nilsT

My truck starts just fine, but when the engine warmed up after few minutes it roughly accelerates especially while going uphill - with lot of jerking still in same gear, and in all gears. first at around 1.8k rpm and then at above 2.8k. I’m thinking the problem might be the fuel pressure regulator.

I have flushed the transmission and changed all engine filters.

I have also replaced the speed sensor Y3/8n1 to get rid of 0717 but to no avail.

Vehicle: MB 320 GL, 2007 250K miles

BlownV8

Turbine speed sensor in the transmission is a known failure point on the GL.

Miguk_Saram

Tune-up 101.

If the car hesitates or jerks when you press the accelerator, check/replace the spark plugs. They may be fowled with carbon deposits.

Max Blast

I think OP said this is a OM642, so no spark plugs.
Full failure of the speed sensor causes limp home mode and the 7G to lock in second gear iirc, I’d not think that jerky acceleration be a result of that sensor failing. But perhaps, some partial failure mode exists that triggers this symptom.I did once have one of those fail and prior to that the throttle tip-in and creep forward felt a little “lumpy” as best I can describe it.

look into the exhaust pressure being too damn high - perhaps a clogged DPF causing stumbling?

nilsT

I think you are on the right track, but I have no DPF - but can stucked turbo vanes be the source?
Any method to read the vane position while driving?

dhurley

Your only active and CURRENT code is for the turbo actuator. The other two are stored aka inactive codes.

nilsT

After replacing the back pressure sensor the jerking/kangarooing has stopped.
The van seems a bit sluggish/weak though, has increased fuel consumptions with 15%, but the gear shifting is smooth.
Some oil leakage from the intake manifold, between the turbo and the cooler hose, and also around the the temperature sensor, overall it seems to be too much oil in the intake.
I'm considering installing a oil catch can, any opinions on that?


Old back pressure sensor

New back pressure sensor

DennisG01

Catch cans are a great idea. I put one in mine after replacing the intake runners/swirl flap motors (due to oily sludge build-up). Figured I was starting fresh with new intake runners and is was a good time to do it. It sounds like your leaks are just due to needing new seals.