Rickcross

• Car: 2018 c43
• Tune: stage 1 at the local Eurocharged
• Problem: Misfire p0300-p0306 (random)
• When: High Rpms, pedal to floor or almost
• Story:

Ran this car as hard as you possibly could stock for 10k miles since I purchased. Ran perfect stock, even the owner before me has an awesome service history. Had roughly 55k miles when I brought it in to Eurocharged. Literally within the hour after getting tuned, it misfired…. I called the shop, got insured that the car “was catching up to the tune” ? I believed it since it stopped as soon as the engine restarted. Within a couple days, it did it 3 times, so I took it back in just for them to say “my spark plugs were dirty” ? What? I got them changed at Eurocharged when I got my tune did the whole service b1, weird? so on I drive the car for a week or so no issue, then it does it yet again, go in to get my coils changed, does it again. Mind you every time I bring it in they swear it won’t do it while they’re test driving… of course I just happen to live 2hrs away and have a bunch of misfire codes and cel every time I bring it in lol they say everything’s fine, well I broght it in for what I think is the 4th time and they say they can’t find anything wrong and reset the learning computer and said that’s good, well of course it does it again same day bring it in and within 45 minutes they apparently checked all my fuel injectors (also unplugged my dashcam?) and said I need to replace 2 of them, cylinder 2 and 5 (even though these cylinders rarely are the ones that misfire?) but said I should do all 6, quoted me just a little short of $4k, if this was the problem all along why have they told me 3-4 other times this and that was the problem and the solution never worked it’s hard for me to trust their input now, they just told me it couldn’t possibly be the tune, even though I drove aggressively for 10k miles previous to the tune %100 perfect (and was told “it’s normal the car has to adapt to tune” now it can’t be the reason?)

I will not list the location of shop as I want to give benefit of doubt but I am in Midwest USA

The shop has always been timely and straight forward I’m just getting deep into this car and don’t want to spend 4k just for this not to fix it

TwoC400s

$4k for injectors is crazy talk.

Straight from MB with new fuel rail seals it's like $1100 in parts.

It's a very simple 3.5 hour job for a competent tech.

Rickcross

Could you maybe send a link? I found “oem” parts for close to $3k after everything, but I also found a set of 6 injectors and seal kits for about $1300 on fcpeuro and going to have to spend about $100-200 on a tool to code the injectors.

TwoC400s

Use the FCP Euro parts.

The Mercedes injectors are Bosch, there's no difference between them and MB parts (you occasionally get one that has the MB logo on it), the seal kits are 100% MB packaged parts.

TwoC400s

Or, you could do what I'm doing.

I found a used set of six with fuel rails on eBay for $250, I sent them to The Injector Shop for cleaning, rebuild and piezo regeneration.

I ordered six seal kits and a drift tool from FCP Euro. My neighbor has an Autel that can program the new injectors.

Rickcross

awesome, definitely taking one of the routes you recommended, going to have to get myself an autel but it’ll be nice to have and will still save me a hell of a lot money

TwoC400s

The Launch x431 Creader 2.0 Pro for Mercedes will program injectors and it's $189 on Amazon

Rickcross

thanks I will be going with that as there’s limited information on obd tools and whether or not they do injector coding. Also getting a special tool to pull the injectors, figured why not.

Rickcross

I did all 6 injectors and seals and still misfiring unfortunately.

TwoC400s

If you bought the Launch C-reader you should be able to monitor some real time data, maybe look at fuel trims, etc and see if something looks out of whack.