Oxygen sensor

[Benjie]

I have code 5 and 9 will a bad oxygen sensor make my van idle rough thanks for any help

[timsrv]

Possibly. If let go for a long time your plugs could be loading up. Long term neglect can also lead to the cat converter getting plugged. Short term use with a bad o2 sensor shouldn't make it run rough. It will just make fuel consumption go up and power go down. Tim

[Benjie]

Thanks a lot for the reply what should I look at for a rough idle and a little loss in power. It all started today on my way home my check engine light went on when this all happened I will replace my oxygen sensor in the am thanks

[timsrv]

Check the wire to the sensor 1st to make sure it didn't get melted off or get disconnected. Running rough can be any number of things. How long has it been since the last tune-up? If it's overdue then do that 1st. Check your throttle body intake tube for cracks and make sure all the vacuum hoses are in good shape/hooked up. Check the injector connectors (the ones you can get to) to verify they are hooked up and the wires are secure. If it still runs rough pull a spark plug wire with the engine running to determine if that cylinder is firing. When you pull a wire the engine should stumble and run worse. If it does, then that cylinder is firing. Try that with all 4 wires (one at a time). If you find one that doesn't effect how it runs, then that cylinder isn't firing. If you find a faulty cylinder, check to make sure there's spark at that plug. You can do that by pulling the plug, grounding the metal case while it's hooked up to it's plug wire. Crank the engine and watch to see if it sparks. If it doesn't then it's likely a bad plug, plug wire, or distributor cap. If it sparks then you likely have an issue with that cylinder's injector or it's injector connector/wiring.

One other thing worth noting is compression. If you have a dead cylinder that's got fuel & spark, then there's likely a compression issue. If you know what to listen for you can hear a bad cylinder just by disabling the ignition and cranking the starter. Tim

[Benjie]

I installed new o2 sensor still runs rough pulled all plugs checked for spark all 4 had spark. I did notice oil behind spark plug tubes and I don't remember that much oil behind them on my last tune up. My oil did seem a little bit more dirty than last time I checked spark plugs were sooty as well do I have a bad cylinder what do you think thanks a lot for your help greatly appreciated

[Benjie]

The plugs were all a little sooty (black) I cleaned them to see if that was the problem. I did do a tune up recently. Oil was a little low how I would love to keep this van going I would attempt to rebuild I am mechanically inclined but I have never rebuilt a motor and live in seattle with no garage so I would have to fix it quick I did check all rubber as well thanks

[timsrv]

Oil in the spark plug tubes can make it run rough, but not sure if that's your problem. Get the new rubber rings for the tubes and that should take care of the oil issue. As for the sooty plugs, that was likely due to the o2 sensor. When the ECU doesn't get a signal from the o2 sensor it will default to a "limp" mode. Since running too lean can cause damage, it goes to a rich mix. Running rich will create soot, rob power, waste gas, and eventually plug up the cat converter. Tim

[Benjie]

I checked the injector wires they all looked good checked the compression 170 164 165 158 so I think the cylinders are ok the distributers cap looked worn so I replaced the cap and rotor not exactly sure where to go from here. It still runs rough and smokes just smoke no steam any ideas did I miss something thanks

[timsrv]

If you haven't cleared codes yet, clear them, then run it for an hr or so & check them again. Tim

[Benjie]

Found the problem it is the air flow meter I opened it up and the measuring plate (flapper) is getting stuck I am going to take it apart and clean it with brake clean and brush this weekend at idle the van now purrs like a kitten since I put in new o2 sensor distributers cap and rotor. Has anyone had this problem and cleaned meter for good results. Thanks

[Benjie]

Cleaned and scrubbed out the air flow meter with brake cleaner; it then stopped sticking. Bought spark plug tube gaskets which solved the oil leak. Put on valve cover gasket and a new PCV valve that I bought at the dealership for $13. They were cool enough to put my valve cover in the parts cleaner for 20 minutes. I changed ps fluid and installed a new alternator and o2 sensor. I can't believe how good the van runs; it purrs and has much more power. I think it will also get much better mpg. Prior to these fixes, it got about 18 mpg in the city. Now it will hopefully get around 25 mpg. Next up, I'd like to replace most of the hoses and replace the speedo cable to know how fast I'm going. This will help determine my mpg as well. My odometer does not work. with a new speedo cable it will work as far I know. What is the process to replace the speedo cable and where is a good place to find one on the cheaper end. Thanks for the help!