Misfiring! PLZ HELP!! =) - Page 6 - Perth-WRX.com

Taktics · #51 13-05-2009, 10:13 PM

Sphooling, keep me updated! Ill have a crack at it after, since my problem sounds very similar to yours.

WhiteRX · #52 13-05-2009, 10:38 PM

Tak does your car have pfr6b's or pfr6g plugs. because the b plugs arent recommended for our cars. they require pfr6g's which are the ngk racing electrode type.

Rossco · #53 13-05-2009, 11:05 PM

Quote:

Originally Posted by slg

1.2 Bar is not really a 'boost monster', they should last more than 7k.

Investigate the plug condition and take it from there. If the 7b's are cooked, you may need to run a cooler plug again. If they are sooty and fouled, then go back to the hotter plugs.
Otherwise you could be replacing plugs every 7k, when you could have bought a couple of cartons of beer instead and sat back admiring how good the dakdak has been running this last year

7's are COOLER than 6's in NGK plugs.... overheated plugs don't foul/fail unless you melt the electrodes off them!

Turbo cars always have sooty plugs, they run cold off boost but hot on boost....There's zero comparitability with N/a plug reading, they're always a compromise with turbo engines.

going to a hotter plug may lead to detonation if driven on boost for extended periods (track) = fucked ring lands / spot melted crowns.

Rossco · #54 13-05-2009, 11:08 PM

Sphoolin:

Your issue could be either leads, coilpack or engine earthing or over fuelling.... Unless you run Octane boosters?...Octane boosters have been known to foul plugs over time.

the cheapest option is to earth the engine block directly to the battery and see if there's any improvement.....Subarus have shit engine earthing.......

slg · #55 14-05-2009, 01:09 PM

Quote:

Originally Posted by LegacyRS

7's are COOLER than 6's in NGK plugs.... overheated plugs don't foul/fail unless you melt the electrodes off them!

I know 7's are cooler, read my post...

[/QUOTE]
Turbo cars always have sooty plugs, they run cold off boost but hot on boost....There's zero comparitability with N/a plug reading, they're always a compromise with turbo engines.[/QUOTE]

Please, cold off boost, come on, they just run hotter on boost, if the engine has been tuned correctly, over-fueling off boost shouldn't be an issue, and is not putting out a huge increase in power over std, then a #6 plug would be absolutely fine. I believe the rule of thumb was about 100hp per heat range, roughly.
As far as plug reading goes, sorry I think you'll find that reading a plug is fairly universal, you can get the same info from a N/A or turbo plug if you know how to. Nitrous was the one can be a little tricky!

[/QUOTE]
going to a hotter plug may lead to detonation if driven on boost for extended periods (track) = fucked ring lands / spot melted crowns.[/QUOTE]

Correcto moondo. One hot engine.

Sorry I just had to clear that up, probably hate my guts now but believe it or not I am a qualified tradesman who actually took an interest in his job!

Taktics · #56 26-05-2009, 01:46 PM

Bump this thread again.

Sphoolin, how are things going with you and the whole missfiring situation?!

Tom - My car is running PFR6B's which you said its not recommanded for our cars.

Might be looking at the PFR6G's in the coming week.

Rossco · #57 26-05-2009, 02:57 PM

Sorry Tak,

Missed this before......

Quote:

Originally Posted by slg

I know 7's are cooler, read my post...

Please, cold off boost, come on, they just run hotter on boost, if the engine has been tuned correctly, over-fueling off boost shouldn't be an issue,

Sorry I just had to clear that up, probably hate my guts now but believe it or not I am a qualified tradesman who actually took an interest in his job!

I was refering to 'the traditional method of Reading the plugs by insulator colour' on a turbo engine....... You cannot read the plugs of a turbo engine as you can with N/a engines.

The short Idle down period after a 'power run' is enough to re-soot the plugs enough to make them look too cold (sooty).

<Back on topic>

Elrico · #58 26-05-2009, 06:23 PM

Sorry Taktics, i havnt had time buddy. I will change em over on the weekend, possibly saturday arvo hopfully.

Elrico · #59 23-06-2009, 01:45 PM

Ok well, took me a bit to find this thread again hah, but yeah.

I decided instead of sitting on here stirring Tj up and him getting me back id do something productive. I have reinstalled my NGK PFR7B's that had done 10,000kms over the NGK PFR6B's that had done almost 10,000kms.

After bending my arms 7 different ways from sunday i eventually got the plugs out, swapped them over, warmed her up and paid close attention to my knock sensors just incase. I had her at 6,200 (1000 short of limiter) @ 1.3bar, read a knock of 10, and the missfire is gone. The 34 holds very strong till 6,200rpm which is all i took her to. I dont understand, how could the tempreture of a plug (7bs being colder from memory) dictate a missfire? 6B's getting too hot? Also feels alot smoother to drive aswel.

Captain Enrico reporting for duty :P

nicebus · #60 20-11-2009, 11:17 PM

Would the NGK PFR 7B's be ok in a 99 WRX. Has VF43, FMIC, 3 inch cat back and autronics. Shows 17 psi.
Has a stutter miss on boost and after 4000 rpm.
What gap should the plugs have?
Does an increase in boost mean you should decrease the plug gap ?