G60 Black smoke when warm - Fixed

[g60ff 0]

Last week on my way to work i was stopped in traffic and my c started billowing black smoke out the back and was really struggling to idle and almost impossible to drive, luckily was only round the corner from work so parked up left it.

 

Came back to it at the end of the day and it started fine, no smoke or anything. Got a few miles from home and the same thing happened, i noticed that if i floored it it would run fine, no misfire, no smoke. Pulled over and popped the bonnet, noticed straight away the ISV was sucking like mad, unplugged it, no difference, then tried HT's one at a time but this made no difference to rough running, even if i unplugged two! Then unplugged the BTS and all settled down so thought i found the problem, drove home, slight mis-fire but nothing major.

 

Next day swapped the blue and black temp sensors and all seemed fine for a while but after a day or two it started doing it again, got a new BTS from vw, still same thing, then on the weekend unplugged the lambda and it settled down has been fine since (just slightly over-fuelling, about 200 miles to a full tank!), time for a new lambda.

 

Fitted new lambda this evening and it has made no difference. On the weekend i replaced the ecu, coil and co pot have already checked and replaced ecu vac hose. I've used the search and tried things that others with the same/similar problems have reported to cure it but no luck.

 

Possible dead new lambda? going to check over earths again and try and to test lambda tomorrow. Any ideas?

 

Supposed to be going to the nurburgring this summer, there are other things i would like to be spending money on!! (sorry for the long post)

[jon_g60 0]

is your wot switch stuck open????

[flusted 0]

was guna say the same, check throttle switches

[g60ff 0]

Should there be any change to how it runs at idle if i press the wot switch, i tried this the other day (with lambda disconnected) after reading this is how you (flusted) have/had yours running and nothing seemed to change. I've got a spare TB in the shed, something else to try, cheers guys!!

[g60ff 0]

Checked the throttle switches and they're both working fine, have also tested new lambda and earths to the side of the head and to the body/battery all seem fine.

 

It will run fine for a few minutes then start running rough, black smoke out the back and i have to unplug the lambda then unplug/plug back in the BTS before it will stop doing it. Runs fine like this but is dumping fuel in, any other ideas anything i've missed.

 

cheers again for the help

[Rob_B 0]

what lambda probe did you use?

a GSF one?

[g60ff 0]

Lambda was from vwspares.com

 

Problem does seem to occur much quicker with the new lambda but i assumed this was because the probe was warming up quicker, the one i had on there before was a universal jobby.

[Rob_B 0]

i have had problems with the universal probes before, so i got a bosch replacement and this done the trick

[Pickard1 0]

Ive had this same problem. Overfueling caused by a knackered lambda probe.

When we fitted a new one the black smoke didnt go away for a little while, I think the exhaust baffles might have been full of soot.

Has been fine for 3 yrs now though!! :)

[g60ff 0]

I have tested the new probe and it does seem to cycle but i'm only doing this with a multimeter so not 100% how accurate it is, could i be that unlucky that a new probe is also faulty?!?

 

I've been at a mates this evening checking things again, checked the timing, set to 6 degress, cleaned up the plugs as they were black and checked spark, also checked compression and have 10 3/4 or 11 bar across all 4. Also checked for resistance on the wiring to the ecu and ecu to earth and all is ok. Also changed BTS again.

 

Still the same, will idle fine for a few minutes then drive it up the road and it starts blowing black smoke out the back sounds like its going to stall and is a pig to drive. Have to unplug the BTS, unplug lambda then plug BTS back in and will run fine again other than using loads of fuel.

 

Any more ideas?

[Pickard1 0]

Is the lambda wiring ok between the plug and the ecu? I presume you have tested the lambda signal at the plug, could a wire have come out the back of the plug? I once had a loose connection going into the black 4 pin plug that caused a repeat of the problem.

I really am sure the lambda or its wiring is where your problem lies as I think the signal is ignored when cold and at WOT, which would match with your symptoms.

[g60ff 0]

Checked a few earths and BTS to the ecu earlier but forgot to do the lambda, will whip it out tomorrow and test it, will also check the plug.

 

Cheers again for the help.

[Rob_B 0]

you could have a rubbish probe, i did have the same symptoms and a new probe seemed to sort the problem out. might be worth disconnecting the battery aswell for a little while to see if that will clear the ecu of any faults it might have picked up. the wiring for the probe is normally the problem, be it a crap earth or a crap joint in a universal cable. the bosch probe i bought had the corract 4 pin plug already on it, plug it in a job done.

[g60ff 0]

The new probe i've got has the correct plug on it and i've added an earth from the engine mount by the plug up to the body on the strut.

 

Didn't get a chance to check the wiring to the ecu this evening but can't see just this one wire failing when it is a loom with loads of others but will check anyway.

 

Where did you get your bosch one from?

[Rob_B 0]

a company called APD in norfolk, was about 70quid

[g60ff 0]

Went a saw a friendly mechanic today for any further ideas and he kindly lent me a fuel pressure gauge, plumbed it in and with the engine running at the rail there was 8 bar!! :shock: :shock:

 

Replaced the pressure regulator and got a solid 3 bar again!! Just been for a drive and its all fine with all sensors plugged, i love my car again!!

 

Thanks again for all the advice.

[Tempest 0]

Good stuff! Yes, it's handy what a fuel pressure manometer can tell you.

 

Reminds me: Need to ask someone for mine back again :lol:

 

Glad, you sorted it :-)

 

Tempest