Half the Engine Won't Start, Help
 

Hi. I recently encountered a problem where cylinders 1-6 on my 2003 S600 stopped working. The car runs on 6 cylinders now, and it has a very rough idle. I tried leaving the car sitting for 3 days then restarting it, but the problem continued. Only cylinders 7-12 work (I used a code reader for my information).

I heard some people say the coil packs went bad, some people say the ignition control module went bad, and some people say the MAF system went bad. I still don't know for sure what the problem is yet and I am very confused. Can someone please tell me what's going on with my car and what I should do? Thank you very much!

search the forums - the answer is there!

ignition inverter or coil pack. Don't change any parts without a DAS analysis.

OReilly or autozone offer a lifetime warranty so get these expensive parts from there

Don't worry about store brand name they are oem

Can a Mercedes-Benz Star Diagnosis System (SDS) tell if the ignition ignition is bad?

XENTRY/DAS can only tell if the ECU has registered (stored) misfire codes. It can't tell the cause.

If you've got a coil problem, it will store the misfire code for the cylinders that are misfiring as well as the P0300 code for generic or multiple misfire. If you've got a transformer problem, you'll get the same codes. If the transformer is bad, you can usually see that by pulling the cover off the transformer and looking at the capacitors and the potting compound in which they sit. If they look fried, then they are fried. If they look OK, then they probably are...

Six cylinders shut down leads me to believe it's the coil pack...

I just opened it after reading your post. It looks good no sign of it being fried. The plastic covering around the 2 big things are coming of tho.but it doesn't look damaged. If it was would it make both banks not work or just one?

I replaced the coil pack 5 months ago and again 3 days ago with coil & new plugs. So I take it it's not the coil pack or plugs. I'm using autolite Iridium on both banks. People say it has to be ngk but I don't think it has to because the other side is working and both sides were working fine for 5 months. So could it be the ecu

Wondering if the OP's car has the M275 twin-turbo motor, or the earlier V12 that includes cylinder deactivation by design? The NA V12 was designed to run on 6 cylinders by design, right? I'm questioning because I wondered if the problem described is something that happens on the M275/M285 motors...

Yes op car Is the twin turbo

At this point, you're just guessing. Guessing that the coil pack is still OK, guessing that the Autolite plugs are working, guessing that the transformer is OK.

Time to measure the voltage from the transformer, or swap it to figure out if it's the transformer. http://www.v12icpack.com/ - these guys will rent you a transformer so you can start troubleshooting it. They will rent you an ignition coil pack as well.

And yeah, if everyone says "use NGKs" and you used Autolite...well, that could be a cause....

But you need to start measuring/trying things, because only with more data can you begin to chase this down. Do you have XENTRY/DAS? OBD code readers are next to useless on this car.

That rental program is a great way to figure out what part is causing the problem

They just repaired my passenger side coil. $315 including testing and shipping for one cylinder that was misfiring. I knew it was the actual coil for cylinder no. 6 because when I replaced the plugs, that coil was loose. Physically easy to move, so the solder joints to the circuit board were likely broken. www.v12icpack.com guys fixed it quickly, shipped it quickly and the car is back to its old, wicked fast, smooth, self...I would recommend these guys in a heartbeat. I can't solder. I can do most everything, but not that...and I'm glad to have paid to fix what was needed instead of buying a new coil pack.

The rental program is a brilliant idea...assuming that those who rent the components are careful with then during installation and removal...or it becomes a "rent to own" conversion pretty quickly...

Yes I ran a sds scan on it at the dealership. All they came up with was codes 300-306 that's it. Don't know if that scan will tell if the ignition inverter is working. They said to change out the plugs. I did that today. Put the ngk what my manuel call out for and still nothing. I asked the dealership if the ignition inverter was good they won't tell me anything. So looks like I'm going to rent one from that site Astor said about and let you guys know if that was the problem. Just keeping everyone updated.

Let us know if the rental program works out for you

Hi guys. Ok I used the rental program that astro recommended. response was fast and I received the part in 2 days. Excellence program. It was the transformer. So I'm going to keep the rental and buy it as a used part. And the autolite iridium plugs work just fine. But I am going to change them for what my manual calls out for. I would like to thank astro for info on the rental program. Thanks bud.

Thanks! Glad it's worked out for you. Great to hear that your car is running well again.

I am so glad to hear that ! mine was coil pack , after replace a new one it runs smooth and strong ! Another V12 TT on the road !! Thanks to these guy on the forum !!