Lightly modified MS6 bucking and extremely lean.

Hey y’all. Not new to the forum or the mzr engines. Just picked up a 2007 MS6. I learned my lesson on my ms3 that I still daily and checked compression before buying. 160psi across the board no fluctuation. The car has a AEM CAI and a bnr stage 1 turbo. Other than that it’s stock. It runs extremely lean and will go into the near 25s (afr) under throttle. I feel really bad because I had to drive it home. I did the fuel relief valve test. And it climbs over 1800 before releasing. So I believe that’s not the issue. It’s making plenty of fuel pressure. (I’m monitoring on my MS3’s access port). I’ll have a data log as soon as I get home this evening. It has a couple codes such as random misfire and overboosting (which it’s not) and MAF volt to high or low. The AEM intake doesn’t have straighteners in it so I don’t know if that could be an issue. More than likely getting that replaced because I don’t like the filter being in the bumper. any help would be much appreciated. I forgot to mention that when I got it, it was on a stock tune and I tried the stage 1 plus sf with no success

i did this yesterday and i almost had a heart attack looking at the afrs when I was driving home.

 

I remember the pulled the intakes without the straightener for causing issues like in 2008 or so and they brought em back with the straightener.

 

That fluctuation seems too extreme for just a missing air straightener

Any way of testing the O2 sensor?

 

Okay new intake will be on the way. I pulled the spill valve for fun. It’s rather dirty and there’s metal shavings in the spill valve area. The rod looks off center. I’ll be rebuilding the pump and putting fresh autotech’s in. I’m sure the pump may be freezing. I just hope the injector baskets aren’t clogged with shavings.

The hpfp seizing would cause huge fluctuations right? I just ordered the internals I’ll come back in a week and post my findings

Just wan

Just wanted to correct myself. That isn’t the piston pictured.

 

@Rustyms3 , get some Corksport hpfp internals. I did that when my autotechs seized up.

Oh and welcome back!

 

Well I just rebuilt the pump after I got off work today. It had factory internals in it and it did have some metal shavings but nothing looked worn. I put a corksport seal set and autotech internals. It still runs the exact same. I should be getting my intake tomorrow. Here's another data log. I didn't realize I had some of the log options messed up. This might give the trained eye more insight. These are just free revs.

 

I just tested the in tank fuel pressure, with it running and Revving I saw above 60psi the entire time. so I believe there isn’t an issue with fuel getting to the pump. Just trying to run down the list of possibilities.

 

Fixed the issue. I pulled the intake off my ms3 and put it on the MS6. It runs perfect. My Cobb should be here today. Thank y’all for the help. Hope y’all have a good weekend.

 

Hey Rustyms3 I was wondering why that intake was your problem and what exactly was making your car act the way it was. Thanks

 

I fixed this problem by tuning for the intake and replacing the MAF sensor. The intake is much larger than stock and the ecu wasn't happy with it.