Ignition miss

[gtirx2]

Ok this may drag on but i will try and explain it quick,in my old black R it had a miss when holding the throttle at set revs, idling or driving, not a bad miss but a fuely sort of stutter in the exhaust sort of sound every now and again.At the time i tryed changing almost everything you can think of ecu,injectors,maf,every ignition componet,injector resistor pack,distributer,lamda,fuel pump,etc etc,but to no joy.
It all started or became notisable when i tryed to re-gap the plugs tighter,and the only way to get rid of the miss was to open the gap up on the plugs pretty wide but then i would get spark blow out on only standed boost.
In the end i blew this car up, cracked the ring lands but i don't belive it was to do with the miss as i had started running more boost by this time :doh: .
So i took this engine out the black one and forged pistoned the engine and put it in my white R,and at this time i change the knock sensor,water temp sensor,idle control valves,cold start,engine loom and proberbly other things that i can't remember right now:yawn: .I also took all the inlet manifold/ throttle bodys off and checked to see if it had behine leaking and also put petrol down each throttle body and they were all petrol tight and all seemed to open at the same angle and seemed fine.I also changed 99% of the vacum hoses and checked all the ones on the back of the block and they also seemed fine.
So with this engine in my white R it ran fine did not have the miss like the black one, it did still sort of have the sort of fuely sound in the exhaust but not anywhere near as loud as the black ones stuttering sort of miss and it was defentaly not notisable when driving.
Now to where i am now i have just fitted all this msd ignition stuff [6a control box, blaster ss coil] and the miss is back,the car still runs very very well and you can't notise it when you are flat out, its only at when you hold it at set revs that you can feel/ hear the miss?It also does not miss when it is cold and only misses when warmed up[the same as the black one used to]:? and even if i open the plug gaps up still using the msd kit i get spark blow out:shock: and i only gaped them to 0.8:shock: :shock: .
If i go back to the standed coil no msd stuff the miss is like before hardly notiseable ecspecialy when driving?
So why on earth would my miss get worse the better/stronger the spark i have?if i gaped my plugs wide on the standed coil i am sure the miss would go [i will try tommorw]but then i would get spark blow out again.
My conclusion is that it is on just one cylinder that is messing me about but i am still unable to track it down yet but even when i do i still won't know what is causing it!,why on earth would a better stronger spark make this miss worse and why am i still getting spark blow out even with the msd stuff gaped at just 0.8:? ?
This is doing my head in so any advise would be welcome,i am starting to think it could be the throttle body but i just don't now why or how,or maybe valve, even tho i checked them when i cleaned the head up for the forged engine rebuild??????????????????
Even with this stutter/miss the car runs great as fast as ever:twisted: but it is realy pi55ing me off as there is obviosly a problem:evil: :evil:
Help!

 

[stevepudney]

What boost are you running when you get spark blow out ??

What plugs are you running ??

I would get spark blow out at 1.7 bar with anything over .7 gap with the Blaster SS coil and Denso IK27 plugs. I have changed the Blaster SS (which, when run without the 6a control box I don't think is as good as the standard coil) to the HVC Blaster, I can now hold a .9mm gap without spark blowout.

Your miss sounds like fuel, could it be injectors or the injector loom

TPS perhaps

Steve

 

[gtirx2]

Atm when the turbo first kicks in its at about 1.1-1.2 bar,it don't get blow out if i am running 0.7 gaps or below but last night it was blowing out on 0.8 gaps as i enlarged the gaps to see if the miss would go.
It is a funny sort of miss as i am sure that a better spark be it from the msd kit or tighten plug gaps on a standed set up makes it worse,like you say it does sound fuely like a stuttery pop sort of sound from the exhaust but only when you hold the revs at set revs?
I am pretty sure it must be just one cylinder giving me grief but still unsure on which one.
The plugs i am running atm are just cheap platinum champion 8's but are pretty new,i have also tryed my old set of hks 240i's and its still the same.
What i don't get is that asuming it is just on one cylinder why should a stronger spark make the miss worse and why should that cylinder get spark blow out before the others?as i am pretty sure its got to be connected.
I will try and change them rubber nipples on the throttle bodys for the new ones i got of you and see if that help as i have not changed them yet as the old ones still looked and felt alright.
Also just to add if i tighten the gaps tighter say 0.6 the miss is silghtly worse than it was at 0.7,also if i do a lamda check it is fine fueling wise except when i get the miss/stutter.
Tbh if i go back to the standed coil the miss is not that bad you can't feel it when driving like you can with the msd conected,it is also better holding the revs when in neteral not as stuttery.The thing is i must have helped it somehow when i rebuilt the engine and put it in the white car as the miss was worse on the black car when just using the standed coil but i can't think how i helped it.
Other than this little miss the car is running very well for the boost it is running and the plugs look perfect and my compression is also perfect,but i need to work this one out as it will become a bigger problem when i want more power.
Oh and also when you first start the car when cold the miss is not there it is only when it warms up that it become noticeable:?

