405 TD failed MOT - smoke test

dvhttn · Post by **dvhttn** » 27 Sep 2005, 01:23

Hi,
I had my 405 earlier in the year by the Dervdoctor and generally it's been fine since. Definately went miles better. But I've always been a little concerned about the amount of smoke that appears, not just as the turbo is about to kick in either. Not really done anything about it though ... I did change the fuel filter and that reduced things noticeably but the smoke is still there.
Today it has just failed the smoke test at the MOT. Instead of a reading under 3 it was a minimum of 4.42. That was after a good thrash beforehand.
Can I tweak the injector settings myself to reduce this? If so, how? It's a 405 Turbo Diesel, with the 1.7 engine, the earlier one. With a Luca Cav pump.
I didn't check the air filter (though it was new 6K miles ago) nor did I use injector cleaner beforehand like I normally do. BUT would injector cleaner have that large an effect (4.42 -> 3)? And any particular make of cleaner you'd recommend?
Thanks for any info.

Quinny · Post by **Quinny** » 27 Sep 2005, 02:08

In my experience,a good injector cleaner like Millers Diesel+,used a few days beforehand,a new air filter,and the old Italian tune up,before going for the test,works wonders.
I've never had a car fail emissions using the above method.

Quinny · Post by **Quinny** » 27 Sep 2005, 02:13

Millers is about £7-£8 a bottle,but lasts about 250 litres,or something like that,but used regularly,can improve the cars mpg,make it run quieter,and more responsive,so the bumpf says.
To find your nearest stockist,click on the link below,and go to stockists.
http://www.millersoils.net/

razzleuk · Post by **razzleuk** » 27 Sep 2005, 03:42

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by dvhttn

Can I tweak the injector settings myself to reduce this? If so, how? It's a 405 Turbo Diesel, with the 1.7 engine, the earlier one. With a Luca Cav pump.
<hr height="1" noshade id="quote"></blockquote id="quote">
Seek out one of the many tuning guides on the web. The lucas/CAV pump on my 1.9 306 DTurbo has a "boost compensator" setting on the front of the pump. It's an allen key adjustment held by a 14mm locknut. Loosen the locknut and wind this clockwise as far as it'll go and it should cut down the amount of fuel added significantly. If it subsequently passes, just wind it back out.
This setting governs the amount of fuel added "on boost" but also affects off-boost fuelling as mine became really smokey off-boost with this wound right out (when I was experimenting!).
If this fails then it'll be back to the doc to get the maximum fuelling turned back down (a pig on the lucas pump!).
Raz.

fastandfurryous · Post by **fastandfurryous** » 27 Sep 2005, 03:57

Injector cleaner and a hoofing works wonders. Have you changed the oil recently? You can also submit the car with no air filter in it.
My mothers old pug 106 1.4D used to fail the emissions every single year without fail with an off-the-scale 9.99 reading. That was because she had been driving it at 2500rpm everywhere. Oil change, tub of injector cleaner, and down the motorway in 3rd, flat out, and we get a sub 2.0 reading. Until next year that is.

reblack68 · Post by **reblack68** » 27 Sep 2005, 10:56

I'm told that it helps to test the car on a cold, damp day too.

bad driver · Post by **bad driver** » 27 Sep 2005, 22:24

Looking at the front of the pump you will note 2 things, one is a big black plastic plug to the right of it is a small allen key screw with lock nut poking out a metal cap.
Firstly, dont just wind the boost compensator right in. You will underfuel on boost which is not good for the engine. Overfuel doesnt harm it just causes black smoke.
Right you need to establish exactly when your car smokes, there are 4 options which I will go through along with remedies to them.
1st, only on boost, requires adjustment of boost compensator only.
2nd, first few minutes of driving and on boost, requires adjustment of both fuel and boost compensator.
3rd, Normal driving up until boost but not on boost, requires adjustment of fuel and possibly boost compensator dependant on test drive.
4th, All the time, adjustemnts of both.
Now you ask how to adjust them.
Max fuel setting, remove the black plug by tapping it round anti clockwise with a screwdriver. careful, you dont take the edge of it or you may experience difficulty resealing aftrwards. Be warned though it will dump a load of derv out the hole when removed so watch your feet and done poor it onto obvious fire risks etc. It will splash the alternator but this wont do any damage. Now this is removed comes the tricky part, inside you will see a large cylindrical object with a hole in it. Inside this hole is another bit that turns. If you put the car in second gear and push it forwards carefully (engine off clutch out) the inner part will trotate. Its tricky but use a small mirror and watch inside, you will see at one point there is an allen key headed grub screw comes in line with the hole. You need to get this in line so you can use an allen key to turn it clockwise to reduce the fuel. Do it in 10 degree increments as its quite sensitive and min to max is only about 70 degree rotation. Once done refit the cap, prime the pump and test drive until optimum smoke and performance is achieved. Get it redlined in 3rd to check its not underfueling. Re adjust as required asits a case of trial and error.
Boost compensator, simply loosen the locknut and turn the allenkey screw, in for less, out for more. Remember to keep allen key in position when tightening locknut back up. As standard they are roughly screwed right in the turned 360 degrees out. If your boost is upped to around 18psi (usual derv doctor standard) then put it right in and screw out about 540 to 620 degrees.

