Ben

Anyone experience pre-ignition with their MB? I get some clatter/rattle when going up steep hills while on throttle.

I use premium gas (92) and had the ECU upgrade done. The ECU upgrade actually corrected 99% of the clatter but now I'm starting to hear it again when my windows are rolled down.

Any advice/info is appreciated.

chiromikey

i don't drive a 63 but i used to get detonation frequently upon hard acceleration during the summer because of increased heat (iat's) and poor summer gas blends but since i've ugraded the intercooler i don't hear it like i used to.

be careful bringing this up with your dealer. their quick fix will be to set the ecu to run on 87 or 89 octane and you can figure out what that will do to power (and good luck getting them to change it back if it reduces the problem).

jangy

doesn't it sound like the timing is advanced and not retarded?

jangy

I would look into another brand of gas?

chiromikey

yes, and by setting the ecu to run on a lower octane fuel you're retarding the timing.

i also a agree with trying a different brand of fuel before anything else.

jangy

Any other mods on the car? These cars love to run pig rich. Anything to push that will have you balancing between max detonation and dumping fuel, loosing power and efficiency.

I'd look into what the ECU mod was and why? Do you have other mods? If no on intake and exhaust, then why do an ECU mod?

Since it is running that way, try a different brand of gas and maybe even some higher octane?

Ben

Thanks for the input guys.

Nope. No mods done. Bone stock.

The ECU upgrade (by dealer) was done to allow the 1st-gear start when in Sport mode. Prior, Sport mode always started in 2nd-gear.

The highest octane available up here is 92, unfortunately.

I was thinking gas initially, but I'm using the recommended gas station (Chevron). I'll try another Chevron station and maybe another company.

jangy

Got it. You shouldn't be having issues. I would let the dealer diagnose it. make sure you take it in hot and try to duplicate the issue. There are many ways you could try to troubleshoot this, but why not let MB do it?

BlownV8

I was having that same problem. My fuel filter was partially clogged. I didn't get detonation all the time but it was pronounced when taking a sharp turn from a stop with a heavy dose of throttle.

jangy

Hmmm, not sure if the E55 examples are the same as the E63s.

Ben

Thanks. I meant a different gas company like a Shell station.

I think I'll try a new gas station before dropping her off at the dealership. Chiromikey got me spooked about the dealer adjusting the ECU to accommodate the lower octanes thus losing power.