And the black smoke?

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Andrew McIntyre

Active Member
Posts
223
Location
Nth Yorks
Well Hiya folks.
I've been ****ed off for a couple of days, but now I'm happy again.
My TD4's been smoking a bit for a while now, not badly but grey noticeable smoke. I had a longish trip coming up for a wedding, (around 240 miles away) so I thought it was probably time to change the oil, oil filter and air filter before I went. Did the oil a couple of weeks before, and the air filter the day before.
On our way down it still smoked a bit, but not badly so, however, on the way back home yesterday, it got really bad and at points I was laying down a grey smoke screen on the M25, not good! As I proceeded it got worse and worse and at times under pressure uphill got really quite black. (very embarrassing).
I struggled home, going as easy as I could on the throttle, and next day had a look to see if any hoses were split or collapsing, but all seemed OK. While I was looking for anything obvious, I took off the sensor plug on the intake hose and give it a spray of contact and switch cleaner, don't really know why, maybe I'd read something here on the forum. I then phoned a localish independent landy garage to ask then if I could pop in for them to have a look, they said OK so I set off to see them. :eek: Bugger me! she went like a good un and no smoke to be seen :eek: I gave it some stick uphill and clean as a whistle. Guess it was just as simple as cleaning the contacts, and probably saved me a ton of money. Just thought I tell you, as it isn't always as expensive as you might think. :)
 
hiya buddy

sorry to be so dense but mine has also been doing this lately, ive also got a 2002 td4 and u mention a sensor, may i ask where abouts is it located plse and u also mention a contact cleaner, ive tried to find this in halfords and there is an endless range and dont know where to start

any details would be great plse as ive ordered anew air filter and turbo filter, got the bmw crankcase breather but haven taken it apart for 2 years

thks again

gary
 
it wouldn't suprise me .. if a deterioration of that sensor / grime on the plug contacts ..
would be a root cause for some folks less-than-favourable mpg figures ..

i'd been wondering about winter mpg versus summer mpg
and given no other changes at all .. 'n all engine systems are in good condition ..
what's left is how that sensor causes an alteration in injector fuel delivery

cold temp air intake keeps electrical resistance in that sensor high ..
heat makes the resistance drop ..
ecu sees a high resistance .. and assumes the intake air is cold and therefore dense ..
and as a result will inject more fuel into the cylinders

if the sensor gets the reading wrong ..
reporting a high resistance .. when it should be lower ..
the fuel/air mix will be fuel rich ..

if the sensor goes completely screwy .. like an open circuit
the ecu substitutes a reading of minus 5 degrees centigrade for 'air-intake-temp'
( resulting in an over-rich fuel/air mix for yer average uk temps :)

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

was reading a LZ thread the other day .. where someone went to replace the coolant sensor
only to find that sensors bought on ebay / some internet 'shops'
gave wildly different ohm readings at the same temperature ..
and they finaly had to get a sensor from a LR dealer ..

both coolant and air-intake temp sensors effect the fuel injection ammount ..
the glow plugs operate via the coolant temp sensor .. primarily ..
if the coolant temp sensor is screwed .. the ecu reverts to air-intake temp for g.p. operation

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
for Winter temps ..
i had in mind experimenting by wiring a 2 or 3 ohm resistor in parallel with the air-intake-sensor wiring ..
figuring that might fool the ecu into calculating that there's less air/oxygen availablefor the fuel ..
and therefore inject less fuel at any given time ..
am going to have to check with an electrical engineer friend to see if my theory might work :)
it's either that or ..
fit an adjustable flap in front of the intercooler .. so the air-intake is warmer than it would otherwise be .. i can watch the air-intake-temp on the 'scangauge' ..

~~~~~~~~~~~~~~~

good to read a simple plug clean solved the problem ..
and it weren't something worse :)
 
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got a 2002 td4 and u mention a sensor, may i ask where abouts is it located plse

i think on vehicles Not fitted with an air-intake-temp sensor on the top intercooler hose ..
the air-intake-temp sensor is part of the MAF circuitry ..

( and when one uses a pierburg maf in conjunction with a synergy box
( i believe r.ron has a compensation circuit for air-intake sensing
( there Is something mentioned on his web pages about that
 
Yes - the little temperature sensor is on the short turbo hose which was only fitted on later models as hd3 says.

When that sensor goes wrong you can get all sorts of faults - I had at various times:

Smoke
Limp mode/lack of pulling power
EML

Intermittant and very annoying - cleaning and or wiggling it about was a temporary fix - eventually cured by replacing the thing.
 
'gstuart' ..

just sent you a PM .. regarding a part i aint using .. and your welcome to use it ..
 
found this page the other day
it's 'toyota' related .. but i think the basic principal is the same ..

"temperature sensors"
http://www.autoshop101.com/forms/h32.pdf

am going to check the info with a friend who knows electrical circuits better than i ..
my knowledge of 'ohms' is limited to connecting loud-speakers to amplifiers :)

~~~~~~~~~~~~

btw: from what i've read .. the td4 uses only the 'coolant' temp. sensor for recognising a cold-start
( i could be wrong :)
 
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'gstuart' ..

just sent you a PM .. regarding a part i aint using .. and your welcome to use it ..

thks buddy, sent pm back, a very humbled thks to u kind sir

so this sensor on mine then will be the maf sensor that sits right at the back on the left hand side,

will look for a picture of my engine to see where the different sensors are

thks so much again

gary
 
I think pretty much all has been said as regards gstuarts questions, except maybe the contact cleaner one. The one I used is Darathene spray, switch and contact cleaner, but it's one I've had kicking around for 20 years or more, might not even be in business anymore. I'm sure though you will find similar ones. try this for instance. 6130001500 - AMBERSIL - CONTACT CLEANER, AMBERTRON, 400ML | Farnell United Kingdom
Cheers.
 
where i'm at .. halfords and maplin are next door to each other

for cleaning / degreasing on the car i'll use "gunk" from halfords
then clean that off with some 'isopropyl alcohol' spray from maplin
if it's an electrical contact i'll spread some 'contralube' on the bits ( maplin )

i suppose i could use / or should use a proper electrical contact cleaner for electrical plugs .. but i keep the alcohol spray around the house for other purposes
 
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hiya

thks so much for the great info and help, am so grateful to you all

thks guys and will be getting me some contact cleaner

gary
 
Merry Hill by any chance?

i'd like to say "i live on merry hill" :)
( yeah i googled it .. some shopping centre in west midlands ? )
but alas .. no ..
i be @ Bradford .. west yorkshire
 
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