Ignition :(

[Lennart Sorth]

didn't care to replace it Saturday as I didn't have my rubber-arm-kit with me

Hey come on! - you have small kids - at least one of them even mechanically inclined! :-)

But since you originally (in this thread) managed to keep your engine running on the choke, that takes the suspicion a bit off the coil... 

/Lennart

[Anders Dinsen]

didn't care to replace it Saturday as I didn't have my rubber-arm-kit with me

Hey come on! - you have small kids - at least one of them even mechanically inclined! :-)

You must be thinking of Troels...

[macaroni]

Blimey he's got strong fingers!!

[Anders Dinsen]

A few more thoughts and facts...

- Fuel consumption is somewhat too high, only about 7 km/l (16-17 mpg)

This is partly due to the fact that I do only/mostly short range city driving, fuel was leaking out of the carb with the o-ring broken, there seems to be a small leak around the accelerator pump, there may also be a very small leak on the fuel pump, idle jet has been set a bit too rich, and I tend to like the sound and acceleration when flooring the pedal around 3500 rpm

I will replace the fuel pump with an electric pump as soon as I find time to get me a 90 degrees drill head to make the holes in the engine compartment to fit it on (it will be fitted in the fuel tank side) - and to do the job of course

During January I'll take the carb out again to replace the accelerator pump membrane and to inspect the o-ring. Replacing the accelerator pump membrane can't be done in the car as the fuel in the float chamber will spill out when I remove the membrane. So it has to be dried out first.

- Running a fast-road Holbay cam as I do with the relatively large overlap of (I think I recall) about 90 degrees, means that there's a risk that at low rpm (especially cranking!), exhaust gasses are pushed back up into the inlet manifold. This is probably part of the explanation of the starting problems I had that day with the many explosions

This is not a problem in general, the engine runs very well even in low rpm once it's warmed up, but when it's really cold, it needs a well accelerated idle to avoid dying on me.

Roy is an advocate of this cam and with the experience I have with it so far, I agree with him as it really adds to the fun factor of the Murena. The performance of the cam probably depends a good deal on the exhaust side to create the necessary suction to get the actual performance and avoid exhaust being spit out into the inlet, whereas the inlet side is much less critical and may even benefit from the single carb setup that I have.

- I haven't had any starting problems sice that day, so I might just keep my spare coil in the trunk for now.

- Sunday when I fired well under the car on the motorway it acted odd when I turned off, as it was slightly reluctant to run and idle ended up being around 2000 rpm... carb ice! It cured away after a few minutes, but tells me that I should find a piece of aluminum tubing to take the inlet air from the exhaust area (the automatic switch in the inlet isn't connected).

But with black ice all over in our neighborhood this morning (!), I decided to take the Espace though, so Murena is standing still today

[Lennart Sorth]

carb ice!

Yep, - that does deflate a lot of the talk about poor ventilation at the top of the engine.
When driving, there really IS a lot of fresh (and in DK currently too cold) air up there - so the added temperaturedrop of evaporating fuel becomes a problem. Boy, do I remember that :-)

/Lennart

[Matra_Hans]

Well Anders if your main concern is fuel economy you should not be driving a Murena but something like a Polo HDI.
With your Holbay cam with big overlap (under some conditions) part of the unburned gas must be blown out through the exhaust, resulting in bad mileage.

I agree with you Lennart the front side of the engine with the carburettors is not hot as the airflow in the engine room is up the front side of the engine across the top and down at the hot back side of the engine.

regards Hans

[Anders Dinsen]

Well Anders if your main concern is fuel economy you should not be driving a Murena but something like a Polo HDI.

Oh no, not a polo! 
Actually I'm only concerned with fuel economy when it comes to keeping an eye on the carburation, and this is something that I've disucssed with Roy: He thinks it can do better and that something may be wrong.

With your Holbay cam with big overlap (under some conditions) part of the unburned gas must be blown out through the exhaust, resulting in bad mileage.

Yes that is correct, but again I'm relying on Roy's experienced numbers with this cam, and they are better than what I get, which indicates that something is not quite right. But then again, it's running well overall, so it may also be my driving style that's making my numbers. I have done only one or two longer jurneys with the car while I've had it (100-150 km), everything else has been 20-30 km per day, and this may really make a difference.

