Check engine light on, code B2600

The timing not changing is likely the root cause as it needs to advance as the rpms rise, when it doesn't you get the issues, you have. That distributor should have a mechanical advance in it as well as the electronic system, from your description I would say the issue is the mechanical parts as failures in the electronics would set a code due to the timing being off, the mechanical parts however won't set a code as they are not monitored. It's also possible as you see no advance at all that it's a combination of both.

Hi,

I noticed it has been a couple of days since we heard from you. Has any progress been made? We're interested in knowing.

Joe

Hi,

Thanks for the update. If you can, let us know how things turn out for you.

Take care,

Joe

Okay, as a recap, the truck starts and runs fine with the timing at 12 btdc, but it has hesitation and lack of power when you accelerate. Is that correct? You replaced the distributor and went through the ECU. The timing doesn't seem to advance though.
Fuel system has the correct pressures as well, correct?

When you say hesitation, how long does it last? Is it short term like you step on the pedal, and it bogs a bit then picks up quick, or is it more step on the gas and wait 20 seconds or more for it to catch up? Those engines are not super powerful, but they still shouldn't lag a lot if things are working. The lack of timing changes still makes me think there is an issue with the advance but with a new distributor that shouldn't be the case.

When you say it goes away, do you mean it hits that area of RPMs and then corrects itself or that it just gets worse from that point? What does it do if you put it to the floor? Does it hit the same point and stumble and recover or does it drop off? That is about the point that the timing should be advancing to compensate for the higher RPMs.

It almost has to be ignition related to that description. Fuel flow would cause issues above that rpm as well and adjusting the timing wouldn't do anything for that. Does this one has a vacuum line to the distributor? That was around the time they removed it but if you have it, start the engine then disconnect it and plug the line, take it for a drive and see if it improves or gets worse.

Okay, you have the newer system where that is all controlled electronically. Wouldn't it be the coil, those start to fail you would see it start breaking up and just get worse as the rpms climb, it wouldn't get better again. That's the strange thing is it getting better after it acts up. It's a long shot but how about disconnecting the EGR and see if things change. If it was suddenly opening at that RPM it could cause problems that would go away as the vacuum dropped off.

Hmm, this is a 90 correct? It should have EGB unless it was removed.