Every now and then, when on fairly high boost, my car misses a beat. Its as if the sparks just die for about a quarter to half a second. It only ever happens when its boosting hard (1.2 bar+). I'm thinking it may be the knock sensors retarding the ignition right off as it senses detonation. It certainly never did it with the Novitec.

I'm always running Optimax, and max boost for day to day is 1.3 bar, with the very occasional spike to 1.35bar.

When I rolling roaded the car, it was quite rich all the way through the rev range.

Any ideas?

BTW - still running standard plugs, which have also been changed recently - I guess it could be a dodgy plug failing under load, although I'm convinced it ALL the sparks being cut, not just one cylinder, as its actually quite violent in the way it dies and cuts back in.

have you tried flushing the ecu??

Is it only lately its happening as well by the way ie the last 2 weeks if not less or ALL the time since august or such like?

Nigel,
Have you managed to contact GRAHAML regarding this matter to see if he can give you an explanation??

Jamie

Nigel as you know,the Gtech 2 runs about 2-3 deg ignition advance,both the Novitec & Gtech 1 run no advance,so certainly a knock sensor could be kicking in and retarding the ignition.

Hmmmmm, I wouldn't have thought any ignition retardation would be that violent more of a spluttering/misfire type event if noticeable at all. While the G Tec II introduces a few degrees more advance than other chips low down I'm not sure how much more if any it has at high rpms. I think it is unlikely that you are getting detonation what with your charge cooling setup, cold weather and using optimax especially as it was shown to be running slightly rich. Try using better plugs and/or swapping back to the Novitec.

Nigel,
Does your inlet temp display high readings when on boost for extended periods?? I know that the PACE sidemount isn't as good as a FMIC and this could be contributing to yuor problem???

Jamie

Im running Gtech2 and side mount and no problems at all, had ir rollin roaded not long back and it fueled well little rich in one place, but operater was very happy with figures, are you using colder plugs?

Jamie, Nigel has a chargecooler in conjunction with the uprated sidemount so temps shouldn't be a problem.

I would honestly think either coilpack or plug going and then look towards the fuelling again as the fuel at this time of year if the charge temps are too cold cold be causing problems as not atmoising enough and not giving enough fuel for the super dense air being forced into the engine...

k, struggling to suggest anything else that could cause this kind of issue.Maybe go to an Iridium plug of a cooler grade.

Jamie

Nigel, it doesn't sound like retardation, I've had that happen and its not that violent, and with your good proven chargecooling and the cold air, and still reasonable boost, I do think this is unlikely.

Twice in the past I've had a similar occurrence , but can't say what it is.
Interestingly they both happened at high boost with the standard fuel pump, and never since the 255l/hr one,.. are you running a standard fuel pump Nigel?

joe

yea I agree flea,I was in the middle of editing my post to say exactly as you have typed (when my pc kicked me out...It has a bloody virus just now )as you said ....it would feel like more of a mis-fire than annything `violent`.
Nigel has it just started doing this with this spell of really cold weather ? ....................I came back form Edinburgh today and Tuesday and I`d swear i had another 50 bhp under the bonnet ...............I actually backed of for fear of breaking something ,it hit 160 in no time it was honestly still pulling like a standard coupe at say 120................scary

Good point Joe...could well be fuel related........you would get a violent jolt if all cylinders got starved of fuel

Nigel recently went to the Powerstation RR day when it was near enough 0 degrees and it was here they checked with a wide band lambda that his fueling was slightly rich throughout and also on full boost.

I used to get a real jolt when I had the aquamist pump spliced into the cam variator relay but this was low down at 3000rpm. It was almost as if the car stalled but due to the inertia it quickly jump started again. From what I gather most of the chargecooler installations use this relay for a 12v ignition feed therefore it may be worth checking although not sure why it would affect higher rpms as the cam variator has already switched at this point.

I would start looking for an electrical problem which as you say may affect the spark across all 5 cyclinders and/or perhaps as Joe says the fueling is momentarily cut off due to an electrical problem with the pump or injectors.

i have the same symptoms as Nigel a misfire only on full boost between 4500 and 5500 rpm at 1.3 bar mainly in third gear (not done much testing in forth or fifth) its fine after that, this has only started while running the gech2 i also get a puff of black smoke and the turbo stops whistling for a split second was thinking my actuator rod was set a bit too tight on the rs?

Kev

Thanks guys - you might have alerted me to another possible solution

About three times in the last couple of months, I've driven my car home, and then later, either a few minutes later, or sometimes a couple of days later, it hasn't started.

I'm using a Walbro 255l/h pump, with a heavy duty feed direct from the battery, to a relay switched by the original fuel pump feed.

About three months ago, the car died and I found that the fuse block I spliced into the feed had completely melted. I replaced it with another spade fuse adapter, and it shows no signs of overheating since.

