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Discussion Starter #1
Hi all

Wonder if you can help ive just got my GTS today and it seems to be stutterign quite a bit at 5,000 rpm. now the garage says the battery to the ecu was replaced and that it will adjust to my driving style and then stop stutter (to be honest im not sure wether to believe it or not)

Would some kind perosn let me know if this is correct or does anyone know abt this and prehaps has a resolution

Cheers

Andy
 

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My first guess would be that it needs new plugs. Iridiums, gapped at 0.8mm will do lovely.

The garage is fobbing you off because the ECU re-learns it's ignition det/retard settign very quickly.

Use the search engine on this forum, look for misfire etc. and you'll find loads of cases of this sort of problem and the various cures.
 

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Discussion Starter #3
i figured as much, im gona ask a really stupid question now, where can i get these iridiums and are they easy to fit (show me a computer and i can do anythign with it, show me an dengine and well i know where to put the oil in)
 

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Any of the advertisers ( Abbey / Sumo / SVS ) on the site will be able to supply them for you.

If you use the search engine, there is a procedure on how to get at them in the RB25DET. That said, if you're not confident with yourself doing the job, then I would really recomend going to someone who is.

I think your nearest specialist will be Rod Bell in Lancashire.
 

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PLUGS

i had the same thing with mine.
yes it was the PLUGS
but if i was you and beleve me,change the plugs,then get the car re mapped on the rollers,then your pride and joy will be safe
all the best m6beg:D :D :D
 

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Discussion Starter #6
Cheers for the info all, just spoke with rod bells and ordered some nice iridiums for me car :)
 

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When my car did this it turned out to be the fuel pump not giving enough Jungle Juice.
I had to upgrade and havent had the problem since.

Does it "drag its feet" through the revs and how old is the car/pump?
 

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Discussion Starter #8
Forgot to reply, got the new plugs installed and wow its nice and smooth not, well did notice slight corrosion on the ignition coil, but as cars under warranty im going to get that sorted :)
 

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This problem seems to plague the GTSts and has numerous causes.

When the car reaches 4500/5500 the boost will up at this point, cams are up etc and its usually about this time the missfire starts. The problem is KV or Firing Voltage, the amount of voltage it takes to fire the spark plug. Certain conditions can cause this KV to increase to an unacceptable amount at which point the sparkplug will missfire causing the stutter.

Incorrect Plug Gap, perhaps due to wear and tear and bad setting

Increase In Compression, as the boost pressure and cylinder temp increase the firing voltage also has to rise.

Fuel Mixture, the leaner the mixture the higher the KV has to be, fuel is an electrolyte, the more fuel the easier it is to fire the plug.

Coils, a faliure in coil unit can cause an increase in KV or a faliure in the coil pack can cause the coil to be unable to maintain or insulate a High KV.


So its easy to think it will just be the plugs but the problem is you could actually be wrong and not know it. If the plug gap is closed the power to fire the plug is reduced and it may not be spiking so no missfire. Problem is the closing the plug gap also cuts down the duration of the spark so it has less time to burn off all the fuel so the car is less efficant.

In effect although you have at first sight "masked" the fault of the missfire you are actually not at top power due to the shortened spark duration.

In my experiance the underlying fault has actually been the AFM not the ignition componants. The real fault is the the AFM is running lean at this point and that is what causes the spike in the KV and ultimatly the missfire.

As suggested before, change the plus by all means but try and get it on a set of rollers and have the fueling checked, you never know it could gain you a few HP but it could also save your pistons.
 

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Discussion Starter #10
Cheers crail, im actaully planning to get that done very soon (this month fingers crossed) :)

And extra hp is always good :)
 
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