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Bad O2 Sensor?

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98_DSM

15+ Year Contributor
35
0
Jan 24, 2008
Springfield, Missouri
Hey everybody I have a slight issue I'm hopeing you guys might be able to help me with. When I was getting my CEL I had it tested at Auto Zone and it turned out to be a O2 sensor on my exhaust going out. And since the car was driving just fine I decided to wait to replace it when I got my new exhaust. Later my CEL went off by itself so I figured it had not gone out completly and I might have a few more miles left on the sensor. Anyways this morning I got in the car at 8am to go to work. (It was actually pretty nice outside I would say around 50F.) The car started up just fine and drove out of my parking lost just fine, from my parking lot there is a traffic light and I had to sit there maybe 3min before it went green. Right when I turned onto the main road towards work the car started chugging and surging, then my CEL started flashing on and off and the car was being very sluggish. When I was able to get the car up to speed and keep a constant speed (40mph) the car stopped surging and chugging and the CEL stopped flashing and went off. When I had to stop again at a traffic light the CEL started flashing again and the car was surging a bit, and when I took off it was being really slow and surging/chugging with the CEL flashing. After I got it up to speed it was fine and the CEL stopped flashing. (See the pattern?) I get the car to work and put it in park to let it idle, I then reved it up and it surged a tiny bit but no CEL. So I popped the hood with the engine running to see if I could hear or see anything. I reved the engine it surged a tiny bit but I did not hear anything or see anything out of the ordinary.

Where I work they repair and sell deisel trucks so I asked the head mechanic if my serpintine belt could cause the issues because it is going bad and sweaks really loud. He said more than likely no, but the first thing he said when I told him what it was doing what a O2 sensor could be going out. Because it cant tell the ECM the proper fuel to inject into the car. So could this be my issue?? The O2 sensor? I have driven many cars with bad O2 sensors for months at a time with nothing like this before. Anybody have an opinion on what the issue could be? Thanks in advance for reading my long winded story and I hope one of you might be able to confirm my issue and it being related to my O2 sensor.
 
*UPDATE*

I was able to get the CEL to stay on so I slowly drove the car to a local parts store to have the CEL checked. It came back with three codes:

P0304: Cylinder 4 Misfire Detected

P0134: o2 Sensor Circuit No Activity Detected (Bank 1, Sensor 1)

P0135: o2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)

I went ahead and cleared the CEL and started it up for a second to rev the engine. It seemed to run like normal. On the way back to work the car was doing what it was doing before, surging and chugging to get to speed. Then the CEL started flashing again. The second time it started flashing I decided to count the flashing thinking it might be a code like how a PC will beep the BIOS Codes in a certain fashion to give a trouble shooting code. And the CEL flashed 7 times if that means anything to anybody. I was going to count the flashes a second time but I could not get it to flash again before I got to work. So far the CEL has not come back on, but the car is still surging and chugging to get to speed and while it is idleing.

The only things that come to mind are replacing my o2 Sensor, and replacing the spark plugs. I have not had a chance to look at my plugs since I bought the car to see what condition they are in. One other thing that comes to mind is maybe a fuel injector is stuck open? I guess i could pull the fuel rail off with the injectors attached. That way I can turn the key to the ON position and if any of my injectors drip or spray fuel that means I will have a bad injector. Because injectors will stay closed up until the engine is running. Anybody have any ideas or personal experiance with something like I'm experiancing because I have no experiance with DSM what so ever.
 
Replace the o2 sensor. You could have your codes checked again tho, to be sure. The ecu stores stuff like that in the memory. So anyone with a decent scanner can read the trigger code.

Anytime the light is flashing is bad!! Having the light on is one thing, but when it's flashing your doing damage.

But start with what you know. (o2)

EDIT: Well the o2 is dead (just read your post above) But do the routine maintenance stuff too. Plugs are cheap and so are wires. That might be what is causing the misfire.
 
Last edited by a moderator:
Replace the o2 sensor. You could have your codes checked again tho, to be sure. The ecu stores stuff like that in the memory. So anyone with a decent scanner can read the trigger code.

Anytime the light is flashing is bad!! Having the light on is one thing, but when it’s flashing your doing damage.

But start with what you know. (o2)

EDIT: Well the o2 is dead (just read your post above) But do the routine maintenance stuff too. Plugs are cheap and so are wires. That might be what is causing the misfire.

Thanks for the fast reply, yeah I was going to replace all of that ASAP and hope for the best. And with the flashing CEL meaning that I'm doing damage well I hope I did not screw something up. I'll have to be a hell of a lot more careful until I can get this issue resolved. Any more ideas come to mind?
 
What plugs and wires should I get? The car is bone stock and will be for some time. Should I get copper core plugs and what ever plug wires they have?
 
A flashing CEL indicates current severe misfire. This could be caused by plugs fouled due to a damaged oxygen sensor. Replace the oxygen sensor, and inspect your plugs. Use NGK BKR6E(S) if you require new plugs.

If you are still experiencing a misfire after changing the oxygen sensor and plugs, inspect the wires and coil-pack.
 
You have a bad sparg plug wire on cylinder number 4. That is what is causing the surging and rough driving. It has the classic signs of doing it only when under a load but goes away once you are up to cruising speed. When this happens you need to replace the plugs and wires both or the problem could continue. The bad O2 is not causing your problem although I would replace it soon. The O2 sensor sends the ECU into a failsafe mode when it is bad, but the car continues to drive normal. It can cause you to fail emissions or get worse gas mileage. You will definitely need to change the plugs and wires now though. Good luck.
 
Thanks for all the help guys I'm glad this can be easily fixed I will be getting my parts some time tonight, and I'll post my results after everything is installed.
 
You have a bad sparg plug wire on cylinder number 4. That is what is causing the surging and rough driving. It has the classic signs of doing it only when under a load but goes away once you are up to cruising speed. When this happens you need to replace the plugs and wires both or the problem could continue. The bad O2 is not causing your problem although I would replace it soon. The O2 sensor sends the ECU into a failsafe mode when it is bad, but the car continues to drive normal. It can cause you to fail emissions or get worse gas mileage. You will definitely need to change the plugs and wires now though. Good luck.

You hit the nail on the head. I bought some NGK Copper Core plugs, Valuecraft wires, and a BOSCH o2 sensor. I did the plugs and wires first and then attempted to do the o2 sensor. I found where the bank 1 sensor was at, right after the manifold. And before I started taking it out I followed the wire to where I would disconnect it. When I found where it was leading to I realised that the one I bought from Autozone was the wrong one. While the plug on the o2 sensor on the car was round with 4 prongs the one I bought for $80.00 was square with 2 prongs. So I left the bad one on there and crossed my fingers that the car was running better. Started her up and took off. All I can say is WOW! The diffirence in how the car drove and accelerated was amazing. The plugs that where in it where no name plugs, and I mean no name they had no names on them. And the iode or cathode which ever it is called on each plug was brown. So that mean that the car is sparking to hot? I can't remember. But yeah the new sensor will be in, in 2-3 days and I'll finish my tune up this Friday afternoon. Thanks for the help guys call this case solved and close it :D.
 
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