cat bad chatter at idle miss under load

They always smoke when a cyl. is missing, unfortunately it is not easy to learn to read smoke.

 

FWIW: I had 6 new injectors installed at CAT back in Jan this year. It has been missing since (It was missing around 1300rpm) . Took it back again (for the 2nd time) a few weeks ago and they say its an injector, but do NOT know which one and cannot replace it until the computer tells them so. Although they say its an injector, they changed the software in my ecm and it is not missing as bad as it was. It is missing between 850-1000 rpm.
They told me to run it little bit longer and bring it back before warranty runs out if it does not do any better. Don't know what they did software wise, but my truck actually has little more pep to it and more boost. Going to take it back aroun thanksgiving unless it chokes before then.

 

Would a infrared temperature gun be reliable for this? Would the temperature difference be more noticeable if he drove it around and got the exhaust a little hot and then checked it(obviously not with his fingers at this point!)? Mine runs fine, but I hadn't thought of this and it makes me want to try it sometime.

 

The infared temp gun is the best, but everyone doesn't have easy access to one. Before those guns came out, I used the previously described method. When the engine has a miss at idle, I start checking them from a cold start up. This way there is less time for heat to migrate from good performing cyls. to the missing one.

 

OK, that makes sense. Those guns can be had cheap now, I got mine for 20 bucks at Auto Zone. I'm going to try this in the morning, just so I have a frame of reference for the future.

 

did they put the new trim codes in ecm when they changed injectors..?

 

If a cylinder cut out test doesnt show a faulty injector you will not be able to isolate it with exhaust manifold temps, electronic Cats dont have even enough temps to pick a slight miss with this method.
Sounds to me like maybe a loose tappet (did they back of the jakes before setting the exhaust clearances?) or more likely a faulty injector, Cat reman injectors have been really bad over the last few years and the rough running/miss you cant find is common when you fit a reman set. Which injectors did they fit? the older 10R0957s hve been replaced by 10R8501s because of these issuses with the 10R0957s.

 

Have seen several engines with reman 10r8501s that developed an almost skip/flutter around 850-1000 rpms at the time the injectors were installed.

 

5232 Is probably 90% of your problem especially is you used that on REMAN injectors.

I would put the trims back to STD as per each trim stamped on each injector and test. Maybe too late now as she may have dragged a piston but you can only try.

12 months for a set of remans is very good as some don't do 12 miles and being Reman with 5232 the fuel would be all over the road.