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All Cylinder Balance Codes

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khills

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Hi y'all. So my 98 2500 has all of the possible cylinder balance codes available. The codes are p0263, p0266, p0269, p0272, p0275, p0278, p0281, p0284. The truck starts and idles fine then after a couple of minutes it starts to run rough like it has a miss. You rev it up just a little and it runs smooth again. All the while it smokes. It has no power and black smoke out the pipe. My question is why the codes and is the wastegate open with the lever up or douwn. Thanks in advance guys.
 
A turbo boost gauge would be mighty handy. Fuel pressure ? along with a section of clear hose in place of the return hose off the front of the injection pump.
Bright shiny clean ground connections ?
That would all be a good start in diagnosis.
 
I agree with MrMarty51 on the grounds. that is the first commandment of the 6.5's on the wastegate lever. if you have the GM8 turbo where the vacuum actuator is mounted over the top, the lever up is closed. notice it when the engine is off the lever will be down and the actuator rod will be fully extended and relaxed.

do you have a scanner to read the data stream? this may be helpful in determining issues.
 
yes. under full vacuum the PCM is set up allow full boost allowed. the PCM monitors boost levels using the MAP and baro sensors. once boost levels reach the desired pressure it starts venting vacuum through the solenoid mounted by the glow plug controller. this makes the actuator lower the wastegate lever. I haven't looked up any of your codes yet, are any of them for boost, wastegate, MAP, or baro sensors?
 
All 8 pf those codes are the same thing, just cylinders 1-8.
It is a fueling issue imo, nothing to do with turbo. How are all 8 going to give an imbalance not related to fueling, And you have no boost codes. I have been wrong before though.

Imo
Clear line on ip return is step 1
Fuel pressure at ip inlet is step 2
After that start chasing electrical to the ip.
 
Ok thanks guys. One other ?. I thought I read somewhere that the 98 6.5 has the baro sensor built into the boost press sensor. There is no baro sensor on the firewall and no plug for it dangling anywhere in case someone removed the sensor. Any ideas?
 
Ok thanks. So this engine runs like it has a miss at idle and smokes out the tail pipe but when I unplug the coolant temp sensor it revs up just a bit and runs awesome. No knocking no irratic idle just the sweet sound of a smooth running diesel in all its glory..... but still smokes a bit. What do you guys think?
 
Ya I was second guessing myself on that one since I changed it a few months ago but even a new part can be junk. It’s been running bad for a few months now and I found a cracked head. It was cracked between the valves. Through a couple of good used heads on her and it helped a lot but still having issues. I’ll try a new ect sensor and see how she goes. Thanks a lot for the help.
 
khills said:
Ya I was second guessing myself on that one since I changed it a few months ago but even a new part can be junk. It’s been running bad for a few months now and I found a cracked head. It was cracked between the valves. Through a couple of good used heads on her and it helped a lot but still having issues. I’ll try a new ect sensor and see how she goes. Thanks a lot for the help.
Click to expand...
Be sure that the sensor wires are capable of a good connection.
Do a search, probably within this forum, there will be some postings about how to test the temp sensor and the reading the sensor should hold at various temps.
 
Here is a really good description of how these codes affect the ds4:

gmctd said:
PCM manages idle rpm on per-cylinder basis based on angular velocity of IP shaft, measured in the Optic Sensor system - any increase in velocity gets reduced fuel, any decrease gets increased fuel - that's how idle rpm is maintained as crank loading increases\decreases, such as engaging any gear from PARK\NEUTRAL, or turning on AC, or lites, etc - a Cyl Imbalance DTC indicates that Cyl did not respond - if the same DTC repeats regularly, would indicate a bad injector, leaky valve(s), leaky rings, etc in that cylinder - not too important if occurs occasionally at cold-start, tho worth keeping an eye on it if it's always the same cylinder, or with increasing frequency of occurance.
Click to expand...

Start with that clear line because simple air intrusion can mess with the optic sensor. Same for any contamination. Then you can see if flow is consistent through it, and with the fuel pressure gauge.
GM set these as the first tests for anything on the fuel system for a reason.
 
Thanks so much for your help guys. I really appreciate how everyone chips in and gives me the info and ideas I need. I’ll mess with it this week as time, hunting season and the mrs. allows. Lol
 
You "parked it" until you can fix it correct?

Air in fuel is the #1 concern and test. You "parked it" because it can also be gasoline or water contaminated fuel: and that gets real expensive real quick if you keep running it.

From your signature ... you fixed the lift pump?! :facepalm: This would be it if it's still INOP...
 
Ya I put a new lift pump on it. Yep I also checked for air at the ip return port and all is good. I’m gonna put a new coolant temp sensor on it and see how it goes. It ran perfectly when I unplugged it.
 
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