recently we finished rebuilding my 360 magnum with edelbrock heads, cam, rockers, chip, etc. we dropped it in and it ran kind of sluggish to begin with, but it wasn't horrible and figured it might just need some break in time or something. at about 150 miles in it has just gone flat dead. its missing on multiple cylinders. i can only push the gas in a very little while driving before it feels like it won't want to push in anymore. i have very little power whatsoever right now and backfires when slowwing down from higher speeds. its running VERY rich and there is a shuddering driving at 45+ that has me a little uneasy but its probably not the motor. after i put headers on way before my rebuild my cat cracked so for ease and times sake i gutted my cat and i used an o2 sim. we think that o2 sim might be an issue with all this but not sure. its not that old but we aren't sure if its set up for the way the motor is set up now. any input would be appreciated before i go spending money or beating my head against the wall

 

Have you pluged the pcm in? What is it telling you?What kind of chip are you using? Get rid of the O2 sim drill and tap the headers and put them back in also get a free flow cat. I would call Jet Performance or Hypertech and let them know what you have as far as the cam specs are concerned it sounds like it is way out of wack for what your computer can read. A quick test is to put the stock cam back in and see how it runs. Sometimes Powerchips just adjust the fuel curveand depending on how big the cam is you might need one burned for you. OTC powerchipor programer about $300.00 a new burned prom for your cam might be in the $500.00 range. I'm in the middle of stroking a 360 to a 392 I'm using R/T heads with 202 valves. My buddywho works at the Dodge Garage said do all of that first but don'tmess with the cam. Then he can reprogram the pcm from mopar performance for about $350.00 best partwarentied for 12m 12K miles. Good Luck!

 

Mojo - There is no o2 sensor in stock exhaust manifolds.Upstream o2 needs to be about 3' from the heads andwillgo in either the stock location(below manifolds)or goin the new ypipe that came with the headers. Chances are it has nothing to do with the o2 simm.

I would look elsewhere before addinganything

Did you set the distributor correctly? Cam position sensor in the distributor affects injector timing in relation to thecam. If its not in sync it could cause major power loss depending on how far off it is. 3deg +/- will have it running poorly. Over 3 deg off and it runs really bad (like u describe).
Need a scanner tool to set cam sync signal. Snap on MT2500 is what I use to set it (parts supplier has one) Need to set the signal to 0-1deg advanced. With the engine running, hold it at 1000rpms to take out any valvetrain slop(set at idle itcan jump 6deg instead of 1 deg/approx) Unlock the 1/2" hold down bolt for distributor and give it a small twist. Doesnt take much to move it a couple degrees. Keep adjusting till its on 0-1deg advanced then lock it down.

Chances are the plugs have fouled now from running so rich. Best to double check ignition wires as well to make sure they are on the right plugs and that they are routed correctly and not overlapping anywhere.

What are the specs on the cam you installed?

Hypertech and other programmers/chips are not intended for big cams, flowing heads and larger ci. They are intended for stock or near stock trucks. MP PCM would be able to run it better or a flashed pcm (B&G Chrysler) If you have a JET chip, remove it and just run the stock computer. JET IS CRAP!

 

the cam specs are 264 int/274 ex and .512 lift. figured that wouldn't be too radical to screw with anything. and we've been a little curious if the computer might be screwing up in some way with this setup or not. don't know a whole lot about this gay computer **** yet. gonna run through everything in the coming days

 

Thats amild cam, the stock computer would be able to run it without any issues. If your Eddy headshave beenported computer would still run it.Wont give the most hpbut can handle it.

What year is the truck?
How did the truck run before doing the rebuild?
What chip was added?

Best to double check all the electrical connections on your igntion and fuel system as well as any sensors.
Only takes one or two semi loose connections to wreak havoc. Hate to see youbuy parts if its something simple