JohnnyTurbo

Hey guys I just bought an 08 535i and was told that it had been tuned and boost turned up. How do I verify that this information is correct? Is there a way to see how much boost it is making without an aftermarket boost gauge?

Persian_535i

Depends on what type of tune he had done, was it an ECU tune which was programmed or was it a tune done by adding hardware such as a Cobb, Prestige, or JB4. If it is hardware then you will see it when you look at your physical cars ECU since it attaches to it. I'm gonna take a guess and say it was probably a hardware tune since it is much cheaper, the next question is did he leave the hardware on the car after he sold it to you.

JohnnyTurbo

I dont know what type of tune was done. Bought it at a dealer and they told me they think it has been tuned and the boost was increased. They told me after I bought it so I don't see why they would lie. I don't see any hardware mounted. I know it is making over 300hp, I have felt 300hp and it has to be making more than that. I am going to dyno it just to check the A/F and get some rwhp numbers next week. Where is the ECU on this model?

I also need to check for boost leaks just make sure there is not uncharted air coming in. Is there an aftermarket boost leak tester available for this model or will the computer tell me there is a boost leak?

I have some background knowledge on forced induction and other mechanical experience; however, this is a totally new animal for me and I am intimidated and excited about it at the same time.

Persian_535i

ECU is in the far back left corner under the hood when you are facing the car. You have to remove the cabin filter and a few other things to get to it.

zach1328

Your butt-dyno might tell you its more than 300hp, which it is. BMW quoted them at 300hp and 300tq, however the real numbers are closer to 320hp and 330tq bone stock.

You've driven other 300hp cars - not this one! The 535i is very quick for its power numbers. There aren't many 320hp, 3700 lb cars that are as fast as a 535i thanks to its torque band which spans all the way from ~1400-5200 rpms.

It could be tuned but there is really no way to tell without dnyo numbers or directly seeing the software. Try holding the volume down and channel down buttons on your steering wheel simultaneously with the radio turned off. The JB4 is the most common tune and it is controlled by those steering wheel buttons.

Also, post your dyno results after you go. Stock numbers should be somewhere around 270whp and 275whtq. Anything over 300whp and you've definitely got a tune or other mods.

JohnnyTurbo

Thanks for the info, I will post the numbers when I get them,

JohnnyTurbo

This may sound ignorant but how do you turn the radio off? Dose the car need to be running to do this?

Duperstar

It's never really off, just muted. Push the volume button in.

Booyaazaa

Yep just mute it. OP- nice color combo.