So i have been battling this problem forever it seems like. Had a lifter ticking for a while so i changed them out with some new ones. HAd also been having a problem of fouling plugs (especially those on the passenger side) extremely quickly and pulling code 64 Right O2 Lean Indication. There had also been what i thought was a miss which i assumed was caused, at least in part by the lifter.

Once the SES light is triggered thanks to the code 64 the car will run better. The light will stay on until i slow down then will take a couple minutes to trigger again after the car starts going. Wires are good coil and icm were just replaced opti is 6 months old or so. ANy thoughts would be extremely greatly appreciated. Myself and my mechanic buddy cannot seem to figure this out. why am i dumping all this fuel and fouling plugs so quickly. Literally after 30 miles four passenger plugs are black. Plus this obviously has killed my gas mileage when i checked today it was less than 10mpg.

 

Your right side O2 sensor is shot. It's not sending a voltage to the PCM and in turn the PCM thinks that the right side is running lean. To "fix" the false lean condition the PCM in turn is dumping fuel into the right side which fouls out your plugs and wastes gas.

 

Have you checked to see what the o2 sensors are actualy reading? Do you have split fuel trims? Also you have to check and see if the o2's are fluctuating at an acceptable rate.

 

i do not have a cable or software to read what is going on. i am taking care of that issue shortly. I know it would be a heck of a lot easier to diagnose if i did, sorry.

 

There can be several other cause of a "false" lean condition, including exhaust leaks before the O2 sensor, misfires and improper valve adjustment.

 

Don't forget another (almost common) issue. The O2 wires getting burned and the signal wires touching the ground wire. By pulling the signal wire toward ground, this gives the O2 signal the appearance of being lean all the time.

Most common with headers and the most common place is where the O2 and starter engagement wire go down the passenger inner fender. Right under the foil is where mine got cooked after having headers on for 2 years.

Incidentally, it would be a problem with the passenger side.

Easiest way to find out is scan the O2 signal with the O2 unplugged. It should go to about .450 and stay there. If it stays low when unplugged, you at least know it's some sort of wiring issue.

The reason it runs better once the SES sets is the PCM goes into open loop mode. AND it is not a good idea to run it like that since a rich mixture or "souping" can wash oil from the cylinder walls causing ring degradation and cylinder scratching not to mention crankcase dilution. Smell your oil.

I'de be willing to place a bet on O2 wires.

 

Thanks for the help, i will be replacing the o2 shortly and lets hope that is my issue. i have been leaning that way for a while but wanted to at least get some backup that could be the problem before tossing out money on one.

i havent noticed any exhaust leaks but i will disconnect the headers and check the gaskets to see if there is any evidence of a leak there. that is the only spot on them i would guess there could be a leak because they are around only 6 months old. I will check what i can on them just to make sure though.

i know there is also the possibility it could be a vacuum leak and that will be the next thing i will look at if i have not been able to resolve it with the previous options.

thanks again for the help and i will try to remember to update once i fix

 

If you have to do more investigation the low tech way, why don't you clean up the plugs and switch O2s. Then if the problem stays put you know it's not the O2. If the problem moves to the other side, you know it's the O2.

That is if you REALLY don't want to just throw money at it.

Then there's always the ability to pull the outer wrap from the wires where the foil is and see what the wires look like. Doesn't cost anything either.

Did the problem you're having occur before or after the header install?????

 

I know this thread is old but I having the same issue.

I have a 95 T/A, A4
Mods are :

​​​​​K&N cold air intake
BBK 52mm throttle body
Solomon mailorder tune
MagnaFlow ypipe
Bullet dynomax resonator
MagnaFlow exhaust
Granatelli maf
MSD Coil Pack
Dyna Ignition module
Cc502 Cam Kit

Parts I replaced :
Map sensor
Iat sensor
Maf sensor
Knock sensor
Battery
Alternator
O2s sensor (both sides)
Summit racing Optispark
Intake manifold gasket
Head gaskets
Exhaust manifold gaskets
Tps sensor
Iac valve
Tbi gaskets
Fuel pressure regulator
Fuel filter
Waterpump
Radiator
Radiator hoses
Heads rebuild
ECT sensor
Timing chain

Only brand I use is ac Delco or Delphi. But recently I brought two o2 sensor (delphi) after having a lean issue on the driver side (Long term ft 160). When I install them the lean switched to the passenger side and now I'm getting code 64.

