misfire or backfire??

[rb26dett]

hey guys, need some help. what's the difference between a misfire and a backfire?? i understand they all make that pop pop pop out the exhaust right??

so how do u identify which is which?? also, what are the symptoms of fouled plugs, i.e. how do u know they are fouled?? and what does your car do if ur plugs r fouled??

my car sumtimes has power cuts, not when i push it, but when i'm driving like a granny...i have been told by my mechanic to stop driving my car like a granny cos the rb26 needs to be stressed. is this true??

the power cut feels like a jerk, and usually happens between 2000-3000rpm...up high it's fine n just revs n revs...any ideas guys??

thanks for any help guys.

[Steve]

Well, purely from a theoretical point, a misfire can cause a back fire, but over fuelling, eg on gear shifts if running a stock ecu or worse a ext venting bov as well.

If your plugs are fouled, a good thrash is one way to clean them (thats the way I used to do it many, many years ago ). If you are running from map without closed loop, there is a good chance you will be running rich when at cruise and part throttle. Fouled plugs, may cause the car to feel like it is hesitating.

Also, I am starting to stretch into the unknown here, but what heat range and gap are you running? Does this only occur when the car is hot or cold or both? Any more info could be helpful.

RB26DETT needs to be thrashed? Not unless it has been played with. Dont think any jap company would put a car into mass production that didnt have impecable manners as a daily driver.

[rb26dett]

heat range....i would think right throughout...

everytime i start my car i let it idle till the revs die to about 1090 (on my turbo timer n avcr), before moving off.

it happens when the oil temp gauge hasn't moved, but has happened when the oil is at operating temp.

i think my gap is 1mm.

[adam 32]

plug gap should decrease with higher boost pressure

ie 1mm is good for 8-10psi

.8mm is good for 12-14psi

and .6-.7 for anything over 1 bar

also pay attention to heat range, nissan recommend anything from 5-7 on NGK plugs. (5=hot, 7=cold)

sounds like a plug problem though, so just unbolt the intake pipe and coil pack cover and you should be able to get them out easily enough

[rb26dett]

thanks for the information guys. will have a check.

[Steve]

make sure you let us know what the problem is, I am betting from your comment about the oil temp that warmer range plug would fix the prob. My understanding though is that warmer plug is more prone to knock at higher revs/load. There is always a trade off somewhere.

[rb26dett]

yep...but will be in a couple of weeks...i got exams n assignments

will keep u guys posted

[Talej]

hmm I seem to have the same or a very similar problem atm. happens when cold at around 3000 revs and then all the time even worse up around 5500... i dont like it