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View Full Version : Am I in LHM? What to do?


mrkbrnblm
02-21-2019, 04:54 PM
Sprinter wizards,

I recently changed the air filter on my 2003 158" WB 3500 NAFTA T1N, and immediately encountered what seems like a LHM issue. When I attempt to accelerate (e.g. up a hill, to get to speed on the highway), the engine RPMs are extremely low (between 1 and 2K) and I lack the power needed to actually accelerate. If I downshift manually, I have normal power and the engine revs react as expected. Once the van gets moving fast enough to be at higher revs even in 4th or 5th gear, the van's power seems normal. Based on all of this, I think the issue is that the transmission is going into too-high a gear at too low a speed.

Based on reading many posts related to LHM, and the fact that this happened immediately after replacing the engine and cabin air filters, I figured I had a leak in the engine air filter system somewhere. In the process of trying to troubleshoot the issue, I tightened the hose clamp on the air filter housing and accidentally broke it. I've replaced it with a normal home depot clamp which is wider than the MB clamp and doesn't fit exactly perfectly, but I don't think that's the issue.

I dropped the van at a mechanic today to ask him to look into the issue, and he suggested that there's something wrong with my turbo (something about a turbo boost cylinder?). I find this very hard to believe given that the turbo system was recently replaced by the prior owner, that the issue started the first time I drove after changing the air filter, and that the van seems to accelerate normally as long as I shift manually. I told the mechanic not to touch the turbo, but am not sure what to do at this point.

Any ideas on what I should check? I don't have a scan tool but have just ordered one. I've looked through the suggestions in this thread: https://sprinter-source.com/forum/showthread.php?t=7173 and am tempted to try the method involving turning the van on and off 7 times. Given that the issue seems mechanical, I don't think that'll resolve anything and I worry about deleting stored codes, but I'm not quite sure what else to do here.

In case it's relevant, I'd add that I've had a "water in fuel filter" light that goes on and off intermittently. The mechanic claims my fuel filter is completely clogged and needs to be replaced. Not sure if that makes sense given that the van is clearly getting fuel (no stuttering or anything suspicious). I also have a glow plug light that reignites after the van starts, and likely have some injector leakage (haven't been able to get the cover off to confirm, but I suspect that there's at least minor leaking). I also have an SRS and traction control light permanently on. None of these issues is new, though, so I don't think it explains the sudden loss of RPMs.

Thanks in advance for any help and advice! The learning curve on these sprinters is quite steep, but this forum has been an incredible resource for getting up to speed.

Aqua Puttana
02-21-2019, 05:01 PM
The diesel mantra applies to Sprinters too. "Operating/performance problem? First change the fuel filter."

:cheers: vic

P.S. - Don't let anyone even muck around with your turbocharger, let alone replace it.

Cheyenne
02-21-2019, 05:40 PM
Check the vacuum solenoid located beneath the air filter, I would guess you have dislodged one of the vacuum hoses in changing the air filter.

Keith.

mrkbrnblm
02-21-2019, 05:41 PM
Thanks, Vic! I figured it couldn't be the turbo... Let's see what happens with the fuel filter replacement (though I have a feeling I'm being ripped off on that and the filter could in fact be cleaned... shoulda checked it myself!)

Midwestdrifter
02-21-2019, 05:48 PM
Being an 03, the turbo actuator is electronic (earlier models used a vacuum controlled unit).

Did you mess with the MAF connector? If so, pop it off, inspect, and lubricate with with WD-40 before assembly. Listen for the faint click when it seats fully.

Check the ambient pressure sensor and wiring on the top of the filter box as well.

It sounds like your mechanic is guessing. These diesels are not terribly complicated, but require a specific understanding of how the ECM controls fuel and turbo boost. Without this you end up shotgunning parts (often very expensive).

The Grand Tour
02-21-2019, 05:59 PM
It sounds like your mechanic is guessing. These diesels are not terribly complicated, but require a specific understanding of how the ECM controls fuel and turbo boost. Without this you end up shotgunning parts (often very expensive).

Yup. And he's guessing with the OP's money.

And another thing- in the year 2019, anyone who refers to themselves as a "mechanic", probably isn't one. Vehicle repair technicians have been referred to as "technicians" for decades.

