baddar

Hello everyone,

I had my intake manifold replaced after several engine misfires and finally one of the flaps broke. I have also replaced spark plugs as it was due. I have the stored codes reset.

Car was working great until the next morning! Engine light turned on again and the car was misfiring, you could feel the engine shake. Luckily it goes away after the second engine start. However I went back to the workshop to have it scanned again and I found the following codes:

- 0629 Misfiring (P0300)
- 0633 Misfiring of cylinder 1: Damages TWC (P0301)
- 5408 Undervoltage supply
- 9048 At the control stored unit, the supply voltage for the warning elements is outside the permissible range
- 9001 The supply voltage of the control unit is too low (undervoltage)
- 90E1 Can communication with control unit IC is sporadically disrupted

The car never misfires when I start it after work or any other time on the afternoon. So far only in the morning or apparently when I leave it off for several hours.

Do the undervoltage codes imply a bad/loose connection from the ECU to the intake manifold or the spark coils? Or that could be one of many possibilities?

And why only in the morning? Have any of you guys seen this before?

One final note: The dealership recommended that I change the battery but I still didn't. Guess it's a bit outdated but still starts the care with no problems.
Thanks in advance.

jandmtv

Could be a bad coil.

baddar

Thanks jandmtv,

Do you know how to locate Cylinder 1?

jandmtv

Sorry. Don't. I'm sure one of the other members will chime in here shortly. You can also go to your dealer and speak with one of the techs. I'm sure they will tell you which cylinder is #1

AMGAffalterbach

It's viewed starting from the power output end (cylinders 1 through 4) so where ever the engine sends power to the transmission is the lower number. P0300 is definitely common of a failed coil... I've had two issues with this thus far and it always ends up being a coil that causes the problem since when the engine is not at operating temperature it will tend to have more issues with ignition timing on a bad coil. It could also be an issue with plugs and wires if it's pulling voltage codes... once again the problem is probably magnified by a cold engine if the ignition system is struggling. An ECU issue is also not out of the question but it's more likely a coil or wiring problem, especially because it's on one cylinder that it's complaining of misfire not all of them - sort of how a compiler in programming will set off 20 errors for one small issue in your code.

baddar

Thank you AMGAffalterbach,

very well explained. I couldn't have traced it that way.

One more question? why it always work from the second start? Would that along with the voltage codes indicate a bad wiring more than a bad coil? Any hints on how I could spot that?

The thing is. It's not easy to find an experienced technician where I live. So I probably have to tell the techs what to do based on your logic.

Plutoe

Have you tech check out the charging system---sounds like you are also under voltage in the morning

AMGAffalterbach

Meant to reply to this earlier, yes have the tech check out the charging system as Plutoe said, also I would think just replacing the ignition wires would be a lot less expensive than tearing everything apart and trying to determine which part is bad so that's probably a good idea. Not sure about voltages, but I assume it always works on second start either due to the charging issue or temperatures.

baddar

Thanks Plutoe and AMGAffalterbach,

Today it was shaking a bit but the engine light didn't turn on. So I guess cylinder 1 spark wasn't firing properly at the start but not enough for the ECU to trigger a cylinder shutdown and turn on Engine light.

Changing wiring is a good approach only if a bad coil wouldn't be a reason for under-voltage . If we could exclude that then it should be wiring. Also it's only in cyl. 1 and I guess I should be focusing on wiring getting into that. I'm not an expert so perhaps they should be replaced all together.

Thanks again for your help.

AMGAffalterbach

For sure man, hope you get it worked out, and for future people reading please post what you find! Good luck and welcome to the forums.

baddar

Sure I will keep you posted.

Thanks again

baddar

One more question guys: How can I locate cylinder 1?

AMGAffalterbach

Cylinder 1 is closest to the transmission so if it's mounted longitudinally it is the one closest to the firewall/inside of the car.

baddar

Thanks AMGAffalterbach,

I'm not sure if I got you correctly. My understanding is there are 2 banks (right and left) and 3 cyl. each. So there should be 2 cylinders closest to the transmission. Driver side and passenger side. Which one of those is cylinder 1?

baddar

Yesterday I went back to my indie for further inspections and found out that misfiring was on another cylinder. He was kind enough to leave his OBD scanner to me and I have run live data while engine was running. Nothing unusual, charging system is perfectly functional and battery voltage before starting was slightly below 12 V. That wasn't a problem as far as I'm concerned. Also under-voltage codes disappeared

Then something came to my mind that I guess I should have thought about it earlier. I had reset the cold start adaptation and so far the engine didn't misfire in the morning. I guess that was necessary as my old intake manifold flap was broken, so less air pressure into the engine and when replaced the ECU was confused with the performance of the new one.

If it doesn't misfire in the upcoming days I could say this adaptation reset has fixed the problem

Thanks you guys I really appreciate your help here

Plutoe

It's always nice to learn that the barn door was open before the cows went out---to ask a question does any one know why the cows went out!!

Now you can appreciate why customers get pissed when they receive their bill----Oh I forgot to tell you!!!

N_Jay

In a "V" engine the banks are offset by a small amount.
One bank is further back.

baddar

@ Plutoe: I am the customer lol. I'm not a techie I just love to learn.
@N_Jay: Thanks. All sorted now

LaVaughn Faison

Hello.. I have a Gl450 and I replaced all 8 ignition coils and spark plugs. The problem is my vehice still have that shaking. I took it for a 30mile ride and that didn't help. Could someone help me out.. Thank you...

N_Jay

1) Probably a different issue, start a new thread.

2) Any Check Engine Light?

3) Any codes

jimmytran2411

I ve my gl450 got an engine light miss fire

1. I ve to change to genuine coil of mb
2. I change allyhe new spark plugs

but it s still show the lights. And the gine still viberation when stop. Any suggestions?

ps2cho

You bump a 5 year old thread with a completely different model and engine.

its beyond me...I wouldn’t call the cubs coach and ask his thoughts on the patriots routes

post a new thread in the correct forum

N_Jay

Did you get the codes read?

Leloh

I am having issues with my 2008 Mercedes-benz E350 with the 272 Engine, engine runs rough and after taking it to the workshop, it was detected that the whole right side that's the passenger side of the engine is not working. Now the coils and plugs have been changed, same problem persists the valves have been checked and they are ok yet the 3 cylinders still missfires... please I need an urgent advice on this. And can working on the headlights and fog lights cause this?