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Weird Misfiring At 2000rpm? (rb30)

BradyJ_R31

By BradyJ_R31,
in Engines & Forced Induction

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BradyJ_R31 Apprentice

BradyJ_R31

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Hey pplz.. I guess this is the fun part about owning a car i was sposed to be going for a roadworth cert. last friday but now shes playin up :D okay..saturday last weekend i put all new plugs in my R31, that afternoon it worked perfectly...(quieter..no smoke) then the next morning i started it up, it idled fine, let it warm up then lightly put my foot down and the revs dropped? to about 500Rpm and nearly stalled, then once it got past that stage and revved it to around 2000rpm it started unevenly revving (1500 - 2500)... so any help would be greatly appreciated, changing the plugs is all i have touched under the bonnet since it started playing up..i am trying to avoid a mechanic atm as they'll no doubt charge more than i paid for the car :)Brady.

post-29588-1150186036.jpg

Edited by BradyJ_R31
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SKY031 Grand Master

SKY031

Posted
Posted

Did you put the leads back on in the right order?

Have you re-checked that one of the leads hasn't come loose?

Did you buy the right plugs?

How did the old plugs look? (colour/condition)

Did you touch anything to do with the distributor?

You mentioned smoke prior to changing the plugs, what colour was the smoke?

BradyJ_R31 Apprentice

BradyJ_R31

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Um the guy at supercheap auto picked out the plugs for me....they fit perfect and all but would surprise me if they are wrong, nah i checked all the leads and lead numbers, the old plugs had barely any soot on them but were very very old, i was going to try putting the old ones back on but i threw them all bar one : the smoke prior to the new plugs was like wispy blue smoke, evn after it had warmed up, i had a look in some other forums and some ppl said there AFM was gone....wats that lol...thnx brady

Nosmo Enthusiast

Nosmo

Posted
Posted

Everyone seems to jump to the AFM (Air Flow Meter) conclusion, but its rarely the cause.

If your car ran fine before you changed the plugs then there is really no reason to look at things like the AFM.

Start by looking at the plug leads - are they clean and tight fitting. Are they in the correct order?

Look at any inlet piping removed during the replacement - are any hoses loose or missing (some are under the inlet / plenum and can be hard to see).

Look at the electrical connectors - are any loose or disconnected?

Hope this helps! If not, let us know and we'll give you some other pointers!

Cheers,

J

BradyJ_R31 Apprentice

BradyJ_R31

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Ahh ok, because i did have to take all the inlet piping off above the rocker cover, i did not know about too many hoses under the plenum lol, so i might have to check it out, how much (average) would all new spark plug leads cost? could be a wise investment, the old ones could be the cause aswell as they arent the best lookin ones ive seen :D

Nosmo Enthusiast

Nosmo

Posted
Posted

I have a set of standard leads on mine original from factory - still working perfectly.

Mate of mine had a set of after market 8mm leads on his GTS - ran like shit. Ended up putting my standard ones on the GTS...

Also, make sure your oil filler cap is tight and sealing properly. This will make a big difference if not right!

BradyJ_R31 Apprentice

BradyJ_R31

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Geez i never realized how many things it could be lol but yeah this weekend i might just get in there and try it all out, maybe go back to supercheap and check the polug type, could it be anything fallin into a cylinder (dust,gunk) thats doing it? from when i took the plugs out,?..thanx a heap

BradyJ_R31 Apprentice

BradyJ_R31

Posted
  • Author
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Yeah it sstill starts 1st time everytime, and it idles fine (around1000rpm) but if you slightly put your foot down the revs will drop....then pick up again and at round 2000 it just fluctuates the revs, but nah i havent checked the gaps yet, thnx brady

rob82 Mentor

rob82

Posted
Posted
make sure you have the right gap in the spark plugs as well this makes a big difference.

For 33's its 8mm's off head. Dont know about yours but should be similar

8mm thats a big gap!!! I think he means 0.8mm. And for a naturally aspired RB30 it should be about 1.1mm gap. Check that you didn't crack a plug when you installed them would be my advice.

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