OMG please help. I was having problems the other day with my battery. I had to jump it a few times and then got it home and bought a new battery. Everything at this point ran fine except the battery. I changed out the battery. Now My car won't even run. It starts up.. revs high for about 20 sec then drop out and stalls. I try to press on the gas and there is no/late response and the rpms are all over the place. I'm driving 99 SLK230 with 56,000 miles. I have tried resetting the ECU by disconnection the battery but have no luck.. What could this be? What can I do? Any ideas?

1) what kind of replacement battery did you get? specs? could it be faulty?

2) have you checked the POSITIVE terminal on your car to make sure all the wires are secure? The fact that you jumped the car a few times then replaced the battery - maybe a wire or connection was pulled apart - pay particular attention to the positive cable.

3) I don't even know where the battery is in an SLK, trunk or engine compartment? But before you freak - make sure no connections were knocked off while doing the battery change.


4) just a guess and do a search on this - but isn't there a resetting or warm start resetting if you start the car with the gas peddle pressed all the way to the floor?

You might need to reset the adaptation values, noting the age of the car.
If the fuel trim and maf was way out, losing battery power can cause this. The car needs to re-learn it's parameters.

1. same battery specs brand new from costco. (car does start up without any problems) just won't stay running

2. yes check a million times so far :-(

3. engine compartment.

4. I tried to do that. Not sure If i did it right.. if anyone has more info on this that would be great.

I am looking into this now. sounds like it might be it.. Do I need have a dealer do this or is this something I can do myself? what I'm finding so far requires a tool from snap on or the likes.. any more info would be a huge help.. thanks in advance!

Try this:http://www.continentalimports.com/ser_ic60442.html

The author is a moderator here, and is a factory trained shop owner.

It's probably best to let someone who knows, use a scanner and relearn the car. The scanner costs a fortune, and it takes a bit of know how to do it right. IMHO.

Does this car have OVP relay? Or is that only on older ones?

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2012 E350
2006 Callaway SC560

Well at lunch my buddy came over and we hooked it up to find the fault codes. Before we hooked it up to the computer we unpluged the MAF sensor thinking that it might run on a default code. this didn't seem to be the case cause then it wouldn't idle at all before stalling out. We plugged it back in and when we first hooked up the computer there where no codes. This makes sense casue I just cleared out the ECU by disconnecting the battery for a while. We started it up and let it run as long as it could and it came up with the code P0302 cylinder 2 misfire. that was the only code. It seems to be running super rich as all we could smell is gas while it was running.

Any thoughts?

The fuel trim needs to be reset, and the misfire probably comes from the rich mixture.

The scanner needs to be a MB tool, or a Snap On model with the correct software.

Read Steve Brotherton's article.

Well the good news is it is running. I will tell you exactly what I did just in case this happens to someone else but it really makes no sense to me. First of all I pulled the spark plugs to see if I was getting gas in all four cylinders. Next I check for spark. Now mind you I had to take off both coils to get to the spark plugs. While taking the coils out I made sure to put them on the shelf in the same order that they were on the car. After spark and gas checked out I put everything back together but the coils I put on the opposite of what they were. I figured if it was the coil that was producing the code P0302 that I would now get a code of P0301.

I hook up my computer to it and start it up. It starts up about as rough as it did before. I put the car in neutral and this is where I start to notice a difference. I can actually press on the gas and it response to it. WOW So I then take the RPMs up to 2500 and let it sit there for about 10 min. All the while I am getting 0 codes. I shut it down and re-start it back up.. Bingo.. It’s idling just fine.. Took it out and spun around the block a few times starting off really slow then faster and faster. Not sure if running it in neutral at 2500 had anything to do with it but before I switched the coils around I couldn't even get it to do that. Maybe the connection on the coil was bad? not really sure at this point.

The car starts up fine this morning. On my way to work I notice that it hesitates when I step on the gas. It seems to do this until it warms up completely.

Is it possible it just relearnt the adaption values?

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1985 190E - Gone
1989 230E - Gone
1995 C200 - Gone
1993 280E 120000KM - Built like a brick, the best one yet

Yes, the car will relearn by itself, though it takes a (long)while and if they are too far out, it will run very badly. Using a scanner with the right software can reset the adaptation values right away, and there is a specific procedure for doing so.

The lesson to be learned here is that when changing a battery, don't interrupt the 12v supply to the car. Most shops use a small 12v battery to ensure uninterrupted 12v, while the battery is disconnected.

Yep - I had the same experience with a 96 E230 - was hunting and spluttering. After a 1200 Km trip, and putting up with the rough idle it was running smooth as silk.

Just out of interest, does the M104 from 1993 have an adaptive ECU?

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1985 190E - Gone
1989 230E - Gone
1995 C200 - Gone
1993 280E 120000KM - Built like a brick, the best one yet

i would also be interested in knowing the answer to kiwis last question as my friend is planning on changing the battery in his 95 e320

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E30 B25
126.036
123.130 with 616-Frankenbenz (sold)
124.030-Greyhound (sold)
124.030-Schnauzer (sold)

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