Misfiring??

alright,
i picked up my new '83 series 3 2.25 petrol on friday. it was running fine, until it warms up. Then it develops massive amount of misfire, almost un driveable, i put my foot down and it just stutters and spits flames out the exhaust. not good!
its running a weber carb, electronic ignition and a snorkel with no air filter (btw is that a good idea?)
i started it again today, and it was fine until it got warm, and underload from driving up the road, it then started to mis fire badly and spit out flames.
ive timed cars before (minis and n/a diesel landrovers), but non with electronic ignition, is it just the same as timing one with points? i.e just moving the dizzy round to make it advance or retarded?

Any ideas?


thanks for any help,
i did do a quick search, but couldnt find anything on series 3 misfring.

Yes it's the same and it sounds as if that may well be your problem. How old are the leads these can fail once hot but usually just cause missing not flames out of the tail pipe. Use a strobe on the timing marks and then turn the dizzy as you say. I have the same set up and also have Mini's with Electronic Ign. and they are all the same as far as timing is concerned.

i had the same prob and it was the disty.

Hi

I had the same problem but I don't have electronic ignition. Turns out it was my cylinder head gasket, and dammit....the old dear packed in today AGAIN...and the same symptoms.

Check your compression pal! I hope it's something simple, for you, I really do.

oldminiman said:

Yes it's the same and it sounds as if that may well be your problem. How old are the leads these can fail once hot but usually just cause missing not flames out of the tail pipe. Use a strobe on the timing marks and then turn the dizzy as you say. I have the same set up and also have Mini's with Electronic Ign. and they are all the same as far as timing is concerned.

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Doubt if turning the distributor will make any difference if it runs ok until it warms, sounds more like something throwing the ignition timing out all over the place. However if you can get it to run steady then a light will help to illiminate the distributor, look for a steady timing mark, if it's dancing all over the place then distributor or timing chain.

If the leads were arcing all over the place or even at the ignition coil then you get some good bangs and flames. Run it in the dark and have a good look and listen for it tracking, particularilly around the coil area, and look for cracks inside the distributor cap another common cause of bangs and flames. I also usually pull all the leads out one at a time and check them to see if they are mouldy in the cap.

If it wasn't electronic I would have gone straight for the condenser, but presumably that doesn't apply.

alright, thanks for your replies, i will have a go at timing it tonight, but i dont have a strobe light, will have to try and borrow one from somewhere. i will also have a good look at the cap, leads and compression.
the electronic ignition unit runs into the cab, and this seems to get rather hot, around the same time that the engine is warmed up, is it meant to get hot, or just stay warmish?

thanks

had a go at timing it tonight, and i think i may have cracked why its mis-firing.
who ever has fitted the electronic ignition in the past, has just fitted the electronic ignition modual to the standard dizzy, which still has the points in, and the condenser has just been cut off. is this how you do this conversion?? as in minis its a complete new dizzy, with the modual on one side, and just a rotor arm in the dizzy.

any help will be appreciated, thanks

JoeBodge said:

had a go at timing it tonight, and i think i may have cracked why its mis-firing.
who ever has fitted the electronic ignition in the past, has just fitted the electronic ignition modual to the standard dizzy, which still has the points in, and the condenser has just been cut off. is this how you do this conversion?? as in minis its a complete new dizzy, with the modual on one side, and just a rotor arm in the dizzy.

any help will be appreciated, thanks

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Usually the points are replaced with a more reliable optic trigger, but yes that is the way I have done them in the past something has to trigger the module.

I take it the cap has no cracks and is dry inside, the reason I say this is that I have had occasions when somebody has pressure washed the engine and it gets into the dizy, when the engine gets warm it evaporates and caused dampness in the cap, have had to use a hair dryer to dry them out.

You tried the darkness test yet, sparks everywhere?

If the distributor cap does not have any scratches inside it, then I would put the low tension ignition circuit back to standard by cleaning the points up, fitting a condenser and bypassing the electronic ignition module, and set up the static timing using a multimeter. That way you can find out if the ignition module has gone wrong. Check out the prices of dizzy caps, HT leads, coils, condensers - good news: they are very cheap

fenby1976 said:

If the distributor cap does not have any scratches inside it, then I would put the low tension ignition circuit back to standard by cleaning the points up, fitting a condenser and bypassing the electronic ignition module, and set up the static timing using a multimeter. That way you can find out if the ignition module has gone wrong. Check out the prices of dizzy caps, HT leads, coils, condensers - good news: they are very cheap

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Good idea, must be a **** system anyway if it's using the points, there are plenty good systems on the market and cheap aswel

ok, yeah think i will revert it back to points and condersor system, nah havent done the dark test yet, as i havnt been able to get it to run since its turned really cold. will have a go in a bit i think

thanks

My electronic ignition system got totally fcked up and the damn thing was backfiring like a mofo when I got it on the highway. I replaced it with the old style points and condenser and it worked like a charm.

Smilemon said:

My electronic ignition system got totally fcked up and the damn thing was backfiring like a mofo when I got it on the highway. I replaced it with the old style points and condenser and it worked like a charm.

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Had the same problem using the cheaper Luminitions unit on an MGB and that packed up within 100mile. Unfortunately I was in France, house hunting and of course with no points and no garage able to supply them the car and I had to be recovered back to the UK where, as you say, I replaced the old system and she fired up on the button.

My Landy has the top end Luminition system (came with it) and that works really well so my conclusion is go for a top end unit or remain with the old set up and replace the points and condensor at every service.

Merry Christmas to all!!!!