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View Full Version : HELP, diagnosing strange idle and throttle issues


rossco
03-12-2013, 08:43 PM
I have an '05 Sprinter 2.7L 2500 180k

It has been running well except for a slight squeak when i first start it that goes away after it gets warm. Just drove 7hrs straight this Sunday.

On Monday afternoon when I went to start it again, it started perfect, after 2 minutes or so it started shuddering. Sounds like it's bogging down then gets a burst and comes back to life. Eventually it stalls out and dies. I can restart it no problem, even drive it around after a bit without it dying.

It goes in and out of LHM... was able to get an EGR code and MAF codes cleared and they have not come back.

I cleaned EGR. Checked all intake hoses, There is oil and a little moisture in intake hoses, but it's now very clean and problem still exists.

Driving it, if you lightly press throttle it bogs down, if you give it throttle aggressively it revs well. power seems ok but not great.

I have a really important trip i'm trying to get to this weekend and i'm in a total panic trying to figure out what is wrong. I am worried about the turbo not working....??? How do I check???

Any help is very appreciated!

rossco
03-12-2013, 08:45 PM
having difficulty knowing power as it is in and out of LHM. Definitely not great power and lagging throttle

Colorado_Al
03-12-2013, 09:56 PM
When was the last time you replaced the fuel filter?
Do you have a DAD or other MB specific code reader? What codes, if any, are present?
If you have a DAD or a Scangauage you can view the boost pressure to verify the turbo is working, however, if in LHM the turbo will not go above a set boost pressure.

rossco
03-12-2013, 09:58 PM
Probably 10,000 miles ago for fuel filter

I only have a basic reader so I can't find boost pressure. Going to try borrowing one tomorrow but last try it was in LHM.

I cleared codes and none came back but it was

P0100
P0102
P0401

Colorado_Al
03-12-2013, 10:05 PM
You need to get your hands on a MB specific code reader. A generic code reader will not pull nor clear all codes on the Sprinter. Where are you located?

rossco
03-12-2013, 10:17 PM
Yes. For sure. None around that I know of. Marquette, MI. Looking to try getting through as much as I can through other options

Aqua Puttana
03-12-2013, 10:31 PM
...
It goes in and out of LHM... was able to get an EGR code and MAF codes cleared and they have not come back.

...Any help is very appreciated!
I'm certain that you realize that just clearing the codes doesn't repair any problems.

A problem with having used the generic code reader to clear codes is that you may have cleared some specific information which may have helped in diagnosis.

An example...
I was having trouble with my 2004 going into LHM and cutting off the turbo. Using a DAD scan tool (very Sprinter friendly) I read a Air Mass DTC, an O2 sensor code, and another that I'd need to check my notes to recall. I recorded and cleared the codes to see what would return. The Air Mass code returned... again and again. I never saw the O2 code again and figured that it was old history. Long story short, after trying many things my LHM and no turbo problem was corrected when I replaced the O2 sensor. I got that initial O2 DTC and never saw it again even though the O2 sensor was the total problem.

So the point of my story is, just because a code doesn't return does not mean that the original information wasn't accurate.

Was the rotating valve on your EGR sticking? Did you check for that before cleaning the EGR? If the EGR valve was not hanging up mechanically then just cleaning the EGR may not have resolved anything.

Air Mass is a calculated/verified value. Air Mass DTC's can be related to EGR, MAF sensor, IAT issues, O2 sensor, Boost Pressure feedback, and others which don't come to me now. An Air Mass code doesn't necessarily mean that you have a MAF sensor problem.

Sorry I can't offer more. vic

rossco
03-12-2013, 11:30 PM
Yes. I'm aware that I didn't fix anything and I need a better computer to diagnose. I also know that it could be the o2, iat, maf or none. Everything I did today was because it was easy to do and easy to clean to rule out a simple thing like dirty egr. The wings spun open easily. I cleaned the o2 sensor with electric cleaner but not the maf. The Egr was just replaced with new mb a few months ago

Looking for ways to diagnose a turbo issue without a computer or any other way to check through things. It really seems like air is either not going in properly or out properly. Just don't know why.

I really appreciate any and all help. I live far from any good mechanics that I trust up here.

Thank you

autostaretx
03-12-2013, 11:47 PM
P0401 EGR Sys Failure

--dick

Aqua Puttana
03-13-2013, 12:03 AM
...

Looking for ways to diagnose a turbo issue without a computer or any other way to check through things. It really seems like air is either not going in properly or out properly. Just don't know why.

I really appreciate any and all help. I live far from any good mechanics that I trust up here.

Thank you
IF it is turbo pressure related, some information, not a diagnosis.

The Garrett turbos are very reliable. I'm convinced that many get blamed and changed out only to find that it doesn't cure the problem. It could be bad, but I wouldn't jump to replacing it.

The OM647 turbo actuator linkage has some history of seizing up. It is fairly easy to access to check movement and grease it. A search from the blue bar above should get some information.

