Hey all. I have a strange problem with my 4.7l ngc 02 durango sxt 4wd. The motor lopes within the first 10-500 feet after initial startup and drive. When this happens its like it runs on 5-8 cylinders, stops, runs again, stops. So for 2 seconds it sounds like its on, next 2 it sounds like the motors off, then on so on and so forth. During this time the lights go dim, bright, then dim. I have no cel. At some point the cat clogged due to rich running. I cut it out and it ran worse during these hesitation times. It would bog down, not go over 1200 when floored then suddenly take off.
Here are things I have done so far.

New cat is in with new o2 sensors.
New plugs, vpower ngk's.
New MAP, TPS, and IAC.
Backprobed iats and its fine.
Fuel pressure is 55psi at idle.
Fuel leakdown is holding at 53psi after 15 minutes.
Coils had an ohm test. 1.2 at secondary. .6-.8 at primary.
Coil boots had no carbon tracking, just some yellowish white corrosion. Didn't clean all of them. One had a very small tear in it.
Evap system is fine.
Sprayed intake manifold with carb cleaner while cold and warm to check for leaks. Nothing.

I'm at a loss here as far as what could be the problem. The only other things I could think of is that I noticed yesterday my cam position sensor has oil on the plug and wires. I had no cleaner for it so it's still dirty. And I have a small...very small leak at my exhaust manifold. Any ideas. Local stealership wants me to leave it there at 75 dollars an hour for diagnostics.

 

well one thing that probably isnt helping is you put the wrong plugs in there, you want copper core champions and make sure the gap is .040

have you reset the computer since you replaced the 02 sensors????

 

The plugs that are in there are of a direct result of the copper champions i pulled when the issue first started. I know people stick to the factory standard but honestly its because they are the cheapest to put in for the factory. The champs that where in there ended up being less than 300 miles used before I switched to the vpower due to me thinking it was a spark issue. I've ran champions before and hated their performance. The vpowers are copper core anyway. The battery was disconnected for the etire swap so the pcm was "fresh" after the install.

Forrgot to add that the battery is a brand new mopar batt that was put in after an accident I had cracked the old one I had in there. The battery tray was full of acid...or so the tech said.

The charging system seems to be fine. The batt has 12.8 volts off, and 13.6+ volts idling. I need to get it load tested just to make sure.

 

+1 Sharps

 

chrysler spent millions (if not billions) engineering these engines, they designed them to run a specific plug, if you go and change that you are changing what chrysler intended the engines to run, regardless of what you think (that they only used champion bc they are cheap) they are what these engines run best on for a good reason, i dont mean to insult you here, but you do NOT know better than the chrysler engineers that designed the engine

 

I'm not trying to be rude or start anything or even have a pissing contest. I've ran champs, autolites, and ngk v powers in it with not much difference. Autolites idled smoother, vpowers gave some more economy, and the champs seem to last longer relative to the price. The "specific plug" needed in these motors is copper core with nickel alloy center and ground because of problems anything else might cause with coils. Straight from the mouth of a dodge tech. In any case this all started with champ plugs in it. I figured possibly a bad batch, but the local napa...which sucks cause they're the only shop local....didn't have 8 and couldent give me a date on the next shipment or order. So I got the ngk's and it didn't change much.

I forgot to mention earlier that my friend hooked in his modis to get information. Everything came up fine since this problem is intermittent. One thing that didnt look so hot was when he tried to pull up my old stored codes. It got a memory checksum error. So he hooked it up to an older scanner and was able to see all old codes. IDK if it was a bug in the computer or scanner or what. Theres no pcm codes coming up and no record of a checksum error. Just kinda grasping at straws here.

 

Well sounds like you know what your doing above us. You should probably talk to your "dodge tech" and have him fix it for you.


I think I'm done here. ....../&out

 

i agree with hydra, if you werent trying to start anything you wouldnt have made that post, the fact of the matter is that dodge spent many more dollars designing these engines than you have spent on them, and they will know whats best, and they will put the best parts in em for the factory set up, now if you are modding the engine then you may have to figure out what is best to work with your upgrades, but until then stick with what the factory tells you is the correct part JMHO