LHM Limp Home Mode Experiment

hi ...thanks for this much needed thread- my sprinter predictably goes into limp home mode (2000rpm,70km/h)..and I'm over it! any thoughts very welcome.

Well you could just carry on regardless!
I have one coming in that has done 10,300 miles in limp mode!

The passengers all have a canoe paddle with a MB star emblem painted on it!--Got 'em in Canada! To which they make paddling attempts out of the passenger window hoping to get an extra punt and aid acceleration!

Of course the two guys & wives are a Brit and an Auzzie bunch who are on a North American walk about!--whattah combination for a pizz take on MB!
Just have to add this though!

https://www.youtube.com/watch?v=0TCgRqKbTIM

Dennis

I have been getting a fuel rail preassure code for a few months on and off. When it happens I'm limited to 2800 rpm while driving pedal to the floor and around 70mph on flat road. I have been monitoring the fuel rail sensor for a couple of days now. Today when I started up and drove off it happened right away. The pressure goes from reading normal psi to zero 0.0. For a few seconds or so. If I'm driving I can make this happen by pressing quick on the accelerator. Now when this problem is occurring I noticed the idle psi is around 1000 psi or better HIGHER a than normal. If I restart then it's normal at 4,500 psi or so. I also monitored the fuel rail solenoid and it seems to always have a reading never dropping out. Idle around 400 bar or so. I also noticed something strange while I had the computer hooked up to it. While the van was running idle, I cleared the fuel rail code and the idle changed pitch. So while in the fuel LHM, the engine isn't running the same even at idle. Do I just change the front rail sensor ? Is there another reason the psi reading would drop to zero intermittent like that. ? HELP LOL. My next step will be to give docTOR Andy a call.

Howboutcha-

Aqua Puttana said:

I'm trying to get my head around what consitutes LHM. I know, or think I know, that there are different levels of LHM. The transmission only allowing 2nd gear and reverse operation is the most severe level. One of the questions is often whether the computer(s) have set LHM or if it is just a regular old component failure causing a regular old lack of power.

Some recent discussion got me thinking that there may be simple check to determine if you are having a computer set LHM incident.

"Emergency Running Mode" limits to 3200 RPM. That must be "Limp-in Mode" or "Limp Home Mode" as I've seen the various descriptors used even in MB "official" publications.

View attachment 37249

So-o-o, I'd like to start an incident log in the form of this thread. It may not be the best method, but unless someone comes up with a better idea this is what we got.

Should you experience a lack of power please try raising the engine speed before you shut down the engine. If the engine will not go above about 3200 RPM, you are most likely in a computer set LHM. If the engine readily goes above that RPM you are most likely not in a LHM mode. After you determine whether you actually were in LHM or not, and you resolve your problem(s), please post what you found here.

A description of symptoms, DTC's found, etc. would be very helpful. Please don't clutter up this thread by asking questions specific to your present problems.

By the way. A problem with the Fuel Rail Pressure Sensor may limit to 2800 RPM. The difference between 2800 and 3200 RPM should be noted when doing the engine speed test.

We'll see how this thread progresses. Maybe it will just die quietly. vic

Click to expand...

On the last day of a 4000 mile trip my 2006 SMB conversion T1N went into LHM going up the grade toward Donner Pass. We limped home and I did some research and it turned out to be a broken plastic Turbo resonator.,Replaced it with a metal part and have had no problems since.
No indicators came on. It just happened out of the blue. Luckily we were right at the summit and it's all down hill from there, albiet at a very slow pace with very little acceleration.

Mine turned out to be a wacky fuel rail pressure sensor , watching it live while driving helped figure it out.


Howboutcha-

We were on a trip in Oregon. Climbing a hill I noticed that there was no power and could not figure out why we were going so slow. Once over the hill we speeded back up. Thought maybe it was the grade. Once again on the next hill the power was low. We pulled over to let the dogs pee, shut van off. When we started again I punched it and everything worked.
There was no engine light or messages.
We are now back in CO and no problems on the way home. After thinking about it that night it felt like the turbo was not kicking in on the climb. Not sure if this was a LHM or some other blip. I started researching on the forum and came across this thread.

Limp can present it self in several ways. The check engine light may or may not be on.

Very common the engine will not rev over 3000 rpm
If you have scan gauge you might see MAP ( turbo boost) is limited and way below normal.

There are many reason for limp and or reduced power:

There maybe an emissions malfunction like EGR or DEF or any other system on the truck. There maybe a pending code stored that has not yet set the light. A dealer scan may show a past temp code.

There maybe a leak on the inlet or outlet side of the turbo system. These leaks cause a reduced power situation.

Either of the above problems might reset themselves with a key off cycle until the problem happens again.

