DTC's Blowing Up

[Rodd]

I was driving about 30 miles yesterday and all of a sudden my SES light comes on. Some of them I know what the issues are. Others are intermittent and appear every 6 months or so. Here they are:

P0236 - Turbo sensor - This is a known issue since I put in my T/M. A heath computer will fix this.

P0263,69,72, & 84 - Cylinder 1, 3, 4, & 8 injector imbalance. - I think my filter may be failing and passing bigger particles than it should. The injector were rebuilt by diesel pro (aka Mike) a year ago.

Finally the one that stumps me that comes up every few months is:

U1026 - Lost communication w/ trans control system.

Any thoughts?

 

[buddy]

What kind of tranny do you have?

No Subs came with EGR right? You dont have one of those or never did?

What happens when this happens?

 

[Acesneights1]

I don't know if this is your issue but when I changed my injectors I had cylinder imbalance issues when I was trying to get the air out of it. I forget the technical reason why but GMCTD said something to do with PCM trying to correct cyl imbalance with air in nozzles. I guess my point being have you cleared codes since doing them ?

 

[nvmtnlion]

Check your grounds and then check where the transmission harness goes into the tranny. It can get bad chafing on the cables over the years.

Also unplug and re-plug in your connectors on the ECM.

 

[Rodd]

What kind of tranny do you have?

No Subs came with EGR right? You dont have one of those or never did?

What happens when this happens?

automatic. They all come w/ the same tranny.

 

[Rodd]

What kind of tranny do you have?

No Subs came with EGR right? You dont have one of those or never did?

What happens when this happens?

No egr. It is an f code engine so no egr.

 

[Rodd]

I don't know if this is your issue but when I changed my injectors I had cylinder imbalance issues when I was trying to get the air out of it. I forget the technical reason why but GMCTD said something to do with PCM trying to correct cyl imbalance with air in nozzles. I guess my point being have you cleared codes since doing them ?

Yes I did clear the codes.

 

[Rodd]

Check your grounds and then check where the transmission harness goes into the tranny. It can get bad chafing on the cables over the years.

Also unplug and re-plug in your connectors on the ECM.

Will do. Anyone know where the harness goes into the tranny?

 

[gmctd]

In the "tranny", of course -

Cylinder imbalance codes occur only at idle - PCM manages idle on a per-cylinder basis, measuring angular velocity of the OS timing tracks in the IP to determine if crank is speeding up or slowing down, metering less or more fuel to compensate - this is how idle is maintained under varying loads, such as ac on, turning on the lights, shifting into any gear range from P\N, etc - there is no "fast-idle" like in a gasser (patooie!), which burns unnecessary fuel (gasoline is a fuel, after all, just not our favorite fuel!)

If your cyl imbal codes keep occuring after being cleared, those injectors may not be quite what they seem - PCM has no way to compensate for higher-flow injectors, particularly if injector flowrates are not evenly balanced or matched - only the expensive ones are.............

 

[Rodd]

In the "tranny", of course -

Cylinder imbalance codes occur only at idle - PCM manages idle on a per-cylinder basis, measuring angular velocity of the OS timing tracks in the IP to determine if crank is speeding up or slowing down, metering less or more fuel to compensate - this is how idle is maintained under varying loads, such as ac on, turning on the lights, shifting into any gear range from P\N, etc - there is no "fast-idle" like in a gasser (patooie!), which burns unnecessary fuel (gasoline is a fuel, after all, just not our favorite fuel!)

If your cyl imbal codes keep occuring after being cleared, those injectors may not be quite what they seem - PCM has no way to compensate for higher-flow injectors, particularly if injector flowrates are not evenly balanced or matched - only the expensive ones are.............

Thanks JD!

 

[Matt Bachand]

If your cyl imbal codes keep occuring after being cleared, those injectors may not be quite what they seem - PCM has no way to compensate for higher-flow injectors, particularly if injector flowrates are not evenly balanced or matched - only the expensive ones are.............

Great piece of info right here.

 

[Rodd]

I think I realize what caused the cylinder imbalance. I was playing w/ my AE last week and it allows for each cylinder to be tested at an imbalance. That is probably what did it.