 

[gtirx2]

Just checked the tps and seems fine 0.445 closed and 4.150 open.Strangly it seemed a bit better today if i put the standed coil back on you could hardly hear it if holding the revs and seemed pretty normal,but with the msd kit on you can still hear it at idle but felt better when driving?I think its all down to what plug gap i run atm so i will buy a good set of plugs and see if that helps,i don't think it will help but its worth a try.
I don't think this little gremlin is much of a problem atm with the boost i am running as the car is absolutly flying but i know when i go for more power its going to bite me in the ****.
I also tryed that check light rich/lean thing and when normal driveing it is on off on off same as when you hold the revs in neteral,when deaccelerating it is on and under hard acceleration it is off so i think the fuelings alright if not a little rich.

 

[stevepudney]

I'm very suprised you get spark blow out of any sort at such low boost.

What are you calling "spark blow out" is it just a misfire ? Because when you get spark blow out, it's like you hit a brick wall, the car momentarily stops pulling with a huge stutter.

yours still sounds like a fuel issue

Whilst you've had this miss, have you always had the same injectors ?

Also the other thing (and your not going to likr this) is the major part thats stayed the same through both engines is the head. Did you rebuild the head when you did the engine, did you inspect the head at all, did you have the valves out and lap them back in. The only reason I say this is because the miss only happens when things have warmed up, so I was just wondering if you had a sticky valve that only shows itself when warm.

What do you think

Steve

 

[gtirx2]

I am surprised i get spark blow out aswell,i was getting spark blow out when i started playing with the boost on the standed setup on only 1.2-1.3 bar so i thought instead of messing with the old nissan coil and that i would go for the msd setup just to be sure it never happens again even when i go for more power.
I asume it is spark blow out as like you say its sort of like a mild fuel cut feeling with a loud limiter style pop bang splutter sort of sound.
On the black car when that engine was in i changed almost everything including the injectors to try and sort it but it did not help,i will proberbly change the injectors again soon just to be sure.
As for the head,when i first got the black car it had a blown engine[rod thought block] so i brought a cheap second hand engine off a guy that had took his car to nissan with a top end knock,at this time this guys car was under warrenty so nissan told him to just change the engine as it would be cheaper.So i brought this engine off him and gave it a good check over and it turned out that it had behine rebuilt at some point with 0.20 oversize standed pistons and some cowboy had used normal size piston ring and not oversize ones like you are ment to and this was the top end knock.
I rebuilt this engine with new shells rings etc but used the head that originaly came off my black car with the thrown road,and at this time i think i replaced a couple of bent valves checked the head and lapped all the valves back in and it all seemed fine.
Then when i put this engine in the black car early on it was fine no misses just down on power and on a run up the road i hit a fuel cut which i thought was strange,so i got back and was pissed that it was running like crap and other things went to bounce it on the limiter/fined the fuel cut and work out what was going on and it throw a rocker,turned out it was chipped :doh: .
Replaced the rocker and shims compression checked it loads of times over the time it was on the road and it was always good[till i broke that engine] but i did always wonder if i had court a valve when i throw the rocker.
So when i went to rebuild this same engine again for my white car i had the valves out off that cylinder where i throw a rocker and they all looked straight and fine so i lapped them ones in again and bolted it on after a clean.
But like you said the head does seem a bit suspect:? :sad: but i just need to get my head round what/why this miss is worse with a better spark and why is it getting blown out even with the msd connected.
I will have to open up the gaps on the plugs one by one to try and track down what cylinder this is happening on as i am pretty sure this miss and spark blow out are connected.
Tbh it is a very small miss but if it is connected to the spark blow out i need to work out why.

 

[gtirx2]

Here a pic of the head, and by the looks of it i have replaced a valve on number four as it looks like it is the later style exhaust valve but this would not cause it would it?
http://i102.photobucket.com/albums/m114/gtirx2/cleanedupheadvalveshot.jpg

 

[pulsarboby]

why dont you do a kv check on the leads to see what sort of kv's its putting out at different rpm? that way you can remove them from the picture if there ok, if your round my way sometime il do it for you, it will only take a few minutes!

is it popping out the exhaust or airbox if you hold the revs (when misfire happens)?

doesnt sound like a fuelling prob to me.

have you checked valve clearances with engine hot, are any of them tight?

