Would you be suspicious?

[KurtsM5]

Took my car to a shop to have the injectors sent off for cleaning and testing, and check the plug gap. Car has BM3 stage 2 93 octane, catless, aFe intakes.

Couple days go by and the shop calls me, say they need me to put the stock map back in it to troubleshoot an issue. I go down there and the guy tells me he thinks the car is down on power, 1 wastegate isn't working right(oh yeah? Which one?) BM3 is crappy compared to MHD(NO he doesn't have BM3), that BM3 somehow blocks the DMEs from throwing codes, and I have to put stock intakes back on it before he will work on it because these cars hate aftermarket intakes.

The car hunts a teeny tiny bit after it gets warm. Always has, since I got it.
The guy told me that until that is fixed, he's not pulling the injectors or plugs.

What do you guys think of this? Dude drives a 335, never owned an F10 M5.

[M5_Raz]

Some cars have shown weird behavior, especially on cold starts, with the aftermarket intakes. The oiled filtered intakes are worse because it clogs the MAF sensors.

What do you mean the car hunts after it gets warm?

BM3 is much better than MHD for S63TU engines. They’ve had support for us for many more years, whereas MHD just got it fairly recently. BM3 doesn’t block any codes.

Honestly, if it was my car, I would take it to someone that knows S63TU engines very well, preferably even builds them.

[KurtsM5]

By hunt I mean the rpm at idle varies a little. I mean a little. As it's always done it I assumed it was the DMEs doing DME things, adjusting something or another.

I went and got it yesterday and took it home. As I approached the place I noticed a brand new set of drags on their street. When I got in the car, D was in 1, S was in 3. I never do that, unless I'm going to punch it---M1 has both D 3 S 3. So I'm pretty sure my car got beat on by their mechanic. Never going back.

[M5_Raz]

Everyone wants to take these cars for a joyride. They’re rare, I seldom see one on the road in California. Even more so if they’re stage two, catless, and modded.

Idle variation could be if plugs/coils are old or gap is too small.

I’ve taken mine to renowned bmw performance shops that left me disappointed in their diagnosis and mechanic skills. Currently drive pretty far to Steve Dinans shop, Carbahn Autoworks, if I need anything.

[KurtsM5]

Thanks, Raz. I'm going to take it back to the place that I used before that is a hike for me, but the guy who worked on it before owns a modded F10 M5. The lsat shop that worked on it in Ga replaced the plugs and coils. They couldn't determine what tune was in it-it definitely had a tune as no CEL and catless. So they asked if they could stock flash it and I agreed. I emailed that shop the other day about the gap, and the shop owner said that since they stock flashed it they left the 97506 plug gaps alone, being .024-.025, which I'm really sure is incorrect. From NGK's website,

NGK 97506 SILZKBR8D8S Laser Iridium Spark Plug
Thread Diameter12mm
Thread Pitch1.25mm
Seat TypeGasket
Reach26.5mm (1.04")
Hex Size14mm Bi-Hex
Terminal TypeSolid
Overall HeightISO
Gap.031" (0.8mm)