I agree with you Lennart the front side of the engine with the carburettors is not hot as the airflow in the engine room is up the front side of the engine across the top and down at the hot back side of the engine.

I bought an IR-thermometer recently: After a 20 km drive in the cool weather we have now, I measured the carburettor temperature to about 20 degrees, while the exhaust side of the engine was around 90-100. The inlet manifold is a good deal warmer than the carb because it is heated by the coolant (and the carb is thermally insulated from it), but this only makes the difference more is notable. You are probably right that the airflow means that the front of the engine is cooled a lot in cold weather, but we should not neglect the thermodynamic effect of the (cold) inlet air passing through the venturis, which will cool down the carburettor considerably independently of the rest of the engine block and manifold.

- Anders

[Lennart Sorth]

if your main concern is fuel economy you should not be driving a Murena

my 1.9i does 13km/l and can be pressed as high as 14.5 (once!)  if I drive ridiculously careful (=boring) -  which I normally don't.
My 1.6 engine normally did 12, and as far as I remember hardly ever under 11 km/l unless something was wrong. (carb problems)

My 1991 Peugeot 106 1.1 "spare car" does 17 on average, and I have twice managed 18 and 19 on a full tank - (thats 850km on its 45 liters!), so If I want to conserve fuel, I can always take the spare-car, in which my son has fitted a 1600Watt Boss amp and a 8" sub. Thats fun in its own way.   :-)

I'm actually using that for the moment, as my altenator in the 1.9i has gone berserk, and sends 18V to the rest of the car. New alternator (or regulator) goes on next week.


/Lennart

[krede]

everything else has been 20-30 km

Using the choke any amount of time spoils the milage completely..

[Anders Dinsen]

Time to revive this thread... I haven't had serious problems like what I had on that day back in December, but I had to replace the ignition coil the other day. Strictly speaking, the coil didn't fail - I broke it myself when the minus tab broke off. Getting the old one replaced wasn't easy - apparantly they designed the car for mechanics with very long and flexible arms, but I got the job done with the help of my son, and there is a good difference in starting and running.

An ignition coild is an ignition coil, and as long as it's working it's good enough seems to be the rule of thumb, but there's little doubt that the 25 year old rusty orange cylinder with copper wire inside was wanting to go on pension

On the other hand, I have also played with carburation, Will kind of suggested that I convert to a Weber but my old Solex 34CIC is in perfect order, the only thing that has been wrong with it has been seals and gasket, and my messing up with these parts. The worst thing to get right is the o-ring in the accelerator pump fuel line, which tends to break if it's not the correct size, and since the size supplied with the repair kit is completely wrong, there almost 100% chance of getting fuel spillage if the gasket kit is used as-is. Like I did. And then it took some five tries to get it right. Details are on http://dinsen.net/murena/carburettor/maintenance

Getting this right has also improved the running, especially the cold starting and running on the choke.

So the conclusion is that the problem was probably a combination of the two: Ignition problems caused by moisture, and carburation problems caused by fuel leaking in the carburettor.

I'm happy again

Cheers to all,
Anders

[krede]

As for milage.. I've averaged 7,8 km to the liter since i came home....

[Matra_Hans]

To be honest I have newer calculated the consumption during the 10 years I have had my Murena where I have been driven more than 50.000 km.

I try to calculate fun per km instead.

If mileage is important get a Pole 3L of a Smart

Regards Hans

[krede]

Yahh.. my point excatly
I get alot of 5 mile smiles for my money... and possibly some hearing damage aswell 

[Anders Dinsen]

To be honest I have newer calculated the consumption during the 10 years I have had my Murena where I have been driven more than 50.000 km.

I try to calculate fun per km instead.

If mileage is important get a Pole 3L of a Smart

You are repeating yourself, Hans!

But I agree, Murena is a fun-car, not one that's fuel effecient. Still, I do understand Krede. He's got his Murena as his only car, so he needs it to be better than it is now, and I think he can do it.

[Waldo]

I know this doesn't help in anyway... but this kind of problem was exactly the reason I decided to go for a HDI engine!

I won't have all the carb issues, and the mileage should be around 20-22 km/l without decreasing the fun factor... though the engine might not be as thrilling!

So I figure there's no need to spend ridiculously money driving a fun car, but I will also be using the car everyday!