E63 5.5 TT Misfire - It's STILL Doing It...

[E55BOF]

My previous thread on this topic sets the scene: E63 5.5 TT Misfire

A quick recap:

The initial problem was an intermittent ragged misfire under hard acceleration at high revs. Most of the time it did not occur under the same conditions.

There was oil at all four camshaft position sensor connectors, and at the ECU connector, so there was (and still will be) oil in the main engine wiring loom.

The plugs had done 40K miles, so I fitted new ones.

I'm using an iCarsoft MBII as a diagnostic tool. The previous set of trouble codes (with the new plugs in) was for misfires on 5, 6 and 8. I fitted new (genuine MB) coils and leads on cylinders 5, 6 and 8.

I fitted four new (genuine MB) camshaft position sensors, and cleaned up/out (lots of contact cleaner, blow dry with an airline) all the oil at the camshaft position sensor and ECU connectors. It ran fine, pulled as it should, misfire gone, all in the garden was rosy......

Until today. I took it out, "Warp Factor Nine Mr Sulu", and the misfire is back. God, I hate intermittent faults!

It's a little different, though; the misfire was not ragged, but a single thump, something like I imagine the rev limiter kicking in might be, and it went straight into a sort of limp home mode - runs okay on minimal throttle, misfires on anything more, and misfires at idle.

The trouble codes are a little different, too. I drove home, switched off, plugged in the MB II, and now had misfires on 1, 5 and 8, all stored codes only.

There was no oil at the ECU connector.

I left the MB II plugged in, started the engine, ran the diagnostic, and now I had codes for:

Misfires on 1, 5 and 8 - all stored;

Stored code P069704 - "Output 3 for reference voltage of sensors electrical fault or open circuit. There is an internal fault".

Stored code P007012 - "Charge air temperature sensor cylinder bank 1 short circuit to ground. Short circuit to positive."


I left the MB II plugged in and took the car for a little run. It ran perfectly. One new, current, code appeared - P026A00 - "Charge cooling insufficient". There's a tear in the flexible inlet hose for cylinder bank one, which may account for that.

I can't find a decode anywhere for P069704. Does anybody know what it means? (Please God, not the nuclear - for the credit card - option, a new ECU...)

 

[m2287]

This explains the first part of the code:

P0697 Sensor Reference Voltage C Circuit Open

 

[m2287]

Not sure what the 04 part of the code means but causes of the base code p0697 are:

• Damaged, open, or shorted wiring and connectors between control modules (including the ECM)
• Damaged, open, or shorted wiring and connectors between engine sensors
• Damaged or defective ECM

 

[E55BOF]

Thank you for that; it's very helpful. Reading the first link, one of the possible causes is a failed sensor. If the inlet air temp sensor on bank 1, or its wiring, shorted out briefly, that might (and only might) account for the P0697 code. I'll change it, I think, and see what happens.

Of course, the problem I then have is to know whether the fault is cured, or just biding its time. God, how I hate intermittent electrical faults...

 

[m2287]

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Skip to 1.15 - looks like you will have a short circuit somewhere within the wiring or the multitude of sensors associated with this! Not sure if that tool would actually be any good for you to try out.

I think that sensor is a good start, the only thing that doesn’t make 100% sense to me is that you have misfires on both banks!

 

[cheddar]

I would be a little concerned at the oil that was in the engine ECU plug, I know there is no comparison between your lovely car and a humble vauxhall corsa, but the corsa's suffer from a failure of the oil pressure switch, and because the plug connector for the oil pressure sensor has a good seal, the oil travels through the core of the cable and through to the ECU, eventually filling it with oil. Even after the oil is cleaned out from plugs and ECU, they throw codes for O2 sensors usually, making them run pretty poor due to getting incorrect O2 voltages. proper cure for these little wrecks is new ECU, new engine loom, and 2 new o2 sensors (normally way more than the entire car is worth).
Hopefully your fault is nothing like this, but sure worth a regular check that the oil does not make another visit into the ECU.

 

[E55BOF]

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I think that sensor is a good start, the only thing that doesn’t make 100% sense to me is that you have misfires on both banks!

