I have a 1998 E300 and I have recently noticed that after the car sits at idle it loses turbo bost and acts like it is in Limp mode, but this doesn't trigger the Check engine light. Once I turn off the car and restart everything works like it should. Has anyone out there had this Problem?

Thanks

hi mate,

not on e300 but on Vectra turbo diesel also,I had similar thing
it was bad intercooler hose and some old overfill hoses.

not much sense but when changed those, car was alive again

cheers

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w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded
next wish/project: w114 coupe OM603 powered

I will check them over. I appreciate the help.

I'd still check for fault codes. It might be seeing an EGR fault (which is most detectable at idle).

-J

__________________
1991 350SDL. 230,000 miles (new motor @ 150,000). Blown head gasket

Tesla Model 3. 205,000 miles. Been to 48 states!
Past: A fleet of VW TDIs.... including a V10,a Dieselgate Passat, and 2 ECOdiesels.
2014 Cadillac ELR
2013 Fiat 500E.

agreed 100%, when I changed intercooler hose I aslo clean EGR valve and re check vacum line (as the EGR is right on top of IC hose...)


.

__________________
w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded
next wish/project: w114 coupe OM603 powered

ok will do. Where is the Diagnostic port on this car is it under the Hood?

There is a plastic cover under the driver dash next to the hood release.

... if the OBD connector is not in the opening it is probably tucked up inside the dash behind the cover. Please note that you can only retrieve faults from the DM (diagnostic module) using the OBD connector. All other faults are read with the Mercedes HHT (hand held tester) at the round data link connector in the fuse box under the hood.


cheers

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__________________
w126 500SEC gen II euro, powered by OM617 turbo stolen from 84 300SD 2.88 diff,EGR blinded
next wish/project: w114 coupe OM603 powered

Thanks for the help.

The OBDii port is directly above your left knee in the drivers side under dash panel.

If the CEL isnt lit, I doubt it will yeild any info.

I can't think of what is going to trip the IFI computer into limp mode without also setting a code and that also resets itself by cycling the ign?

Maybe a MAF thats on the verge of failing? Dirty air filter? Clogged vents on wastegate or EGR tranducers?

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Terry Allison
N. Calif. & Boca Chica, Panama

09' E320 Bluetec 77k (USA)
09' Hyundai Santa Fe Diesel 48k (S.A.)

My first thought is the MAP sensor. Reason being, the ECU will never set a code for low boost. However, if the ECU doesn't see boost (even if it's there), it won't authorize full fueling which will make the car feel sluggish.

The second thing I would investigate is the integrity of the vacuum system feeding the wastegate. If there's a leak, you won't develop full boost. Again, the ECU won't set a code for low boost since there are too many natural scenario's where boost is low.

The only way to make an accurate diagnosis is to attach a boost gauge to the manifold to measure actual boost and at the same time, use an OBDII gauge to measure the output of the MAP sensor for comparison.

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-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250