90 Geo Prism... Toyota Corolla....emissions help

Sep 11, 2003 3 Replies
M

Of course it started stuttering right before emissions time. Came on rather suddenly.



Noticable stutter under load but drivable, less noticable at higher speeds.



Had the emissions test anyway to help diagnose. Can't afford too much on this good old car. Plugs look fine and balanced, with the low NOx it doesn't seem to be EGR. Obviously running rich but I'm not thinking oxygen sensor as it degraded fast.



Any ideas appreciated.


1725rpm max is HC (PPM) 203 1097 CO % 1.15 1.17 CO2% 12.6 O2% 2.9 NOx 1577 312 Dilution 13.8

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L

Ignition coil, cap, wires? Use only dealer parts. You can't afford the aftermarket on this.

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J

Probably so, though it may also be the cat. They only last 10-12 years.

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R

Your HC is really high, you're almost certainly misfiring (which would explain the stutter). Ignition components would be the first things to check.

If the CO is still high after the misfire is corrected, the O2 sensor is another suspect..

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