View Full Version : Intermittent Boost

02-19-2017, 01:15 AM
2003 T1N Sprinter, OM612 engine. I have intermittent turbo/boost issues. Some times the turbo works great, other times it doesn't at all. I have re-flashed the computer with GDE. I have replaced the Vacuum control switch. But still issues. Any ideas? All that is left to replace is the actual turbo actuator. I'm not sure what to do next for diagnosis.

02-19-2017, 03:19 AM
The turbo will be turned off if the ECU senses a bad sensor reading, which can come from MAF, AIT, pressure sensors, or leaking turbo hose or connections, or a hose to the actuator is developing a leak.
Clean all sensors and sensor connections, take all hoses off and inspect for splits, cracks etc.

02-19-2017, 04:19 AM
I also have no check engine light, so no codes to read. I will try some of those sensors. My outlet hoses from the turbo have no cracks. Is there was way to diagnose each of those sensors with out just throwing new ones in?

02-19-2017, 05:36 PM
If you have a scanner like a ScanGauge or UltraGauge, it can report the boost (MAP: manifold absolute pressure).
(the UltraGauge may also be able to access the MAF ... i'm not sure about that).
Better diagnostic tools (Autel M802, iCarsoft, etc) can look at more stuff, and some (the DAD at least) can run the turbo actuator through its range.

Since you have an OM612, your problem could include vacuum leaks.

When my resonator (which you don't have) was "lightly" cracking.. it only turned on the CEL about once per three losses of turbo. So small leaks can be silent limpers. (the ScanGauge's MAP readout certainly told me about it instantly)


02-19-2017, 06:34 PM
In my 2003, it was the EGR, both times. No CEL.

If a re-start "fixes" the turbo for a short period of time, that's a clue. The EGR on the 02-03 wears out and needs replacement every 100-200k depending on driving conditions. There is no rebuild.

I also replaced and inspected everything you list before finally arriving at the EGR. By the time my replacement failed, I forgot, and did the same steps again!

*from what we can determine, the shaft in the EGR that opens and closes the valve deforms and wears against the bushings, losing the seal, which in turn causes discrepancies between the MAF and boost pressure readings, making the ECU think that there is a failure in the system and it turns off the turbo as a default safety measure. The EGR will start dripping oil as the seal starts to fail and allows more of the oil-vapor filled boost air through to the cam chamber of the EGR, but that in itself is not "failure", and my EGR went for 50k+ miles with oil dripping before going into the turbo shut-off mode. An EGR block-off plate will reveal very little, because the pressure is escaping out the cam shaft seal, and not the exhaust side.

02-20-2017, 03:47 AM
I do have the Autel MD802 and can measure manifold pressure. It does some weird things. I can be with out booth driving down the road, and then with out moving my foot it might built boost to 25psi for 1/2 second and then drop back to atmosphere/14-16psi. I have cleaned the EGR a few weeks ago before i got the green diesel computer flash, which I thought it was going to eliminate the EGR from activating. Is that incorrect? Could it be that the cam of the EGR is worn in a spot? I will check those out. I am about to order the sensors as well. I do not have oil coming out of the EGR externally.

02-20-2017, 05:52 AM
How old is the EGR?

Nobody has been able to answer the question about an already failed EGR working with the GDE tune. It seems like if it's a mechanical failure, a software bypass isn't going to correct the issue.

Have you checked your charge air system for leaks? Oily residue on a hose or fitting? My main hose going into the intake developed a crack. Sometimes the ring clamps get loose. You don't have a turbo resonator, so that's not a source. If the turbo only shuts off when you are approaching a high PSI, it might be a leak in the charge air system, that only opens up after failing to contain a certain PSI.

Cleaning the EGR just removes soot from the exhaust side, which MIGHT build up enough to prevent the valve from closing all the way; cleaning shouldn't affect oil dripping.

02-20-2017, 10:30 AM
Is there a EGR blank plate modification available?

Sent from my XT1032 using Tapatalk

02-20-2017, 05:42 PM
Is there a EGR blank plate modification available?

Sent from my XT1032 using Tapatalk

A thin piece of sheet metal cut to mimic the steel EGR gasket, except with the exhaust port solid (the small hole on the gasket). Made of 5x8 roof flashing from hardware store with drill and tin snips. FOR TEST PURPOSES ONLY. For emergency use, a cut up beer can strip that just covers the exhaust port; loosen the bolts slip it in tighten the bolts. Not a secure seal because it is an extra strip over the gasket, but pretty good. FOR EMERGENCY USE ONLY.

This block-off does not prevent oil dripping or boost pressure lost through the cam side of the EGR. It also traps exhaust in the pipe from the exhaust manifold to the intake, and could cause corrosion or heat problems. some have suggested a permanent block-off be installed at the exhaust manifold end of that pipe to prevent this. Voids warranties, breaks emissions control laws (where applicable).

