What could cause a misfire on a 20xe??

[comptoncj]

After a week or so outside i finally had the chance to look further into my misfire problem, i thought i would double check on a cylinder leakage test and it came up ok, i know its got a spark and by the looks of the plug its got plenty of fuel... What sensors on a 20xe could cause a miss? I've double checked all the earths on the engine and gearbox and all the wiring connections but yet it still misfires. Any help would be appreciated as its annoying me now lol

Cheers :)

[Adam]

Whens it misfire? Constantly??

[comptoncj]

Yeah constantly chap

[Adam]

Bad spark plug? Dodgy HT lead? Dizzy cap? Rotor arm?
Loads of things tbh

[comptoncj]

I've changed all of those lol might try an injector on it, could a fuel pump relay cause a constant miss?

[John]

Do you know which cyl? if so swap stuff around till you find it.

[comptoncj]

Its on number 3 chap

[John]

ok swap stuff from 3 to 2 and see if the miss follows. If you've done the obv stuff, then try the injector first.

[comptoncj]

Ive tried that lol, well i havnt moved an injector yet hmm lol

[yayoboy]

as above, as its confined to one cylinder, it wont be your pump relay, swap the injectors round, check where it goes into the fuel rail for any blockages and see if fault transfers

[comptoncj]

Yeah im going to try another injector tomorrow and see what happens, im also going to use a pulse tester on the loom to see if thats working as it should because i've heard that plays up. Grrr hope i get it sorted soon lol

[comptoncj]

Did a bit of investigating this morning and i checked the injectors for resistance and they all showed up the same so i doubt its an injector itself causing the miss, im going to try and check the supply voltage tomorrow, if that shows up ok im out of ideas as to what is causing it :S

[Adam]

Injector might be stuck closed, or injecting hardly any fuel....

[comptoncj]

Injector might be stuck closed, or injecting hardly any fuel....

Oh right, is that a common problem? i havnt got any spares but i might move the injector along the rail tomorrow.

[Adam]

Well injectors do get dirty/blocked, not enough fuel can cause a misfire....

Probably a long shot tbh, but worth a try

[comptoncj]

oh right, i will have a look, could an AFM cause a miss???

[dougie_boi]

i would do a compression check and that would rule a few things out

[General Lee]

Leaky inlet, could have a perished gasket on the inlet causing it to miss!

[comptoncj]

i would do a compression check and that would rule a few things out

ive done a similar thing and its ok :) im going to have another look this evening and see what i can find lol

[comptoncj]

Right had enough now! got 11.6 volts at the injector plugs, swapped the injectors round, still got a misfire, plug looks slightly wet car kicked out black smoke on start up but then clears, got compression, got spark, got fuel WTF?? any more ideas? think im going to take the engine out if i cant get it fixed this week .

[djbrowney]

what the fook ???

[comptoncj]

I duno ive had enough of it to be honest whatever is causing it is beyond me.

[djbrowney]

if i wernt on call i would have come and had a look mate !

[comptoncj]

lol dont worry chap its too far for you to come have a look, I dont know anyone local whos actually done a conversion on one, ive worked on a few but ive never had problems like this :S

[djbrowney]

i dont understand why you have had so money problems, it ran fine, drove fine, was rermoved fine and you chucked it in the back of your motor fine lol

[comptoncj]

I know lol its doing my head in i cant see why it doesnt want to know on that cylinder

[djbrowney]

ecu ?

[comptoncj]

Possible i suppose but its sparking and fuelling so i cant see it being the ecu :S

[comptoncj]

Could it be a bad earth? ive checked the gearbox to inner wing and the two little earths on the fuel rail and the earth on the starting/charging loom which i put on a inlet manifold stud.Am i missing anything?

[Adam]

So what have you done??

Compr. test? All good?
Getting a spark on that cylinder??

Did you try swapping an injector?? 12v at the injector means nothing if its a bad injector.....

[John]

So what have you done??

Compr. test? All good?
Getting a spark on that cylinder??

Did you try swapping an injector?? 12v at the injector means nothing if its a bad injector.....

100% agreed!

[comptoncj]

So what have you done??

Compr. test? All good?
Getting a spark on that cylinder??

Did you try swapping an injector?? 12v at the injector means nothing if its a bad injector.....

Right its got 175psi on all four pots, ive swapped injector 2 and 3 over and it still misses on number 3 and its got a good spark, once its run for about a minute i took number 3 plug out and it was wet but not soaked. After i rev it up it pops 3 or 4 times when its back idling. :S

[John]

Have you tried a cts?

