missfire 1.3 sr

[mk3 vinny]

I havent been using my car latley but since my last problem with the clocks I have develeped a missfire when accelerating notisble when the second choke kicks in, in 4 and 5 gear. Could this be the coil pack at fault as I suspect that blew the revcounter and clocks up on 2 sets in 2 days

or could it possibly be fueling?


thanks vinny

[marc69]

Coil pack on an SR? Should just be one simple coil.

The misfire could be caused if it is under heavy load in those gears by the accelerator pump jet being blocked, or if your 2nd choke is opning and the wee fuel pipe being blocked?

Although, when the 2nd choke kicks in, if it is fully you will feel a lurch, therefore ot may just be the shock of it opening?

YOu blew 2 revcounters? seriously bad wiring issue there, which will probably lead to serious problems later on, coil failure etc.

[mk3 vinny]

ye its just a coil lol normaly deal with coil packs these days

yes you can feel and hear the second choke open so i think that side is fine

also yes 2 sets in 2 days the wireing was and is still a mess in places however i am trying my best to sort it out bit by bit.

the clocks started to bounce all exept the speedo as thats manual then after about 10 mins of that they went off on the first set the second set was the same but at the end the rev counter was the only one i lost.

any way thanks mark will possibly try and sorce a cheep new coil to see if that helps.

[jimbob-mcgrew]

are the 2 vacuum passages for the secondary throttle clear ? they block up easy and can cause a lean, sluggish performance.
might be worth checking the tiny gauze filter, within the neck of the 'fuel in' pipe inlet, might be clogged up a bit.

[mk3 vinny]

thanks jim bob i will try that first thanks and ye i think the two passages are fine as the second choke opens fine however the auto choke dosn't work so may need adjusted so that may also have something to do with it.

[jimbob-mcgrew]

its a little fiddly setting that up, but have a good look at the mechanism and youll figure how it works, it has steps or stages if you want to call it, says a bit in the haynes about it.

when the engines cool, pull off the auto-choke housing and give the coil spring inside a clean with cotton bud sticks and some alcohol / meths type solvent. i hear they get dusty and dont operate as well as they should.

also the housing adjustment, personally i adjust it to the point that its just touching 100% off when its fully warm, that way you'll get the most out of it when its cold, as well as it flicking off 99% or completely. i like to set it up while its running (but, watch out youll burn your fingers) or you can mark the housing and notch it back and forth while its off or cold if you want.

check all the vacuum hoses are a tight fit too, sometimes when you think there ok, there weeping air slightly

check the choke pull down too, a small 3mm or so allen key adjustment from the frontside of the carb on its end, you can see the slot in the side of it engaging with the lever on the carb. i find it runs better on mine with it wound in a bit more than usual, so the choke kicks off earlier, whilst revving, but every engine setups slightly different so have a play and see how it goes :)

[mk3 vinny]

thanks jim well its already set all the way to one side ( i assume off ) and i need to replace the black vaccume mushrum thing on the back of the carb as mine is broken thats £33 new so not that much then i will be able to have a fiddle.

however the car as always been fine when running no miss fireing or spluttering till now but that vaccume thing on the back has always been broken but i will still give it a go

[mowgli]

stick a new coil on it. they always knacker up on the early carb ones.

then new plugs & maybe ht leads if you haven't already changed them

[mk3 vinny]

thanks mowgli i will be fitting a new one to it and may as well change the leads as there cheep and do a full service as it could probs do with one then do the carb stuff to but will test it before i do the car to see if it was the coil.

what are the ones on ebay like and is there any point putting the performance leads on or will i just put standard ones on

[mowgli]

performance leads are simply more money & a different colour. std ones work fine, as do std spark plugs.

as for a coil, one from intermotor should usually be ok.

[mk3 vinny]

thanks will order them now

[mk3 vinny]

i took the car to York race way on sunday and it was doing the usual at 70mph killing the power and the odd pop and bang, so after the first run I changed the coil, leads, dizzy, dizzy cap and plugs run 2 the same, so I retired her after that as my times were 19.22 and 19.44 still not bad for a 1.3sr. then on the way home it got worse and ended like this
http://i848.photobucket.com/albums/ab43/mk3vinny/002_zps16e1cc68.jpg
turned out that was a wireing fault and took 5 mins to fix but 6 hours of wating but the car was cranking like it had no compression so I thought the fuel pump packed in but it ran fine once the got it running.

this is what was fitted plus the leads that turned up the next day

http://i848.photobucket.com/albums/ab43/mk3vinny/011_zpsaa2cb2fd.jpg

Any ideas as im stumped

[jimbob-mcgrew]

broken wire you say ?

[meritlover]

Well does it have compression? is the timing belt slipped or snapped? is it firing regularly? Does it have fuel?

[mk3 vinny]

Yes they jiggled the wires and it fired up but I cant see how it is an electrical fault as its fine in the rev range 1st and 2nd

yes its got compression just sounded like it didn't hence I thought it was a fuel problem its firing fine and it has fuel like I say its only in 3rd at 70mph it dose it the AA let me drive the 50 mile home and it was fine.

If I floor it in 1st and second even 3rd it revs right through the rev range until I hit 70 then as if it is cutting out and restarting in quick succession. No back firing like as if it is not sparking as the fuel would be there and explode in the exhaust causing a back fire.

my zetec turbo done this and it was fuel starvation but surly a standard sr shouldn't be fuel starved cos even if you put it in 4th or 5th it as if it is in a limp mode with no power ( yes I know there is no ecu and no limp mode) it never done this when I got the car it had a bit of power in 4th and 5th compared to now.

