Increased Boost and still misfiring

[rb25]

Take it back and get it tuned with good spark plugs. I cant believe they tuned on shit plugs at stock boost, what a joke. Dodgy and very lazy....

Sounds like a fuelling problem, lack of...

[Reedy]

Just done another coil last weekend thats number 4, does any one know if something might be causing them to die or just a bit old 1/97 with 100,000km and are all going to slowly die? Cars been running fine at 10psi for last couple of weeks had the following problem at any higher boost, now idles rough as coil is gone, this whats happened from previous thread I posted.

"I've got the same problem a misfiring at hi boost (> 11psi) but with different mods on my R33 Gtst with a full exhaust, FMIC, pod, dual port bov. I got a wolf 3d ems tuned last september with a new bosch fuel pump and NGK BCPR7ES sparks set to 0.8mm. Car was running fine at 14psi from a bleeder until march this year when two coils went one after the other, I then thought another coil had gone with misfiring. But coils were fine they had replaced the plugs with autolite App 3924 double platinum plugs but gapped them at 1.1mm I then got them to change it to 0.8mm which I thought made the car run better with not as much misfiring at hi boost (10 psi is fine but much more than that). They also cheaked the heat range of the autolite plugs and the same as the ngk 23-37 i think. I've reduced the overall trim of the ignition timing by up to 5 degrees and it did not make any difference also the battery voltage is almost alway 14 V on the handcontroller during normal usage so I think the battery is fine but havn't checkit under hi load. I reloaded the origimal wolf settings and didn't make a difference so I don't think theres anything wrong with the wolf and I starting to run out I ideas so any ideas are much appreciated."

[WLD747]

Did u read my message above. " I use to have the same problem. Remove the nissan cover for your coils, cause they fry under there. :flamed: Thats why your losing coils . And all should run sweet :Bang: "

[deano_82]

I think i have a similar problem when i accelerate hard i hit about 5000rpm then you jusT get a flat spot or misfiring, but then sometimes it seems ok?

just in the process of purchasing fuel pump, i might try the idea of the battery?

any other thoughts

car is r33 rb25det standard boost full 3" knn has iridiums still at 1.1mm any other thoughts i have changed plugs cleaned air filter changed fuel filter clean afm so i have determined its either the fuel pump or coil packs? i didn't clean the coil packs when i changed the plugs!

[Reedy]

Alright thanks, i'll give it a try and take the cover off.

[morlock]

Yeah.... I had misfiring at high rpm (anything above 5000rpm) and BD4s tested my coils and found 2 faulty ones. Am having them replaced today...so hopefully should fix things up for the track day in 2 weeks. WLD747 thanks for the tip on the nissan cover...ill take it off for the day....out of interest, what do you do with the black box that sits on top of it at the rear of the cover?

[GunMetalR33]

Your plugs might be the wrong heat range for the boost you are running. I think you should run 6's if running standard or close to standard. For anything above that you should run 7's but this is just an idea if nothing else is working...

[deano_82]

How essential is it to gap them back to .8 rather than 1.1

if i'm not running huge boost or anything like?

is it possible to safely gap iridiums as the tip is so fine?

[deano_82]

i know what gapping them does but whats the point if i dont need to?

[riggaP]

i know what gapping them does but whats the point if i dont need to?

My story was similar to yours. With only a cat back zorst, and stock boost (well the zorst probably increases stock by a few psi), she misfired like a dog between 4500-5500. I put copper plugs in and gapped them to 0.8mm. This reduced the misfire until I added a bleeder and misfire became a problem at 10.5psi. I then put in a chipped ECU which removed boost cut and now I'm running 13psi without any hint of misfire.

Another thing to check is the stock boost solinoid. If its not working properly the added juice from VVT will cause misfire...

[deano_82]

yeh i have thought about because isnt that when it hits the higher boost on the solenoid.

going to check my coils this weekend, remove the cover

also how any one give me any ideas on how i easily check the solenoid?

cheers

[GunMetalR33]

its fine to gap iridiums, mine are gapped to .7 just be carefull when doing it

How essential is it to gap them back to .8 rather than 1.1

if i'm not running huge boost or anything like?

is it possible to safely gap iridiums as the tip is so fine?

[deano_82]

Cheers gun,

i checked out fuel pumps last night,

you think i should go with 040 internal or 044 external, i guess it would be wise to also run surge tank aswell?

[GunMetalR33]

You dont need a surge tank unless you like running till your tank is almost empty, they are not really needed unless you do track work or something like that. I reakon you would be better spending the money on something else. Dont know what pump you should go for, I have a supra TT Jap Spec which flows way better than a GTR one and you can get them fairly cheap.

[[ant]]

hm my dr30 has a misfire .. hoping its the leads, one doesnt click onto the top of the plug all that well .. fingers crossed

misfires suck, theres just so many possibilites to try when attempting to fix them, its pure luck if u stumble onto the right one straight away! plugs is easy but after that it can get more complicated!

also have u reset ur ECU? silly thing but sometimes it helps too, once u change ur plugs and etc that uve done, undo ur battery for a while then re connect it. it may help.

[crooser]

installed my old GTSLink ecu today. misfire gone