I'm thinking that the way to prevent boost loss through the cam shaft on the EGR on a GDE equipped van would be to remove the shaft and valve from the EGR, install exhaust side block-off, and plug the hole where the shaft was by threading it and installing a bolt. Just a concept, I don't think anyone has tried this. The GDE tune supposedly tricks the ECU to think the EGR is operational, so removing the shaft from the cam should have no effect; the cam will rotate as if operational and the servo sensor will relay cam position to the ECU. OR I could be wrong, and the GDE causes the EGR cam to remain closed but sends signal saying it's moving the way the ECU wants.

02-20-2017, 06:31 PM
That's in depth! Anecdotally I have seen the carbon deposited in the inlet valve on a ford Mondeo 2.2tdci engine, from the EGR valve, andi don't see this as being environmentaly the best idea in the world!

Sent from my XT1032 using Tapatalk

02-21-2017, 01:40 AM
I also have no check engine light, so no codes to read. ?

I saw no CEL when I suffered intermittent boost loss due to a hose split. My Ultraguage did see the loss in charge air pressure.

02-21-2017, 03:07 PM
I ordered over the weekend a MAP sensor, MAF sensor, air intake/charge sensor, and a temperature sensor. I need to check the hoses better, but from the after-cooler to intake is a good hose. I believe the rest of the hoses are good too because it does develop good boost and will sustain it until shifts, but I will still double check those. Those parts will not arrive until Thursday so I can try the EGR block off plate. I do live in California so I do have to deal with smog and emissions, but there are so many grey areas with smog on a diesel here that a lot can happen before anyone knows that something has been tampered with.

02-21-2017, 04:24 PM
In CA for the diesels it's just a visual inspection of engine and tailpipe, a so-called opacity test. They also check for codes relating to emissions. At least this was the procedure when I would get my van smogged.

02-24-2017, 09:11 PM
Alight, I just replaced MAF, Temp, and Pressure sensors today. I will be driving up to big bear this weekend and will be giving them a shake down. This is the first sprinter I have owned, so is the amount of oil in the intake normal? see the pictures. Also in the pictures are the EGR Cover removed. The cam swing back smoothly and freely. It does not appear to have a wear spot in it.

02-26-2017, 10:07 PM
Just got back from Big Bear for the weekend. It was beautiful. First real trip in my converted van. The van seemed to run better after replacing those sensors, but turbo went out on the way up. Stopped, turned the van off for a minute and went on my way with a functioning turbo. Then on the way back, same thing. Turbo ran great, then stoped working. Tried stopping and restarting twice with no luck. Turbo would still activate sometimes from first gear, but then not after. Or work work while at speed intermittently. So now I'm going to check vacuum. Are there any write ups on where to start with this? Is it just a matter of how many inches of vacuum there are, or are speed to achieve vacuum also applicable.

Sent from my iPhone using Tapatalk

02-26-2017, 10:55 PM
Yes, that's normal oil. Scary, but normal.
You won't feel a wear spot; someone thought it might be a slight misalignment and there is sideways pressure on the rod, causing wear. The constant motion of it would smooth any transition, there wouldn't be "bump" as it goes through it's travel.
You might want to buy a new turbo next. :D:
When you finally get around to replacing your EGR I bet the problem will go away. :2cents:

02-26-2017, 11:01 PM
Vacuum check: with engine running, push the fresh air/cabin air button and listen for the flap to close. If it closes, you have vacuum up to that point. There is a hose that goes down to the turbo actuator from there. You can unplug it from the actuator with the engine running and put your finger on it to check for vacuum. That's the end of the line for vacuum, so if you have suction there the actuator should be working. Those little hoses get old and brittle, it's worth the time to replace them. If you want to measure vacuum, Harbor Freight has a cheap vacuum gauge. There is a vent and filter to allow air into the system up by the cabin air filter, you might check that, too. I went through this twice, exploring the entire vacuum system, and both times it turned out to be a bad EGR.

I found it easiest to mess with the actuator by removing the headlight. Which requires removing the grill.

02-26-2017, 11:03 PM
Oh, maybe check and clean the wire connector that plugs into the EGR? If it's really oily one of the pins might not be contacting.
Also, if you only lose turbo under load, like going up a hill or flooring it to pass someone, that would be an indication of a crack in the system that opens up when pressure gets high enough.

02-26-2017, 11:35 PM
Alright... Ill try blocking off my EGR, I was just hopeful the GDE tune would have eliminated this as an issue. I have some thin stainless sheet metal, assuming I should just use the gasket as a template and block off the exhaust side leaving the air intake open? I will double check my hoses for any cracks. But the loss of boost is so random. Had a great drive up the mountain roads, it seems random when it goes out.

Aqua Puttana
02-27-2017, 12:33 AM
Alright... Ill try blocking off my EGR,
A big FWIW on this reply as I have no experience.

The mechanical blocking off of the EGR port may help as a troubleshooting test if the valve is allowing exhaust gas into the intake at the wrong time(s). Mechanically blocking the port will not necessarily help with identifying EGR control/module related problems.

The EGR control and monitoring circuits can be a bit complex.

Good luck.


02-27-2017, 01:55 AM
I forgot you had GDE. Maybe they can help figure it out?

You might be on to something with the vacuum, replace those soft rubber lines. The hard lines are probably OK.

