Still Hestitating after all this work!?

1997 Olds Aurora with 88000 miles
OBDII Codes pulled:
P0138- Input voltage from O2 sensor in Bank 1 is too high for current operating conditions


P0307- Misfire in Cylinder #7


P1139- not exactly sure does anyone know?


I have replaced all the spark plugs and wires and coils with AC/DELCO. I am still getting the same error codes seen above. Quite frustrating to say the least. Still lurching at a light with the brake on and loss of power. When the A/C turned on the entire car starts to shake. Should I consider the fuel injectors as my next step? Any help would truly be appreciated.

I would start by rechecking the plug wire routing to ensure that all wires are connected from the correct plug to correct coil. Can you hear any misfiring? Does the engine start properly with no backfiring? I would tell anyone who is planning on keeping the car, purchase the GM Shop Service Manual set, they will repay you many times over providing you are mechanically inclinced and can read the technical information.

There is no backfire when starting the vehicle..it actually starts right up fine. Just a rough idle and under acceleration the car hestitates but then the power would kick back in and the car would pull again but it is a back and forth process. Not a smooth acceleration as before. Would fuel injectors having anything to do with this?

I would be inclined to say it is electrical in nature. Did you set the spark plug gap at .050? It is possible you could have a bad plug wire. Where did you get the DTCs from? GM service shop? #7 cylinder is on the rear head. Check wiring again just to eliminate that possibility. As a last ditch effort, get the GM shop to DIAGNOSE your problems, and then fix it yourself. Again, I think the source is electrical, but it is possible, although unlikely you could have a fuel problem, but no fuel DTCs are showing. I assume the MIL on the dash is lit.

The codes were pulled at Autozone. The dealer wanted to charge $90 for a one hour diagnose. And I figured I could use that money for needed parts. The plugs were gapped to factory standards listed on the cover under the hood. Could it possibly be the control module under the coils?

If I can make time to look in my service manual at the DTCs you have listed, maybe it will shed some light on the problem.

P1139 HO2S Insufficient Switching Bank 1 Sensor 2

Dunno what it means precisely, but there it is...

It would seem that it's plausible at least that you just have some serious misfire issues on one side and the o2 sensor is picking up the uncombusted gases and saying 'whoa!'.

Even brand new wires can/will arc to the engine if you or whoever put them in there scrunch them up against a conductor just right. Find another mechanic to diagnose if nothing else. Around here the standard rate is $60 and hour, but maybe you're in a high cost area.

on my 89 toronado, i had that problem and it was a MAF sensor. sucky thing is, dealers dont just hook up a scan tool, they've got the equipment to figure that stuff out, if all else fails, you might have to pay up, some dealers dont charge for the diagnostics if you end up having them repair it, but im sure there labor/parts markup makes up for it

P1139 HO2S Insufficient Switching Bank 1 Sensor 2

Dunno what it means precisely, but there it is...

It would seem that it's plausible at least that you just have some serious misfire issues on one side and the o2 sensor is picking up the uncombusted gases and saying 'whoa!'.

Even brand new wires can/will arc to the engine if you or whoever put them in there scrunch them up against a conductor just right. Find another mechanic to diagnose if nothing else. Around here the standard rate is $60 and hour, but maybe you're in a high cost area.


Thanks for the effort...Labor rates here are $80 per hour. The dealer wanted $90 for a one hour diagnose. Funny thing I did not drive the car at all this weekend and today heading to work it was driving better with little to no misfire at idle and power was better than before. Strange...

Hey mike95aurora, don't you mean the MAP sensor...manifold absolute pressure? When my EGR valve malfunctioned I read my scan tool that the EGR was out of range and the MAP was also. Makes sense. When the EGR is not opening fully, exhaust gases that are normally controlled by the EGR will cause the exhaust manifold pressure to increase, thereby affecting the MAP reading.

Try replacing the Fuel Pressure Regulator as well as checking all vaccum lines, intake bolts and PCV valve. I have had many of the same issues and while at their exteme, this is what fixed it for my Olds.

When was the last time you replaced the O2's?

never replaced the O2 sensors but will try pulling them out this weekend and cleaning them...as of the FPR it was changed last summer plus when I took the car in for the recall of the fuel rails they put a new one on then also

I am getting the p1139 also and my EGR valve needed cleaned and the check engine light went away. It's an easy to get to part and throttle body cleaner works fine 3.00 tax included at auto zone. :)

are you losing coolant?

I have been losing coolant ..what gives?

well you might have a head gasket leaking which is causing your cylinder to fill up with coolant and there for your having a misfire.

http://www.muller.net/sonny/crx/gotboost4/index.html same thing happened to this guy.

I think Silverbullet might be onto something with that. I have a 96 that is doing the same thing i took it up to gm and they said i had a crack in the block. I suggested a blown head gasket, but he told me i was wrong. Question for you does it only happen when the car gets heated up. If it does then i think you and i might have something in common unfortunately.