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sprinter MX17
09-18-2014, 07:10 PM
Limp mode?
Hello everybody, I have posted in regards to the turbo resonator in the past.
However my van still occasionally goes in to limp mode, no check engine light, no codes!
I've done some research but could not find any definitive answers or recommendations.
What would you all say would be my next steps to take?
Thanks in advance

BaywoodBill
09-18-2014, 09:25 PM
Sprinter, what resonator do you have? Might you have a sporadic leak in tubing? Does the LHM generally happen under the same conditions?

jmoller99
09-18-2014, 09:26 PM
Some things I have encountered that never threw obvious errors/p-codes:

If your MAF sensor is off, it could throw you into Limp Mode - On the 2002/2003, the EGR valve is pulsed (PWM signal) and the voltage from the MAF sensor is subtracted (electrically) from the signal levels that are being sent to the EGR (I suspect that the 2004 thru 2006 work pretty much the same, but I have only put an osilloscope on my 2002 to see what its doing). The ECU monitors this and can tell if your MAF sensor is dead or not (which throws mine into a mode that uses some standard MAF level once the ECU figures out there is a problem) - I suspect that this is why unplugging the MAF sensor will allow things to work if your EGR is not working right. However, some combinations of failure of each of these (MAF and EGR) can throw you into occasional Limp Mode.

My Boost sensor had corrosion on the connector (after many rainy days in Colorado) and it would throw me into Limp Mode occasionally (once it dried up the problem usually went away) - after a while the bad connection was a problem all the time and I was always in Limp Mode - Cleaning all the connections (with some spray electrical contact cleaner from the auto parts store) finally addressed it (I went thru all of the sensor connections in the front of Sprinter to finally find this). The only errors I ever saw on my DAD were MAF errors (I changed the MAF unit and nothing changed) - I had one very old Boost Pressure error, however it never appeared after resets to the error codes). This one took a long to to figure out (I even swapped EGRs - I got a used one and installed it after cleaning 1/4 inch of what looked like tar on the side that the exhaust comes in on - so now I have a spare EGR valve).

NOTE: I bought an UltraGuage EM and watch it all the time to see if my Boost looks out of the ordinary. There are other devices that allow you to look at these run time parameters in real time via the ODBII port.

I also had my intake air temp sensor go out of spec (according to my UltraGuage EM, the air intake temp was 300 degrees, for which the ECU immediatley decided that there was something wrong) A $20 replacement fixed that - I carry a spare at all times now.

Even with a diagnistic tool like the DAD, you still have to figure out what is causing an imbalence, often you get an error that tells you what it did, not why it did it.

My Sprinter used to blow the turbo hose partially off between the Turbo and Intercooler on occasion - that left the hose clamp partially on the Turbo Hose (2004 thru 2006's have a Turbo Resonator in the same general area) - so it was more of a leak than anything else. My clue to this issue was my Turbo Spool up was much noisier when this was happening and my MAP Boost readings were a little lower than normal (about 4 PSI) - This would occasionaly throw me into LHM that a restart fixed. Getting under the front of the van and re-adjusting the hose / hose clamp coming off the Turbo fixed this.

Step one - alway look for turbo hose air leaks.

There are a lot of Limp Mode discussions here - often people get it fixed and they never tell us what fixed it. However, always do a search for past discussions on any topic subject.

sprinter MX17
09-18-2014, 10:20 PM
Thanks for the replys,
I have the aftermarket billet aluminum resonator.
I have not seen any cracks in hoses, will go they them all again to make sure.
Also, it seems to be completely random, and a restart always fixes it. And after restart it's usually good for while.

sprinter MX17
09-18-2014, 10:23 PM
Can you tell where the 3 mentioned sensors are located,
The MAF sensor
The intake air temp sensor
And boost sensor

Aqua Puttana
09-18-2014, 10:36 PM
Can you tell where the 3 mentioned sensors are located,
The MAF sensor
The intake air temp sensor
And boost sensor

Here

62498

62500

62501

62502

vic

sprinter MX17
09-18-2014, 10:41 PM
Awesome! Thank you sir!
I will report back as to my findings and results!

J.Johnson
09-19-2014, 02:33 AM
I have had the same issue on both of my 2006 sprinters. Lhm but no codes. I found oil residue on the inter cooler hoses that go from the inter cooler to the intake. I replaced those hoses and the lhm has not returned. I figured the turbo was over boosting due to an air leak indicates by the oil residue on the plastic coupler. The plastic coupler houses the IAT sensor.


Sent with this high tech chingadera!