Missfire

Post by **Peetee** » Fri Nov 29, 2002 8:42 pm

Following on from 'all coiled up' I have replaced dizzy. leads, plugs, air and oil filters as part of a routine service on my 948cc car and it now runs as if it is suffering a missfire. Leaks and poor attatchments were checked as was the float level in the carb. I had to change the coil cos I replaced the combined dizzy cap and leads for top entry cap without realising the fitment in the coil was different.
Before the service the car was running OK ("why did you bother then?" I hear you ask - I'm begining to wonder

).
All parts came from DSN (who have proved to be an excellent company for supply and advice) with the exception of the coil which was from a local motor factor and is Ballasted. I now no this not to be correct and have a ballast resistor to fit in.
Should I be looking for something else at the same time as fitting this resistor.
Thanks for all your help so far peeps. Some of my questions may seem like they are coming from a thicky sometimes but what with the weather, short days three young kids and a working wife, time is precious and I can't afford to learn by guesswork

Post by **Cam** » Fri Nov 29, 2002 10:31 pm

Peetee,

Don't run the car with a ballasted coil without fitting a ballast resistor and altering your starting circuit.

If you do then the coil will probably suffer and the whole system will heat up (including points) which can then soften (melt) the plastic bits causing the points to close and misfire.

This sounds bizzare but my mate has just had exactly the same thing on his VW T2 campervan.

I would suggest that you buy a correct non-ballasted coil (the proper one for the minor) as it will save a lot of headaches. But if you absolutely want to go the ballasted route, then don't run the car until you have finished modifying it!!

Post by **Willie** » Sat Nov 30, 2002 12:19 pm

How come that a 'motor factor' sold you a ballasted coil for
a Minor?? They should have known better....take it back and
swop it for a proper type.
Willie

Post by **Peetee** » Sat Nov 30, 2002 3:03 pm

willie,
It was my fault. The minor wasn't listed and I suggested it would be the same as a mini. The coil I removed wasn't labeled either way and it wasn't untill I ased the question here about the diffence that I realised my mistake.
Moving on I have now fitted the ballast resistor in series with the coil and there is no difference.
Help! Wifey is begining to think I have wasted my money again!

Post by **Cam** » Sat Nov 30, 2002 7:19 pm

Check your points. They may be damaged (as explained earlier) from when you did not have the resitor in place.

Also, while you are at it, check to see if you are getting a good spark by connecting a spark plug into one of the leads while holding the body of the plug against a non-painted part of the engine and observing the elecrodes while someone cranks the engine over, you should be getting a strong blue spark.

Might be a good idea to check all 4 cylinders, just in case (coincidences can happen!!). Also, have you gapped the plugs correctly??.

When you were servicing the car, did you adjust the timing at all?

Post by **Willie** » Sat Nov 30, 2002 7:25 pm

think simple! if it was running ok before you started changing
bits then put the original distributor cap and coil back on and see
how you get on.
Willie

Post by **Peetee** » Sun Dec 01, 2002 10:28 am

I would but the screw cap from the coil lead has gone missing.
Cam, I will try by replacing the points. I have a Magnatronic electronic ignition module I could use but I don't know where to connect up the two wires from the sensor.

Post by **Cam** » Sun Dec 01, 2002 6:15 pm

Peetee,

Stick with the points system (new set) for now until you have solved the misfire problem.

Like Willie says - think simple, before getting multiple problems which can be a nightmare to find and cure.

Good advice.

Post by **Peetee** » Sun Dec 01, 2002 8:13 pm

Cheers cam,

I found a website with details of how to wire it in. I set the rest of the car up and he fired and ran.

For long enough to get him to the garage anyway. Everything seemed fine and he pulled well but every now and again I would have a major stutter (as if the coil lead were coming adrift rather than a single plug lead). Anyhow the batttery is very low so this may be contributing. I also noticed before that the fuel filter was the wrong way round (there wasn't the usual large arrow moulded into it.
In the garage Borris will have a good dry out and I will fight the right coil and give a thorough inspection in the warmth and at my leisure

Thanks for all the help folks

Post by **James Goodwill** » Tue Dec 03, 2002 1:09 pm

I don't want to 'muddy the water' too much, but don't discount a worn distributor.

I spent the whole of last season attempting to solve a misfire problem. Like you I changed all the obvious components - plugs, coil, leads, distributor cap, rotor arm, points, condenser - even a cheap new carb (I was desperate!). All were replaced with MM recommended spare parts, but did not solve the problem.

The misfire occurred under normal running conditions.

