Car Misfiring And Backfiring When Coming Onto Boost?

[R31HOOCH]

Hey everyone... My RB20DET is f**ked at the moment... Well in most aspects its fine, just when it starts coming onto boost it loses all power and backfires like a shotgun... When taking off and driving slowly with boost pressure in vacuum its fine but as soon as you put the foot down it dies in the ass... I've replaced 2 coil packs, the AFM, the o2 sensor, o/hauled alternator, checked fuel pressure, pump and reg.

Can anyone give me any ideas on what might be causing this??? Its starting to do my head in...

[Cubes]

More coil packs, ignitor, cracked spark plug porcelain.

[R31HOOCH]

The ignition module is next on my list then the rest of the coilpacks but if that doesn't fix it then i don't know what i'm gonna try... its weird coz it idles fine and mostly revs fine when in nuetral, just when driving it and trying to boost it up its got nothing... (except huge backfires and flames...)

[Cubes]

Double check sparky's. Its fairly easy to accidently crack the porcelain when torquing them up.

When my coil packs die I'm not going to waste time fiddling with second hand items, straight to nengun and a 3 week wait for me.

To me... it sounds as if spark is jumping to the point of less resistance, in other words look at your coil packs and or spark plugs.

[Fixxxer]

Read the sticky thread on missfiring up the top of the General Maintenance section. Have you checked spark plug gap? You should try 0.8mm gap, using NGK Copper BCPR6ES spark plugs.

The thread also mentions steps you take to identify arcing coils, and how you can solve some of those issues. Try these steps first before anything else.

Fixxxer

[R31HOOCH]

hey guys... i'm still having problems... i replaced my plugs the other day with the gaps set to 0.6mm... I also pulled all my coil packs out, checked them, and taped them all up. I also replaced the ingition module on top of the cam covers and it has all made no difference... It still dies in the ass as soon as it starts coming onto boost!!! i'm gonna pull my fuel pump out next and upgrade that as one of my mates had the same problem and he said thats what fixed his... but other than that... any1 esle got any more ideas???

[mad082]

sounds like a bit of a stretch, but it could be a crack in the exhaust manifold. only taking a stab in the dark though.

[Cubes]

Look for arc's on the coils?

[TurboX]

I would be double checking the actual true boost - it may be spiking badly and your not seeing it for some reason??

[schultzr33]

I am having the same problem...what u need is a fuel cut defender. r u running non-factory boost? if so, the ecu cuts fuel as the boost is raised to prevent damage. if u get a turbosmart fuel cut defenfer ($120~) and fit it, it tricks the ecu and ur car will run fine. When my car was doing it, i spent like $200 just on the iridium sparkplugs, thinking it was them, but its just ecu. Alternatively, u could replace/ tune ur ecu...hope this helps

[khunjeng]

if 2 coild have been replaced I'd be 98% confident its the coil packs. What power/boost u running?

There is a a sticky with about 500 members with this problem, most were fixed with new coil packs and/or re-gapped plugs i..e from 1.1 to 0.8 etc

I too had this problem and dispite all the DIY about taping them up etc, the coil can break down inside and die..just replace them. If you buy thorugh nengun expect a good 4 week wait. but good prices.

mine were crapola running 0.5bar with 175kw...Now I'm running with somew new packs and 275kw, 1bar and no worries with the spitfires (and the same plugs / igniter cos I have a S1)

[BSK]

that dude over in NSW will do a retuned eprom for the same price as the defender. could fix your problems plus performance gains...

sorry cant remember his nickname or website but u can get him at [email protected]

speaking from a similar experience i had this week although mine was missing rather then backfiring. the problem started when platinum plugs were fitted by a smartass without my authority. i then replaced the plugs with cheaper copper plugs 0.8gap (as per SAU recommendations) and still had the same problem. if the gap is too small i was informed by someone (in another thread somewhere) that it also could have a negative effect causing it not to ignite the excess of fuel if the car is running rich.....?

in the end i lightly sanded back the contacts of my original old iridiums and it worked a treat.... i cant explain why the coppers didnt work but its gonna be iridium all the way for me now.

[Cubes]

Unusual..

I think your solution was a fluke... Maybe you lucked out some where or there's an issue some where else that you have some how managed to fixed unknowingly.

[khunjeng]

copper, platnium or iridium they all should work. I use the iridiums just cos I feel like it, but I have seen numberous results from others with copper stds which were really just as good.

there is nothing wrong with platniums..I'm guessing the gap was wrong in the first place or they were the wrong heat range.

as for the other issue, I put $5 down on coil packs if others have already failed and been replaced. Its like only replacing 2 plugs that are faulty. its likely the other are on the way out also just do the lot and don't waste ur time.

[yummy]

Loose cooler pipe?

[Kennedy]

Loose cooler pipe?

What he said...

[blind_elk]

Someone had one a few years ago - similar to this problem. Turned out to be a crack in the weld of the IC endtank; it was fine under normal driving, but open up as soon as boost was applied.

The coughing and farting suggests overfuelling because the AFM has told the ECU how much air, but that air then escapes on boost.

Check all your connections and welds in the induction system.

[GTR_Legend]

mines playing up too, replaced the plugs with a smaller gap and has corrected a bit, as soon as i hit around 9psi it starts dying.

Have new splitfire coils on the way from Japan!

[R31HOOCH]

thanks for all your ideas guys... i've still got the problem and its now a little worse... i had a Walbro 550hp intank fuel pump fitted and now its mega overfuelling... I'm gettin pretty fed up with it now so i've gone out and bought a Microtech ECU and i'm just gonna fit that and start from scratch... i've done basically everythin except ECU... the plugs, coils, alternator, AFM, ignition module, I/C piping and fuel pump have all been covered so i think this is my last straw...

I'll let you all know if i have any luck...

[GTR_Legend]

thanks for all your ideas guys... i've still got the problem and its now a little worse... i had a Walbro 550hp intank fuel pump fitted and now its mega overfuelling... I'm gettin pretty fed up with it now so i've gone out and bought a Microtech ECU and i'm just gonna fit that and start from scratch... i've done basically everythin except ECU... the plugs, coils, alternator, AFM, ignition module, I/C piping and fuel pump have all been covered so i think this is my last straw...

I'll let you all know if i have any luck...

wouldn't the fuel pressure reg stop it from over fueling?

im thinking that the ecu would be a work around rather then a solution. Iv done the plugs afm etc.. but still waiting to replace my coils, they should come in today or tomorrow!