Questions and Answers

Hyundai Accent Multiple DTCs
Q. Hi I have a 1997 Hyundai Accent GT with a 1.5 liter DOHC with 116,000 kilometers and automatic transmission. Recently the car has been idling very badly.

The rpms will come very low under 500 rpms then come back a little high for not very long and turn down again but when I run it on the road it is going good except for the check engine light that start blinking. The trouble codes are P0130, P0300, P0301, P0302, P0304, P1124, and P1128.

I tried changing the spark plugs and it did nothing. The wires were changed about two year ago. I had the spark plugs changed at that time too. If I unplug one of the farthest wire on the coil it doesn't seem to change any thing but if I try unplugging any of the two closer to the front of the coil then the engine almost stalls. I listen to the injector and I can hear them clicking as when they come on and off.

As I was doing some verification the exhaust become more and more loud, the car has always had a loud exhaust sound even when I bought it 5 year ago, and now there is a big leak just in front of the catalytic converter.

Could it be my problem because there is an O2 sensor before the converter and one after so I think that if there is a big leak just between them the computer must think that the two readings are not right one to one another and that could cause the computer to try running the engine leaner and that could cause the bad idling I think.

Am I on the good way or completely out of track? What do you think? I'm waiting for your advice.

Thanks,
Steve

A. You have multiple problems here that need to be addressed Steve. It seems fairly obvious that either you or the previous owner has not been maintaining this vehicle very well.

The first thing you need to do is get the exhaust system replaced. I'm talking from the exhaust manifold back. And I think you should include the catalytic converter. After that a complete tune-up with distributor cap and rotor, ignition wires and spark plugs. In this case I would recommend getting the parts from the Hyundai Dealer. And I highly recommend using only NGK BKR5ES-11 spark plugs.

A new air and fuel filters is a must as well. We need to know that ALL the basics are good before we go looking for other problems. In doing this we may very well fix the DTC P0300 Random/Multiple Cylinder Misfire Detected, P0301 Cylinder 1 Misfire Detected, P0302 Cylinder 2 Misfire Detected and P0304 Cylinder 4 Misfire Detected and the P1124 and P1128 Air/Fuel Control system.

Don't skimp on cost, go to the dealer and get the OEM parts for this. Once it's all done, we can recheck the codes and go from there. But I really think if you take my advice there will be no codes returning.