[comptoncj]

No i havnt tried one of those yet, would that cause a miss?

[let_nova]

that can cause a number of things.

[comptoncj]

I see, well i better get myself one of those lol its bugging me now as ive been looking at it for so long i just want to know if ive missed anything lol

[John]

Yeah a fooked cts will usually cause it to overfuel from cold start, thus generally making it run rough, miss etc.

[comptoncj]

Yeah a fooked cts will usually cause it to overfuel from cold start, thus generally making it run rough, miss etc.

oh right i will change that then, well this 20xe misses all the time would the cts do that if it was fubar'd?

[djbrowney]

if i have one i will send you one mate !

[John]

oh right i will change that then, well this 20xe misses all the time would the cts do that if it was fubar'd?

Normally if the cts (coolant temp sensor) goes tits up, it sets a default reading. (it sends a signal to the ecu to tell it the temp of the coolant, if it's cold, it overfuels slightly till it warms up) If it's fooked, it'll overfuel massively, usually stuttering, spluttering misfiring etc. They're about a tenner for a new one.:thumb:

[comptoncj]

oki doki I will try one :) yeah it does overfuel so might be onto something there, the engine is in a corsa b with the managent light wired up, does anyone know how to make it flash? It will be different to just earthing out one of the 16 pins like as its running the xe?

Edit, Cheers Browney would be great if you have got one how much?

[djbrowney]

you can have it mate !

[Mazz]

To flash the ecu light you need to put the brown/yellow wire from the green iirc XE dash plug to earth

http://img.photobucket.com/albums/v310/TheSimps/Nova/Nova%20LET%20Build/3Plugs.jpg

[comptoncj]

Cheers for that I'l try it in the morning and see if it tells me anything lol

[comptoncj]

Friend sent me a ECT sensor and its still got a miss, fresh pair of eyes on it showed up that it was only running on 1 and 4 and missing on 2 and 3, ive swapped injectors, plugs round it doesnt cure it, now bearing in mind its got 175psi compression on all 4 pots, Im wondering could this be an ecu/ loom issue? im rapidly running out of patience with it, any advice would be appreciated :)

Cheers

[craig green]

Put some new plugs on it & gap them to 0.7mm. Dont just chuck them in out of the packet. The plugs are probably so fouled from continuous cranking & missing that they wouldnt spark nicely now anyway.

[comptoncj]

Done that got a really good spark :(

[John]

Have you actually taken this for a run yet?

was it a new cts?

[comptoncj]

Not yet havnt got shafted bolted in properly yet, want it running on 4 before i move it.

[comptoncj]

could it be an ecu problem not switching the injectors off as it smokes like you wouldnt believe , the two plugs its running on are black and the two its missing on are soaked.

[John]

worth trying the ecu i suppose. You got one to try?

[comptoncj]

No i havnt got one, a mate of mine mentioned some LEDs that go on the injector loom to see the loom pulse, might try and get hold of some, given up tonight i cant belive how its running on just 1 and 4 lol

[John]

node lights.

You tried another loom?

[comptoncj]

No ive got no spares with it chap, I think the faults been narrowed down to either the loom or ecu. Meh more money eh its getting expensive this little project.

[Mazz]

Is it an an early or late engine?

[NitrousVaux]

Right then, I think I have finally sorted the missfire and the management light flickering. I have been tinckering with all of the sensors and the loom for a while now. I finally had a breakthrough on the Mig Website and had a look at the wiring the the CTS. Low and behold below the outher rubber cover only one wire was connected. I have since found a new plug off an old loom and rewired the plug. For the 3 seconds it would fire before I had run out of fuel, the engine sounded smooth and miss free. I now have to get some petrol as all I am getting out of the fuel rail is air at the mo! that will teach me for not wiring up the fuel guage yet! LOL.

But if you have a miss fire problem on the C20XE I would deffo take all the protective covers off the plugs and check for coroded wiring and or broken wires. The looms are old now and this will become a more common problem like it has with the Series One RST. I should know I used to own one of them too!

As posted on my query!

[comptoncj]

Its now running on 4 after a few hours of tinkering and rewiring :P but it wont rev up :S it will on light throttle but as soon as i try and open the larger butterfly it tried to cut out and backfires :S but hey im half way there now any ideas chaps hehe :)

Cheers