Current situation
As you know I got stuck in limp mode a handful times yesterday. I'm theorizing that when I put the sprinter in cruise control it uses more of the turbo on hills resulting in me going into limp mode more often. So, I quit cruise control and made it 200 miles @ 70mph to St. Louis with no problem.
The cruise control does not downshift when it could/should (after all, *you* can *see* the hill you're approaching), so it has no qualms about forcing the engine to 100% load.
"Gentle" it ain't.
Theory on Diagnoses
I think its more than likely that my turbo resonator is cracked. It sounds like a common problem with the 2004s and I don't think the hoses are leaking. I'd like to make it the 850 miles to boulder CO before taking her into the dealer and thinking of risking it.
Since being gentle lets you get to 70, that's most likely the case and Boulder an achievable goal.
- having misdiagnosed the problem and getting stranded and/or damaging the sprinter, although it seems like there are only a handful of reasons the sprinter goes into limp mode and its very probable that it is indeed my turbo.
Many folks would say "there are
far too many reasons the sprinter goes into limp mode..."
..and you're not really seeing "limp mode" .. you're seeing more or less "whimp" mode (see after next quote)
((true Limp Mode entails "stuck in 2nd gear" and "cannot exceed 2800 (or 2000) rpm))
- the turbo resonator crack getting worse and getting stranded and burning my turbo out.
Your turbo is safe... "whimp mode" happens due to the engine control module (ECM) deciding to *stop* trying to use the turbo.
So your diesel becomes a "normally aspirated" engine ... the ECU sets the turbo to "don't boost, just coast" ... no way it's going to get burned out.
I know you haven't seen the sprinter, but if we're on the right with this theory, is the issue stable? or can/will it worsen?
Mine went from "so lightly cracked that it wasn't noticeable (except for a suspicious light build-up of tarry oil deposits nearby)" to "blooey at 65 mph" by driving over a significantly bumpy railroad crossing (and even then didn't really "show up" for another 60 miles).
So: yes, it
is possible for it to suddenly get worse (we're talking plastic expanding a crack... so significant shocks while boost is pumping could certainly enlarge it).
But: Cleaning it, adding JB Weld, some wire-wrapping and duct tape have shown to effect permanent repairs for other folks (which is why i went shopping for such when mine blew ... but "gentle(r)" meant that i could drive another 1000 miles (Glacier Park, Waterton, Dinosaur Park, Edmunton, Jasper, Banff, over the Rockies, up Mt Baker, home) without actually having to stop and
apply the patches. I was lucky (crack didn't expand further), but i was also prepared in case i got unlucky.
Attitude helps ("Yes, Sprinter: i
promise i'll fix it when we get home. Your job is to get me home.")
--dick
(recommended reading: John Muir's "How to Keep your Volkswagen Alive for the Compleat Idiot" and Robert Pirsig's "Zen and the Art of Motorcycle Maintenance")