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Dodgerench, ASE Certified Technician
Category: Dodge
Satisfied Customers: 3385
Experience:  30+ years Dodge/Chrysler exp., ASE Master with L1 certification. Driveability/ combustion specialist
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Dodge Ram 1500: 000 miles..I am getting a random misfire code , that

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I have a 03 Dodge Ram 1500 4.7, 2 wheel , 180,000 miles. I am getting a random misfire code , that came on all of a sudden . I put some Heet in it , incase of bad gas . ran it though . nothing . Changed out all spark plugs , driver side extremely black and the passenger side over heated white, this didn't help much and is worse . The truck is stuggling worse and worse , especially at take off , At first it would stuggle, rattle the entire engine , but then get going and run fine at a higher speed , with in 24 hours or driving 100 miles ( was out of town ) Its now extremely slugglish at higher speeds , and died once I got off the freeway at the 2nd light, but did restart to make it home . no backfires yet and the ezhaust doesn't smell like rotten eggs (catalytic) . have put in on a trouble light comp many times and stills says Random misfire . oh I also replaced the pvc valve when changing plugs . Was going to work on it today , figured i better hit you guys up for advice, non of the auto parts guys really had any great suggestions . Also going to be away from comp for a couple hours. Oil pressure seems normal and hasn't stated to overheat any, battery is a gel cell and registered at 69% and hasn't given me any problems but also seems to be operating fine . Car parts guys said thats wasn't it. I would change a fuel filter , but they said the filter was built in the fuel pump and would have to replace the entire pump to replace filter ? Anyway thats about all I can think of all I have experienced so far. The problem came on all of a sudden , before that I had driven open highway for about 7 hours . good luck and thanks, XXXXX XXXXX
Hi, my name is Ed. Welcome to Just Answer!.

I have a feeling that you may have jumped time on one of the cylinder head banks, Scott. Each engine bank has its own camshaft and timing chain (overhead cam type), which means you can have one side timed correctly and the other side can be skipped a tooth or two.

I'm pretty sure that your 03 Ram truck will have a single upstream oxygen sensor that will be mounted at the convergence of the two exhaust downtubes before it goes into the catalytic converter unless it's a special emission market application like CA or MA/ NY. With a single 02 sensor sampling both engine banks' exhaust at the same time... and very dissimilar air-fuel mixtures between banks being mixed together... you can wind up with the bad side looking black and the good side being run too lean.

If you happen to have two upstream sensors, you may simply have a bad 02 sensor on the driver's side, which is the sooty black side. When checking for 02 sensors, it's important to understand the difference between the upstream and downstream designations. An upstream sensor is always installed ahead (upstream) of the cat, which downstream sensors are after. Only the upstream sensor will have an important impact on air-fuel mixture, so let's just concentrate on that for now.

Oxygen sensors look like spark plugs with a 4-wire connector attached to the top end by the way.

If you find that you have only ONE upstream sensor (also called the 1/1 sensor), see if you can do a compression test on the engine to compare the two banks. A cylinder bank with "slow" cam timing will also have reduced compression as compared to the good side, so what's important is that you have numbers that are within 10 psi or so of each other. Lowered combustion temperatures and reduced breathing on a bank with slow cam timing can also contribute to the sort of sooting issues you've seen on your spark plugs.

Normal squeeze readings run around 170 on this engine when checked at wide open throttle and ten compression strokes (all plugs removed), but compression gauges vary... so rely mostly on consistency between the two sides. Consistently lower numbers on the sooty driver's side as compared to the blistered side will almost certainly mean you have timing chain problems.

Let me know if you have any problems or questions, Scott. Good luck!

Dodgerench and other Dodge Specialists are ready to help you
Customer: replied 5 years ago.
So pull the timing chain cover ? Proably I would also want to have the heads rebuilt for the following reasons . I overheated an engine, lack of water, bought rebuilt heads and bought new generitic timing chains set , The engine worked great until this happened, but always had a sort of click click noise , which non mechenics friends always asked if I adjusted the heads when I got done rebuilding , I really couldn't find anything on how to adjust any settings, expecially without any hydrolic head adjustment knowlegde , but knew I wanted to go back in a adjust what ever I needed to adjust . The engine seem to run fine and get the same gas mileage , so being I have to work , haven't felt it was extremely important . proably really dumb on my part. but did enjoy saying to my friends and co workers , " I built that " with it the clicking noise. ( joking around ) Anyway I don't mind going back into it , but kinda expected maybe a comeback answer of a sensor or Cat replace answer. So I guess I needed to tell you about the click click noise , and maybe the heads being out of adjustment . also just passed my inspection last month and one mechenic said it sounded sick and said I thought that sound was coming from a head adjustment issue .
Actually, you're right about there being no adjustments other than setting the chain timing, Scott. This engine uses hydraulic chain tensioners and hydraulic lash adjusters at the valves, so there would be nothing left to do after reassembly except hope for the best.

I'd sure check compression first before ripping back into the engine, though. Slow cam timing will almost always compare unfavorably with correct timing, so it would be good information to have on hand before you peel the cover off. With no report of backfire and only random misfire, my feeling is that you don't have a broken valve spring or a valve follower spit off.

Be sure to check for the number of 02 sensors you have before going too far as well. Engines that use dedicated left and right bank sensors basically turn the 4.7 into two 4-cylinder engines from a fuel management standpoint. A system with a single upstream sensor averages the two banks which sometimes benefits either side.

Given enough engine misfire, you just might wind up with a bad cat at some point from internal melt-down. The cat's job is to finish the burn process that the engine missed, turning hydrocarbons and carbon monoxide into carbon dioxide, which releases heat within the catalyst body just as it would in the engine when burned. If enough heat is produced from misfire, you can wind up with a melted cat that blocks exhaust flow but this would be a cause-effect sort of thing that probably doesn't apply yet.

Given the sudden nature of what happened, I'm still of the opinion it's going to be related to cam timing. Just be sure to cover your bases with a compression test and an upstream 02 sensor head count before going back into the engine. I'm encouraged by your mechanical ability and familiarity with this engine... and am quite optimistic we'll sort this thing out.

Talk in a bit,
Customer: replied 5 years ago.
You were correct about jumping timing , I found that the new timing chain set I bought , one of the tensioner's didn't lock in position, ever , there fore causing the unexplained clicking noise I had after build . I had the old parts still , so I put one on that worked correctly and a old chain , because the new old had become alittle sharp , also replace new gear because it was chipped , I sure appreciate your help . Scott Burr

Awesome, Scott! I sure appreciate the update! :o)



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