Jump to content
SAU Community

Feels Like Misfire But I Think Its Fuel Shortage At High Revs. Help Please.


nosking_178
 Share

Recommended Posts

hey guys.. i used to have a misfire problem with my car r32 skyline gts (non turbo) about 4 months ago. but i fixed it and now it feels like it is misfiring at higher revs again (full throttle).. but i dont think it is misfiring.. i think it has something to do with fuel shortage. it has happened about 1 or 2 months ago and i changed the fuel filter and it went away but now its back ..... :S

wen its at high revs and at 90% or full throttle.. it makes a put put put sound...

low throttle runs fine and this problem occurs on some days usually the days when i run it hard... :S:S:S::S::S

any help is much appreciated!

Link to comment
Share on other sites

Have you investigated the spark plugs at all? How recently were they changed? Were they appropriate heat range? What gap were they?

Might pay to test your fuel pressure. Injectors may be leaning out too.

I have a similar problem that occurred just lastnight after lots of driving, but was gone this morning. This suggests it was heat related so I'm putting it down to my spark plug heat range.

Link to comment
Share on other sites

hey thanks for the input. much appreciated...

when my car was misfiring 4 months ago.. i changed the spark plugs, coil packs, coil pack ignitor module. and i have done approx 3000 since then. im not sure what gap they are but my mechanic changed them.. think he used high performance ones.. cant remmeber what their called exactly tho.. mayb iridium but they should be suited for my car since he knows what he is doing.

oh and 1 or 2 months ago.. it used to do it when my engine was cold temp like morning starts etc..... i realised after i had to give it full throttle and to overtake sum 1 and it made a put put noise :| and now since then i changed the fuel filter and now its back after a month or 2.

how do i test fuel pressure that sounds a good source to my problem.? and could it have something to do with fuel pump? or nar.. \

and would u reconmend me using fuel injector cleaner (those additive in a bottle)

cheers for ur help mate. =]

Link to comment
Share on other sites

It might pay to check the gap they were at or the heat range of them. I have Iridiums in my car but they are only heat range 5 which is probably too low, yet they were recommended for my car by the NGK catalogue. Normally they do fine but I did alot of high RPM driving lastnight which may have overheated them, lagging their performance in the mid-high RPM range. This would be akin to an intermittent problem.

Fuel pressure can and should be tested at the rail...I'm not that familiar with these engines yet but there should be a fuel purge valve on the rail somewhere that you can attach a pressure gauge to for a reading. It can certainly be a fuel pump problem, as a faulty pump will not be supplying the required pressure to deliver enough fuel at high RPM. This would be akin to a constant problem, not something intermittent.

Injector cleaners in a bottle...meh...they aren't fantastic at cleaning and some of them even leave deposits in your injectors that worsen the problem down the track. The only way to properly clean injectors is to take them out and have them serviced/reconditioned.

Link to comment
Share on other sites

a couple of days been driving.. my problem has been gone. But im sure it will come back again.. :)

ill change the fuel pump and use injector cleaner sumtime this weekend when i get a chance and let ya know how i go... and if it still misfiring... ill change my spark plugs. cheers for all your help mate.. ill update ya on how i go. =]

Link to comment
Share on other sites

  • 3 weeks later...

hey sorry about the delay on this post i havent bad a chance to change the fuel pump until today.. but unfortunately this did not solve my problem.. it runs alot better but the problem still exist..

ill have a loook at my spark plug..

and do u think the air/ fuel sensor has sumthing to do with this problem?

Link to comment
Share on other sites

hey the coil packs were new. so i dont think it would be that causing the problem....

ill clean my AFM with carby cleaner??? would u suggest using that or would that damage..

oh and umm yerh i mean the oxygen sensor, my bad. the auto baurn staff told me that it might be that causing my problem.

i found it onli like misfires wen 90% or full throttle... and onli on days when idrive it hard.. it will start mis firing at full throttle..

low/mid throttle is perfectly fine.. :S im confused

any advice is much appreciated!

Link to comment
Share on other sites

oh and when i get a chance ill check what spark plug my mechanic used... from memory they are denso brand but i got no idea what gap or heat rating they are.. ill have a look on tues since i got a day off.. and let youse know.

Link to comment
Share on other sites

mate sounds like it would be cheaper (50-100 bucks) and get it checked on the dyno! sounds like u are pouring money into your car without finding the problem.

