well, i know my cars been running rich for a while, it all started when i did headers/exhaust on my car
I do NOT have a tune yet, i know it would help, but i wanna get anything mechanical figured out yet

I put the car on a snapon solus scanner, and monitored the o2's
at idle, their both around .450 volts or so, as soon as i give it a quick rev or anything, they jump to around .750-.800 volts, and it causes a backfire around 2500.

now, i do work at a mechanic garage, so i have the access to any tool i need.
Couple things I thought caused it were:

bad o2 sensors (origional ones, 150k or so on them, just ordered 2 new ones and extensions), we cut and spliced the wires when we did headers, so that coulda messed with em


couple small tears in the intake elbow (thinking about siliconing those together and putting some tape on them)

what do you fine members of cz28 think?

 

The O2 sensors shouldn't be anywhere close to steady at idle... they should be jumping all over the place, swinging over the full range of 0xx - 9xx mV's. Sounds like it might not be going into closed loop. Check the coolant temp sensor reading. If it was indicating a low coolant temp, it would make it run rich, and keep the PCM from going into closed loop. However, if the O2's are indicating 450mV at idle, it isn't idling rich.

 

Also, I have heard people on here say the new headers messed up the 02's if the headers are ceramic coated. I haven't personally had this happen but people have mentioned it before. If you put new 02's right after you installed the headers, they could have caused them to go bad?

 

actually, we just cut and spliced the origional o2's for the header install, so i figured its due for new ones anyways

injuneer - it does not idle rich, right when it starts, it is fine until i give it a rev or so. It does idle kind of rough though, and has since ive owned the car, it kind of bounces so to speak, so the o2s could have been going out for quite a while and finally gone out.
Wheres the coolant temp sensor at? It never did it until i did headers/exhaust, so the problem has to be somewhere in there.
The first time i have ever taken the intake elbow off personally was for headers/exhaust, and than for plug wires (when i noticed it was ripped).
I'm 99% sure it goes into closed loop too, because thats when it starts doing it the most (after the gauge reads 180* or so), so i would think its going into closed loop, and running rich there.

 

The PCM gets its signal from the coolant temp sensor in the water pump housing. The gauge reads a sensor on the driver's side head. Don't worry about what the gauge reads. Use the scanner to see what the PCM is reading from the one in the water pump.

 

alright

also, i think i might need to tighten up my header bolts, could a loose header cause this?

 

Supposedly a loose header will suck in fresh air. Then the o2's read too much O2 which makes the computer think it is lean - therefore adding too much fuel.

I don't know if that is true. But after my engine rebuild I was running PIG rich. I found a few problems, and it runs much better now. RR's were tightened too much and intake plenum was not torqued down, among the worst problems!

 

i just hope i can get it figured out, because it started it about a week after i got my headers installed, making me think that something could have fouled out or something

 

Yes, that is correct. Misfires will cause the same problem.

 

The tears in your intake elbow can cause it run rich to.

 

welp, got the tears in my intake elbow fixed
got my headers tightened up (has 2 bolts that turned 1/4 turn or so)
fixed one of my plug wires (was loose on the opti)
started it up.....revved it....POP

still backfiring, not running rich anymore though
so, i have a miss about 2k RPM, plugs looked good....plug wires looked decent, had 1 that has a mild burn on the outside, wrapped it in electrical tape, its not arching to the header or anything, so i'd still say its fine
my boss thinks its my cap and rotor, so, im going in next saturday and replacing all that since its my day off at work, hes letting me put it on the lift and what not

 

Check your plug wires with an ohm meter, if you have one that looks burned you probably found your problem.

 

it had the same problem before doing plug wires too, but, how do i check them?

 

Take the ohm readings of all the wires, they should all be pretty close to each other in measurement.

 

well, did it the old fashioned way, took the wires off, put a screw driver in, turned it on, and all of em were showing spark, so its not my plug wires


so
cap/rotor
opti

one of those two....hope its the 1st one since i already have em ready to go on