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My GL350 travels on freeway on cruise control at 80km/hr or faster . Say at 110 - tacho on 1900, tacho will jump up to 2200 and GL goes into limp home mode. If you stop turn everything off open the door it usually goes back to normal. Last night it went into this as soon as left 60k limit to 100k on freeway. Tried the above including locking the car and would only last in normal for about 2kms then it happened again. Left in this for around 80km. Left freeway stopped at traffic light and it returned to normal when i took off. Service can't find anything as no fault codes are recorded. Any ideas as is to what may be the cause.
background : was great til went to MB dealer auto service where they updated the software even though i told them only change oil and filters and adjust if needed @150000km . It then would not go into 7th til got to 125- 130km/h - after 4 return trips gave up and it eventually started going into 7th at 100 as before. At 185000 new turbo , pcv egr and after that this started but had ahppened once or twice before turbo.
My GL550 did this today on my way home. The check engine light came on and the vehicle started to shake like it was miss firing. I’ve only had the vehicle for 2 months so this is the first time this has happened. I got it home pulled in the garage, turned the vehicle off and started it back up and it ran normal. I pulled out of the garage and drove for about 5 mins around the neighborhood to see if it would happen again. Nothing. Now I’m nervous.
My GL550 did this today on my way home. The check engine light came on and the vehicle started to shake like it was miss firing. I’ve only had the vehicle for 2 months so this is the first time this has happened. I got it home pulled in the garage, turned the vehicle off and started it back up and it ran normal. I pulled out of the garage and drove for about 5 mins around the neighborhood to see if it would happen again. Nothing. Now I’m nervous.
Dealing with the GL550 (not the 350).
Use a borescope and look through the spark plug holes for signs of cylinder scoring. Cylinder number 5 seems to be the main culprit but they will all do it. Search this forum for ‘M278 rebuild’.
I hope you find another problem other than this but it scares me when you say the ‘M’ word (misfire) when talking about a M278.
My 2015 350GL does the same thing. When I am on a longer trip (over 200 miles) it will lose power, usually when I am climbing a hill on cruise control. The check engine light does not turn on. I have to pull over turn off the car and restart it and it acts normally. It usually happens once on the trip. I had the dealer look into it, but like yours since there are no error codes stored they cannot identify the problem. It seems that it started occurring after the egr system was worked in under warranty.
The Bosch ECU watches the crankshaft rotate with high granularity. It can tell how each cylinder is contributing to taylor fuel qty. based on velocity.
It used to be low contribution was caused by poor spark or fuel atomization hence the name "misfires".
dry-lubed.... scored cylinder
Now there's a modern addition to poor contribution. It's the high blow-by scored cylinder shown above slash fragmented or cracked pistons.
This is happening to "save gas" - Modern engines combine most advanced oils to dry lube oils at normal driving RPM. This works amazingly well until the last day.
There is an experimental 5mn trick to provide conventional cylinder oiling with approved MB oils.
Have a look here.....
Last edited by CaliBenzDriver; Apr 15, 2024 at 12:05 AM.
Check for codes, I recently had a similar issue, on the highway and then loose acceleration/power. Flooring the pedal does nothing much but very slow increase in speed. Stopping the vehicle, turning off and then back on would resolve until it did it again not too long after. I was also hearing a loud suction sound during acceleration which was hinted me to a leak somewhere.
In my case I was getting a "123900 - Boost Pressure is too low" code in Xentry and was a result of a damaged intercooler hose on the turbo side. Initially, I was not able to see any problems but noticed signs of diesel oil near and around the connection from the intercooler to intercooler hose that leads to the turbo muffler on the drivers side. Once I took the hose out (2 clips) I found the rubber hose had a tear at the connector. Seems to be a common issue based on research online.
Ordered the replacement hose, changed out in 10-15 mins. Everything is back to normal, no longer goes into limp mode.
Last edited by Mikey178; Apr 15, 2024 at 09:41 AM.
Check for codes, I recently had a similar issue, on the highway and then loose acceleration/power. Flooring the pedal does nothing much but very slow increase in speed. Stopping the vehicle, turning off and then back on would resolve until it did it again not too long after. I was also hearing a loud suction sound during acceleration which was hinted me to a leak somewhere.
In my case I was getting a "123900 - Boost Pressure is too low" code in Xentry and was a result of a damaged intercooler hose on the turbo side. Initially, I was not able to see any problems but noticed signs of diesel oil near and around the connection from the intercooler to intercooler hose that leads to the turbo muffler on the drivers side. Once I took the hose out (2 clips) I found the rubber hose had a tear at the connector. Seems to be a common issue based on research online.
Ordered the replacement hose, changed out in 10-15 mins. Everything is back to normal, no longer goes into limp mode.
what was this part number Mikey178?
replaced clips as well or ok to reuse?
can use show where on the engine this was located as I haven’t touched intercooler yet. Thanks!
The part number is 1665280028. I bought my replacement from Rockauto (Gates 26454), its for the hot side. The clips come with the hose.
Word of caution, I initially bought from FCP but the part they sent was shorter, they sent a replacement thinking it may have been a 1 off issue but it was still short. I don't think it is FCP's fault but they should remove it for the GL350 as its not accurate which is why I went with Rockauto.
You can remove yours to see if it's damaged or cracked anywhere and check for signs of oil splatter. In my case there was oil all on the water fluid reservoir neck. If your is in good shape without any signs of damage, your issue might be different.
Here is a picture of the hose in the engine bay (Drivers side, front). I moved the intake hose out of the way to see it better.
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