Engine stuttering between 4-5000 RPMs???

[leemullan16]

Hi there i have just brought a noble m12gto the car itself has not covered many miles 15000 and its a 2000, it was the second one ever built. the car has been running fine up until last week. i went to move it and when i started it up it must of only been running on 4 cylinders. it would just about start up and would not tick over at all. i left the car a few hours and tried again and it was running back on 6! after taking it down the road for a blast i noticed when putting the engine under full load between4-5000 RPMs the engine just stutters as if the ignition is completely cutting out and back in again. this only occurs under full load of near full load. the car seems to be very tempremental. one minute its fine the next time you start it, its misfiring if you rev it up it seems to clear the mis-fire! sometimes it might just cut out on idle but if you re start it, it seems fine again. i have spoke to a few people and they recon itcould be the coil pack. i was just wondering if anyone has experienced anything like this?? and any ideas where i could start my fault findings from. i have checked the conditions of the connections and they look fine.
Thank you

Lee Mullan

[Gadgeroonie]

Try some new spark plugs and some leads - it may be something as simple as that

did the engine bay get wet at all ?

[Naso Grande]

I had the same problem. Looks like it was crap in the fuel filter. After I cleaned the debris out I went for a run and things were much better although not perfect as the filter is probably shot. I've been out of the country since then and there is a new filter waiting ready to be fitted when I get home.

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Mine is a GTO-3

HTH,
Graeme

[leemullan16]

cheers for the info. im guessing my first step is to remove the plugs see how they are burning. i might chuck a new set in depending on the condition of them. my first thoughts were the coil pack, now i dont seem so sure im thinking more the fuel filter. Where would be a good place to order a new filter element?? as i might as well put a new one in. Many thanks.

Lee

[leemullan16]

cheers for the info. im guessing my first step is to remove the plugs see how they are burning. i might chuck a new set in depending on the condition of them. my first thoughts were the coil pack, now i dont seem so sure im thinking more the fuel filter. Where would be a good place to order a new filter element?? as i might as well put a new one in. Many thanks.

Lee

[RobP]

Lee - also had a similar issue and the culprit was the bit of low pressure fuel hose between tank and filter. It was collapsing under full load (at high temperature) thereby effectively shutting fuel off. Try plugs and fuel filter first, but if these don't do the trick replace the low pressure hose with some high pressure hose. Not a difficult job (escpecially when you get someone else to do it

[daddysumo]

Eventually got round to replacing all the fuel hoses at the weekend. It can be done without removing the undertray.
I had two solid 90 deg elbows put between my pump and filter so no more bending of the pipe, and I used high pressure all the way from the tank.
The other thing I did was to put the filter outboard so as to minimise the bend radius in the pipe from the tank with the pump nearest to the fuel tank.
HTH

Steve

[noble1978]

I had exactly the same problem, all it was was the plugs. Suppose coils would be exactly same symptoms though.

http://www.pistonheads.com/gassing/topic.asp?h=0&a... running turbo&mid=153645

[stewey]

Mine (2003 3r) is in Peter Smiths sportscars (proper Noble bods), near burton on trent as we speak having similar problems. Been standing for 4 months over winter, had a new battery and fired up first time. Drives normally at slower sppeds, boost gauge reading correct, but if i floor it (especially noticeable in 4th, 5th, 6th), gets to about 3-4000 and cuts out or splutters very slightly. Revs drop off for a split second then kicks back in. If you keep it floored it gets up a few more revs and accelerates normal up to 6000 when it starts doing it again! Sounds exactly like 1978's problem so i told them what it could be from other peoples experience on here. Will let you know what it was tomorrow. Also needs a rear shock replacing (leaking) and handbrake shoes.

[NobleGuy]

noble1978 said:

I had exactly the same problem, all it was was the plugs. Suppose coils would be exactly same symptoms though.

http://www.pistonheads.com/gassing/topic.asp?h=0&a... running turbo&mid=153645

Yeah, mine was a corroded coil with those symptoms.

[leemullan16]

very strange indeed. i went ou tin it again today and started the beast up. it started mis firing straight away and after reving it up to 4000 it cleared the mis fire and would idle perfect. i took it down the road for a blast and the engine was running alot better and smoother but still a slight few stuters. i believe this problem is heat related, im started to believe it must have something to do with the coil pack. the fuel starvation theory would be correct if it was doing it all the time but this is different it sems to be more random. i have checked the low pressure side of the fuel ppump and its a proper braded one. i may just replace the coil pack and fingers crossed. anyone aware of how much one will cost me and where would i source one from?? thanks for the help guys

Lee

[noble1978]

There is no single coil pack.

