HELP - another P0299 limp mode mystery

sprinternovascotia

2006 t1n. 80k km's. nova scotia
Hi,

I realize this has all been asked and answered before but as I am so far unable to diagnose my issue, I am hoping someone could at least help me cross some possible faults off the list.

Sprinter 2006 T1n 2500

Symptoms:
Van goes into limp mode, usually not until I am on the highway and almost always shortly after I get into 5th gear ( If I am shifting manually ). Sometimes it will go into limp mode before I lay into it, but usually the turbo operates as it should gears 1 - 4 and then goes.

Since the turbo works on every reset before limp mode occurs, Does this mean I that I can rule out the actual turbo being faulty, or the actuator ?

I don't have the money to throw parts at this issue so I would really like to avoid that. So far I have:
- replaced the turbo resonator, looked like it needed it and that it might solve my issue, but no.

- I noticed a LOT of oil residue and buildup on the hot and cold side that connect to the plastic piece of the turbo to intercooler hose so I took that assembly apart, cleaned it up, and could not find any leaks, but I swapped the hoses for a used assembly that also looked fine and did not help.

- I noticed the o ring on the map sensor was broken - so i replaced that. nothing. Can this broken O ring cause the sensor to fault ?

- I let the van idle and sprayed (almost) all of the vacuum related tubes with propane and noticed no change in idle. Should I if there is a leak? I tried wd40 too and couldn't find anything. I have posted some pictures of the seal here - wondering if this looks a little loose ?

To summarize - I am wondering with these symptoms - are there any issues I can rule out ?
- Should I be using a diagnostic tool to check vacuum?
- Will rust in my exhaust cause a turbo leak?

What should i do next ?

Thanks
 

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sprinternovascotia

2006 t1n. 80k km's. nova scotia
Forgot to mention that I removed the EGR Valve, Cleaned it, and replaced the gasket (because it leaked the first time i put it back on).
 

vanski

If it’s winter, I’m probably skiing..
sometimes, depending on the source of the fault, p0299 can be tough to work through.

sounds like your turbo and actuator are working fine. to double check the actuator you can disconnect the MAF sensor and you will see the vain move if it's working correctly. I think clockwise IIRC.

you may want to get a smoke test completed to see if there's a hole/crack in the intercooler or perhaps somewhere else you haven't checked. Or you could take the intercooler out and have a look for where 'charged air' might be escaping, although it's a bit of work to get all that out.
 

sprinternovascotia

2006 t1n. 80k km's. nova scotia
Is it possible to get the crank case breather tube off to inspect whats inside/? there is some leakage at the seals - would this affect my vacuum ?
 

vanski

If it’s winter, I’m probably skiing..
No..

And it’s not a vacuum system, it’s actually the opposite; ‘charged’ air from the turbo all the way to the intake manifold and then into the cylinders. That code typically means there’s a leak, as in pressure escaping, between the turbo and the intake manifold. I guess you can say there’s vacuum between the air intake on the pass side to the turbo, but that would be a different error code.

There has been some record of wiring faults in various locations pushing out the p0299 code, but usually it’s a small amount of air escaping from the charged air system.

Smoke test..
 

autostaretx

Erratic Member
For what it's worth, the steps you DID take (replacing O-rings, resonator, etc) all could have been a cause for a limp-home turbo shutdown.

I'd try cleaning up the oil spray and see if more accumulates ... and track its source down.

If you're gentle on the pedal, you can keep the system running with the turbo ... try for excessive speed/load/power, and it'll "see the leak" and stop trying to use the turbo until you turn off the engine again.
I drove through Glacier Park, back and forth across the Rockies and up Mt Baker with a leaky resonator that would trigger the drop-out at 27 psi Manifold Absolute Pressure (shown by ScanGauge). As long as i kept the pressure below that, it was happy.
My oil spray pointed at the resonator's seam, and upon removal the crack was obvious (but "springy" enough to not leak *enough* for the ECM to notice ... usually...)

good luck hunting
--dick
 

sprinternovascotia

2006 t1n. 80k km's. nova scotia
UPDATE

today on a whim I disconnected the maf on a long drive (in limp mode) and power is back. No limp mode and turbo working. It doesn’t seem like power is back to normal - normality that is. Anyways - no limp mode when maf is unplugged. Is this is ant indicator of what my issue could be ?
 

sprinternovascotia

2006 t1n. 80k km's. nova scotia
Does this
“With the engine at idle, if you disconnect the MAF sensor the actuator should move the turbo to LHM almost immediately, and as soon as you reconnect the MAF the vane position of the turbo should return to its normal position.”

Suggest that the issue could be the actuator?

Going a bit mad here thanks.
 

autostaretx

Erratic Member
Does this
“With the engine at idle, if you disconnect the MAF sensor the actuator should move the turbo to LHM almost immediately, and as soon as you reconnect the MAF the vane position of the turbo should return to its normal position.”

Suggest that the issue could be the actuator?

Going a bit mad here thanks.
I would think that your "drives great with turbo when MAF is disconnected" totally exonerates the actuator ... the turbo is **working**

I'd look at the MAF or the wiring to it.