There's some info in this link about how I pressure tested my turbo system.

http://sprinter-source.com/forum/showthread.php?p=161278#post161278

Good luck. vic

autostaretx
03-13-2013, 03:57 PM
On Monday afternoon when I went to start it again, it started perfect, after 2 minutes or so it started shuddering. Sounds like it's bogging down then gets a burst and comes back to life. Eventually it stalls out and dies. I can restart it no problem, even drive it around after a bit without it dying.
The "2 minutes" sounds like it's transitioning from the "slightly rich, higher RPM" "cold engine" mode to "warm engine".
If it was a typical carburetored gasoline engine i'd be thinking that the main jet was plugged/dirty (of little consequence when the choke was closed)

Given the injected diesel we have, i'd guess that more than one injector was not working... when cold, the higher idle speed gets the engine past the whimpy cylinders... but when it tries to "idle down", the lack of a few becomes very apparent.
But yes, it could still be an over-active EGR pumping too much exhaust back into the intake stream, starving the engine of useful air.
It could be a leaky injector (perform the leak-down test)... at low RPM the rail can't keep up pressure, but at high RPM it can?

How clean is your air filter? (but working well at faster speeds speaks against that guess)

You could call Dr Andy: 412-366-6165

--dick

rossco
03-13-2013, 06:12 PM
Thanks Dick:

I just replaced fuel filter, Air filter is dirty, little bit frozen (lots of bad weather here and just drove through a storm of rain and snow). I am going to replace that today too but doubt it is cause.

I did a DIY leak off test this fall after replacing a couple injectors and everything looked really good, hope that they are still good but I will probably check next.

calbiker
03-13-2013, 10:23 PM
I've had that on my '91 VW Westfalia. During the first ~ 2 min the engine operates "open loop". No O2 sensor control. Van ran great. After 2 min, like crap; fuel way too rich. It was a bad O2 sensor.

Cal

The "2 minutes" sounds like it's transitioning from the "slightly rich, higher RPM" "cold engine" mode to "warm engine".
If it was a typical carburetored gasoline engine i'd be thinking that the main jet was plugged/dirty (of little consequence when the choke was closed)

Aqua Puttana
03-13-2013, 11:12 PM
I've had that on my '91 VW Westfalia. During the first ~ 2 min the engine operates "open loop". No O2 sensor control. Van ran great. After 2 min, like crap; fuel way too rich. It was a bad O2 sensor.

Cal
Cal,
That is interesting, and good, information to have. :thumbup:

I did some searching to try to nail down our Sprinter 2.7L diesel operation.

I tried 2.7 Mercedes O2 start, sequence and a few other combinations with no definite information. I then tried using Bosch with O2, control, etc. That got me closer, but I never did nail it. I did find this which I think is related more to gas engines:

"The sensor does not begin to generate it's full output until it reaches about 600 degrees F. Prior to this time the sensor is not conductive. It is as if the circuit between the sensor and computer is not complete. The mid point is about 0.45 volts. This is neither rich nor lean. A fully warm O2 sensor *will not spend any time at 0.45 volts*. In many cars, the computer sends out a bias voltage of 0.45 through the O2 sensor wire. If the sensor is not warm, or if the circuit is not complete, the computer picks up a steady 0.45 volts. Since the computer knows this is an "illegal" value, it judges the sensor to not be ready. It remains in open loop operation, and uses all sensors except the O2 to determine fuel delivery. Any time an engine is operated in open loop, it runs somewhat rich and makes more exhaust emissions. This translates into lost power, poor fuel economy and air pollution."

http://www.gnttype.org/techarea/ecmsensors/O2sensors.html

I know that the Sprinter Bosch designed engine control uses a heated O2 sensor for the Sprinter 2.7L engine. That MAY mean that the "open loop" mode doesn't apply for our Sprinters. I know that information still leaves many questions, but maybe it will spur some discussion. FWIW. vic

rossco
03-19-2013, 06:01 PM
Thanks for the help gang. It was my Mass Airflow Sensor. MAF

I was able to figure it out by unplugging it. I forget where i read that... once i unplugged it the weird idle and low end throttle response went away. Also, my friend has identical model sprinter and I pulled his charge air sensor out and put it in mine which had no change so I eliminated it being a false code read from a different sensor.

It was hard to get it narrowed down by this because it took a really long time to get the MAF code to appear. At one point I had an EGR error code as well, but further investigation found it working fine. (i did clean it to be safe)

I think my next big project after looking through everything is to clean out my intake/egr manifold. Super caked walls with soot from EGR. Seems like a pretty intimidating job.... any tips?

surlyoldbill
03-21-2013, 12:50 AM
Thanks for the help gang. It was my Mass Airflow Sensor. MAF

I was able to figure it out by unplugging it. I forget where i read that... once i unplugged it the weird idle and low end throttle response went away. Also, my friend has identical model sprinter and I pulled his charge air sensor out and put it in mine which had no change so I eliminated it being a false code read from a different sensor.

It was hard to get it narrowed down by this because it took a really long time to get the MAF code to appear. At one point I had an EGR error code as well, but further investigation found it working fine. (i did clean it to be safe)

I think my next big project after looking through everything is to clean out my intake/egr manifold. Super caked walls with soot from EGR. Seems like a pretty intimidating job.... any tips?

Switching to a good oil and using a fuel additive cleaned my manifold gunk, after a while. You can find EGR cleaning tips in the Write Up section. I use carb cleaner. Remember to get a NEW gasket.