4ac, Having A Bad Miss

[tas_ae71]

hey,

 

been driving along for a while, fairly problem free.

 

it starts missing badly, just cruzing along then it just misses like a bastard

 

i have put heaps of fuel cleaner shit on the fuel, mixed it strong, held a few revs on it. its had new plugs and dizzy cap recently and i ave swapped a few spare leads around.

 

it dosent do it all the time but when it does it does badly, it has an exhaust leak which I'm getting a gasket for but i dought it could make it miss like this

[tas_ae71]

any ideas people? was running resonabley well up until resently.

[tas_ae71]

put a new rotor button on, also tried a spare set of leads on still doing it. need some more ideas..?

 

as i said it doesn't do it all the time but when it does I'm just waiting for it to stop completely, its my only car, can't borrow a mates cause his doesn't have a motor atm. so really need this fixed, i can't afford to go and replace everything or take it somewhere. with my current job I'm earning 50 bucks a week because they are being stooges and aren't giving me any work, thanks John Howard you shithead, for giving me a stable job

[KE70-from-mt-panorama]

Hey,

My mate has a similar problem in his RA40 Celica. It used to miss really bad at idle. My dad static timed it for him and then it stopped missing at idle but now misses everywhere else in the rev range. The problem with his car is that his vacuum advance is rooted.

don't know if this s the same problem but i hope the information could be useful.

 

Good Luck with it mate.

Cheers

Jake

[philbey]

Hey mate,

 

Although you got new plugs in it, I'd pull them out and take a good look at them. ie are they black, white or brown, or are any of them clean?

 

I used to own a CA18 turbo, and those things are notorious for shitting plugs.

 

I used to cruise along and it would miss every now and then, then one day it started running on 3, ecspecially bad on boost etc. It was intermittent, some days bad some days good.

 

New set of Iridium plugs (80 bucks a set!) and it was smooth as.

 

Check them and let us know.

 

tp.

[tas_ae71]

ke from mount panno - have checked timing recently was where it should be for standard.

 

Philbey- sounds quite simerla to what you described but i think it bay be cutting on l cylinders, only for a fraction of a second, its quite violent when it does, will check them tomorrow. it has its good days also, sometimes it runs without incident seems to becoming much more frequent tho.

 

thanks both for your ideas, if this doesn't work I will swap the carb and dizzy from my old blown 4ac, only thing was that it didn't idle which is a common problem with the stock carbs.

Edited June 9, 2007 by tas_ae71

[mitch13]

Theres an adapter that you can buy that you put over the plugs and it supposed to stop this sort of thing. Run it till it starts to miss then pull the plugs out and see if they are wet or sooted up, if they are then the adapter should work, sorry I can't think of its name.

Or maybe just check the mixtures or do a compression test.

Does it only happen when the car is hot?

[LittleRedSpirit]

I had a weird miss in my car once. A loose wire which had broke off the condenser, was grounding itself on the body every once in a while, causing it to miss each time. It was wierd because it would be good for a bit but as you sped up it would get worse as air pushed the wire around. So have a peek around for a loose wire which might make something similar happen. Good luck.

[tas_ae71]

thanks for ideas mate, no loose wires to the dizzy or coil.

 

i whipped the plugs out and they are abit orange

 

 

I'm not sure what color they should look like, none seemed particualy sooted up although it wasnt missing whn i swiched the car off last, plugs tend to get hot when it has been going and because it only does it for a few seconds when I'm driving its abit hard to stop becuase by time you find somewhere to pull over and switch it off it would have probaly stopped it. it dosent it when it feels like it, its gradually getting worse has done it on idel a few times.

 

when driving its like steping totally off the throttel for half a second, it may continue doing it for 10 second or a minute then its fine again.

 

have also swapped a spare set of plugs from another motor just to be sure.

Edited June 11, 2007 by tas_ae71

[philbey]

Those plugs look alright, thats the sort of colour you should be aiming for: Black would mean too rich, and white too lean (corrections anyone?).

 

LittleRedSpirit makes a very good point: A dodgy wire, or cracked insulation on a lead may cause a spark "leak", which would generally result in a weak spark. Pop the hood while its running in the dark and look for any sparks jumping from leads to the chassis.

 

May also have a knackered lead - they usually are a graphite core, and if they get flexed too hard or played around with too much, they can crack internally which would affect spark.

 

Also, perhaps the coil is on the way out, but I don't know much about how they die and the symptoms.

 

If you can't get it nailed soon, I highly recommend seeing an Auto Elec. Last time I had an issue like this, he took a quick look at it, told me what it was and how I can fix it myself! No charge. Failing that he might charge you for an hours labour, about 60 bucks. Well worth it.

[tas_ae71]

As i said, have checked all the wires going to coil/dizzy have put a spare set of lead on. I'm not 100 about coil failer either, i have a spare one kicking around so i will try that. Drive to the sticker guy 1KM each way and it missed all the way there and back so it definately getting worse.

 

Also f@$k the local auto electrician, last time when i had problems (stuffed condenser) he came around muched around with it, abuse me for the dodgy way i had the started rigged up and afetr about 30mins he told me that my dizzy was f@$k and that i should get another. I grabbed another from a mates car knowing full well that this bloke didnt know what the f@$k he was doing. i got my old mans mate to come and have a look, he ran over evenything with a multi meter and found the problem and it was running in 5mins.

 

I was thinking the plugs looked ok, but i thought i would check. Coil will be swapped next i think.

[Xany]

Coils normally either work, or don't work....they don't normally have intermittent problems. Personally i'd be checking the condensor again.....replace it with another one, and at the same time if you have a points dizzy.....just check the gap with some feeler gauges.

[tas_ae71]

i swapped a spare coil over and i seem to be back to square one, it having an bad miss at times... any idea what the points gap is surposd to be?

[philbey]

Also f@$k the local auto electrician

 

Fair enough - doesnt help when they're muppets. The guy I go to is great, but no use if he's in melbourne for you.

 

Coils normally either work, or don't work....they don't normally have intermittent problems. Personally i'd be checking the condensor again.....replace it with another one, and at the same time if you have a points dizzy.....just check the gap with some feeler gauges.

 

Cool. I wasnt sure if that was always the case or not. Last time I had a coil go it died completely.

 

As for the points, no idea. Anyone with a workshop manual should be able to make that call.

Edited June 13, 2007 by philbey

[LittleRedSpirit]

This might be out of left field, but how is the fuel supply, new filter, clean tank/fuel, etc.? If its not electrical, then who knows. Is it making the same power when its not missing that it always had? It might be firing fine, do you have an intermittent vacuum or compression leak? Battery terminals? How about the ground from the body to the block, is it in good order?

Edited June 13, 2007 by LittleRedSpirit