--dick
 
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Sassbe

New member
Hello all,
New to the forum. 2004 3500 Sprinter. I too have the LHM on the turbo. But when my wife drives it , it doesn't do it all the time. P0299 code pops up for under boost. I checked all hoses and connections and all look good. So I did the MAF plug trick with the engine at idle. Nothing moved. MAF bad or not? Any help would be great.
 

jrod5150

Well-known member
If your just taking a guess based on an underboost code I’d say the resonator would be your best bet
 

vanski

If it’s winter, I’m probably skiing..
If the vehicle was code free and you unplugged the maf and the actuator arm didn’t move there’s a good chance the actuator is bad.
 

marklg

Well-known member
I've been annoyed by intermittent underboost and LHM for a couple years. Solved by looking for and finding dirty oil leaks in the various lines and resonator three different times. Wipe everything down, drive it for a while and look for dirty oil leaking from any of the lines on both sides of the intercooler, the resonator and any connections where an O ring might be leaking. My final issue that fixed it was an O ring. Aftermarket O ring was not nearly as good as the original Mercedes / Dodge one.

If it is already in LHM, the actuator won't move. I can see the actuator move if the vehicle is started and someone hits the accelerator in park. If you have a scanner that will give you live data, that would be very useful, but the difference between a happy ECU and one that throws codes and goes into LHM is only one psi. Max boost when broken was 19-20 psi. When fixed is 20-21 psi. If something is really leaking, it will be lower, but the point is the ECU is very sensitive and one psi is enough to complain.

Knowing control systems, that one psi on the boost may be a result of a bigger change in the actuator position. A sprinter specific scanner with live data will give you commanded actuator position, but I have no reference as to what it should be under typical conditions. I'll bet that is what the ECU uses to throw the codes and go into LHM.

Just for a hypothetical example, the boost should be 20 +/- 2 psi and the actuator should be at 55 +/- 10% when the MAF is at 950 cfm, something like that. Those are just made up numbers, but I bet Mercedes knows what the real numbers are. 20.5 psi when the MAF is 950 cfm is a real number from my live data, but I could not capture the actuator position at the same time. I can say that my live data showed boost around 20 psi when MAF was above 900 each time when things were good. When things were bad, boost sometimes only got to 15 psi when MAF was over 900. I don't have enough data to confirm that is always the case.

Regards,

Mark
 
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Hi,
I also have P0299 code on my 2005 sprinter 2500. It has 340k miles. The previous owner replaced many parts which I think was trying to fix the issue. and I did smoke test and it was OK. however, my mechanic told me that the problem can be from faulty computer, wiring harness, or turbo,
The turbo actuator, resonator, pipes are new. No leak. I run into some posts that they suggest that the clogged muffler and DPF can cause the issue. Which can make sense. Since there is a blockage, the turbo cant spool and the there is no pressure build-up by turbo. So the lack of boost pressure is causing P0299. Thats my guess. I am looking to have a shop to cook the DPF/muffler for me lets see what will happen. Mean while I am using the DPF cleaner from Autozone.
One more thing is that in the freeway entrance if I go slow I will get Limp mode at 5th gear. Same problem as yours. But I push it hard on pedall , it will not get the Limp mode, but it will be pending code. Beacuse my turbo work hard to boost air, so I have a little bit air pressure there.
Also on the up-hill in freeway. It slows down to 60 miles/hr with pedal to the metal. Meaning turbo is working but not hard enough to have the constant speed. That I think is because of clogged exhaust.Will post laterwhen get results. First I have to find a shop that does the DPF cooking. Lol
Here is the picture of my exhaust layout. Yo those that think my 2005 sprinter doesn’t have catalytic converter, see item # 10
 

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I am still struggling with this P0299,
I used Catalytic converter cleaner and DPF cleaner, no difference, I think my exhaust is fine. Today, I installed Aluminum resonator delete kit with OEM Oring, it went to limp mode on steep freeway entrance ramp. Cleared the code couple times during the freeway trip and was able to manage the turbo to work with 5-10 psi boost, when cruising without too much pressure on gas paddle.
But I am sure that if I push the paddle it will light up the CEL,
One thing I noticed was that the plastic resonator and Aluminum one when pushed into the turbo will not match the 2 bolt holes on the bracket (on the alternator) , its a little off. Meaning if I want to align the bracket bolt holes with the resonator, I have to tilt the resonator slightly. And that will cause the Oring to be twisted and causes the air to escape on higher boost,
Also I want to see if you have some pics from a busted or cracked hose , so I can get idea about it.
Any suggestions? Please Help, thank you so much.
 

Cavah

2002 Hymer RV, 2500 chassis
When I installed the aluminum resonator delete, I had to loosen the bracket screws to get the resonator holes to line up better. You might want to replace the other hoses just to eliminate them for sure, at least you will have back ups if nothing changes.
 
No one was thinking that a new part installed by previous owner can be the cause. Everyone was saying its new and it should be OK, but it was not. MB Dealer diagnostics, checking by mechanic specialists and a lot of back and forth in many forum discussions had no results, But after talk with MMS in Instagram, he suggested that the actuator is the issue, and when I replaced that with a newer one, the problem of P0299 went away completely!
 

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