Hi everyone!

I have turbo converted my OM606.910 with OM606.962 exhaust manifold and turbo, replacing the wastegate with a manual one, boosting about 0.6 bar.

It is however not running too well, bogs down a bit when I give it full throttle. I have the stock fuel pump, untouched.

Could this be happening from getting too much air/too little fuel? If so does anyone have a guide to adjust the fuel for a RS203 pump? I am only finding guides to MW and M-type pumps.

Thanks a lot in advance!

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1985 W460 300GD OM617.912 w/ STT turbo (ongoing OM606 engine swap)
2011 W212 E220 CDI

RS203 is the governor type, you have an M pump (although to confuse matters you actually adjust the governor anyway...)

Although I've never heard of lack of fuel bogging down as such (ie worse than when it was NA?) but you'll want to adjust the fuel setting anyway otherwise there was virtually no point in turbocharging the engine

I'd check your lift pump just in case its a fuel shortage issue FWIW

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1978 300D, 373,000km 617.912, 711.113 5 speed, 7.5mm superpump, HX30W turbo...many, many years in the making....
1977 280> 300D - 500,000km+ (to be sold...)
1984 240TD>300TD 121,000 miles, *gone*
1977 250 parts car
1988 Toyota Corona 2.0D *gone*
1975 FJ45>HJ45
1981 200>240D (to be sold...)
1999 Hyundai Lantra 1.6 *gone*
1980s Lansing Bagnall FOER 5.2 Forklift (the Mk2 engine hoist)
2001 Holden Rodeo 4JB1T 2WD

Thanks for your input!

Oh, it's an M pump? I thought that was for OM617? Where is the RS203 used then?

First impressions is worsened performance. I don't fully understand diesels. I know they run lean by design, but can this be a case of it becoming TOO lean, from the turbocharging? I expected same performance, since I haven't touched the pump, but it got worse...any ideas?

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1985 W460 300GD OM617.912 w/ STT turbo (ongoing OM606 engine swap)
2011 W212 E220 CDI

The M pump has been around since the OM616/617 days and probably longer than that in non-Benz applications. It became the standard pump on the OM60x series engines.


Turbocharged engines either run excessively rich under a no-boost condition, or have some scheme to increase fuelling with boost pressure. Mercedes (and a lot of other manufacturers in the 70s/80s/early90s) went with the aneroid capsule (ALDA). The basic idea being that as boost pressure built, the fuel was enriched to build boost further ensuring that the fuel was matched to the incoming air for complete combustion, lack of smoke, and good economy.


If you just bolt a turbo to an N/A engine and do nothing to the stock fuel setting, you've just installed a restriction in both the intake AND the exhaust. There is no excess fuel to spool the turbo, and even if it did build any meaningful pressure, you have no additional fuel to take advantage of the extra air charge.


I don't know about tuning the OM606 style pumps or if you could get away with swapping in a pump from an OM603 turbo (there are far more people that know WAY more than I do about things like that on the Super Turbo Diesel forum), but something's gotta get done to increase fuel or that turbo is pointless!

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Hi Diseasel300,

I’m referring to your explanation “ There is no excess fuel to spool the turbo, and even if it did build any meaningful pressure, you have no additional fuel to take advantage of the extra air charge”

I’m somehow experiencing lack of fuel pressure only on 0-2000RPM, there is hesitation for 2 seconds to move the car. Car is 300GE swapped OM606A with IP and stock turbo. Maybe you can enlightened us to solve this issue? Thanks Chris

For anyone curious, the RS governor adjustment instructions are on pdf page 329 (M21) in https://ia902907.us.archive.org/24/items/warchive/W-400_003.pdf from the collection https://archive.org/details/warchive. There are also test specs in the WP pdfs.