Check Engine Light, Car Running Rich???

[Yellow02NeonLE]

i recently had a performance exhaust system installed on my 2002 neon. I went with an obx-r header and downpipe, magnaflow hi-flow cat, 2.25 piping and a straight-thru style muffler...just something cheap i had around. Ever since i have had a check engine light, and i know this has to do with the o2 sensors reading different temperatures and oxygen readings because of the backpressure changes, but im going through a lot of gasoline, and im seeing a lot of carbon building up on my bumper just above the muffler... im wondering what i can do to get my car running a little bit better... im thinking about getting a new muffler in a few days, looking into a mugen style twin loop muffler... but who knows... im hoping for now that the msd ignition coil and performance wires along with some new plugs should help clean the exhaust up... or so im hoping... any insight to this problem feel free to ask.... any other questions for me about my car... feel free to ask me...



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[ricebike]

hmm, did you read the actual codes & reset the ECU to see if the codes return?

[das2123]

Originally Posted by Yellow02NeonLE

Ever since i have had a check engine light, and i know this has to do with the o2 sensors reading different temperatures and oxygen readings because of the backpressure changes

How do you know this, did you read the codes? There are no backpressure changes in your car, that is a huge misconception. The MSD coil pack and wires won't do anything performance wise for your car. The MSD is a stock coil pack painted red, granted it looks nicer and is cheaper, but it won't do anything performance wise. Read the codes doing the key dance and let us know what you get. To read any OBD codes, perform the following sequence.

1)Cycle the ignition key ON-OFF-ON-OFF-ON within 5 seconds.
2)Count the number of times the 'Check Engine' lamp on the instrument panel flashes on and off. The number of flashes represents the code. There is a slight pause between the flashes representing the first and second digits of the code. Longer pauses separate individual codes. For example, flash-flash-flash [pause] flash-flash represents the code 32. The last code you should get is 55, which is end of codes.

To cycle the ignition key ON means to turn it only as far as it takes to get the dash lights to respond. It does not mean to crank the engine.

[ricebike]

To read any OBD codes, perform the following sequence.

1)Cycle the ignition key ON-OFF-ON-OFF-ON within 5 seconds.

wow, das...

I didn't know u can do that on OBD II cars... i know it worked on my obd I dodge shadow & plymouth K car (when i had those POS)...

I'd just go str8 to autozone for a free scan... & they can also reset codes using the scanner!

[Yellow02NeonLE]

i have had the car in for a tuneup recently and they checked the diagnostic codes... error code 21 was indicated....

-------> 21 = o2 sensor problem (oxygen sensor), upstream or down stream

upper sensor is in the 4-1 collector in the header... lower o2 is in the downpipe just before the cat.... the stock system had the lower o2 located in the cat....

[vamc]

They only seem to work on neons and a few other dodge cars NOT all obd2 computers. IE.honda,chevy.