There's probably a simple explanation for that; the codes on bank 2 are all stored. I can't seem to get the iCarsoft MB II to clear codes on my car. Every time I try, I get the message "Clear Trouble Code Unsuccessfully". I don't know why, and I don't know enough about the MB II to be able to find out. I'll post another thread and see if there is a more experienced, and IT-savvy, user than me (not difficult...) on here in due course.

 

[toolman1954]

Hi,
I know this is possibly a bit of a stupid suggestion, and it will raise eyebrows, but have you opened up the bonnet when it is very dark, and looked to see if there are any sparks tracking across leads. Sometimes you need to wiggle the wiring with a piece of wood or non conductive material. It has worked for me in the past, solving awkward misfires.


And then of course waving the piece of wood at it , you can shout " I am going to give you a damn good thrashing if you do not behave " ! "Yer B*stid"

Steve

 

[toolman1954]

Hi,
Sensible head on now....Just spent an hour on a Sprinter form reading about MB 11 Scanners. Seems some codes will not be removed in "Automatic" selection and you have to use "Manual" setting to clear them.

Steve.

 

[E55BOF]

Got there eventually - see this thread Advice on iCarsoft Needed for how.

I think there's a good chance that the code P069704 - "Output 3 for reference voltage of sensors electrical fault or open circuit. There is an internal fault" - was triggered by the P007012 - "Charge air temperature sensor cylinder bank 1 short circuit to ground. Short circuit to positive."

Another b****y intermittent fault! I'll change the faulty sensor and see what happens. At least I've cleared the significant stored codes, so if I get another misfire, I'll have more chance of pinning the cause down.

 

[BlackC55]

Have you done a compression test
?

 

[BlackC55]

I would do a compression test first then check the wiring back to the engine control unit using a multi meter.

 

[E55BOF]

Thank you for that; I may have to seek professional help, but I don't think I need to start throwing lots of money at it just yet... (There's no way I'm taking those b****y plugs out again!)

I've done the plugs and the faulty coils, and that has sorted the misfires on bank 2.

Thinking about it, code P026A00 - "Charge cooling insufficient" - could well indicate a failing charge air temperature sensor giving a false reading; that would fit with the other fault codes I have. It's a cheap and easy job to replace that sensor, so I'll try that first.; if it doesn't work, I've lost only time and a few quid.

For the moment I'll fix what I believe (hope?) to be faulty and see what happens.

 

[E55BOF]

Well, I've spoken to the parts guy at my local dealer to order the sensor, and he's spoken to the techies, and he can't find any reference to a charge air temperature sensor, cylinder bank 1, for the car. I had rather assumed it was the electrical sensor at the rear of the airbox, but he insists that that is a pressure sensor. I can't see how it can be; it's upstream of the turbo.

Can anyone confirm (or deny) that the M157 has two charge air temperature sensors, one for each cylinder bank, and if it has, where they are located? A part number would be very helpful if it has...

 

[Codger49]

Here's the EPC docs for the engine sensors etc for a 157.981 on a generic 212.274.

As far as I can see, only the knock sensors are duplicated, all other sensors seem to be one offs.

If you want more specific docs, post or pm me your VIN.

 

[merc85]

These are all the Engine sensors

 

[merc85]

Think ive found it, number 320

 

[merc85]

a276 905 00 00 Temperature Sensor "charging air intercooler"

MERCEDES A CLASS A160 2016 AIR TEMPERATURE SENSOR A2769050000 | eBay

As fitted to a A class lol

 

[E55BOF]

Thanks for that. I'll whip it out tomorrow morning and see if it looks like that. Do you have a WIS locator reference for the E63 TT?

The only thing is, I gather that's on the intercooler, but my code refers to cylinder bank 1, so are there two outlets from the M157 intercooler, and two sensors? I don't suppose you have a drawing, as you have for the A160? The VIN is WDD212 2742A 735623

 

[Codger49]

EPC for your VIN shows A 007 153 31 28 for 'pressure sensor upstream of throttle valve'. (one per car.)

EPC ref is 'Maj. ass M - Engine' 'M157 E60' '157.981' '14 Intake and Exhaust Manifolds' '030 Intake Manifold'