97 A4 Camaro Hooker LTs,3"ORY, cat air evap and egr delete, custom tune sluggish acceleration, slight vibration at idle..I was going to swap out the passenger O2 but I didnt want to throw money at it until I got other opinions. The car ran fine with all these mods and no codes for 6months. Ideas?

 

Unhook one of the o2 sensors and run it like that...do the driveability problems go away?

 

The P0155 is a code for O2 sensor #1 on the passenger side. Could be the sensor, terminals, or harness. Of course the P0300 is the random, multiple cylinder misfire code. This code is the one that is probably asked about more than any other. Unfortunately, the people who post about it usually do not post back what the problem was. When my car has had that code, it's always been related to the plug wires. An enhanced OBDII scan tool should be able to tell what cylinders are misfiring.

 

The code indicates a problem with the O2 sensor heater cricuit. The diagnostic compares the time required for the O2 sensor to reach operating conditions, to a lookup table based on the driving conditions since startup. I would focus on the harness extension used for the long tubes. Swap the two pre-cat sensors (only) side-to-side, and see if the problem follows the sensor (P0135) indicating a sensor problem, or stays on the passenger side (P0155), indicating a problem with the harness.

 

dang I was hoping the o2 sensor was causing the multiple misfire. Ill switch the front o2 sensors tomorrow night and post my results.

 

It still may be misfiring as a result of the O2 sensor. If the heater isn't working, with long tubes the sensor may not get hot enough to work.

 

Whats weird is, it doesnt misfire when driving to and from work. I dont get over 45mph. But when I get on the highway at 70mph thats when the SES light blinks. So I havent taken it on the highway until I get this figured out. I took tomorrow off, so tonight Ill stay up and try switching the o2s around and troubleshooting. Ill post the results too.


EDIT: maybe it is misfiring on the way to work and thats why the sluggish acceleration and vibration.

 

Swapped the front driver and passenger o2 sensors and then cleared the codes and ran her down the road a few miles. The ses light didnt come on until i got up to about 60mph..Then the light started blinking. I backed it off to cruise at 35mph on the way home and the ses light stayed on but quit blinking. The only code i have now is P0300 Random multiple misfire.

 

Go into generic OBDII mode and you can see what cylinders were/are misfiring

Or pull the plugs. The cylinders with the problem should appear black. Then you have to find out why.

Could be plugs, wires, cap or rotor. Don't forget the coil is a tune up item also.

 

Argh so my car has to be possessed. LOL The SES light went off and stayed off. It only comes on now when I go over 60mph. And at that point its flashing, when I resume to a speed of 30-45mph the light goes off.

 

Is there a question in there somewhere? You have a scanner don't you?

 

No I dont own a scanner, I have to go to autozone and have the codes read. What would make it misfire at high speeds?

 

Cracked or otherwise bad spark plug or plugs
Stessed spark plug wires
Distributor cap cross firing
Cracked or otherwise stressed rotor
Weak fuel pump
Clogged fuel filter
Partially clogged injector
Bad coil
Clogged air filter
bad fuel
etc, etc, etc

 

well thats encouraging. LOL Ok Ill start testing things one by one..

 

You an get an OBD-II code scanner for less the $50. If you are going to pursue performance on these cars, or simpy want to maintain them, its a wise investment.