Miss at 5500rpm

A

Anonymous

Guest
I have a miss at 5500rpm. My R pulls hard untill then, stutters then takes off again untill red line. Any ideas?

Running 15psi, ngk iridium plugs, bp ultimate fuel, turbo back 3 inch exhaust. Hasn't always had this problem. Doesn't matter what boost i run, still the same.

Any ideas will be great.
 
M

Mr Overboooost

Guest
does it still happen off boost :?:

have you changed anything yet like leads/coil/dizzy cap/rotor or ignition module :?:

cheers
gary
 
Fast Guy

Fast Guy

Moderators
Staff member
Try optimax fuel.
A regular misfire tends to be from the ignition side, so I'd check all the things gary listed and maybe even your fuel filter
 
A

Anonymous

Guest
I'm going to put a oscilliscope on it soon. I dont go past 5500 rpm often, dont need to, so its not a big hassle as yet. Just a little annoying (and embarrasing) when i do.

I've tried optimax, found my car didn't perform as well as 95RON Premium unleaded. Only just got ultimate where i live, made a differance to performance, acceleration is much smoother.
 
Fast Guy

Fast Guy

Moderators
Staff member
I missed the Austrailia bit. Optimax is 98ron here, what is it there? You realy need to using the highest ron available, which is 98 for us.
These cars normally use 100ron in Japan, so it could even be a fuel quality issue.
 
G

GazTi-R

Guest
Exact same symptoms as mine on test drive. Check for water in No.1 spark plug hole. Cured my probs. :D
 
A

Anonymous

Guest
BP Ultimate is 98RON as is Optimax in Australia. Its not only my GTi-R that doesn't like Optimax. Its also my Fathers old S14 200sx his current 5.7L V8 Holden Commodore as well as our vintage cars. Other people we know have the same problem. Our problem is not isolated to 1 perticular service station.

Under the bonnet of my car there is a sticker saying that the Nissan GTi-R SR20 DET Engine tune up data. Fuel 95-96RON only. Im new to this, if i could work out how i would post a photo.
It has run perfectly, no pinking, for a year with only 95RON on 15psi boost. It pinks slightly on Optimax. Our VERY modified 1100cc Morris Minor (dont laugh) sounds like its going to explode!

Had the problem for a while, and change plugs since, so i think that rules out water. Working my way back from there. Once dad is back from holidays he'll put the oscilliscope on it. That way its free!
 
G

gtir drew

Guest
I had the exact same problem with my car when i bought it, I changed the spark plugs and it was fine. How ever i know someone who had it and they had to change the leads befor it sorted it. That is were i would go first
 
Fast Guy

Fast Guy

Moderators
Staff member
If it hasn't had a service for a while, I'd be tempted to give it one. You might find it cures it.
If it doesn't cure it, then you need to start looking deeper like ignition amp, maybe a problem with the dropping resistor for the injectors or something.
 
A

Anonymous

Guest
Ordering new plug leads today, i'll let you all know if that helps.
I service it every 3 months religiously. No matter how many k's i do (usually less than 1000km)
 
A

Anonymous

Guest
Tried new plug leeds, didn't help.
Thinking back, it started the around the same time as i put the iridium plugs in it. Might try normal plugs again.
 
T

Tart

Guest
Definately sounds ignition releated..... if u checked the plugs, try dizzy and check the timin......if it pinks on optimax the timin may need adjustin......
 
A

Anonymous

Guest
Thanx
Like i said, it runs fine (no pinking) on BP Ultimate or Premium 95RON. Just not Shell. Have seen tests on shell fuels from local service stations, Optimax as been recorded as low as 91RON, but BP was consistant. Not worth the risk.
Working my way through the list as fast as money will allow me.
The miss started after i changed to the iridium plugs. Might have something to do with it, dont understand why, but changing back might be worth a try.
 
A

Anonymous

Guest
Annoys me a little reading through some of these problem messages that you rarely find out what the problem was in the end and how it was solved.

So i'm pleased to say i fixed my miss. It was plug gaps. They were at about 1.2-1.5mm. Closed them to 0.8mm. All better now.

Thanks to everyone for their help.
 
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