On the forumns you can get pretty good opinions, and some pretty bad ones (NOT POINTING AT ANYONE DIRECTLY). Good that you are changing all these things- but its over kill.

I would be one to say thats its the coil pack- but since you changed it dw!

Good luck and hope that u fix your problem!

Link to comment
Share on other sites

thanks for your advice... any place suggested to go for a dyno tune????????? im from geelong and not many place i can go to that know about skylines..... melbourne is prob the next closest resort to go for a decent dyno tune place but my car prob wont make it up there

i thought dyno tune wud have been alot more.. thats why i been trying to avoid it............

but im quite certain that it is the ignitor module playing up because as i move the wire it will run smooth and when i take my hand off it will misfire and shake lik crazy...

my mate's friend knows some1 who has a r32 as well so his gnna see if i can swap the module with his to see if it fixes it up.... then ill buy a ignitor module

Link to comment
Share on other sites

thanks for your advice... any place suggested to go for a dyno tune????????? im from geelong and not many place i can go to that know about skylines..... melbourne is prob the next closest resort to go for a decent dyno tune place but my car prob wont make it up there

i thought dyno tune wud have been alot more.. thats why i been trying to avoid it............

but im quite certain that it is the ignitor module playing up because as i move the wire it will run smooth and when i take my hand off it will misfire and shake lik crazy...

my mate's friend knows some1 who has a r32 as well so his gnna see if i can swap the module with his to see if it fixes it up.... then ill buy a ignitor module

Isnt there anything around Geelong thats got a dyno? If u wanna go to Melb, theres a thread somewhere if u do a search, shows all the tuner shops and jap wreckers around there,..you could check out status tuning, m-spec, race pace or something. Ive heard good things about them

Link to comment
Share on other sites

they don't have to know about skylines to be able to tell you if it is running lean. all they have to do is put it on the dyno, stick their wideband o2 sensor up the exhaust and then do a few runs.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share



  • Similar Content

  • Latest Posts

    • New R34 owned here (from the US) and found a gem, '98 GTT with ~6k miles, super clean & completely stock. When shifting there's no grinding, shifts smooth, etc. The concern I have are 2 things: 1) Only in 2nd and 3rd... when maintaining a slower speed (in traffic as an example) as I let off/on the gas, the shifter will slightly move and vibrate. If the clutch is engaged, none of this happens. It's not bad, but enough to feel like something isn't necessarily right. 2) This mainly happen in 4th or 5th... the shifter slightly bounces up and down, almost like it's riding on unbalanced tires (and I do think the tires are unbalanced as I get a little of that bounce feel at higher speeds, which is maybe why it only happens in 4th/5th). Lastly, and sorry for this noob question but I want to work on this car myself, can someone teach me some on these manual transmissions? Like servicing them, best products to use, etc.; would be greatly appreciated. Thanks!!
    • Coilovers aren't even the first step. Bushes, subframe position and alignment, HICAS elimination, adjustable upper arms and traction arms in order to dial out understeer. All these things need/deserve attention first. ARBs (There's no such thing as a swaybar. Please, everybody, stop calling them that) are useful if you want to limit spring stiffness. Otherwise you can control body roll with springs. Spring and damper rates are a function of road surface, speed and usage. There is no solution that works for all cases.
    • Define "nothing". Is the starter spinning but not the engine? Engine turning but not firing? If the engine is turning but not firing, then you are missing either fuel or spark. You need to find whichever has gone missing.
    • Shitbox Tiguan updates, got the APR OTS tune put back on (no charge for it to be removed/added back), didn't want to just come in just for that (not a fan of wasting people's time for nothing) so I purchased an APR dog bone insert. The boys at German Performance Garage said they would fit it for free too since they had 1x hoist free. Now that's service you don't normally get from most workshops. Anyhow, tune back on, snow grate pulled out, dog bone insert back in and not going to lie, a few smiles when I nailed it around the industrial area heading back onto the M7. Amayama also said 1 to 2.5 month wait for the RB25DE heater hose, yeah why not, car has been off the road for nearly 3, what's a other 2.5?
    • Hmm I'm going to approach this from the other side... What is the car doing that you don't like or what would you like the car to do that is currently isn't doing (handling wise that is)
×
×
  • Create New...