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coldstart misfire probs
https://www.ausmini.com/forums/viewtopic.php?f=2&t=9486		 Page 1 of 2
Author:  Shard [ Tue Jul 26, 2005 3:21 pm ]
Post subject:  coldstart misfire probs
Mokeys been doing it for a week now and I can't figure it out.

When I coldstart him, one of the cylinders is misfiring (yes, AGAIN!). Prob is it will kick into action shortly after a few revs or on it's own idling before I drive off (no more then 2 mins). The time it misses seems to be related to how long it sits there. <1 hr it will start fine again, any more then that and it will range from having to leave it for a minute to sort itself out (overnight sit) or a few revs to sort it out (ie. go to uni, come back after class and start it up).

After the initial start up misfire the car will run ace the rest of the trip. I'm confused, always thought spark problems were consistent (ie. consistent fail).

Diagnosing which cyl is hard (i'm betting it's #1 seeing as it was the culprit last time) because more often then not by the time I get under the bonnet it's sorted itself out and won't playup till I leave it parked for a while again.

What are the gremlins doing to my car?

Shard
Author:  Circus_Maximus [ Tue Jul 26, 2005 4:19 pm ]
Post subject: 
Shard,
If your distributor cap is a bit on the old side either renew it or remove it then wipe the inside with metho and CLEAN rag / tissues. When its a bit dodgy, overnight condensation can be a problem. Don't use WD40 as that is for temporary water fix only, it will combine with dust and dirt to form a film of "crud" (technical term) :)
Author:  Shard [ Tue Jul 26, 2005 4:25 pm ]
Post subject: 
Caps only a month old :/.

I've been playing around outsdie with the mixture and have leaned it out a bit (thought perhaps the cyl might be flooding on start) and will see if that fixes it. Had a problem before with mixture where it idled great but engine would be a bit jerky on heavy accell so I richened it up again. Maybe the fast idle needs adjusting or something if it's not getting enough fuel under acc :?:.

Shard
Author:  Circus_Maximus [ Tue Jul 26, 2005 4:33 pm ]
Post subject: 
Have you had any rain since replaced? Still wash out the cap with metho though, you gotta eliminate every little thing until you hit the problem. Once had a dodgy ignition coil that did funny things but the good news was it failed permanently not long after. :roll: Carry a spare?
Author:  speedy [ Tue Jul 26, 2005 5:59 pm ]
Post subject: 
I once had a misfire problem that took weeks to fix, "what about the coil" the mechanic would say, "its only 3 months old" I would say, and so we would then look elsewhere.

After alot of frustration, we replaced the #@$% "new" coil, and that fixed it.
Author:  9YaTaH [ Tue Jul 26, 2005 6:16 pm ]
Post subject:  Re: coldstart misfire probs
[quote="Shard"]

Ummmm Shardy....I'm no expert...but one thing I have learned is that when you are trying to track down a problem, try and leave other things alone (so that you don't introduce a new problem on top of the original!).

If you think it is electrical....than work methodically through the whole chain....even change items that are brand new to eliminate them as a source of the problem...so if you have new plugs....try an old set (that worked!!) for a while etc

Fiddling with the mixture AND trying to find an electrical problem (if it is that) can just make it twice as hard.....good luck :wink:
Author:  Shard [ Tue Jul 26, 2005 7:31 pm ]
Post subject: 
hmm. It's annoying having to replace electrical seeing as all the usual failure stuff is only a few mths old. I just went througha whole replace the usual crap when the fuel filter failed :/.

Will have a look at the cap tommorow (and rotor while i'm at it) and go from there if it still does it.

Shard
Author:  Lillee [ Tue Jul 26, 2005 9:31 pm ]
Post subject: 
Define missfire for me Shard. Is it backfiring at the carb end? Is it actually misfiring (running on 3 cylinders) or is it just running rough when it's cold?

I give Lillee a good 6-8 mins to warm up before I start driving (basically at least until the temperature gauge has moved off cold and is at least 1/4). Anything less than this and she backfires from the carb (bang, pop, gurgle) because it is slightly lean at idle, but once it's warmed up it runs like a house on fire. I can't start without using the choke, and when it's cold she runs like a VW on heat. Hence I have a nice long warm up and she runs like a dream 8)

It's been cold lately, just give the old girl more time to warm up! :wink: is that what the problem is??
Author:  Shard [ Tue Jul 26, 2005 9:52 pm ]
Post subject: 
Runs on 3cyl, no backfiring.

Generally if I leave it anywhere for more then an hr it'll go back to 3cyls till it's revved a bit and then run as normal till it stands for an hr+ again. Doesn't matter if I've already driven it around for a few hrs that day. I can understand the morning trouble, but it fires 3 consistently if left sitting with the engine off :(.

Anyway I'm checking the cap tommorow and seeing how it goes. Will post back if it's still doing it after I've been out and about tommorow.
Author:  Lillee [ Tue Jul 26, 2005 10:02 pm ]
Post subject: 
Oh ok, I take it back then :oops: :wink:
Author:  drmini in aust [ Tue Jul 26, 2005 10:49 pm ]
Post subject: 
Having just gone thru a low speed misfire problem with Barney, I'd check your plug leads with an ohmmeter. Any that are over 8K ohm, I'd bin them.
One of Barneys was 17K ohm when straight, total open circuit when bent... :cry:
He's running nice now with his new Bosch leads from SuperCrap, $4.95 each.
ps check the coil lead, too... :lol:
Author:  Rodney [ Wed Jul 27, 2005 9:54 am ]
Post subject: 
Exactly the same same thing was happening to Ribena a week or so back. Found out that the head gasket had been put on upside down, and that was only 7 or 8 weeks ago!!!

Replaced the head gasket - only takes a few hours, and she's running fine now. :D

That's the 3rd head gasket since we went to Minis on the Murray. I'm becoming an expert at the job. :wink:
Author:  Shard [ Thu Jul 28, 2005 6:16 pm ]
Post subject: 
Gasket problems hmm.

It's not stuttering on cold startup anymore, instead now it's missing on accelleration :roll:. Have to really rev it up before letting the clutch go or it pewters out or just behaves like it has no fuel. I think my carby is long overdue for a overhaul :(.

Shard
Author:  speedy [ Thu Jul 28, 2005 6:28 pm ]
Post subject: 
This miss on acceleration you describe, I had the same problem before having to chuck out a 3 month old coil (one of those red GT40 jobbies).

Good luck finding the blasted problem. :wink:
Author:  Mini Mad [ Thu Jul 28, 2005 6:30 pm ]
Post subject: 
Shard wrote:
Gasket problems hmm.

It's not stuttering on cold startup anymore, instead now it's missing on accelleration :roll:. Have to really rev it up before letting the clutch go or it pewters out or just behaves like it has no fuel. I think my carby is long overdue for a overhaul :(.

Shard


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