Hello from Germany
I'm turning to you because we can't get any further here in Germany. And sorry for the long text I just try to describe everything I know or what we did.
I drive a 2002 RAM 1500 4.7l.
The first problem we had was, that the German dealers or workshops are only familiar with the new models from Gen 4 or 5 onwards. So we looked for an independent workshop that is also familiar with the older models.
With what the problem started:
I had the timing chain replaced in October 2023 in an independet workshop, which fixes german cars but also RAMs and other american cars. According to the workshop, the truck ran without any problems, after changing the timing chain. When I went there to pick it up a few days later, it wouldn't start.
After several months of troubleshooting (without any results), I picked up the truck from the workshop two weeks ago. The workshop also told us that they had to charge the battery every 2 days, but they didn't know why it was drawing power.
After the truck was at home, we discovered that the 30A fuse on the control unit had blown. We also discovered the power error, because the workshop always pulled the key out on the ACC possition.

Now the problem:
It starts, revs up to around 1500 RPM, then goes up and down several times and finally dropes down to around 600 and then dies. Sometimes it can take 10 seconds, but it can also take almost 1 minute. We can start it imidiately again, with the same results.

We have already checked and renewed:
-Compression
Cylinder 1 160PSI
Cylinder 2 190 PSI
Cylinder 3 165 PSI
Cylinder 4 170 PSI
Cylinder 5 160 PSI
Cylinder 6 180 PSI
Cylinder 7 165 PSI
Cylinder 8 170 PSI
- Fuel pump (renewed)
- Camshaft sensor (renewed)
- Crankshaft sensor (renewed)
- Control unit (bought a new, programmed one, but works the same as the old one)
- Idle speed regulator (renewed)
- The cable from the idle speed controller had a break, which was repaired
- Fuel line, injectors flushed
- Ignition coil checked, all 8 work (are 1 year old)
- Spark plugs changed
- Current checked at the connections to the ignition coils
- Throttle valve cleaned

Despite all the above measures, the problem does not go away. The error is not displayed or to find in a OBD. We suspect that the workshop caused a short circuit while constantly charging the battery or did not disconnect the battery during the repair, which caused damage to the electronics. But we don't know what or where we should check.
Does anybody has an idea?

Thanks Kaija

 

Vacuum leaks?

 

No, all hose are good

 

Have a scanner that you can read live data?

 

I will ask a friend of mine, I think he's got one