 

[Keira]

are you 100% sure you havn't dropped some felix cat food in there :lol:

 

[pulsarboby]

or maybe some of my special patent shims:lol:

 

[gtirx2]

I don't think its the leads as i have changed them and all of the ignition bits,but thanks for the offer.
It ain't a bad miss its just like a hiccup every now and then out the exhaust and only when you hold the revs at a fixed point and the car does stink of fuel like its not fireing 100% and like i said in the earlyer posts the only way to make it better is to gap the plugs wide on the standed coil but then the sparks/spark are getting blown out.I am sure this small miss and the spark getting blown out is all down to one cylinder and the problems are related?
I did do a rough check on the valve clearences when i had to change the cam chain position over but the car was not red hot then but even so it all seemed fine,i will check again at the weekend just to be sure aswell as gaping the plugs wide one by one to see if i can track down what cylinder is causing it,if my idea is right it should blow out the spark when i gape the plug on the iffy cylinder and should give me a better idea at where to look.

 

[Keira]

have you tried a known good set of injectors ?

 

[gtirx2]

No i have not tryed injectors since it has behine in this car but i did when the engine was in the black car, i will try it again at somepoint just to be sure.
Tbh i went out in it tonight and it was not that bad even with the msd connected up, it was only realy doing it when in neteral holding the revs and you could hardly hear or notice it when moving.
Its just anoying that i know it should not be like this, and it worries me that this spark blow out or what i think is spark blow out is connected to it, i am pretty sure it is spark blow out as it only happened when i gapped the plugs to 0.8 the other night and this is with the msd connected up so there has to be a problem with the ignition,and i used to also suffered spark blow out on silly low boost 1.2+ on the standed set up.And i am pretty sure its just one cylinder causing it:? .
I am thinking i just need to spend some time on it and see what happens over time as it is running great atm,i just know its going to give me grief when i get a bigger turbo and things:sad::roll: .
I am going to get some better plugs soon and that will proberbly help but i don't think it will cure it so we will see.

 

[stevepudney]

Here a pic of the head, and by the looks of it i have replaced a valve on number four as it looks like it is the later style exhaust valve but this would not cause it would it?
http://i102.photobucket.com/albums/m114/gtirx2/cleanedupheadvalveshot.jpg

Looks fine, did you lap all the valves in with a fine paste when you rebuilt the head ?

Like Bob says, perhaps check the valve clearences when hot and like Keiron and I said you need to illiminate the injectors, so try with a known good set or get yours cleaned.

I still wonder if perhaps it is a sticky valve but then why better with a different coil/plug gap :?

If it is a fuelling issue and somehow connected with the injectors, then perhaps a bigger spark from the MSD coil emphasizes a lack of fuel at a given point in the burn cycle, maybe it’s a sticky injector that stays open at a given voltage and the increased fuel causes a mini one cylinder backfire (if that makes sense)

what size injectors are they ? I have good set of 444's here you can borrow if you need them.

Hang on in their mate, it'll come good in the end, I know how you feel, this sort of thing would really get on my tit's aswell

Steve

 

[gtirx2]

Looks fine, did you lap all the valves in with a fine paste when you rebuilt the head ?

Like Bob says, perhaps check the valve clearences when hot and like Keiron and I said you need to illiminate the injectors, so try with a known good set or get yours cleaned.

I still wonder if perhaps it is a sticky valve but then why better with a different coil/plug gap :?

If it is a fuelling issue and somehow connected with the injectors, then perhaps a bigger spark from the MSD coil emphasizes a lack of fuel at a given point in the burn cycle, maybe it’s a sticky injector that stays open at a given voltage and the increased fuel causes a mini one cylinder backfire (if that makes sense)

what size injectors are they ? I have good set of 444's here you can borrow if you need them.

Hang on in their mate, it'll come good in the end, I know how you feel, this sort of thing would really get on my tit's aswell

Steve

Yep i lapped them in with fine paste, its the pot with the rubber glove on in the picture :lol: .
I have a few sets of injectors laying around so i will have a play at the weekend, i will also try another injector resiser pack thingy aswell.
I sort of understand what you are saying,i am starting to think it is a fueling issue a bit aswell,as i read somewhere that if you run to rich it is easyer to get spark blow out because fuel is not a good conductor or something like that,i think micra ed posted it in a thread on here somewhere, i will have to have another look for it.
My first step is to get some good plugs,i think i am going to go for the ik27 like you even tho i am running a lot less power and should realy go for the ik24's, i don't think i should get plug fouling with the msd connected even tho they are colder plugs, and i plan more power in the future anyhow;-)
Just out of intrest would you know if running the msd would get the plugs hotter than just running the normal setup, meaning that i should go for a colder plug anyhow or would there be no change?
Thanks rich.