Must be a really lazy sensor cause voltage cycle around 50s to 200.

It still goes into close loop, but when it does, it will bounce back into open loop after idling for a bit and code 64 appears.

I see the voltage really low when this happens (Passager side)

Once I start driving the code goes off and the voltage starts cycling normally

It still will occasionally get stuck in the low voltage but not enough to pop a code

I just change out the Delphi brand yesterday for acdelco (Driver side)

It got alittle better, my short term ft (driverside) bounce around 128-130s

And the passenger side bounces around 127 to high 30s

Long term ft be stuck at 160 until I start driving.

After installing the new sensor I reset the computer, while warming up code 64 popped up and this time even when I gas it, it stay on.

Car was running rough..

I turned it off, waited like 5mins turned it on and no code. O2 cycling like normal again.

But when the ses was on short term was stuck at 128.

What do you guys think? Defected o2?



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When you installed the new Delphi O2 sensors, and the lean condition switched from Bank ! (did you have DTC 44, or just the high LTFT?) to Bank 2, you made absolutely no other changes? If so, try swapping the Delphi (or AC Delco) sensors side-to-side to see if the code/low millivolts/160 LTFT follows the sensor. Might have a bad one?????

 

Also, check to make sure the AIR pump relay isn't stuck, and the AIR pump keeps running in closed loop. Hard to understand why the problem would switch banks with that one though.

 

The only changes I made was my catalytic converter I installed a week later after changing the o2s

I also added a magnaflow ypipe shortly after that.

I've read that some ppl new set of o2s go bad after installing headers.

I think shoebox mentioned it on a thread about headers needing to cure before adding new o2s

You think that apply to any exhaust changes?

​​​​​

Solomon disable it when tuning my pcm awhile back so it hasn't been running for sometime.

Maybe I should expect the check valves, to see if anything loose in that area.

Other then that, that's all I can think of.

I checked for leaks, no leaks.

What about a leak after the o2s? Will that set off a code?

Today both banks long term ft was at 160, (In idle) but would drop or change randomly when I let go the gas or press it.

And the short term bank 1 was bouncing around 150 and gradually dropped down to 138 as the car got to the right operating temp .

Bank 2 STFT was at a steady 129-134

At one point the o2s was only cycling under 100 for a whole min, it was having a hard time entering close loop.

 

Also another thing that brings to my attention is all of these symptoms are worst when it's really cold outside.

And as my car gets warmer it runs better.

Which remind me of a thread not to long ago i read about the ECT sensor causing lean and rich conditions.

Doesn't the pcm need the ECT sensor to function properly in order to achieve close loop?

I've notice over the pass weeks while situating this lean condition problem that it is hard for my car to re-enter close loop after extended drives when restarting the engine.

There no overheating, or coolant leaks that I'm aware of.

But I do know a bad ect sensor can cause a lot of problems.

​​​​​​

 

Startup of new cera-metallic coated headers can cause damage to the O2 sensors. If the headers aren't ceramic coated, should not be a problem.

The AIR system check valve can be a source of air entering the exhaust before the O2 sensors. If you don't have AIR functioning, removing the check valves and plugging the connections on the headers would be a good idea.

Exhaust leaks after the O2 sensors should not cause problems and does not set a code in OBD-1. Running headers with open collectors would be a problem, due to backwash of the air into the collectors.

The PCM needs a minimum coolant temp to go into closed loop, along with hot/active (at least 600-degF) O2 sensors, and a time since start, usually 206-seconds.. ECT required can vary anywhere from 120-140-degF. There's no code for a faulty ECT sensor unless it basically totally fails, resulting in an open circuit or a shorted circuit. The temps being "off" and inaccurate will not set a code. But it can cause the PCM to think the engine is cold, and richen the target A/F ratio.

I think you need to download Scan9495, buy or make a cable, and run a data log of the PCM under the conditons you are describing. It's a lot easier for me to look at the actual data than to look at bits and pieces in a post.

https://www.camaroz28.com/forums/com...95-lt1-874306/

 

I was looking through the hoses and stumbled upon this, you think this would cause problems?

(This is the brake booster hose btw)