I’m stumped on my E55 issue…

[Vick N]

Hi all,

I’ve got this issue which I’ve been looking at on and off with my E55 S211. It’s been to the dealers and a well known independent and both are stumped and can’t put their finger on it.

The issue is: I feel the car is over fueling. Not only is the mpg pretty poor, the exhaust soots up and I get a whif of it running rich from the exhaust.

It runs and drives ok and has plenty of power.

I’ve fitted brand new correct plugs and both oxygen sensors. I think it’s helped but also feel placebo effect too! Lol

Apologies in advance if I’m not very clear but I’ll try my best to answer anything which may help you, help me!

All advice and help would be Much appreciated.

Thank you

Vick

 

[philnewmerc]

Has the MPG changed?

 

[Jobsworth]

They are set up stock to be quite rich at 3/4 throttle and above. When hooning it’s not uncommon to get the sulphurous whiff of rotten eggs from the exhaust when coming back to rest.
That said, if you think it’s overfuelling but you don’t have an engine light, getting an independent to check the short and long term fuel trims would be a good place to start

 

[ALFAitalia]

Intake pipe leak (post maf) or manifold leak?

 

[Jobsworth]

Intake pipe leak (post maf) or manifold leak?

Leaks after the MAF sensor will make it run lean

 

[ALFAitalia]

You would think so...but the split in my IC pipe (admittedly that's a derv) and my wife's SLK 230k with a cracked plastic pipe after the MAF both ran very rich.....over compensating due the oxygen sensors in the exhaust perhaps?

 

[Vick N]

Has the MPG changed?

It isn’t as good as It should be and single figures driving gently around town.

It’s had:
16 new plugs
Air filters
New oil and filter
Both O2 sensors (pre cats)
Only ever run on Shell V power

Tyre pressures etc are spot on.

 

[fabes]

As per Jobsworth, has the garages you've been to captured the fuel trim data?

 

[north-star]

Hi all,

I’ve got this issue which I’ve been looking at on and off with my E55 S211. It’s been to the dealers and a well known independent and both are stumped and can’t put their finger on it.

The issue is: I feel the car is over fueling. Not only is the mpg pretty poor, the exhaust soots up and I get a whif of it running rich from the exhaust.

It runs and drives ok and has plenty of power.

I’ve fitted brand new correct plugs and both oxygen sensors. I think it’s helped but also feel placebo effect too! Lol

Apologies in advance if I’m not very clear but I’ll try my best to answer anything which may help you, help me!

All advice and help would be Much appreciated.

Thank you

Vick

View attachment 159489

That is one fine looking E55, wow

Lowering Links?

 

[MCFastybloke]

Secondary air injection?

 

[Vick N]

They are set up stock to be quite rich at 3/4 throttle and above. When hooning it’s not uncommon to get the sulphurous whiff of rotten eggs from the exhaust when coming back to rest.
That said, if you think it’s overfuelling but you don’t have an engine light, getting an independent to check the short and long term fuel trims would be a good place to start

As per Jobsworth, has the garages you've been to captured the fuel trim data?

Not to to my knowledge. I have snap on diagnostics machine. What values should be expected?

Thank you

 

[Vick N]

You would think so...but the split in my IC pipe (admittedly that's a derv) and my wife's SLK 230k with a cracked plastic pipe after the MAF both ran very rich.....over compensating due the oxygen sensors in the exhaust perhaps?

I don’t think the E55 has a maf. If it does, I can’t find it

 

[Vick N]

That is one fine looking E55, wow

Lowering Links?

Thank you. It’s on link I DIY’d myself with threaded bar and small ball joints.

Wheels are SL550 NA versions so 1/2” wider front and rear over stock running:
255/40/18 front
285/35/18 rears
Michelin pilot sport AS3+

It lugs my family of 4 around with luggage with ease

Secondary air injection?

I’ve not thought of this. Any ideas what parts or any diagrams please?

I’m pretty hands on and so like to get stuck in.

 

[Jobsworth]

I don’t think the E55 has a maf. If it does, I can’t find it

It doesn’t.

 

[ALFAitalia]

I don’t think the E55 has a maf. If it does, I can’t find it

Fair enough.....I've never owned or even worked on one and did not know that. Out of curiosity how does it measure air intake volume and temp without one?

 

[Jobsworth]

Fair enough.....I've never owned or even worked on one and did not know that. Out of curiosity how does it measure air intake volume and temp without one?

Manifold absolute pressure sensor, and a separate intake air temperature sensor

 

[ALFAitalia]

Ok....my Jeep was like that IIRC.

 

[Alps]

get it on the dyne and get the fuelling read, hopefully will give a clue. also check the fuel pump wiring as they will start melting at the plug if the fuel pump is on its way out, lets hope its not that.

 

[Lenny63]

Lovely wagon that!

 

[Jobsworth]

Also worth looking at the actual readings from coolant temperature sensor, intake air temperature sensor and ambient air temperature sensor. Incorrect but plausible readings won’t log a fault code but can affect fuelling. Similarly a stuck open thermostat that means the ecu will never fully come off cold start enrichment