Mike DZ
02-21-2019, 06:07 PM
Thanks, Vic! I figured it couldn't be the turbo... Let's see what happens with the fuel filter replacement (though I have a feeling I'm being ripped off on that and the filter could in fact be cleaned... shoulda checked it myself!)

If you are referring to the fuel filter when you suggest "the filter" could be cleaned - not a good idea - just remove and replace.

mrkbrnblm
02-21-2019, 06:08 PM
Check the vacuum solenoid located beneath the air filter, I would guess you have dislodged one of the vacuum hoses in changing the air filter.

Keith.

Thanks, Cheyenne. I'll check that as soon as I have it back. That seems like a very logical possibility.

mrkbrnblm
02-21-2019, 06:10 PM
Being an 03, the turbo actuator is electronic (earlier models used a vacuum controlled unit).

Did you mess with the MAF connector? If so, pop it off, inspect, and lubricate with with WD-40 before assembly. Listen for the faint click when it seats fully.

Check the ambient pressure sensor and wiring on the top of the filter box as well.

It sounds like your mechanic is guessing. These diesels are not terribly complicated, but require a specific understanding of how the ECM controls fuel and turbo boost. Without this you end up shotgunning parts (often very expensive).

I didn't disconnect the MAF connector but did disconnect the pressure sensor. I'll give them both a close inspection and report back.

The mechanic seems very confident but it certainly seems like he's guessing.

mrkbrnblm
02-21-2019, 06:11 PM
If you are referring to the fuel filter when you suggest "the filter" could be cleaned - not a good idea - just remove and replace.

Got it, thank you for the advice. That's what the mechanic suggested, so glad that wasn't poor advice.

mrkbrnblm
02-21-2019, 06:11 PM
Yup. And he's guessing with the OP's money.

And another thing- in the year 2019, anyone who refers to themselves as a "mechanic", probably isn't one. Vehicle repair technicians have been referred to as "technicians" for decades.

LOL, to be fair, the guy's business card says "senior technician"

Midwestdrifter
02-21-2019, 06:12 PM
Its fairly trivial to confirm if the turbo is making boost. With a good bi-directional scanner you can command the turbo actuator to various levels. All of this should be done before suggesting the owner replace the turbo. Turbos don't just stop working. And when they do an inspection can easily show if they are physically damaged... Sometimes the actuators fail, but those can be replaced without replacing the turbo.

autostaretx
02-21-2019, 06:47 PM
?? i thought the 2004 was the first with the all-electric turbo, and that the 2003 still used vacuum.
(the 2003 service manual (http://www.diysprinter.co.uk/reference/05%20service%20manual.pdf) still says "vacuum")

--dick

Cheyenne
02-21-2019, 07:09 PM
?? i thought the 2004 was the first with the all-electric turbo, and that the 2003 still used vacuum.

--dick

I've always heard that NAS 2002 - 2003 was vacuum and 2004 on was electrical hence why I suggested the solenoid.

And after all what was the last thing done before it lost power? The air filter which is right above the solenoid!

Keith.

Midwestdrifter
02-21-2019, 07:40 PM
I've always heard that NAS 2002 - 2003 was vacuum and 2004 on was electrical hence why I suggested the solenoid.

And after all what was the last thing done before it lost power? The air filter which is right above the solenoid!

Keith.

You are correct, I had a senior moment there. 03 is OM612, and uses a vacuum actuated turbo.

Disregard my previous comment.

mrkbrnblm
02-21-2019, 08:05 PM
You are correct, I had a senior moment there. 03 is OM612, and uses a vacuum actuated turbo.

Disregard my previous comment.

Thanks! I wasn't exactly gentle when I opened the air filter box, so it's not unlikely that I dislodged something under the box that isn't immediately evident from above. I'll check the vacuum hoses as soon as I have it back.

Midwestdrifter
02-21-2019, 08:09 PM
Also note that the vacuum supply lines also run to the recirculate actuator on the air ducts (top of engine bay). This runs back to the Tee fitting on the brake booster. A leak along this line will result in little or no boost.

Nautamaran
02-21-2019, 08:20 PM
Yup.. the vacuum system is like the HP fuel system in that regard: a tiny leak is tolerable, but eventually leaks will overload the pump’s capacity to maintain the required pressure and then unrelated stuff starts failing.