well all, maybe some of you know i never quite was able to fix my car...the car misses very badly if u let it sit for a little while..we thought it was the opti so we replaced it..nope wasnt that..thought it may be injectors so we replaced those..then come to find out we disconnected the 02s sensors and the car did not miss at all..granted it got horrible gas mileage..it didnt miss..tonight after buying enw ones we hooked them back up (they are both extended also..soldered the wires) car drove like a dream..drove it for like 20 minutes then let it sit for about an hour...when i restarted same old problem..horrid misfiring....im stumped and very very disappoitned..this may bring me to my knees as we have been battling this for ove a year now and i may just sell the car if we cant get it figured out

 

Have you looked at the plugs...fouled??? Any codes in the PCM? Did you disconnect the O2 sensors after it started "misfiring" again? Ignition wires clear of the headers??? These are just a few things to consider.

 

Did you inspect the 02's after it started running like crap again to see if they were black or blocked up??? If sounds to me that the reason your car runs good without the 02's is because the computer no longer relies on the 02's reading when they are detached. The PCM has a default fuel curve of very rich when they are detached. So IMO something is wrong with your car that is eating 02 sensors. I'd check to see if you are burning oil, check the plugs and wires, or even have a short that is frying the 02s. Those are a few possibilites. You may just have to forfeit and take it to the shop...

 

A $24.00 experiment, get some cheap Auto Zone wires and see if it fixes your problem. I had a mystery miss-fire after 5,000 miles on new opti and Delco wires, checked everything and could not figure it out wanted to sell car also.
Installed wires and miss corrected.

 

its a sensor problem...

ummm, does the missing happen after warm or before hand? and any certain rpms?

Thats always been my problems are sensors, trying to make up for one cylinder's bad ignition so the whole thing runs like crap... stupid sensors...

 

have you data logged the car while it is running fine and then again when it is missing?

 

Ok, let me get this right, you had a miss then unplugged o2's and it went away, then plugged o2's back in and it wasn't there at first but the miss came back.

If it was me, I'd unplug them again and see if it fixed the problem. If so then its either the o2's or THE EXTENDED WIRES. My guess is the extended wires are your problem.

 

thats the thing..both the 02s have been replaced..once we replaced them..soldered the wires and extended them, we reconnected them...same old problem

 

no most likely its not o2 sensors... it could be, but its something before the o2 sensors... something that would cause a slight miss, and while the computer slightly modifys differnt air/fuel combos it comes up w/ one that makes it run really poorly where the o2 sensors will be happy...

so when u unplug the o2 sensors it runs on default air/fuel combo and your ok... but its probably, atleast one cylinder isnt getting enough spark or a sensor along the way is misreading something... thats my best stab at it.

if i knew more of the rpm studder, i could help cause i was fiddling w/ my firebird for nearly a year and i've fixed every studder and miss in that car more then once...

 

I'd still bet its the extensions. Did you have them before you got new o2's? My buddies car did the exact same thing when he made his own o2 extensions.

Oh and if this little of a problem is making you want to sell the car you'd hate to see some of the problems I've seen.

 

give us more details...I had to battle with one too, it ended up being the roter in my opti. But we can better help point you in the right direction(s) w/ more intel.
-b

 

i can tell you exactly when ti happens because we can pretty much make it happen..lets say the car has been sitting overnight.you start it up it will run fine..but lets u pull into a gas station..or stop by a friends house and let it sit after tis been running (not substantially long for a period of more then about 2 hours) and then get back in it and drive it..it will miss and studder horribl, HORRIBLY..then after a few mintues it clears up..it kind of bucks around..like it will miss and lag up to about oh lets say 3500 rpms then it will nail into speed..then the next gear same thing

 

Methinks you need your engine analyzed. Throwing parts at a problem is the way many mechanics, especially dealer types, attempt to fix problems and may wind up being successful, but never knowing which part did the trick.

A simple thing like not getting the correct juice to a re located 02 might make a difference or a bad cat, bad grounds, coils, etc.

Certainly not an expert here, but a good analysis of what is going on might help to eliminate possible causes and allow you to isolate; which is preferable to the throwing of parts method. JMHO

 

I'm having the exact same problem. I had a bad misfire, then re-soldered the o2 sensor wires, still misfired. Unplugged the DRIVER side o2 sensor wire - runs pretty well. I'm going to more than likely re-solder the connections (again) and see if that gets me anywhere. Shrink-tape them up real well and HOPEFULLY that'll fix my problem.... otherwise I'm screwed and have a pretty MAJOR electrical problem....

however, i did replace the optispark and it DID make a noticeable difference... damn near brand new o2 sensors though... GM Delco o2's

 

I'm saying a temperature sensor,

probably the most significant detail is the fact that it doesn't do it starting first time around, just starting it while its warm...

like for me, while im driving right about when my car starts to get warm it starts bucking back and forth, surging w/ power for maybe 10-15 seconds sometimes even quits if im not moving and the brakes get hard to hold down, as soon as it gets into open cycle (i think, after its warm) it runs like the good old green machine...

but mine is colant sensor i know this im not sure if its the wiring or its the sensor but... its not ur O2's...