Since the truck is a 2014 under warranty taking it back to the dealer and have them check it out. Tell them exactly what happened.

I have an 04 Sprinter passenger model, 144 WB, with @ 55k miles) While returning from a 100 mile trip last week, about 5 miles into the trip, the Sprinter appears to have gone into a LHM. It would not go over 65mph and the gas pedal was ineffective anywhere past 3/4 and acceleration was very sluggish - no CEL initially. I stopped and got gas and then started driving again. It seemed to drive ok, for the first several miles and then it tripped into the LHM mode again with the same symptoms and this time the CEL came on. The temp never went about about 185 and the rpms stayed in the low 2k.

I have plans to go see Dr. A soon and contacted him about the issue. He advised to have a generic scanner hooked up at a big box store and let him know the codes. Along with the glow plug related codes, I got a P0299 Turbo / Super Charger Underboost code. Dr. A. advised checking the turbo hoses and particularly the turbo intercooler hose. I checked the hose and noted a crack along the top. Since I plan to see Dr. A this week anyway, he advised the following temporary fix:

"Because of oil mist normally present in the intake tract, duct tapes don't work (the glue dissolves). Clean the area and wrap 2 layers deep with a silicone wrapping tape (no glue, the peel away backing keeps it from contacting the next layer which will then melt together). Top with 2 large hose clamps side by side and you have a long lasting repair."

Skydiver007 posted in another thread: "99.99 percent of the time this problem is a charged air leak. All a restart does is clear the faults and let you drive away until the condition happens again. YOU PROBABLY have an air leak somewhere. My 05 had the same symptoms and I could not find it for nothing. Finally after 2 months I was on my way home on a 250 mile trip and the front of my van sounded like the main bearing went bad. Turns out that the turbo intercooler was cracked and the air leakage made that awful noise which finally told me what was wrong." So, it appears that air leaks should be the starting point in diagnosing LHM issues. As M.D.'s say - "When you hear hoofbeats, think of horses not zebras."

I cleaned the cracked area with rubbing alcohol and then applied the Silicon wrapping tape and hose clamps as instructed. I plan to drive it about 500 miles to Clemson, SC and will report back on how it goes.

For the T1N 2.2L 4 cylinder manual transmission when in neutral a 2700 rpm limit may be normal.

crussell92 said:

...
Also while revving the engine to listen out for air leaks from hoses I noticed that the engine won't rev past about 2700rpm. Is this usual sprinter behaviour or is it in some kind of limp mode without any lights to tell me so? I drive a tran**** at work and that revs to the redline and is much newer so I thought that was odd.

Click to expand...

Cheyenne said:

For info my 2.2 127 HP (313 CDi) will also not rev past 2,700 rpm in Neutral. I believe it is some sort of safety device. I think you have to press the clutch to bypass it?
Keith.

Click to expand...

Thanks goes to Cheyenne Keith for the input.

vic

I have a code reader installed because I often received a check engine light (CEL) for the glow plugs. There is nothing wrong with my brand new glow plugs - it just throws a CEL and the reader lets me clear them. Recently my 2006 started to go into limp mode when turbo boost exceeded 8 PSI (as read by code unit). It shows code PO299 and puts the engine into limp mode with only 1PSI boost +/- Basically F-all power! I can clear the code and return to 8 PSI or less boost. Examining the intake air side of the turbo system I think that I have a cracked turbo resonator. This problem discovered while camping in Big Bend National Park, Texas, about 250 miles from the nearest dealer. I limped home to Waco, a wee jaunt of 500 miles that took 12 hours. New aluminium resonator unit on order and will be installed this week. Will report in with results.

I had the low coolant light come on. At first I mistook it for water in fuel. After a little driving the light went off and I took it to be cleared. After about 50 miles it went into the 3200 max rpm mode . Scan Tec showed reduced boost. I thought bad fuel. Water temp was around 180 or a little over. After stopping and starting it was fine. I dropped the MC trailer. Drove an other 100 mile no problem. Picked the trailer up. At start up the low water light flashed. 50 miles later back to the 3200 max. No dash indication od any issue. Today I realized I had had a low water and added about 1 1/2 quarts. Is that all it takes to go into a mode 180 temp and a temporary low water?
2003 3500 freight liner

This is a good thread by the OP....I replaced two turbo resonators 04 model recently. The first one was a Mercedes piece to replace the original ..so it lasted 12 years...The new Mercedes popped in 6 months. Then installed a Dorman...went into limp mode...but found no cracks so I still replaced it with the aluminum non plastic straight pipe........drove for a day now back into limp mode...shows the 0299 code again...go figure..dont see much.........has anybody had to replace the boost sensor just because the plastic resonator failed?