boost control valve problem adjusting - PeachParts Mercedes-Benz Forum

TurboSDL · #1 06-15-2009, 06:36 PM

my boost control valve wont let me adjust the turbo below 14 psi. when i am on the hwy and i put the pedal to the floor the boost goes to 14 psi, iv switched to a different boost control valve and the same thing, its bottomed out and still 14psi, one thing i noticed on this one tho is there is a small hole on it for some reason do u think i should try plugging it? im assuming my performance is suffering since i havnt adjusted the ip yet to be running at 14 psi. from what i hear i should be at 12 psi and before i installed the valve i was at like 9 psi... i can turn it up higher than 14 psi just wont go lower... any suggestionss? the hole thats on my boost control valve now is like on the side almost looks like its there to relieve it if the screw is bottomed out so the wastegate wont stay open all the time or somthing.

TurboSDL · #2 06-16-2009, 03:49 AM

anyone?

LUVMBDiesels · #3 06-16-2009, 05:35 AM

14 psi is fine. If you go over 16 the overboost circuit will cut in and shut off the ALDA (if you still have it) I run at 14 with no problem.

What I did was take the boost controller and hook it up to my MitiVac, set in pressure mode, and then adjusted it off the car to 14 psi. It worked great.
The other thing I did was take off the original connectors and put on 1/4 inch pipe nipples that were the same inside diameter as the original hose.

The best way to tell is by installing a pyrometer. It is the combustion temps you really need to be checking.

TurboSDL · #4 06-16-2009, 05:02 PM

i didnt turn up the full load screw yet tho shouldnt i be at 12 psi and no higher? arent i just choking the exhaust with the extra 2 psi?

LUVMBDiesels · #5 06-16-2009, 06:54 PM

The 2 psi will not matter... The engine will just not use the extra air unless there is fuel to burn

oldsinner111 · #6 07-27-2009, 06:22 PM

My fuel mileage was getting worse as my valve was leaking,boost was 9.5psi. I have it fixed temporary,I keep it under 15psi,sometimes she'll hit 19psi.No fuel cut off.

Simpler=Better · #7 07-27-2009, 09:47 PM

Quote:

Originally Posted by TurboSDL

I didn't turn up the full load screw yet though . Shouldn't I be at 12 psi and no higher? Aren't I just choking the exhaust with the extra 2 psi?

The full load screw adjusts fuel delivery over the rpm range. Removing the rack limiter will give you "2psi" of extra fuel, fyi.

I run around at 12-13psi intake, I can peg 16psi if I stomp on the pedal in a hurry. My exhaust pressures vary from 3psi(idle) to 30psi momentarily (flooring it @ 2,000rpm)

Cruising @ "65" I see 12psi boost and 14psi exhaust at 600*F-700*F. Flooring it continually gets me up to 18/25 and 1,100*F (Up a mountain in 3rd gear)

argus445 · #8 10-10-2009, 07:08 AM

The stock level is suppose to be 12psi? and prolly under 15 since any more would likely just be heating the intake charge air unless u have a intercooler right?

oldsinner111 · #9 10-10-2009, 06:56 PM

Now that frosty morning are back 26 psi.