Towards the end of the season I realised that whenever I checked the points gap, they were always a couple of thou. out. I'd reset them, drive the car to an event - experience the misfire problem - then have to re-gap the points. In the end the points wern't even opening!

I've since bought a reconditioned distributor (£52) from MGM spares in Wigan - and guess what... problem solved.

Regards,

James.

Post by **Peetee** » Tue Dec 03, 2002 9:07 pm

Fair point, and one that I have come across before on a VW (no not a Beetle - Perish the thought - YEUGGGH!

).
However The car was running OK before hand and had never missed a beat. I simply had checked the normal service items and felt replacement was not far away and the best option for a trouble free winter. Tee Hee!

Post by **Cam** » Wed Dec 04, 2002 12:05 am

Peetee,

Glad to hear that you are on the way to solving the problem!!

Keep us updated!! And by the way, Beetles are not all that bad, just that they are nowhere near as good as Minors (and they are German...shhhh!!

).

James,

A couple of thou should not cause a missfire, if the points were closing it sounds as if the adjuster screw was not tight enough. I have had this before when the adjuster screw has threaded and is 'just holding' the points the the correct spacing, but then it closes after a short while. Obviously replacing the dizzy will cure this.

Actually, my MGB has a VERY worn dizzy, the dwell is all over the place, due to the centre shaft being able to move slightly from side to side, but that runs OK without a misfire!

I can relate to your frustration with the problem and the 'replace everything in sight' motto, it is very tempting and I have used it before with success, but as Willie suggests, 'keep it simple'.

I have been caught out on more than one occasion with introducing 'new' faults into the system by replacing OK items with dodgy ones, making matters worse, and fault finding a nightmare.

Post by **rayofleamington** » Wed Dec 04, 2002 9:40 pm

It's a shame you don't still have all the old bits. I've learned my lesson on that one as these kind of things can be a pain.
I got a misfire when I did the same as you - replacing lots of bits to give better reliability. Mine turned out to be a faulty rotor arm which only shorted if I put my foot down at low revs. Well it was only a small misfire for 8 months until it failed completely in the fast lane of the M6.

Since then I make sure the old (working) parts stay in a bag next to the spare wheel just in case. New parts can leave a lot to be desired!

Post by **an_avenger** » Thu Dec 05, 2002 12:20 am

Just like the real thing Beetles should be squashed

! At least when we pull away and change up a gear the engine gives a 'townie boy-racer' '.....vroooooooom......put....!' Not a tank nor a sewing machine

This is no offence to owners of VW Beetles but mearly a rival 'dish the dirt' on the competition! Anyway they have quite a good website

! (I'll probably get banished for saying that!

)

Post by **Cam** » Thu Dec 05, 2002 2:51 pm

an_avenger,

For God's sake!!! Don't compare either us or the Beetle lot to 'boy racers' in their Novas, Mums fiestas, Corsas etc.

or the 'rice boys' in their Japanese cr*p.

The Beetles may sound like a sewing machine running on two cylinders but they have rear engines!! Which is weird and scary but they have more traction due to the weight over the rear driving wheels which makes them a lot quicker at pulling off than us (unfortunately

). AND they don't suffer from axle tramp like we do.

I have had a look at their forums, and they have about 1000 posts in a 24 hour period, and they have many forums!! unlike ours!!! But I suppose it's quality over quantity

.

Also a normally aspirated tuned Beetle engine can produce in excess of 220 BHP whereas the A-series strugges to achieve 130 BHP.

And the Beetles were designed first!!!

But they are not British, or as good looking as the Minor and they don't have that 'charm' that the moggies have.

Post by **rayofleamington** » Thu Dec 05, 2002 10:35 pm

Well if you want power, curves and a rear engine there are far better options than the beetle!

Post by **an_avenger** » Thu Dec 05, 2002 11:10 pm

This is true - even though they were designed first, they were not designed by probably the once best car designer in the world.....good old Sir Alec!

Post by **Peetee** » Sat Dec 14, 2002 5:31 pm

'Ere stop hijacking my thread

Thought you might like to know that a replacement coil of the right type solved the problem.
Moral - dont be tempted to try a mini set up in the mistaken belief that it's the same engine, so.......
Cheers one and all

BTW Apart from the Moggies I've only ever owned VW or Audi cars.
But not those 'orrible air cooled things. Although an immaculate split screen camper is pretty stylish don't you think?

Post by **Cam** » Sat Dec 14, 2002 6:01 pm

Oh yes!, but not as stylish as a split-screen Moggy!!!

Post by **Peetee** » Sat Dec 14, 2002 10:15 pm

Do I get a prize for that obvious feed line?