 

[stevepudney]

Just out of intrest would you know if running the msd would get the plugs hotter than just running the normal setup, meaning that i should go for a colder plug anyhow or would there be no change?

I was just wondering this as well

I now get a random misfire/backfire/spark blow out with the Denso IK27's :shock: :?
and have just ordered some NGK Iridium 9's to see if that makes it go away

I don't expect the new NGK to last long as they are only cheap but it might help

Rich how you getting on with your misfire/backfire/spark blow out thing


Steve

 

[campbellju]

I've got something similar and I'm convinced its only cylinder 1?

I've tried lots of little things to get rid of it, starting with my Mallory system as I assumed I was getting a lean misfire. Like the others when warm at cruise on a motorway its most noticable. The flutter is causing a boost spike through the intake. I've not checked valave cearances yet as I did them all perfectly when we rebuilt the engine. In datalogs I've seen the same thing on full boost occasionally too but it is most prominent on light boost.

IMO, the Mallory/MSD is a red herring. Gtirx2, keep your gaps below 0.7mm and forget about them. Your new ignition system is capacitive discharge and it fire a lot of energy in a very short pulse. This is good at high revs but poor for low revs/loads as the mixture is less dense and needs a long spark duaration to fire. MSD et al get round this by firing multiple times and if you look in the manual it shows it will fire about 4 times to the OE once at low revs. This makes the digital CD systems like MSD etc have all the positives of the CD without the negatives.

One thing I've learnt is even with a mega powerful ignition system, you should run a normal plug gap as the energy required to jump the extra 0.1mm is massive. The system might provide it but it will start to wear out other parts too.

One tip I've found off a mapping site is old distributors can give an incorrect timing signal even tough the rev counter is working as they are sperarte measurements. This could cause the plug to fire too early or late. It sounds feasible so I've borrowed a brand dizzy to try sometime.

Will keep people informed.

 

[gtirx2]

Tbh i have not looked into it much more as i have behine having a terrible time with my R my engine has behine in and out an amazing 3 times since i started this thread:lol: :x and i have only just this moment finiched putting it back together, and i am still not sure about my headgasket:sad:
What i can say is when i changed the head the first time and put it back together i also changed the plugs for some ik27s[i did not gap them, left them how they were] and i had no more issues with spark blow out even when spiking the boost to 1.5 bar so i am pretty sure that has gone.
As for the miss i am still pretty sure that it is still there but only at set revs,but tbh i don't think it is as bad as it was?
Also it is pretty hard to tell atm as my car is running realy rich and is very poppy and bangy.
At the time tho i was sure that the spark blow out and the miss were conected,but saying that i still had the miss on the standed set up but no where near as bad?the miss also got better if i gaped the plugs wide, but then i got spark blow out even with the msd?and i was pretty sure that was down to one cylinder:? :? :?
But atm i just hope the car keeps running how it is as its not running to bad,i just have headgasket worries:?
How do your Rs sound if you hold the revs at say 3000rpm, does it hold the revs smooth or does it sort of cough about a bit?
Also i think low12 or something posted something about the msd setup suffering at low revs,i will have a look.

 

[gtirx2]

Posted by low612...

I would suggest using the crane-hi 6 . The msd is ok above 3500k but something in the design of the msd units cause drivibility issue below that. Idle has been more stable with the crane hi 6 car felt much better with the crane. The msd boxes have been know to fight with ecu signal in some way. Mike Kojima touches base on this with dyno test. i dont exactly remember the issue but it was enough for me to trade out my msd on my sr20det'd se-rs.

heres a little post from years ago http://www.nissanforums.com/forced-i...ighlight=Crane

I have not read it propely yet but this mat be my problem?

What is inducted line noise???

 

[turblio]

I have the same problem with mine just as it comes on strong boost I get 3 to 4 loud backfires as you go up the rev range although tonight it has been better!? and this is at 1.35bar I have changed Ignition module, cap, plugs, Leads, resistor pack, coil, injectors, and am now considering the next option maybe change fuel pressure reg again just to eliminate it for certain, also have bought a new fuel filter in case there is a bit of muck that keeps getting in the flow and restricting it?... eff knows I dont!