However, on all the occasions that it hasn't started, a quick unplugging and replugging of the spade connectors to the fuse block and its been fine again.

Time to replace the simple fuse block with a beefy connector - the kind used in amp feeds

To answer your other questions - yes, I'm very well cooled, so extremely unlikely to be anything to do with chargetemps.

I'm conscious of the fact I'm still running stock grade NGK plugs, even at 1.3 bar and 300bhp. Does anyone have any suggestions as to make / grade?

Its been doing it regardless of weather - obviously very cold today, but its done it in relatively warm weather too.

I'm now tempted to think that its nowt to do with the chip and more to do with an elettrical glitch

I'll keep you posted....

Same here....
http://www.fiatcoupeclub.org/forum/showflat.php?...a8b32d#Post8722

No need to worry about coil packs, plugs or so.. i had them checked over, replaced by better ones twice and it still happens, mostly in 3rd gear between 3000 and 5000 rpm.

I also have it when using the squadra but not as much...
It's not happening all the time, sometimes i can drive for 100's of km's without a single problem.

Having the new paddle clutch and all made me wanna do some serious driving and then ofcourse it occurs more.

I don't know where to look for it but since both the Squadra and the Gtech II have this it sounds only logic to me that it's got something to do with ignition advance, when i tried to get the same with the Gtech 1 it didn't happen.
Also the Squadra uses less ignition advance then the Gtech II so this also might explain it happening less when the Squadra is installed.

I give up, don't know where to look so any more info/ideas would be helpfull.

Edo,From what i recall from talking to Graham, I don`t think the Squadra has less advance than the Gtech 2,it might be the same or maybe even slightly more

I would certainly move to the 7's and try them Nigel.

Also maybe the actual relay itself failing and the power cut from the battery is clearing it? certainly what i would try first of all

Then the fuse as you said...

I've also had this hiccups after fitting it...but the strange parts was that swapping back to the Novitec didn't seem to solve it I've already chuck away the EBV (though still plugged in, otherwise the injector light will come on), now using PRV+Reg setup. I've also recently changed to colder plugs (BKR7EIX-P) but didn't solve the problem Will be fitting the GT28RS soon (it's only about 8 months after I bought it ) to see if it'll solve it.

Anybody been in touch with GrahamL yet?

Strange one. Definitely try changing the plugs to NGK BKUR 7ETs to see if this solves the problem.

In the past I have been in a Coupe that has run higher boost with the old plugs (6ETs), and especially in the morning or when cold (weather) the car would for a split second "stall" under acceleration, which was quite concerning as it felt almost catastrophic. Initially we turned the boost down and this "cured" the problem, but as soon as the boost was turned back up the sudden "stalling" on acceleration re-appeared. Next step was to change the plugs to a colder type "7ET", this immediately cured the problem, we put boost back upto 1.3/1.4 bar with no noticeable problems.

I have been having exactly the same problems here and in particular Nigel & DavidL.

I get the engine feeling like it is cutting out on hard boost (running 1.3 bar here as well) for a split second and then it is OK afterwards?? Can happen every five minutes, or I can go weeks without it happening. Have noticed that the problem only happens at a relatively low speed when in a high gear (ie. 40mph in 4th, 60mph in 5th etc).

I have put my old Novitec Chip back in and I am still experiencing the same problem!!

I have a Pace CC and an Evo6 FMIC, so I know that my CC temps are OK, and I have a Walbro 255 fitted, but I am still running standard plugs as have some of the guys who have posted before me.

Has been a very bizarre experience and any light shed on this would be very much appreciated!

Nigel, the NGK BKUR 7ET's I'm sure will work fine, at high load then the ignition system will be under greatest load and then any potential problems are most likely to manifest themselves.

Joe

I have had no problems since fitting the GTEC II. I have had it in for a couple of months now and have run up to 1.4 bar. I run 7's in mine.

Nigel have you had the plugs out to give them a once over ? Really sounds like plugs or coilpacks to me

Definately get 7ET's! I had BKUR6ET with my set-up (see sig) and got some powersinks when hot. Not anymore!

I'm getting a similar problem but i've only got the basic gtec chip.

Mine only happens when i go over a bump giving it some welly. The injector light flashes on & i get a huge bang from the exhaust. I think it could well be loose wiring on the coil packs ??????

Any idea's ????

Just bringing this thread back to life after almost a year...

I have the same kind of problem as it seems lots of you get.

A misfire for a split second somewhere between 3000 and 5000 rpm. It can be fine for ages or do it a few times in half an hour. Always on boost/power, I suppose you are only likely to notice it then.

I'm running 1.25 bar, GT28R, FMIC, Gtec2 (High Fuel) and std plugs.

Im thinking about putting the other plugs in (BKUR7ET) but wondered if any of the above posters would like to shed any light about how they cured the problem.

Thanks

James