T1N limp home problem solved.

Tooth Fairy

Away with the fairies.
T1N limp home problem solved.

Ive had this problem for a while, the Sprinter is not my daily drive but it was driving me nuts trying to figure out the problem.

Ive posted various thoughts about it on 2 other threads I started about the problem, see below.
https://sprinter-source.com/forums/showthread.php?t=37209
https://sprinter-source.com/forums/showthread.php?t=37870

It was very frustrating chasing down the problem I must say. :thumbdown:

Thinking back it all started when I reinstalled the blower housing and reconnected the fresh air vent, the vent flap is powered from the vacuum source.
Now I know why it was disconnected in the first place, apart from the broken flap pivot

Today I went looking for the problem again.

Start with the basics Al, start with the basics.
Is there vacuum, yes, beauty, thats a start.
Is there vacuum to the turbo actuator, no, why not?
Check voltage to pressure converter, 12v, yes.
Check pressure converter coil for shorting, no, all good.

Ok, so it should all be working fine then, right?, wrong!!

So I checked the hose going to the vent flap, it seems ok.
I disconnected the flap hose at the T adapter that goes to the brake vacuum servo and plugged the T with a screw.

Started the Sprinter and applied the vacuum hose from the pressure converter to the turbo actuator, Eureka, the actuator pulled inwards as its supposed to do and the turbo came to life.

Put it all back together and went for a run around the block, bucket loads of power, and just a hint of black smoke, Im assuming the residual fuel will take a little while to burn through the system.. :bounce:


The vacuum T, small right hand hose goes to the door flap, left hose goes to the pressure converter.


The pressure converter lives underneath the air filter box, I have got so good at taking the filter box out that I can now do it in under 10 minutes....lol :laughing:



Thanks also to this website for helping me understand things a little clearer too.
http://www.mercedes.gen.in/WP35/mercedes-sprinter-turbo-limp-home-los-diagnosis-fault-finding/


Edit:-
I did at one stage plug the end of the vacuum hose at the flap door end with no result, so obviously there is a hole in the 1M long vacuum hose to it, Ill replace it and see what happens.
 
Last edited:

Ciprian

Spark Plugs not allowed!
Great you figured it out.

One thing about the black smoke. Our t1n vans are a bit more polluting than the newer ones, so they will smoke a bit if you step on them a bit harder. It's normal.
 

Tooth Fairy

Away with the fairies.
Quick follow up.
I replaced the vacuum tube and the sprinter is going great, I couldnt find a hole in the tube but there was a small rub mark.
 

surlyoldbill

Well-known member
I am currently experiencing the same initial symptoms; starts fine, runs normally on first few starts, then somewhere later in the day loses it's mojo. Manually downshifting helps with the short steep hills, but pushing in the gas pedal without downshifting yields almost no response on the hills, unless floored and then it automatically downshifts. My MPG is normal. I'll have to check the vacuum lines, thanks for the heads up.
 

Tooth Fairy

Away with the fairies.
I am currently experiencing the same initial symptoms; starts fine, runs normally on first few starts, then somewhere later in the day loses it's mojo. Manually downshifting helps with the short steep hills, but pushing in the gas pedal without downshifting yields almost no response on the hills, unless floored and then it automatically downshifts. My MPG is normal. I'll have to check the vacuum lines, thanks for the heads up.
Youre exactly where I was at with your mojo before the fix.
 

surlyoldbill

Well-known member
I'll check that out tomorrow. On the way home from SFO tonight, I hit the fresh/cabin switch and heard the door shut, but I tried it again and didn't hear it; maybe I did it too soon after the first try and it hadn't opened all the way again.
 

Tooth Fairy

Away with the fairies.
I took the sprinter for a run today and it was running bad again? :yell:

I took off the new vacuum hose and plugged the T with a screw and all is good again, now it looks like the fault may be in the flap vacuum actuator......

Ill just leave it as is, we dont get too many swings in weather or temp to need it shut.
 

Oldfartt

Active member
I had similar issues with my previous van. It turned out to be a leak in the turbo actuator valve, seen on the right in the picture. It can be removed and carefully taken apart. You may find damage around one of the gaskets. It was a number of years ago and I cannot remember all the details. However I think I resealed the gaskets with gasket goo and never had a problem since.

If necessary a replacement may be required.

Cheers

Ross
 

Tooth Fairy

Away with the fairies.
Finally found the bugger, it was a small hole in the hose that connects the vacuum pot for the fresh air door, just a pinprick but obviously enough to lose vacuum.

I found it by pushing the fresh air flap button whilst driving, mojo comes, mojo goes. :hmmm:
Hmm, so the leak has to be between where the hose connects to the flap actuator and vacuum pot..



It was in the top hose going to the vacuum pot.

 
Last edited:

MrTomacco

Mr. Tommaco
While we are on the subject of leaks I had surging under load, ran fine the rest of the time. Turned out to be a hole in the turbo hose to the intake so I was loosing boost.

Rob
 
Surley -
were you ever able to determine if you had a faulty vac line ? having same issues you described with my '03. replaced air intake hose, cleaned EGR valve, all helped, made it stronger, but still having the same issue with uphill and downshifting, loss of power.
I guess the '03's only year using the vac for the actuator before they went electronic ?
 

Top Bottom