[Spudly]

Try a new/different carb on it, the 1.3's have the pierburg 2e3 same as the 1.4 SR dont they, theyre notorious for failing and causing running problems higher in the rev range!

[meritlover]

check the fuel pump, check for crap in a jet somewhere, air leaks in the manifold and replace any fuel filters if you haven't already.

[mk3 vinny]

thanks spudly ye they are knone to be problematic but if it is the car im going to put a webber on and be done with it.

thanks merit lover I will get a new gasket and see if I can clean the jets out and see if it has any filters

[marc69]

Have you checked the accelerator pump jet? they block and cause the spark plugs to over heat through fuel starvation under load. Whilst yoyu have the carb spliut, check all the jets and vacuums. Even the choke vacum afffects the running under load.

[jimbob-mcgrew]

so it drives ok until the load gets too much, and then it starts to limp ?

get a can of carb cleaner - without taking the carb apart and breaking the gasket seal, blast it thru down every pipe / passageway / jet, you get the long nozzle from the can into.

from the throttle pump on the cam carrier, theres a hose to the fuel-in inlet pipe on the carb, there is a tiny gauze filter within the neck of that inlet pipe, pull that out with a pic or tiny screwdriver, and check its not blocked too. there usually knackered after 20 odd years, i'd bin it and fit an inline filter in its place.

the jiggling of wires to start it sounds a bit dodgy, like the coil might have a dodgy feed, or theres a bad earth or corrosion somewhere ?

[mk3 vinny]

I found the wire that made the car cut out its the one on the bottom left of the coil with the grey plug on (main live for the coil?) so I managed to bend the metal clip in side and sort that no slop in it now. i'v cleaned the carb before but it didn't make any difference but I will try and do it again this week cos it is looking abit dirty and I cant seem to find that filter where would it be situated exactly but it looks new so may be an aftermarket one with no filter and the neck is tiny. so I will fit an inline filter this week aswell. thanks for the help lads

[jimbob-mcgrew]

is within the fuel-in pipe (on the backside of the carb as you look at the bay)
it filters incoming fuel, it usually gets clogged with crap and degrades somewhat after years. can cause running issues under load if it gets too blocked.
you'll need a small pic or small screwdriver to hook it out, can be a bit fiddly.
you can tell if there's one in there, as the screwdriver will only go in about and inch and a half or so, as without the filter there, the screwdriver will slide back twice as far.

http://i289.photobucket.com/albums/ll227/photon_09/additional/o-ba05617e9d66e0e95f8c583874b345ba-52332813.jpg

[mk3 vinny]

thanks jimbob I will check later today had a nother problem aswell I adjusted the auto choke and had to disconnect it later as the second chock would open by its self and stay there and I had to ether put the car in to 4th and put my foot flat on the throttle then release it or click it off manualy.

also will it affect the running if the vacumme thing on the back there is broken as mine is

[jimbob-mcgrew]

the backside vacuum unit is the choke pull down, it gradually lessens the choke as the throttle is raised. I think its only used during warmup. once the engines warm, the pressure from the autochoke coil spring holds the flap open there-after.

mine has a manual choke conversion kit fitted. I did away with the vacuum unit also, as it wasn't doing anything with the kit fitted

[kent14sr]

Have you checked all the fuel lines?

Are you running an inline fuel filter?

Do you mean the black plastic mushroom looking thing when you say vacuum?

[mk3 vinny]

thanks jimbob I can see a webber in the future this pierburg is over complicated.

kent14sr I have had a look at the fuel lines and all seam new, the inline filter is on its way and yes the mushroom thing on the picture.

[jimbob-mcgrew]

keep it vin, its actually a decent carb. just take some time to blow out all its passageways as they clog up over time. youll have to set the choke up, already half turned off as the vacuum units dead. should be half decent after that. you'll prob find that you have to hold the throttle down a tad when its cold for a min or 2 to get it idling, being that the chokes only half working.

everyone gives up on them because they never get serviced and end up running pants

[mk3 vinny]

thanks jimbob I will hopfully the filter will turn up tomorrow then will have another look at the carb

[mk3 vinny]

Right I took the butter fly off the auto choke and pulled the screw right back as for some reason the car started ticking over at 3k then adjusted the idle screw now it runs perfect then looked at the filter and cleaned the carb out this was the fuel filter

http://i848.photobucket.com/albums/ab43/mk3vinny/004_zpscb75b59f.jpg

so I left it out and fitted this new bad boy

http://i848.photobucket.com/albums/ab43/mk3vinny/005_zps13de34f2.jpg

now I need to fix the alternator as it has snapped the bolt in the inlet for the adjuster

[Pulsar_stu]

Long shot here!
Could it be the ignition module in the dizzy?
Does it have one?
Back in the early 90's when I had my first 1.3sr mine run like you have described and it was the module!

Worth a try if its got one as they are cheap these days!

[meritlover]

good work!

and kudos for coming back with pics describing the cause of the problem which helps others.

[mk3 vinny]

Pulsar_stu it was the main live on the coil ( grey plug ) if you put a small bit of pull on it the car would cut out.

meritlover I just like to end the post properly

if any one wants one of them filters it cost £6 from ebay its a glass tube with chrome plated ends and a washable filter