03-14-2017, 08:18 PM
After doing some other work at the dealership, I asked them to diagnose what was happening with the boost issue. They confirmed the EGR and that it was sticking in some locations. I talked to GDE and they do not mess with the cleaning cycle, but prevents it from opening while driving. So that is why it has been so intermittent. Only some times after the cleaning cycle has it gotten stuck. I have now been trying to find a good write up about disassembly of an EGR so see if it is repairable or not. I know that I will probably end up with just having to purchase a new one though.
Another question though is, this is for a converted camper van, will the life span of the next EGR be more closely timed with mileage, or with age for its total life span?

03-14-2017, 08:46 PM
I talked to GDE and they do not mess with the cleaning cycle, but prevents it from opening while driving.

If you're still talking about an '03, the EGR doesn't have a cleaning cycle. From another recent post, GDE supposedly said that they keep the valve open a little all of the time - when running. If that's correct, then maybe your valve won't open, even a little bit, some of the time. HKPierce and I have both noticed that the stepper motor can stick open at various points in its travel and not allow the valve to close on its own (spring return). I've also noticed that valve stem wear can make the valve difficult for the stepper motor to open the valve. If it's truly always open when running, extreme wear could also cause the valve not to open the little bit required by the tune by allowing the valve stem to move laterally instead of in/out. The valve can't be rebuilt, but you can easily remove it to look at its condition and clean it.

03-14-2017, 10:02 PM
According to Dr A, the 02-03 EGR is not repairable/rebuildable. It is a maintenance item that requires replacement when it wears out. In my experience it's between 100-150k miles. A lot of highway driving may result in longer lifespan (in miles). "Sticking in some locations" gives support to another member's idea that the shaft gets worn in spots due to side pressure. The shaft getting worn/bent is probably the cause of ultimate failure to hold sufficient boost and oil vapor. Maybe see if a new shaft can be sourced and installed?

03-15-2017, 01:47 AM
Maybe see if a new shaft can be sourced and installed?

Difficult because it seems the valve disc has been TIG welded onto the stem after insertion of the valve stem. Could be done if you could reach into the valve through the access port (port blinded w/ plug & snap ring), grind the weld away, install a new stem, and TIG weld (through access port) the valve disc onto the new stem. All w/o damaging the stepper motor electronics w/ stray voltages.

03-16-2017, 02:50 PM
Thinking more, I remembered that there is yet another barrier to replacing the valve stem. That is that the cam is in the way, so you can't thread in a new stem even if you could detach/reattach the valve disc. Moving the cam is a real can of worms because the cam is also MIG/TIG welded to the stepper motor shaft. Seems to me the best way to "repair" the valve would be to do the mod I'm now testing - provide a system of rollers and guides that makes it impossible for the cam follower on the end of the valve stem to travel in any other direction than in/out.

04-22-2017, 06:15 AM
Alright. Time to bring up an older post. I finally replaced my EGR, and due a perpetual fuel air leak and annoyance with the crappy WIF sensor on the fuel filter I replaced all of my fuel lines to and from the clear engine lines, Bi-passed the original fuel filter, and installed a Racor fuel filter with water separator. (I mention this in case fuel delivery could be an issue, although now I have no air bubbles in my fuel lines and no PITA fuel filters to deal with). I thought things were going great until the 6th time I drove the van since the replacement, I was getting on to the free way when my boost cut off again, and stayed off. Drove a couple miles down he freeway with no boost, got to the off ramp, made a couple turns and then on a slow and steady drive down a side road home I could feel some power come back and then drop off. Now what are some thoughts? Tomorrow I will be taking some soapy water to all of my hoses and radiator to check for leaks. Or is there another preferred way to check for leaks? I am now home and forgot the turn off and back on the van to confirm things resetting. I suppose another thing I should try is going back to an original engine tune and see how things are with that. Maybe I got a hick up in my GDE tune?

Sent from my iPhone using Tapatalk

05-20-2017, 01:17 AM
After checking various spots with soapy water and not seeing any bubbles, I'm running out of things to check. With and with out GDE I have a high boost code.
Can anyone tell me what flow through my MAF I should have at idle? I was informed by a shop that my reading might be low, and then my thinking is that if that falsely reads low, the the turbo might supply too much air to compensate?

Sent from my iPhone using Tapatalk

05-22-2017, 05:11 PM
Talked with Dok A, walked me through trouble shooting the bell crank and actuator. Lines are all clear, with air flow. When I disconnect the vane control arm, the vein arm moves freely and easily. I would say with a bit of slop. I'm not sure if that is normal. Pushing the crank down requires a fair amount of force. Should this move freely and easily? Mine requires almost more the a finger can provide to get it to move. When I start the van, but move from 11:00 down to 8/9:00 after a second for vacuum to build in the system and immediately after running and restarting (with vacuum in the brake booster). Dok A confirmed that my over boost code is a proper MB code.

Sent from my iPhone using Tapatalk

05-22-2017, 05:14 PM
With this, I did notice that the C clip that keeps the arm connected had a glove warm in it. Upon re-install, I turned it around to have a smooth face. https://uploads.tapatalk-cdn.com/20170522/8c7f4538e4c146e137ed6f793ae564b6.jpg

Sent from my iPhone using Tapatalk