You have 6 Coils directly on top of your plugs.

When your car starts up and is not firing on all cylinders, open the rear clam and disconnect your coil plugs one by one to find which one is causing the problem.

When you disconnect a plug and it makes no difference then you have your dodgy coil or plug.

Personally I would change all 6 at once. If one is knackered then it's likely the rest won't be long in following.

Ryan

[leemullan16]

i own a 2000 gto and it only has one coil pack which runs all six cylinders my engine is the 2.5 not the 3.0.

[noble1978]

I stand corrected.

suppose you could still do the test to identify a possible bad plug?

hope you get it sorted soon

Ryan

[JLSELAN]

Could also be a bad plug wire that is breaking down (electrically) at hi-voltage.
FWIW, another interesting test to do is to start the car at night with the rear clam open and see if there is any evidence of arcing (blue flashes) between the plug wires and metal parts of the motor (i.e., electrical earth).

[RobP]

leemullan16 said:

i believe this problem is heat related,

Lee

Lee - my fuel starvation problem WAS heat related. The stutter only occurred when the engine was heat soaked and the low pressure hose became 'floppy'. However as stated previously try the plugs route first (and the coil,if not too expensive)

[stewey]

stewey said:

Mine (2003 3r) is in Peter Smiths sportscars (proper Noble bods), near burton on trent as we speak having similar problems. Been standing for 4 months over winter, had a new battery and fired up first time. Drives normally at slower sppeds, boost gauge reading correct, but if i floor it (especially noticeable in 4th, 5th, 6th), gets to about 3-4000 and cuts out or splutters very slightly. Revs drop off for a split second then kicks back in. If you keep it floored it gets up a few more revs and accelerates normal up to 6000 when it starts doing it again! Sounds exactly like 1978's problem so i told them what it could be from other peoples experience on here. Will let you know what it was tomorrow. Also needs a rear shock replacing (leaking) and handbrake shoes.

Got car back this morning, luckily just needed new plugs!! Only drove 25 miles back but it feels 'tight' after coming back. Cant wait for the weekend sunshine!! Just try and avoid the 'bank holiday numpty's'. Must have seen a dozen caravans on the way home..

[leemullan16]

hi, well i have brought a new coil pack and fitted it and i though at first i solved the problem but it is still here!! i have ordered a set of ngk plugs now and also a set of new plug leads so hopefully when they get fitted in the next few days the problem will go away! quick question really what gap is needed between the plugs for a 2.5l 2000 gto?? i have heard many diff siz gaps so was just wondering?? many thanks guys

[mgbond]

leemullan16 said:

hi, well i have brought a new coil pack and fitted it and i though at first i solved the problem but it is still here!! i have ordered a set of ngk plugs now and also a set of new plug leads so hopefully when they get fitted in the next few days the problem will go away! quick question really what gap is needed between the plugs for a 2.5l 2000 gto?? i have heard many diff siz gaps so was just wondering?? many thanks guys

I think on mine I use 37 thou.

Bondy

[Gadgeroonie]

stewey said:

stewey said:

Mine (2003 3r) is in Peter Smiths sportscars (proper Noble bods), near burton on trent as we speak having similar problems. Been standing for 4 months over winter, had a new battery and fired up first time. Drives normally at slower sppeds, boost gauge reading correct, but if i floor it (especially noticeable in 4th, 5th, 6th), gets to about 3-4000 and cuts out or splutters very slightly. Revs drop off for a split second then kicks back in. If you keep it floored it gets up a few more revs and accelerates normal up to 6000 when it starts doing it again! Sounds exactly like 1978's problem so i told them what it could be from other peoples experience on here. Will let you know what it was tomorrow. Also needs a rear shock replacing (leaking) and handbrake shoes.

Got car back this morning, luckily just needed new plugs!! Only drove 25 miles back but it feels 'tight' after coming back. Cant wait for the weekend sunshine!! Just try and avoid the 'bank holiday numpty's'. Must have seen a dozen caravans on the way home..

pleased to hear it was a simple fix