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Let me preface this by saying that there aren't any Mercedes specific tuning shops within my area and the local Mercedes dealer isn't much help as they do not want to get involved whenever the car becomes modified. Therefore, I'm trying to diagnose and fix whatever may be wrong on my own and with help from others. The dip in the dyno graph was supposedly due to the factory torque limiters kicking in. The TCU flash didn't take/program when I sent it in the first time but have sent it back and had it flashed again. I'm also not pointing fingers or bad mouthing anyone but rather just trying to find out if my car is running properly or not.
While driving, car seems to run very well with no misses or drops in power. I hooked up my Star/DAS system today and the only error that is stored is P2010 - G/36 (right O2 sensor, after TWC {KAT}, Electrical fault (P0136, P0137, P0138, P0140). I am running catless downpipes and it seems that this code points to one of the downstream sensors after the cats, correct? As far as I know, the downstream sensors do not regulate AFR and are only there to report if the cat(s) is functioning properly.
I had the car dynoed last month and it made great peak numbers at 636RWP and 850RWT on a DynoJet. However, the AFR was extremely lean ranging from 14.5-13.5 throughout a 4th gear pull. I asked my tuner about this and they initially said not to worry about it and it was probably due to the dyno equipment being used "old sensor being used'? I asked the dyno operator and they said that they have three sensors which are date coded and they rotate on a weekly basis. The one used on my car was 2 months old. I told my tuner this and they now said that something may be wrong with the fuel system and to be careful. They suggested testing the fuel pumps, fuel filter, and fuel system in general to make sure that it is operating properly.
I do not want to needlessly start replacing fuel system components that may or may not need replacing as the car only has 12k miles. I did however order a fuel filter today of which I'll be installing next week once it comes in. I have a functioning Star/DAS system here and was wondering what my next step should be.
Are there two fuels pumps in this car (one for low and one for high)? Is there anyway to test these with Star/DAS to make sure that they are functioning properly and with the correct PSI? Should I replace both upstream O2 sensors?
I have catless downpipes as well and get bank 1 and bank 2 number 2 sensor codes every now and again. When the cel is thrown it causes the car to run odd and down on power. Just use star and cut the 2nd sensors off.
As mentioned, shut off your secondary O2 sensors. If catless, it can be sensing richness in the exhaust and leaning it out a bit. Shut them off and redyno to check. Bring a can of MS109 and see what kind of gains you pick up so it's not a waste. I'd run a baseline on 93 first to make sure the lean issue is resolved, if not don't waste the race gas or chance it.
Thanks everyone, I'll give that a shot first. I never got an actual illuminated CEL for the O2 sensors on the dash but the code was stored when I checked in Star.
Can someone please post a quick DIY on how to turn them off? I assume this isn't clearly labeled.
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