TheDoughboy

Being a new 300 owner... I was peeking behind the battery just to check out what's there. I did notice a control box of some sorts with a Knob on top, and I'm just wondering what it is. I did not touch the knob. I searched the forums with no luck. Any ideas?

Thanks!

Ron

oliverb

Hi;
This device is called by some the "Engine Control Module" and performs various functions depending on the year of the car. I beleive yours controls four things but I only remember AC function & fuel pump relay. A very important part and quite pricey.
OliverB

mhorn

I believe the older W124's had a seperate relay for the fuel pump and a/c and something else. The fuel pump relay was notorious for going bad. On later cars they combined all those relays into that box. I wondered the same thing about it when I first got my car. It took all my self control not to mess with that knob on top to see what would happen, but hey, I'm the same person that as a kid stuck coat hangers into electrical sockets to see what would happen.

TheDoughboy

Thanks for the info guys I will be sure to leave it alone.

Ron

AMG_Fred

try it out.. maybe you'll get 20 more mpg... haha just kidding.. now im wondering too...

TheDoughboy

Yeah I wish, I am still getting way better mileage than my Grand National did. I removed the resistor yesterday, Big difference in the power I pulled the dist cap for a look, time for a new one. So I ordered a cap, rotor, wires with all the plastic covers.

One of the terminals in the cap is real toasted, so this should help the power and mileage even more.

Ron

AMG_Fred

err, did you take pictures? i don't know if mine are good/bad. and where they are. and it really did give you more power? i thought that was just a myth. about how much mpg are you getting? im getting about 18 mpg with 50/50 mix of highway and streets

TheDoughboy

Pics of the cap & rotor? If so then no. When I get the parts and install them I can take pics and email you them, just so you will know where they are located. I am getting 17mpg with 70% street & 30% freeway. Driving from Phoenix to Seattle (all freeway) I was getting 25-27mpg depending how how much a/c was used.

As far as the resistor goes, Hell Yeah!! I noticed instantly I press the accelerator. I have More giddy up with Less press of the pedal. The complex I live in I have to drive up a steep hill. Now I can go up it barley pressing the gas, before I had to press it down a bit. I have not hit the freeway yet, but on surface streets it feels as if I removed 300 lbs from the cars weight. Revs up a little quicker too.

I only run 92 octane and keep the resistor in the ashtray, just incase of any pinging. Can wait to get the cap rotor & wires!

Ron

Nick_M_51988

i thought that black box was the control unit for the fuel injection

YNVDIZW124

Hey i tuned my benz to get 23-25mpg 70% freeway and 30% street on 87 octane! Yes i said it beeachez 87 octane! LOL j/k I do get the rough idle once in a while but is not that bad. Also i just installed a new set of injectors so that makes the driving smooth as silk and i add a bottle of lucas fuel treatment every 3-4 fill ups. LnkPrk told you that your car is running too rich!! 18mpg! that not a lot.

AMG_Fred

so what do i do to fix it? weren't we going to have a thread for diy stuff?

YNVDIZW124

i guess but it's more of a turn this move this and see what it does. Since it take a little bit for the computer to make the adjustments too.