I’ll try and keep it short. I recently put long tube headers in, EGR delete since I found it a pain to attempt to attach it to the headers. I ran it just off the headers for a week with o2 sensors unplugged until I got a mid pipe for it. Within this time it ran completely fine, no issues. Before I put the mid pipe in, it started to hesitate under load, or stall off of a cold start in the mornings, then drive fine(would also have a hard rev hang from time to time). After my mid pipe was thrown on, it started to run even worse, idling at 200 rpm and revving just enough to keep itself running. Only time it runs somewhat decent is when I have my tuner plugged in, which smoothed out the idle. even then, nine out of ten times under load in any way the car hesitates and struggles to keep consistent power. 5 or 6 codes saying my o2 sensors are detecting lean, rich, or that they aren’t working at all. I’m so lost and don’t want to start throwing parts at it. Timing chain? Blown engine control fuse? I’m at a loss as sometimes it’ll run completely fine for hours then begin to run like crap again. Any input is appreciated
Engine Multiple o2 sensor codes, car runs terrible
- Thread starter 02newedge
- Start date
The story so far, sounds like a lot of self-induced problems.
You have a stock EEC?
What tuner are you using and why?
Is this still a MAF car?
Are the O2 sensors still disconnected?
What headers and mid-pipe are you using?
Did you ever do a [Base Idle Reset]?
Did your catalytic converters get tossed too? If so, what is your plan for the after-cat O2 sensors?
What modifications have been made to the engine to require a larger exhaust?
You have a stock EEC?
What tuner are you using and why?
Is this still a MAF car?
Are the O2 sensors still disconnected?
What headers and mid-pipe are you using?
Did you ever do a [Base Idle Reset]?
Did your catalytic converters get tossed too? If so, what is your plan for the after-cat O2 sensors?
What modifications have been made to the engine to require a larger exhaust?
Yes I have a stock EEC, bought an SCT X4 tuner to tune as I go for bolt ons (exhaust, headers, throttle body, etc). My car still has a MAF which still works, o2 sensors plugged in, BBK long tube Headers and a Shorty X pipe, I did try a base idle reset. Yes it’s a full straight pipe, no cats no muffler, before I bought the car in February. No mods other than long tube headers a few weeks ago that needed a straight pipe, just prefer it. Cats must’ve been tuned out before I bought it as I’ve never had codes for them.
squeak93
15 Year Member
Clear the code(s). Install a tune that adjust for the new FRONT o2 sensor placement and turns off the rear o2. Be sure it includes turning off the egr or it'll toss a CEL again.
Running rough after that will lead to easier troubleshooting. A list of exact codes its throwing will help as well.
Running rough after that will lead to easier troubleshooting. A list of exact codes its throwing will help as well.
Alright, thanks for the input. Do you think itd be possible that my timing is slightly out? A few people have suggested that to me, although I’m Not getting any codes that could suggest that, but just wondering if it’s a possibility. I’ve ruled it out since there are odd times the car will idle and accelerate just fine without problems, but then again I’m not 100%
squeak93
15 Year Member
It's more possible you have chain slap from worn chain guides or a tensioner that isn't holding consistently then just straight jumped "time". Especially if it's intermittent -- jumping time doesn't go back and forth unless you have lots of other issues. It might be time to pull the front cover to inspect things (good time for new timing set- these cars are getting old).
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