Hjartarson

Hey guys,

I had my car dyno'd today, results as expected, 290 rwhp, hot day and no fan blowing on intercooler.

However, in the last pull of the dyno test the check engine light came on. I figured it was just something related to the car's dyno mode being off so I didn't worry all that much about it.

When I came back home (car ran just fine all the way, no difference) I take a walk around the car to check if something is amiss, and under the rear of the car I hear a hissing sound with a short interval between pulses. I wasn't able to identify the source of the sound, but it was definitely coming from the rear end of the car.

Anyone have any idea what it is? I'd rather not have to take the car to my ridiculously expensive dealer (yes, even by MB standards)

Best regards,
Hjartarson

ohlord

the code read and post it here.Borrow a scanner from a buddy,we can get them for $39 over here in the states and some auto store chains will read them for free if you don't want to spend the 39
maybe a vacuum line came loose from the evap canister.Get under her and look around.
ohlord
you should be able to locate the sound and if not any good independent mb shop can,Why go to the stealership at all?

evo2turbo

That sounds like the normal sound of the fuel pump to me.

boohooramblers

A HOT day in ICELAND ???!!!

Sure sounds like the fuel pump to me.

Hjartarson

Went outside again to check if it was still there, and it is. Tried to get as close to the sound as I could, but it's pretty hard seeing as the car is Germany-low, rolling on 17" and I'm a pretty big guy. The only fact I was able to establish is that the sound is about the same intensity at both rear wheels, which also seems to be the part of the car the sound is coming from.

Also, it's not really a hissing sound, it's more of a low-pitch chirp, if you know what I mean

Zeppelin

You have a puncture in one of your rear tires

Hjartarson

Both tires are fine, you can only hear the sound while the car is running

gnma

jack the car up, and find the problem.

ohlord

the code,it will point the way towards what is making the noise
ohlord

Hjartarson

Yeah, I'll go back to the shop tomorrow since they are aware that the light came on during the dyno test (which was performed by one of their employees)

I'm fairly certain that they'll at least diagnose it for free, I hope it's something minor.

Hjartarson

After about 200 km's of cruising, the check engine light disappeared.. so... problem solved I guess?

TopGun32

air pump.. ver common for CEL..

or a loose spark plug wire.. it happended to me a few times.. when I had aftermarket wires