razzleuk · Post by **razzleuk** » 28 Sep 2005, 02:30

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by bad driver

Looking at the front of the pump you will note 2 things, one is a big black plastic plug to the right of it is a small allen key screw with lock nut poking out a metal cap.
Firstly, dont just wind the boost compensator right in. You will underfuel on boost which is not good for the engine. Overfuel doesnt harm it just causes black smoke.
<hr height="1" noshade id="quote"></blockquote id="quote">
It was my understanding that dervs run with an excess of air all the time, (hence no throttle). I quite accept that my understanding may be wrong, but bearing this in mind, I didn't think running a little lean on fuel would cause any damage? [?]
Raz.

fastandfurryous · Post by **fastandfurryous** » 28 Sep 2005, 16:31

You're quite right, running a diesel engine "lean" won't cause any damage at all, it will simply reduce the power output.
If the car refuses to pass the test, then to be honest, the best thing to do is just screw in the maximum accelerator lever stop a couple of turns. This will reduce the maximum governed speed of the engine, and will reduce the fuelling to some extent. Pass the test like this, and then return the stop to its original position. I've done this before on a car that refused to pass, and ended up with a 0.7 reading!

robsons · Post by **robsons** » 28 Sep 2005, 18:42

Ditto Mr Furryous
....and it makes the MOT a little gentler on the car

dvhttn · Post by **dvhttn** » 12 Oct 2005, 22:07

A quick update on this - the injector cleaner and no air filter made NO difference so it failed again! Bum ..... Thanks to those that suggested the boost compnesator - a quick trawl of the internet thingy to find out what it looked like and a call to the Devdoctor (who had tuned the car several months ago) produced the suggestion 'wind it in 2 or 3 turns'. 3 turns it was then and hey presto no smoke ..... !

MOT time again (I also left the air filter out though) and the smoke reading went from an average of about 4.5 to an average of about 2.3 ... RESULT ...!! Also, no difference in power! It'll be interesting to see if the mpg is affected for the better ..

Cheers

dvhttn · Post by **dvhttn** » 13 Nov 2005, 17:09

.. well it would have been a good idea! Trouble is I then wrote the car off - b&gger!!!

Quinny · Post by **Quinny** » 13 Nov 2005, 18:21

And pray,how the (-expletive removed-) did you do that?

Ken.

dvhttn · Post by **dvhttn** » 18 Nov 2005, 19:47

Hmmm. Embarrassing really. In queue for lights. Car in front (205GTi) moved off. So did I. I glanced down for a moment. Looked up and guess what ???? Yep - the 205 had stopped - as did I rather suddenly ..... doh .... Felt a right t!t!!!

Anyhow, drove home and put it through the insurance as I couldn't be ar5ed to do the work myself outside in the cold and wet. It was beyond 'economic' repair for the insurers. About 2K of work on a 1K car so off it goes to that great scrap heap in the sky ... Still they'll pay me £900 when I only paid £1000 for it at the start of the year so not too bad.

I'm now off to VW Passat TD land - just bought a 130bhp Sport estate. It flies .... get it next week. I'll stay about though 'cos my mate has a 406 and I'll be asking questions for him ... see next thread from me ..

Cheers

fastandfurryous · Post by **fastandfurryous** » 18 Nov 2005, 23:24

Was this an estate or a saloon, and do you still have it? I am after a crashed-at-the-front 405 estate (hopefully for free) for the rear half for a rather interesting trailer project.

If it is an estate, and you still have it, would you be interested in parting with it, for it to be recycled?

David.