Yesterday I passed a car and when the transmission shifted back up the engine had a bad miss and the check engine lite started blinking and sounding a bell. I slowed way down and even pulled over & shut the truck off & then restarted. The light no longer blinked, but it stayed on and the bad miss was gone, but a slight miss (like one cylinder) remained. The "gas saver" light never came on again either. On the way back I again needed to pass a car & the same thing happened, but this time I didn't stop, I just slowed down and the engine lite quit blinking.

What's going on? Did I foul a plug when the trans down shifted & the rpm's went up? It's an 09 1500 4x4 w/ hemi & 93 thousand miles. I've put about 4,000 on it since I bought it a few months ago.
thanks,
Mike Sal

 

Possible broken valve spring, dropped valve seat, (though I had thought those issues were dealt with before 09..... maybe not?) Get the codes read, and see which cylinder its whining about.

 

Get the code and if it's a cylinder misfire, you may have a failed lifter that wore the cam flat. Seems to be happening more and more.

 

Went to Autozone & got a code #3 misfire. I'm still trying to understand the failure mode. if the lifter had failed (roller seized) and wore the cam lobe, why can't I hear it? I'm going to pull the plugs from #3 & swap them out. The truck ran great until I passed a vehicle (trans downshifted & the rpm's went up). I would think if the cam was slowly getting worn down, it would be a gradual issue, not something that happened all at once.

 

Where can I find the best solution for a fix, if I do have to tear down for cam/lifters? Can I eliminate the MDS so that I don't have the problems in the future?

 

Most folks diagnose the worn cam lobe by taking the valve cover off and measuring the rocker travel. As far as the MDS lifters vs non MDS, I don't think there is a difference in the way the roller works. When the roller seizes and starts to gradually wear the cam lobe, you won't notice it as the hydraulics makes up for the wear. What you end up getting is a valve that doesn't open enough for good intake/exhaust so you get the misfire.

 

Might be tempted to check compression on number 3 first.....

 

Compression shouldn't change if it's the cam. If it was a broken spring there would be noise. I'm still looking for a "list" of what to buy to do the whole job. Surely there have been enough people who've been thru this to tell me "do this, not that".....I live out in the country & want to have all I need here before I dig into it. I'll pull the valve cover tonight to check movement of the rocker arm....
Mike S

 

Need to know what the problem is, before you can make a list of what to buy.

If the cam isn't opening the valves, compression will be low. If valves aren't closing, compression will be low.

 

From what I'm reading all over the internet, I'm thinking that when I get it fixed I might trade it off....I'm tired of Chrysler's lack of support for issues....first it was the cracked dashes on my 2nd Gen trucks, now this..... I was on the design team for the original Hemi that came out in '03. 3 years of my life went into that thing (cooling system). It was a very good engine and I hate it that it's getting such a bad reputation.....