306 xltd injector fault and some other stuff !

Hi All,

new to this group, hope you'll be patient with me... ;-)

Just got a '96 306 1.9 turbo diesel, 106000 mls on the clock. The car
has been well looked after and runs well. I have a couple of questions
though for your considered opinions. By the way I used to have a 94
version of the same car , though it was the non turbo.

When starting from cold, like if the car has been sitting for a while,
almost as soon as the engine cranks there is like a single 'kick' from
the engine - fools you into thinking it has started. But if you let go
of the key, it hasnt of course. You need to hold the key over a bit
longer, then it starts, with about 2 seconds of rough running and a
bit of smoke, then it idles cleanly. If you then drive off, there is a
misfire for about another 10 seconds or so at certain revs, after that
the car runs fine. Once warmed up the car goes great, although on idle
you can feel a little 'rock' from the engine - its not huge but enough
to be able to be felt in the car.

What I wondered was, is it possible / likely that I could have a
poorly seating injector which is allowing some fuel to drip into the
cylinder when the car is sitting, giving me this kick on starting /
smoke / misfire ? I had the car sitting running from cold one morning
and I swear I could hear an out of time crack every so often like an
injector firing at the wrong time - again, it cleared quite quickly as
the car started to heat up. I got some bargain low mileage injectors
from an accident write off car on ebay, tempted to swap em to see if
there is any difference.

Another question - the rev counter works intermittently. I have been
told to check the speed sensor mounted at the back of the engine,
which I will...but slightly oddly I find that if I switch my lights on
and off that usually kicks it into life. At first I thought maybe the
load of switching the lights on was putting a voltage spike on the
electrics and that was why it did this trick, but if I put on
something else like the rear demister, that doesnt work.. only the
lights.... any thoughts ?

Finally, I wonder what sort of mileage folks with this engine get from
a tank. Watching my tank go down, it was looking like a bout 100 mls
per quarter tank, which would only give 400 mls to a tank. however now
that its on the quarter tank mark, it hasnt moved as quickly and Im up
to 360 miles at a quarter tank, Do these cars have an odd shaped tank
so that you get apparrently more from the last quarter? I had hoped to
be getting 45-50 mpg from the car - i dont make much use of the turbo.

Thanks alot for your patience, look forward to reading some opinions!

Cheers
Craig

 

Question 1.
Fit a new set of glow plugs.

Question 2.
Have a look at the thread on the 306 speedo & rev counter.

Question 3.
Fuel consumption will depend on the type of driving. Round town will always
be lower than a long motorway run. The tank is not symmetric. The only way
to check fuel consumption is to check the miles for each tank full, filling
up to the top each time, and zeroing the trip reading.

 

Have you checked for air in the fuel lines/filter ?

J

 

Hi, no I've not checked for air as yet, knackered my knee recently so
its hard to spend ages hanging over the engine... plus my wee old mini
is residing in the garage now that I have this car, so theres no room
to get out of the nasty scottish weather !

I tried three cycles of the glow plugs this morning, and the car
started without any smoke, or misfire. I have had the glow plugs out
and they all work, but maybe they are just showing some age, or it
could be the relay contacts are higher resistance, or I guess it could
just be a combination of glow plugs, relay, lower compression due to
mileage, slightly low battery etc.

I think if it can be made to work with the old glow plug trick then I
will just leave it at that. However, I just finished the first tank of
diesel, and only got 39 mpg, which seems low, so If that persists (I
am driving like an old lady on this tank as a test) I will maybe swap
the injectors to see if there is any difference.

Having read up on how diesel pumps work, I think my earlier belief
that keeping the revs down to save fuel (ie getting up the gears
early) may be flawed, as this requires more accelerator travel to keep
the car going - and I guess that is just squirting extra fuel in for
no return. gonna go for minimal accelerator travel and sensible gear
changing on this tank. All part of the fun of owning a diesel again !

Anyway, as you may have seen in my other post, I might have bigger
issues to worry about in the form of a creaky rear axle!

Thanks
Craig

 

Having read up on how diesel pumps work, I think my earlier belief

It is a mistake to keep the revs too low on these engines. You will feel the
turbo kick in at a little over 2k rpm. Below this and you have to put your
foot down a long way to get any accelleration. Most people also put their
foot down too far to compensate.
Try this as a test.
Select a high gear, 3rd perhaps, and an empy flat road. At low speed, with
the engine at perhaps 1500, put your foot to the floor. Then slowly back
your foot off until you feel the accelleration rreduce. You will find you
come up quite a way. On the diesel, all you do when putting your foot down
further is pump more fuel, which the engine cannot use.
If you do the same test when the engine is using the turbo, then you will
find the accellerator more responsive, so you don't tend to put your foot
down so far, thus actually saving fuel. On mine I rarely go outside 1800 -
3000. Normally get low to mid 40s, up to 50 on the 306 on a long motorway
run.

 

Thanks.. Yes, I agree it makes sense to try an maintain a light
accelerator. Mind you, what you say about the turbo, I dont feel mine
do anything (regardless of revs) unless I have the foot about half way
down or more. At about half way, I get a nice smooth boost from about
2300 RPM, just enough to help the car along. If I put the foot down to
about 3/4 then I get the noticeable kick from about 2500 RPM, and a
bit of whistle too (probably got an air leak). But as I say, the turbo
does nothing on light accelerator driving.

I'll see how I get on on this tank with my revised driving style!

Cheers

 

Thanks.. Yes, I agree it makes sense to try an maintain a light

Yes, as I said, below the turbo minimum point, any amount of pedal only
produces minimal results, so there is no point in using more pedal than the
minimum needed, you just use more fuel. Get it over 2300, and it's a
different ball game.