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Edit..
Never mind went back and reread the OP

Savage-wp

I hope the tune fixes it for you. Let us know.

But surely the insurance company won't be very happy for spending that kind of money replacing the engine, when there was nothing wrong. Or will MB dealer give a story to the insurance as to why the engine was replaced.

Blake_von_Texas

The engine did have to be replaced, as when a piece of the failed valve guide got into the bottom end, it popped off one of the piston rings and chewed it up. This misfiring issue seems to be a different and unrelated problem.

Blake_von_Texas

Ok guys. I went and got the headers tune today, the car runs better, but it is clear as day that the issue is still present. When at idle in drive, if you gently let off the brake and start rolling forward, the car will roll forward but has a slight rhythmic lurch, much like it is misfiring but at the same time it is not throwing a code. I can also definitely tell that the car is down on power. In neutral the car revs great and is very snappy, but when there is significant load on the car it feels like the car's power is at about half of what it should be. Also, when getting into the throttle a bit and short shifting, you can hear this kind of crunchy/clicky sound but only when the windows are down. Could this be the fuel pump failing? Given that the issues really only arise when the motor is demanding high amounts of fuel? I spoke to another amg technician in Houston today and he is confident (given the symptoms) that the issue is a bad coil. I'm confident now that the issue does not lie in the headers or cats. I'm open to any insight or suggestions.

Blake_von_Texas

I just found this thread and his issue seems to reflect mine exactly... https://mbworld.org/forums/cl-class-...coil-pack.html

He says; "Car ran fine when restarted. But, when I floor it, it throws a CEL again and starts to run like a total dog. Gears all still work, so it's not in limp mode, but feels like it. Restart the car, and it's fine again, until I floor it.

Pulled codes and have misfire on cylinders 4, 5, and 6.

I'm assuming the passenger coil pack went out."

Savage-wp

Sorry, missed that part.
Still awesome that you have a brand new engine. Hopefully the tune sorts you out, and you can start enjoying the car.

Savage-wp

It's worth changing the coil packs.
Did you have the car on the dyno after loading the tune? If so, what did it make.
Can you hook up an external fuel pressure gauge while on the dyno. If the pressure drops a lot at WOT, then you could have a faulty pump.

Blake_von_Texas

Ok so after taking the car back to MB today and going for a test drive with the foreman. The new suspected issue is that the cats are clogged. The car did previously have multiple coils replaced, so I know that at one point lots of unburnt fuel was being dumped into the cats. Tomorrow morning they will be pulling the O2 sensors in front of the cats and running the car to see if that helps.

Blake_von_Texas

Sure enough it was the cats!! They were so melted that the contents of the right bank cat was starting to get forced down the exhaust! I'm shocked that MB or my previous mechanic didn't catch this until I suggested it. I put new high flow cats on the car and my god is it running strong now. On the asphalt roads around my neighborhood it'll spin the tires through 3rd gear. Now the only problem is getting it to pass inspection! I found a place that said they will hook up a different car to the OBD test so that it'll pass emissions and then they'll put all my information on the certificate? Does that sound possible?

Evileight

Glad to hear you have your car working!

That does not sound possible on our obd2 cars. As I understand the emissions machine pulls the vin from the cars ecu to send it in for your registration. What your talking about would also be illegal.

Blake_von_Texas

One other question; at idle when in drive, if I let off of the brake very slowly to start creeping forward, the car will kind of pulsate its way forward, but as soon as i touch the throttle its very smooth. Should I be concerned? No CEL and no stored codes.

zcct04

Glad to hear that you finally got your car running - congratulations!

This is certainly true in Texas with the new single-tag system. The inspection machine records your obd2 codes, sends your results electronically to the State, and the State has to confirm a VIN match in order for you to get registration renewed. I'm not sure, but I no NOT think that your OBD has to show a pass for every one of the tests.

That too . . .

Why do you think that the hi-flow cats won't pass? Or is there something else that'd cause the OBD to fail you?

Blake_von_Texas

Thank you I'm very glad about it to say the least!

And I have twice attempted to get all 8 sensors to display "ready" by driving around with the stock tune very tenderly, but after 15-20 miles it will throw a CEL for "catalyst system below efficiency), and on the other hand if I'm running the tune, the 02 sensor and "heater" will read as "not ready". So I'm in a catch 22 here.

Are you sure that it pulls the vin during the OBD test?

zcct04

From https://www.txdps.state.tx.us/rsd/vi.../faq_obdii.htm
For vehicles year model 2001 and newer, we allow one (1) non-continuous monitor to be Not Ready and still pass the test, but two (2) or more Not Ready's will cause the vehicle to fail.

Re the VIN question - I'm certain that the OBD2 tester will read the VIN off the car. I'm also certain that your VIN is recorded on the test results that are sent to the state. What I'm not sure about is whether someone doing the tests could manually enter a different VIN in place of the one their tool had detected in order to send a different VIN to the state. It seems highly unlikely that the state would spend extra development money to create such a gaping hole in the security of their emissions testing program.

Can the sensors be spoofed?

BLKROKT

I created O2 simulators for my secondaries. Just do a search for those terms with my user name. Easy.

Blake_von_Texas

Well I was able to leave an inspection center today with a certificate so no more worries there! I guess my only remaining hurdle is completing the break-in on the new short block! When do you guys think it'll be safe to give her the beans??

zcct04

Congratulations!!

Cohen63

Glad this story has a positive ending and you are happy with your car, so often issues like these end up in the owner getting rid of the car

Wishing you many happy & safe miles ahead

BLKROKT

Same as when the car was new. 500mi should do it.

Savage-wp

Glad to hear that your car is running strong, and you have passed the inspection.

Blake_von_Texas

There was no way I could let her go! Any C63 is too special of a machine to give up on because of issues that can be resolved. Thanks for the good wishes!

Blake_von_Texas

Finally got my license plates today. 4 months after buying the car! The idiots at the Chrysler dealership I bought the car from never sent off for them! It figures, since they were idiotic enough to sell me a car with clogged cats that ended up doing $30,000+ in damage.. All that's left now to complete the rehabilitation is fitting some new rear shoes!! I've really enjoyed driving the car these past few days, the 2 month wait resulted in me appreciating the car so much more. Thank you all for your help, advise, and support! I feel so grateful to be part of such a superb online community. Couldn't have done it without you guys!!!