Rough idle and engine warning light

[Wrighty]

I've got a rough idle which started a few days ago, originally when starting up in the morning it would have to automatically put on a few revs to keep running.

Then yesterday it was idling rough whenever I stopped even after a good length drive.

Today the orange engine light came on, still the same rough idle as yesterday.

Any idea guys? I don't have access any diagnostic equipment myself unfortunately

 

[Smartbear]

I've got a rough idle which started a few days ago, originally when starting up in the morning it would have to automatically put on a few revs to keep running.

Then yesterday it was idling rough whenever I stopped even after a good length drive.

Today the orange engine light came on, still the same rough idle as yesterday.

Any idea guys? I don't have access any diagnostic equipment myself unfortunately

Unless you get it scanned it’s all guesswork
Rob

 

[Wrighty]

I've got a rough idle which started a few days ago, originally when starting up in the morning it would have to automatically put on a few revs to keep running.

Then yesterday it was idling rough whenever I stopped even after a good length drive.

Today the orange engine light came on, still the same rough idle as yesterday.

Any idea guys? I don't have access any diagnostic equipment myself unfortunately

Unless you get it scanned it’s all guesswork
Rob

Yeah unfortunately so Rob, hopefully it'll flag up exactly what it is

 

[Scooba_Steve]

Breakdown cover may read codes for free. Investing in a scanner should pay for itself in one use though.

 

[Tomsdad]

I agree you need to read the codes. But when I had a similar problem I fixed it by cleaning the vanos solenoids.
It's a no cost repair. Plenty of info on here especially a thread under my name.

 

[ph001]

What model? If it's a 2.0l, Valvetronic motor or eccentric cam sensor a distinct possibility... https://z4-forum.com/forum/viewtopic.php?f=3&t=102843&p=1532625&hilit=valvetronic#p1532625

 

[laurieballard]

If the EML is on, there should be a code to read.

I bought a Bluetooth ODB2 reader from ebay for a few quid and the Torque app showed me the codes.

 

[Wrighty]

2004, 3.0

Codes read,
2882 bank 1 fuel trim
2883 bank 2 fuel trim

Leading towards a split air hose somewhere I reckon. Unable to see where yet though


Knocking noise disappears when the clutch is pressed (in neutral) Definetly coming from the flywheel-cluch area. These have DMF's right?

Edit: realise I didn't mention this second issue in the original post!

 

[Wrighty]

Codes cleared, will see if they return after a drive this evening

 

[Wrighty]

Same light returned a few days later. Spotted a small split in rubber elbow inbetween the airbox and inlet manifold.



Changed this morning and light cleared again... rough idle still present... :thumbsdown:

 

[Wrighty]

Convinced myself that it isn't a vacuum leak anywhere but definitely fuel/air mix related, my average mpg (over a good distance) has dropped by 3mpg since the issue started. Also oil usage noticeably decreased too although i'm not sure how related this is... :idunno:

MAF sensor suspected knackered, after good run C110 was reading this:
10.5kg/h (clutch pedal down)
9.5kg/h (clutch pedal up)

I believe 13kg/h is what it should be, can anyone confirm?

Unplugged the MAF connector earlier and it stared up and it idled as badly as usual. I am unsure as to what this indicates, does the car automatically default to some stored setting when it detects the MAF sensor is unplugged? Or is mine broken hence why unplugging it makes no effect on how the car runs?

Will electrical contact cleaner be a suitable thing to clean it with?

Seems I have created more questions than answered ones today!

Wrighty

 

[srhutch]

If the EML is on, there should be a code to read.

I bought a Bluetooth ODB2 reader from ebay for a few quid and the Torque app showed me the codes.

This

An ELM327 adapter and torque app for under a tenner, you can read and reset EML easily.

 

[Wrighty]

If the EML is on, there should be a code to read.

I bought a Bluetooth ODB2 reader from ebay for a few quid and the Torque app showed me the codes.

This

An ELM327 adapter and torque app for under a tenner, you can read and reset EML easily.

Further codes other than the ones mentioned in my earlier post @srhutch? I was expecting slightly more info from the C110 when reading the codes through that.

Wrighty

 

[ph001]

The fuel trim codes basically mean it can't compensate the injection any further to account for an incorrect mixture. Could be:

MAF
Air leak
EGR valve
O2 sensors (usually bring up their own codes though)

...be nice if you could swap the MAF for a known good one to eliminate but MAF problems are pretty rare on the 3.0l. EGR valves certainly get gunked up pretty often though and the pipe can degrade which leads down to the sump.

The knocking noise which disappears when you press the clutch is a very common DMF noise and nothing too much to worry about.

 

[Wrighty]

The fuel trim codes basically mean it can't compensate the injection any further to account for an incorrect mixture. Could be:

MAF
Air leak
EGR valve
O2 sensors (usually bring up their own codes though)

...be nice if you could swap the MAF for a known good one to eliminate but MAF problems are pretty rare on the 3.0l. EGR valves certainly get gunked up pretty often though and the pipe can degrade which leads down to the sump.

The knocking noise which disappears when you press the clutch is a very common DMF noise and nothing too much to worry about.

Thanks ph001,

Yes hopefully cleaning the MAF will clear it.

Unfortunately I do not know of anyone local to swap it with. I will definitely look into the EGR valve, not something I'd considered.

Yeah the DMF noise is something that it's always had, it has just been exaggerated recently with this rough idle. Starting and turning off the car with the clutch depressed helps massively

Cheers

 

[ph001]

Cleaning the MAF may not be sufficient and some contact cleaners can leave residues so you would be better with carb cleaner or a dedicated MAF cleaner such as this...

https://www.ebay.co.uk/itm/CRC-Air-Sensor-Clean-Mass-Air-Flow-Meter-Cleaner-MAF-250-mL/111977213496?epid=6020958727&hash=item1a125cae38:g:dKgAAOSwcOFaOS1n

I'd be pretty surprised if cleaning it sorted your problem though (esp if disconnecting it makes no difference). I'd be taking a long hard look at the EGR if I were you.