Drove on 7 cylinders, truck lost its way

[Jaxz]

Back in the day one could limp to the parts store on 7 cylinders but now with computers, well...

 

Changed my spark plugs and broke a ignition wire in the process. Driving to parts store that way put my truck out of whack. After putting all new wires on it runs the same way it did with no wire. Huge mistake on my part. Now it won't idle, runs rough like out of sync, trans out of sync shifts hard (and I think late), tach stopped working. Only tossed one code P1404, replaced EGR. Can't for the life of me figure out what is wrong. Has anyone else been foolish enough to make this mistake and found a solution?

 

Forgot to mention that spark advance shows at 39 degrees at 1500 rpm.

Edited November 11, 2020 by Jaxz

[CamGTP]

If you unplug the EGR, does it change?

[Jaxz]

2 hours ago, CamGTP said:

If you unplug the EGR, does it change?

Yes!

Truck will now idle and engine runs smooth like normal. Trans still shifting hard and tach still not working.

So what does unplugging the EGR mean surrounding this issue? Can't run without it can I?

[CamGTP]

This is a shot in the dark here but try doing a hard reset on the computer by disconnecting the battery completely. That should reset the EGR position back to zero.

 

I would remove both battery cables from the battery, wait about 10-15min and then touch both of the terminal ends together for 10 seconds. Then hook both cables back up to the battery and see what it does.

 

Currently by unplugging the EGR it's staying closed completely and letting it run normal. I'm not sure why you got transmission and tach problems at the same time. Do the battery/computer reset first and see where we stand.

[Jaxz]

Assuming the EGR was to be plugged in again. Back at square one.

[Jaxz]

I read somewhere that misfires can cause the crankshaft position sensor to lose its place. Had a lot of them during the 3 mile drive to the parts store. Could that have something to do with the tach, trans, and 39 degree advance?

[riverbanks]

Do you see rpm's on scanner?

[CamGTP]

The timing figure you saw on the scanner means nothing. That is likely just a snap shot of the timing value. Timing changes are instant and move around very quickly based on airflow/throttle position etc etc. It's a moving target at all times. Normal timing can range from 10 to 50 degrees.

 

Did you try unhooking the battery and plugging the EGR back in?

[Jaxz]

Yes, did the battery disconnect for 13 min, touched together 15 seconds, plugged EGR back in.

[Jaxz]

7 minutes ago, riverbanks said:

Do you see rpm's on scanner?

Don't have a scanner, it's a OBD 2 unit that shows rpms in real time.

Edited November 12, 2020 by Jaxz

[riverbanks]

6 minutes ago, Jaxz said:

Don't have a scanner, it's a OBD 2 unit that shows rpms in real time.

Does it show?and was the wire on the plug,sort of

[Jaxz]

3 minutes ago, riverbanks said:

Does it show?

Hunh?

3 minutes ago, riverbanks said:

and was the wire on the plug,sort of

Originally there was no wire to the plug on initial drive to parts store.

[Jaxz]

Just following up with what ultimately was wrong with the truck. It needed a new computer. There were signs that it was failing for awhile but I didn't make the connection. Driving on 7 cylinders was the last straw to push it over the edge. New computer fixed all issues.