Something weird happened with our GL x164 2008 420 v8 diesel.

Long story, fyi the cars only done short runs due to Covid recently but hasn’t missed a beat. We are in the UK its June and on the hottest day of the year so far when this happened (28.5c). We were driving from Newcastle to Blackpool about 140 miles and about 50 miles in when this happened.

My wife was driving and overtook a long line of lorries. When we reached the next big hill we experienced what was what I’d describe as limp mode with no CEL or other faults on the dash.

We pulled over and swapped seats (without turning it off) an I drove it to try and troubleshoot the issue. No dash errors or lights, no issues with idle or engine temps, auto box was shifting fine, but down on engine power. Could get her up to 60 an carry the speed but throttle was topping out around 2100-2400 revs. If I tried to blip the throttle either gradually or sharply it would respond by about 100revs and drop back down, even tried gradually increasing to full throttle and it stayed at 2200 revs.

So drove/limped on to Mercedes Carlisle who were helpful on the phone, but the workshop manager wasn’t interested and said it would be a couple of hours atleast before someone could look at it.

Before I went in I checked under the bonnet and under the car no leaks or pipes dislodgeed. Turned the car off and back on and it would rev fine all the way to redline. So in my head I was thinking sensor for a magic restart to cure it.

I was weighing up all the risks and thought based on what I’ve seen and fact we have AA recovery I thought restart the journey. So we drove on to Blackpool and returned the same day (220 miles) no further issues. Even towed a 1800kg caravan on way back no issues.

Got home checked for codes nothing.

thoughts/ideas welcome?

PS didn’t turn it on and off when we swapped over as didn’t want to be stuck if it didn’t restart!

 

interested to know what this turned out to be as I have the same engine and year and most of the Turbo / limp mode issues seem to be on 320s...

thanks for help.

n

 

WOW! Very old thread.

Which model scanner are you using to look for codes?

 

sadly don’t have one. Garage told me it was a turbo fault but need to check in more detail...

any recommendations for a cheap scanner would be well received!

thanks

N

 

A long shot as it could be many, many things, but I've just experienced this with my 420 and it's due to the No.1 bank intake swirl flaps not actuating correctly. It was sporadic going into limp mode (no turbo boost and won't rev past 3k) but generally always had a fault recorded or pending (P2015). having taken the intake off I have found it full of horrible goo, probably courtesy of the EGR valve. The car has done nearly 150k miles so I'm sure all the others around this mileage will be full of goo too!

 

My 320 CDI had this goo at 12k…we lived with these intermittent limp home events for another 20k miles and then dumped it.

 

This happened to my 2008 GL320 around the 105K miles mark (beginning of Covid). I used the swirl motor resistor mod and have put about 18K troublefree miles since. I think I accidentally bought 100 resistors for $6 😂

Swirl Motor Resistor mod

 

Swirl vane and actuator are just the victims here, the egr system is the criminal. There's a lot of airflow % been lost with the ports being clogged up. The swirl mod may get you back on the road but I think im doing a bhp recovery procedure here! Im not finished yet as im doing other stuff too, if i go quiet it hasn't worked!

 

Holy ****.

 

I have 2010 GL 450 that went into limp mode. It ended up being the ABS sensors going bad that caused it. I swapped out all the sensors myself and that solved the issue.