

 

http://cgi.ebay.com/ebaymotors/Magna...Q5fAccessories

that is the only bolt on for a 3.8 I could find, and there is no way I am paying 275! there has to be another one out there for cheap..anyone?

 

Here is an expensive way to do it, but the gains are really nice. The whole downpipe is ALWAYS a great addition to a car.

http://www.milzymotorsports.com/miva...Code=9899MC_dp

 

that is not bad at all as long as it is a direct bolt on to a '98 LTZ. either way, will i have to reprogram the ECU or will it be a truly direct bolt on? lol

 

well i plan to replace my fuel pump as well. this car is being ridiculous. now it just shuts off out of no where like the fuel pump is failing..dunno what to think now, but if replacing both remedys it, that's fine. either way, i believe it is the original cat on the car and it has 140k on the body so that is a long time.