Hi Fellows and hello from Baden-Baden.

OK, so cruising down the A5 just past the Hockenheim Ring at a easy 105 MPH and coming fast from behind is an RS6. So to make him feel really bad I wait until he has to get on the binders. Already in 3rd I nail it and I'm gone! Around 160 MPH and an IAT of about 135, instantly I'm seriously down on power with a CEL. Alright, I recognize right away I've lost at least 2 cylinders. Now down to 60 MPH I read the codes on the DASHDAQ which tell me I'm now driving a 4 cylinder E55. 1-3-5-7 are deader than Kelsey's nuts. So, I exit the A5, park and shut down; clear the codes; re-fire and the Beast is back; no CEL. Really a strange anomaly. I recently turned off my secondary O2 sensors, but I can't draw a connection there. Obviously the ECU shut down the entire bank, but why?

Okay - - - there you have it - - - let the speculation begin.

My first thought is that perhaps an O2 sensor is on the way out.

Oh yeah, I left my STAR DAS back at the house (Don't leave home without it) and I won't get home until next week.

 

In DAS you will see cylinder shut off for protection so chances are you detonated a bit and the save the engine the cylinders were shut off.. my speculation since the car runs fine after reset

Go fault counter in the ECU and you should see the shut off

 

What kind of cooling do you use? 135 at 160MPH isn't that bad from what I've seen.

Sorry for the offtopic, I'll let the more knowledgeable among us speculate.

 

At an extended WOT and about 5500 RPM with a Big H/E, phenolics and Johnson pump it seems about right. The I/C's just don't have the capacity. It recovers quickly to about 15F over ambient while cruising at 100 MPH.

 

That was my initial thought, but only cyls 1-3-5-7 showed misfire (on DASHDAQ). As I said, my DAS is back at the house. If that O2 sensor is going bad, that might cause the problem. 75k on original sensors. Probably a good idea to replace them. What do you think?

 

very well could be the problem. try to see if you can duplicate the misfire again

 

Most people don't consider 'sensors' to be wear and tear items but they do go bad. Funny, it's same guys who say 'lifetime coil packs' on a heat soaking M113K engine.

On another note, do you really think a bad sensor reading would cause an entire bank to just cut out? Seems like a crazy safety measure. Curious to see what your STAR DAS spits out.

 

if the knock sensor is bad a code will be store which you can view via DAS, it will not trigger a CEL.
Never seen a knock sensor go bad on a M113k but on a M156 all the time

 

Interesting - I'm curious to see what DAS has stored?

 

Scary, I'd be panicking and parking up till I could get to a DAS but I'm probably a little over cautious when it comes to my 55. I know you were barely there but at the higher end of the E55 speed scale she starts getting a dry throat from not drinking enough fuel though of course that's more likely to affect number 8 cylinder. I'm looking to put a looped fuel rail in for that reason and some peace of mind. Far more knowledgeable people here than me though - good luck bro, hope it's something simple and at least you got the kill in first.

 

About 10 days ago while in Salzburg, Austria in stop & go traffic, it threw a code, but no misfire that I was aware of. The DASHDAQ indicated a possible cat problem, but I didn't jot down the code before I cleared it and there was nothing stored when I later checked it with DAS. So, I'll go ahead and replace the 02's when I get back next week. I suspect that's the problem.

 

Of course - - - what could possibly go wrong, go wrong, go wrong, go wrong.

I think Shardul may have hit it. If an 02 sensor went weird on one bank and resulted in simultaneous detonation on a bank of 4 cylinders, the safety system instantly shut them down. We'll see.

 

I have a continuous rail with 6 port injectors and it was the other bank. Looking more like the O2 sensor.

 

We'll have to wait until Tuesday.

 

I don't believe the o2 sensor would cause this problem, given you were at WOT when the problem happened...My guess is really bad knock or defective knock sensor....

 

The reason I was thinking O2 is that whatever it was it took down only one entire bank (don't forget it threw a code last week sitting in traffic relating to a cat and I believe that could only come from an O2 sensor). I'm running ARAL 102 octane, which is more than adequate.

A couple of questions as I don't have DAS/WIS/EPC with me: Where is the knock sensor located and is there 1 or 2 sensors?

 

under the sc in the valley pan.
2 knock sensors

 

So, maybe the cat is not doing its job properly and spiked a reading on the o2 sensor? You are running a higher octane fuel. The o2 sensor simply reads afr ratio on that bank, and the spiked reading might have caused the ecu to enter 'safe mode'. Still worth checking the ignition coils and fuel system on the left side, plugs too maybe.

 

If one of the cats are clogged it could cause a lot of heat from the exhaust on that bank and maybe shut down for safety but it would be a first, check cats and O2 sensor, curious to see what star says

 

Not necessarily 'clogged' just 'worn out' in a sense. Clogged cats are not intermittent problems. I had a broken/clogged cat in a z06 that was a result from the entire rh bank coil packs going bad. It ran like crap every time we started it. I would also like to see what codes it spits out.

 

Yeah, I figured it had to be there, but as you said, they seem to be very reliable.

Good thought, however everything (except the packs) are new within the last 3K miles.

Yup, I'm curious too. Still leaning towards an O2. Still I have to wait 'til Tuesday when I get back to the house.

Yup, me too. The DASHDAQ has only limited capabilities.

The fact that today I cautiously made 2 WOT runs through 3rd with no anomalies suggests to me a faulty O2 and remember I threw a CAT code about 10 days ago while in traffic.

Thanks for all good ideas fellas'. We'll know more on Tuesday.

 

Fact of the matter is the o2 sensor does ONE JOB, read the AFR in the exhaust. It read a spike, the ecu saw this and hit the safemode button. I'm putting my money on a cat issue. How many miles on your vehicle and have you ever changed the coil packs?

 

Kind of weird referring to a bank of cylinders going down when 1 & 3 are on the right bank, and 5 & 7 are on the left bank??

 

Just read this thread and that's exactly what I was thinking

 

You are absolutely correct Sir! Assumption is the mother of all F***UPS. My assumption, my F***UP.

I have brand new pumps and filter . . . hmmm. Got to think about this. Could be a one off event. Ill know more when I read the memory next week.

Anyway, off to the MB museum tomorrow.