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View Full Version : Limp home mode. No boost.


Nett51
06-23-2015, 11:49 PM
I have been having this issue and read a lot of posts. Haven't found a solution so thought I would post. Sorry if it gets long.
I have a 2004 sprinter. It runs perfect most of he time. The only time it acts up is when I am going 65 mph or more going up an incline with the cruise set. The turbo will shut off and has no boost. If I shut the van off and restart it goes back to normal until I go up an incline above 65 again. I have replaced the resonator with the aluminum eliminator. Replaced all inter cooler hoses and map sensor. Also replaced Maf and intake air temp sensor with used ones. (Don't really know if they are good or not. I bought and scan guage 2 and check codes. No codes. Any suggestions would be greatly appreciated. thanks in advance. Nick.

autostaretx
06-24-2015, 03:51 AM
If you had something like a ScanGauge, DashDAQ or equivalent, you could see if it's MAP (manifold absolute pressure) -related.
When my resonator (i realize you have "the pipe") was *slightly* cracked, it would only lose it in the situation you described:
about 65 mph, or a bit under with a hill. If i tried to exceed 27 psi MAP, it would kill the turbo.

There have been occasional reports of people having the metal intercooler crack... but that would seem to be an "all the time" leak.

A shop diagnostic would be to pressurize the system (don't exceed 20 psi "gauge pressure" (which is 35 psi MAP)) with a smoke source. See the smoke, fix the leak.
Even the hose under the hose clamps can leak (there's a thread about that).

good luck
--dick

Nett51
06-24-2015, 11:15 AM
I have a scan guage and the most boost I see is around 18 psi. Does that seem ok to you? Have you seen the turbo its self leak causing a boost leak? Right before the turbo shut off boost doesn't seem to drop or change at all. Turbo just shuts off.

MillionMileSprinter
06-24-2015, 11:50 AM
The 18 psi you are seeing is most likely not that the turbo only producing 18psi, its most likely that you still have a leak somewhere that only shows itself during full throttle applications. A test you can do is to get a helper, pop the hood, have the helper put the van in REVERSE, set the parking brake, plant his left foot on the brake and push on the accelerator. Meanwhile, you have your head under the hood listening for the leak in the turbo plumbing. Good luck.

cloead
06-24-2015, 12:18 PM
The 18 psi you are seeing is most likely not that the turbo only producing 18psi, its most likely that you still have a leak somewhere that only shows itself during full throttle applications. A test you can do is to get a helper, pop the hood, have the helper put the van in REVERSE, set the parking brake, plant his left foot on the brake and push on the accelerator. Meanwhile, you have your head under the hood listening for the leak in the turbo plumbing. Good luck.

OOF

how about a boost leak tester? lol

http://www.benzworld.org/forums/attachments/r170-slk-class/333196d1285401296-diy-boost-leak-tester-image0261.jpg

pull intake off the turbo, clamp a boost leak tester on the turbo, pressurize the system.

you should be able to hear any leaks and track them down with a bottle of soapy water if need be.

Nett51
06-24-2015, 12:31 PM
I'll pressure check the system and hopefully I find the leak. What is normal under load boost psi?

cloead
06-24-2015, 12:32 PM
for testing purposes i wouldn't push past 20psi, you should be able to hear the leak way before that though (assuming there is one)

Nett51
06-24-2015, 12:42 PM
I am wondering for after I get it fixed. So I know what psi is normal to verify it is fixed.