Jaybird123

Have by had two cylinder misfire events in recent past, I am seeking info on approximate costs for each test, plus any tips on what to ask before and after?

Is it recommended (or required) that dealer perform these tests in order to qualify for MB extended warranty claim on engine?

CaliBenzDriver

Let the independent MB dealer diagnose your "misfiring" issue the way they like.

They may start with ignition tune-up before replacing couple injectors and conclude it's a low cylinder contribution when the same faults keep returning.

Jaybird123

Well, being a 12/2014 engine, I only have until this December to prove it warrants the big replacement job.

It only has 57k mi on it, however I noticed in the carfax history that ignition coil(s) were replaced in 2020 and spark plug(s) this January. I have asked a friend to try to secure the VMI so I can inspect the ‘WHY’ for coil replacement(s) at such low mileage. Going into limp mode two weeks after purchase doesn’t leave me wanting to wait around and see after extended warranty expires

CaliBenzDriver

I hear you... it's not gonna be easy.
The establishment is gonna play the clock against this issue.
Pay dealer for a compression test so they don't delay your job.
Based on the results get the misfire worked on to warranty the misfire fix.
..

JettaRed

iTrader: (1)

Jaybird, do you have XENTRY? There is a relative compression test you can do that measures the difference in rotational speed for each cylinder. If the difference between the fastest and slowest is minimal, then you likely don't have a compression problem. If the difference is significant, then I would proceed with a manual compression and leak down test. There are probably YouTube videos showing you how to do each. Are you handy mechanically? If not, take it to a shop.

That said, I would not jump to the conclusion that you have a compression problem because of misfires.

PeterUbers

i had bad coils as early as 36,000 miles ... then routinely replace them every couple years. I have a 2014 that I bought brand new, now has 46k miles. 2018's and 2019's w213 e63's also getting new coils occasionally - plenty of threads on that on the 213 amg side

Jaybird123

I don’t have XENTRY…yet! That sure does make it even more urgently desired. Thanks. I had heard of that test, but then read other comments about it no longer being…available? Or conclusive or something

Jaybird123

interesting…I certainly want to be overreacting about the issue. Yet at the same time I don’t want the window to close on coverage for such an expensive repair should it prove necessary. I hope to have this car for 5 years, preferably without frequent misfires and limp mode scares. I’ve found out tonight that only the #1 cylinder coil has been replaced previously. Also, since I replaced #5 coil and plug, I haven’t had any misfire issues.

Jaybird123

I’m noticing (suspiciously) that FCP is showing Backordered status on their coils, while every other site I visit (AutohausAZ, Amazon, etc) has plenty in stock. Any idea how long FCP has been backordered? Guess I’ll call today and see if they can provide an ETA for stock

JettaRed

iTrader: (1)

I would be cautious about buying from Amazon unless the seller has been listed for a long time and has good ratings. WRT AutohausAZ and others, check to confirm they have the product in stock. Just because you can complete the purchase doesn't mean the item is available. For genuine parts, some sellers simply drop ship from a Mercedes distribution center and they don't have real-time knowledge of what is available.

JettaRed

iTrader: (1)

When you are ready, I recommend contacting @BenzNinja about XENTRY and the other components you will need.

Jaybird123

I’m still hoping to hear from anyone that has had these tests performed…

Approximate costs, time to perform, dealer or not, etc

JettaRed

iTrader: (1)

Have you searched and watched any YouTube videos on how this is done? It’s not rocket science. I would do it myself, but that’s just me.


But if you want to pay a shop to do it, you will need to call around.

Jaybird123

I had not but just did, thanks to you! I’m off to buy test gear now, as I already have half of the coils and plugs removed. THANK YOU!

JettaRed

iTrader: (1)

Good luck. It's been a while since I did a physical compression test, and then it was on a traditional port injection car. On that car, I pulled the fuse to the fuel injectors so I wouldn't flood the cylinders with gas. You may want to check if you do the same with a direct injection engine.

JettaRed

iTrader: (1)

This guy says to disable both the fuel pump and the spark ignition by pulling fuses. (The interesting this is that when using XENTRY to perform a relative compression test, the fuel and spark are electronically disabled by the ECU.)

JettaRed

iTrader: (1)

Just watch for tips. I don't know if a running test is needed.

JettaRed

iTrader: (1)

I've never done a leak down test myself, but this is interesting.

JettaRed

iTrader: (1)

More good info. Seems every video you learn a little more than the last video.

Here's the leak down tester used in this video: https://a.co/d/5pPvNzo