This problem of misfire in the damp is commonly caused by faulty HT leads or electronic coils. Check all plug leads first.
P1123 fault code is often associated with a faulty MAF on Hyundai cars. However first start at the air inlet tube, checking for obstructions or leaking vacuum hose which may also cause this code to show.
John
These codes indicate Random Misfire (P0300) & Misfire on Cylinder 3 (P0303)
Nine times out of ten the work you have carried out resolves the issue. These codes are nearly always coil related.
There is a possibility that this is an injector problem but this is a rare problem on the Hyundai.
I have included a link to Hyundai's own procedure for diagnosing misfires below;
http://www.hmaservice.com/local_viewer/d...
The Hyundai specific codes give your oiginal P1123 error as 1) Fuel System Rich on Idle and 2) Timer Position Sensor - Malfunction
I have also included a very useful PDF link covering all of the Hyundai specific error codes for your reference http://www.jerrystout.us/sonata/Hyundai_...
If have already replaced the O2 sensor the Timing Position Sensor seems to be a potential issue.
Unfotunately with intermittent errors such as these it can be very difficult to pin down a direct cause. I hope this info will be of some help. Do feel free to get back to me and let me know how you get on.
Just to add - on the Hyundai link - when it opens click Engine Electrical System then Misfire Code Diagnoses.
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Thanks for the quick response. I had previously changed the MAF and plug wires. Will try the coils next.
I changed the coils and the spark plug wires. Have been waiting for the weather to cooperate to test the effectiveness. Yesterday morning the weather was cool and damp, Car sputtered as before. Code that was associated with this is P0300, P0303. Have fairly new platinum plugs, and have replaced the MAF within the past year.
What would be your next best guess?
Thanks
John
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