Very Bad Skyline Problems

Ok where do i start i swaped a car for a gts-t m-spec skyline its got a standard rb20det in it. i drove the car for all of about seven hours then it started to miss real bad every time i hit boost. so i suspected coils and/or ignition module i replaced both but no change. so i pulled out the plugs to find each one had melted the tips off. i brought new set of plugs it ran fine when i replaced them. Then i stupidly put regular 91 octane fuel in it not relising (half asleep) relised what i had done after filling the tank so i took it for a drive to see if it would effect it badly or not. IT DID it droped a cyl half way down the road. i took it to a mechanic who discoverd it had burned a pretty hole through the no.6 exaust valve so i had the valve replaced and iv just got it back but it still has a miss in the 3-5 rev range then it smooths out ive had the injectors and coils tested and they are mint. i still have no idea what it could be any help would be great cheers.

Ok where do i start i swaped a car for a gts-t m-spec skyline its got a standard rb20det in it. i drove the car for all of about seven hours then it started to miss real bad every time i hit boost. so i suspected coils and/or ignition module i replaced both but no change. so i pulled out the plugs to find each one had melted the tips off. i brought new set of plugs it ran fine when i replaced them. Then i stupidly put regular 91 octane fuel in it not relising (half asleep) relised what i had done after filling the tank so i took it for a drive to see if it would effect it badly or not. IT DID it droped a cyl half way down the road. i took it to a mechanic who discoverd it had burned a pretty hole through the no.6 exaust valve so i had the valve replaced and iv just got it back but it still has a miss in the 3-5 rev range then it smooths out ive had the injectors and coils tested and they are mint. i still have no idea what it could be any help would be great cheers.

Have you tested the airflow sensor yet? if not, do that before it's too late.

ok i will try ill keep u posted

tested air flow meter came back fine but in my travels i found 3 cracks in the sparkplug (porsiline bit) going to change plugs i will update tomorrow

Seeing as you have melted spark plugs, burned a hole in a piston and now cracked a spark plug, those are all tell tale signs of running to lean and/or overboosting. What boost is it running (keep in mind to check out the boost gage source pressure location/plumbing), what mods have been done, etc.

I would expect that you're overboosting, which is causing the missing, and leaning it out which is causing the various parts melting/cracking.

*screams* I can't believe you put 91 in it :nono: :disappoin . I really don't know what to say to that. Jap cars were designed to have much higher octane levels in their cars (I think they have 102 there??) than what aus & US offer, which is why you MUST have the car tuned when you get it. Leaning out and/ or over boosting is going to destroy your engine pretty quickly. I personally would take it straight to a performance workshop with a dyno and have it tuned. Check what levels the boost is set to, I would reset them to my own.

The car is running standard boost (12.5psi) and is prteey much standard pod filter and heat sheld the car is running lean as i found out today i put it on the fuel analyser and the were the results

AT IDLE

co .17%
co2 12.0%
hc 122ppm
02 3.73%
air/fuel 17.5 to 1

so shes running pretty lean after more problem solving we found more than 5 vaccume leaks which is making it running lean will keep you posted
cheers

i doubt its gas since all they have at misawa is 92. i put octane booster in there every once in awhile

Your lean problem is most likely caused by a dying fuel pump, which is a common problem. I'd replace it with a bosche 044 pump. Check your fuel pressure at the fuel pressure regulator also. You need to have a min of 35 psi under boost in standard trim.

AFM's can "check out fine" and still be a problem. Dry solder joins are a common problem with them.

The car is running standard boost (12.5psi)
Standard boost for a GTS-t RB20DET is 7 psi. 12.5 is pushing it.

standard boost is .7 to .8 bar, which is 10 to 11.6psi. 12.5 is a bit high, but well within limits. A stock RB20DET can take 1 bar (14.5psi) safely.

Couple of things to do/check...

1) Change the fuel filter...
2) Never put in 91 octane, try for 94
3) Your boost is kind of high... you risk blowing #6 Cylinder... (common)
4) Reset your ECU, it may have been tuned for more octane.

This section has a lot of helpful info... see the PDF's...

http://www.jdm-imports.com/skyline_specs.html

standard boost is .7 to .8 bar, which is 10 to 11.6psi. 12.5 is a bit high, but well within limits. A stock RB20DET can take 1 bar (14.5psi) safely.


you keep talking about PSI... what is it ?

PSI is Pounds Force Per Square Inch (lb/in^2), which is a pressure measurement mainly used in the US but also in some other areas.