Vrodman

Hey Guys,

Well, it finally happened. Round 2 of tweaks on my AMS ECU caused a misfire this last Friday on cylinder 1. I parked the car, shut it down, restarted it, and the misfire was temporarily gone. But as soon as I punched it 10 minutes later, it came back. I was warned by their tuner that this could happen. The good news, as they told me, is that by resetting it (taking it out of the car and re-installing it) the misfires seem to be gone over the last few days. Something in the adaptive process causes the timing to eventually advance too far that a knock is sensed and then the cylinder is shut down. FYI, there is no mistaking that a cylinder is shut down when it happens! lol Rough idle and strange sounding exhaust.

Here is the problem though:

I can't clear the trouble code ("misfire on cylinder 1") with my OBD II reader. Now I have had this reader for a very long time back to my 2000 E55. It did work to clear codes on the E55. When I try to do this on this car it looks like it is doing it. It asks "are you sure you want to clear all codes?"), and I click YES. Then it appears to be doing it, but when done, nothing is cleared. Same trouble code is still there, and the CEL symbol in the dash is still there.

Any insights from you gear heads? Do I need a better, newer OBD II reader? I did have an initial discussion with the guys at AMS and they said I should be able to clear the codes. Although that was one of their sales guys and not their actual tuner.

BTW, when the stock ECU goes back in the codes are not there and the CEL is not on. I did this to make sure I didn't fry a coil or something. I also could not get the misfire to happen even with the engine hot and pushing it hard with the stock ECU.

Thanks in advance for any help.

PeterUbers

Vrodman

A battery pull overnight is not going to be any different than removing the ECU entirely for a day which I did. After looking around at OBD readers I see that it is likely mine is just way too old. I do not think it has the latest protocols which came after 2008. Also this iCarSoft i980 reader seems pretty highly reviewed by the Mercedes techs. It is made for MB, although it supposedly works on other makes as well. It's only about a $100 so worth a try.

As far as compatibility, the tuned ECU just had this happen 4 days ago. No CEL or trouble codes for the first 2 rounds of running it over a 3 month span. AMS tuner did warn me that a cylinder shut down may occur, but nothing to worry about. After reset, as I mentioned, everything runs great again. Just can't clear the events from last Friday.

Here in N Cali, we only have 91 octane, or very expensive 100 race gas. AMS guys told me that these ECU's are very sensitive to pre-detonation detection. They said with pushing the timing toward the top end and blocking the timing "pullback" that the adaptive process creates, that this might occasionally happen. If the ECU were inside the fender or something this would be a problem. Fortunately, for us the AMG wizards practically put a quick-release handle on it for us! lol

FastWgn

Vrodman,
I went all out and got the iCarSoft version episodically for our cars. For someone like you, with a tuned ECU< it may be worth getting one as well. Reads all the subsystem codes individually etc.

iCarSoft MB specific unit

e65

If it's just a check engine light that's bothering you it goes away on its own after a while. I was only ever able to have the codes properly cleared at the dealer. The generic code readers will clear the code on a Toyota Matrix, not on a Benz.

PeterUbers

e65

Don't waste your money on race gas. Add about methanol to the gas tank (~1L per 10L gasoline) it will increase your octane, if that is really your problem. You should drive around a bit to let your fuel trims adjust.

if you have E85 try ~ 1.5 - 2 liters per 10L gasoline

Vrodman

jvakos

K - have a basic Actron scanner thats 5 years old and its been OK for clearing codes on my 15 E63 when they randomly come up (i'm stock, so its been rare). If your scanner is logging a "permanent stored code" (instead of pending code) my understanding is even if you clear it, the ECU will not immediately fully clear the code because it (somehow) requires the car to be driven (XXX miles or time) to verify the issue causing the permanent code is gone. i had a permanent code with a fluke random cylinder 1 misfire (again, i'm stock 28k miles on original plugs) and after clearing it the car drove normal but it took about 4-5 days of driving to clear the permanent code (i drive the car maybe max 1 hour per day).

Vrodman

jvakos

Just re-read this - - so car runs great, even with stored codes?

If so i think those should clear once you drive it for a while as the ECU (again, somehow...) it knows to verify the issue is gone before clearing permanent codes.

e65

ive run 10s times with CEL on.

jvakos

Lumi

Lumi

Savage212

I had the same problem, CEL for a misfire could not clear it with any OBDII reader. I have an "iCAR soft MB2" no luck. I had a friend with a PC based scanner ( VAG-COM mainly for audis ) no luck. Also a local shop with a professional type system... no luck. The car was running fine, I ran it for a week or so, but ended up sending the ECU back to the tuner (AMS) they turned it around in a day. All is well since. I also popped the stock ECU in with the same result as yourself, no codes, no cel.

Vrodman

Yep, since I reset the ECU the car has been running great for the last few days. As I recall, my reader said "pending codes". But I honestly now am not sure now. I will check it again tonight after work and let you guys know.

But, YES, the car seems just fine after resetting the ECU.

PeterUbers

try m3

I had new oem plugs gapped to 0.022 they ran okay but I noticed a little hesitation above 5k rpm in 3rd-4th gear on really hot days so I switched to NGK Laser Iridium 97506 plugs and the car pulls smoothly all the way to redline in each gear. I run a Eurocharged stage 2 tune which may be slightly more aggressive. Only thing I've noticed with these plugs is cold start idle is not as smooth but not really a big deal to me.

PeterUbers

Vrodman

I did. No issues related to plugs so far. And it really hauls *ss my man! You are gonna love that tune. Make sure to tell them you want the same low gear extras that they did for me. You know my name. Just tell Chris I love the latest tweak and recommended it to you.

PeterUbers

Vrodman

Well Savage,

Looks like we have the exact same thing going on. I got the new iCar reader and it won't clear them either. It's not really a big deal to have the light on anyway as has been mentioned. I will likely wait a bit and see if I have any other tweaks necessary for AMS before I send it back to them for this.

I will say the iCar reader is pretty nice though! It does a ton more stuff than my old reader so it was worth it anyway.

Cheers

MBWUSER_0450

Would something like this work for clearing your codes?

Vrodman

Highly doubtful. The ECU is somehow write protected by the tuner (AMS). I just sent the ECU back to AMS and they will be getting it tomorrow and should be able to fix the issue according to Savage and the guys at AMS. However, I won't be putting that ECU back in until I get the engine ticking noise resolved at the dealer on the 15th. I will update everything later at that time.