poppabusa Posted May 9, 2012 Report Share Posted May 9, 2012 My 03 with 43,000 miles started running rough and I pulled a P0300 code. I have researched the forum, and found multiple possible causes.I cleaned the MAF with electrical spray (it looked nearly new before I cleaned it). What is a normal reading of the MAF at idle? Any ideas what I should look at first? Quote Link to comment Share on other sites More sharing options...
zachm89 Posted May 9, 2012 Report Share Posted May 9, 2012 Theres a specific cleaner for the MAF, not sure if electrical contact cleaner will harm it or not. Have you checked your plugs and wires? Most common cause of a random misfire code being tripped. Quote Link to comment Share on other sites More sharing options...
Blown 346 Posted May 9, 2012 Report Share Posted May 9, 2012 I myself would replace the plugs and wires. Quote Link to comment Share on other sites More sharing options...
Fireman31 Posted May 9, 2012 Report Share Posted May 9, 2012 (edited) Theres a specific cleaner for the MAF, not sure if electrical contact cleaner will harm it or not. Electrical Contact Cleaner will not harm your MAF..... Have you had a flashing CEL at all? Any drop in fuel economy? Strange rattling noises? Wierd smells from the tailpipe? Alot of times, this code is caused by a failing catalytic converter, and will set before any of the cat trouble codes set...... Edited May 9, 2012 by Fireman31 (see edit history) Quote Link to comment Share on other sites More sharing options...
poppabusa Posted May 9, 2012 Author Report Share Posted May 9, 2012 No flashing CEL, no rattles or strange noises, no smell from the exhaust or drop in fuel economy (can it get any worse ). Quote Link to comment Share on other sites More sharing options...
poppabusa Posted May 9, 2012 Author Report Share Posted May 9, 2012 The truck has now started to run even rougher. The CEL starts to flash when the engine is under load. It now has the bad exhaust smell. I think it is safe to assume that the catalytic converter is bad. Quote Link to comment Share on other sites More sharing options...
The_aSSet Posted May 9, 2012 Report Share Posted May 9, 2012 Get it towed to a shop or cut them off yourself, I would not drive it at all. Iirc can't a clogged cat mess up an engine? Quote Link to comment Share on other sites More sharing options...
poppabusa Posted May 9, 2012 Author Report Share Posted May 9, 2012 Is it recommended to replace both cats at the same time? Any recommendations on brand? Is it recommended to replace both cats at the same time? Any recommendations on brand? Quote Link to comment Share on other sites More sharing options...
MARTYW Posted May 9, 2012 Report Share Posted May 9, 2012 From what I have seen on here, most guys that replace their converters use Magnaflow. Quote Link to comment Share on other sites More sharing options...
poppabusa Posted May 9, 2012 Author Report Share Posted May 9, 2012 I haven't driven it since I discovered the smell and flashing CEL. Exhaust shop is 1/4 mile away. Should both be replaced at the same time? Quote Link to comment Share on other sites More sharing options...
The_aSSet Posted May 9, 2012 Report Share Posted May 9, 2012 I wouldn't leave a stock cat on there with an aftermarket. Just a good idea to do both Quote Link to comment Share on other sites More sharing options...
poppabusa Posted May 10, 2012 Author Report Share Posted May 10, 2012 Took it to the exhaust shop today - they say both cats are fine. Spark plugs and wires next. Quote Link to comment Share on other sites More sharing options...
poppabusa Posted May 15, 2012 Author Report Share Posted May 15, 2012 Replaced the spark plugs with AC Delco iridium plugs and now the truck runs excellent. The plugs were original NGK/ACDelco plugs. I assumed that the plugs would last longer than 43000 miles. Cats turned out not to be the problem. The smell was from unspent fuel going into the exhaust. Thank you to everyone for your help. Quote Link to comment Share on other sites More sharing options...
kissfans03ss Posted May 16, 2012 Report Share Posted May 16, 2012 I am getting the same code however mine does not run rough and if I remember the fault deals with the right bank running rich? Can someone please verify this or tell me where to start diagnosing?.btw my mass airflow might have 5k miles on it and I am supercharged. Sent from my DROID BIONIC using Tapatalk 2 Quote Link to comment Share on other sites More sharing options...
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