Jimbos01hd

Heres my newest issue. When I start the truck on damp mornings and let it warm up for a little bit when I come back to drive it there is a horrible miss. shakes really bad, Service engine light flashes and shifts horribly. Ill drive it for a few miles then I can feel it get better and finally it smoothes out and the light stops flashing. Ive had a 135, 155 and 300 light showing since I bought it. Last week I swapped in new plugs, cleaned the throttle body, MAF, and repaired a vacuum leak. yesterday I swapped out a O2 sensor to try and figure out the 135,155 issue and had the computer reset. The truck drove great all last night (about 50 miles) smooth, no misses, sputters or any other issues and the service light never came back on. Before the sensor swap it didnt run bad either just wanted the lights off. This moring it was cool and damp, started just fine with no service engine light, I went into the house to grab some clothes and my coffee and returned about 3-5 minutes later and I could hear missing from the front door. Drove it rough for about 2 miles and smoothed right out.

Ive had another car (jeep) that ran like crap in the wet weather due to a ignition issue. It did it every time it was damp no matter if it was rain or a really foggy morning it did it. Ive had the truck out in the rain several times with no issues, Ive had it out on foggy nights.. no issues. Weve had a few mornings in the 30's but dry no issues. Cool and damp in the morning.. Issues!

My guess is ignition coils. any other ideas?

Jimbos01hd

Figured I would update this since no one ever updates their finding or fixes once its taken care of. I replaced both of the O2 sensors, all the plugs and removed the throttle body and gave it a really, really good cleaning. The first time I cleaned it I just sprayed some carb TB cleaner into the air inlet tube with out the filter being in it. This time it was removed, all the sensors taken off and I had to use simple green to clean a large amount of carbon that was built up in the opening. I replaced the gasket which looked like it may have had a small leak, cleaned the idle air control valve, reinstalled it all using dielectric grease on the connections, fired her up and she instantly ran better. I had the computer reset and its been 2 weeks with 0 problems, my p0300 code has not come back on no matter how long I let it idle for. Ive put 110 mile on my first 1/4 tank of fuel ( I know not very accurate but last 2 fill ups I was getting less then 70 mile on the first 1/4) which is looking like a 3-4 mpg increase from before. Im hoping in the next week or 2 to get a CAI and have a local shop change my 2 in 1 out exhaust to true 3" duel pipes. Then the comp is going to Justin at black bear for a tune.

ericnottelin

Congrats. Sorry, I missed your initial post. I would have swore it was a coil going bad. Glad this worked for you. I will keep your work in mind if I have a similar issue.

Thanks

Eric