Saturday, September 05, 2009 - 04:09 pm, by: Scott Wilkes(Scottywilkes)
This has only just happened suddenly, i didnt have any access to 98 octane fuel, so had to use vortex 96, from what i can remember the problem has only started after filling up with this fuel.
Now the problem is, that under load, say 3rd or 4th gear, full throttle, the car builds boost nice and quick, but then starts to surge and backfire out the exhaust.
The problem is more prominant the more boost i push through it.
I thought it may have been coils, but ive pulled them out and had a look, and theres no cracking around the main part of the coil, only the odd fine crack on the tabs.
Pulled the spark plugs out, and had a look, only put them in last service 4500ks ago, there NGK and they look fine.
So this leads me back to the fuel, im hoping this is the problem, but if people have had a similar problem that could help that would be great.
Saturday, September 05, 2009 - 04:55 pm, by: Scott Wilkes(Scottywilkes)
thats the thing, i thought it was detonation, but it does it on standard boost to, ive hooked up the ultimate to the laptop and watching the knock sensors and they are not sensing any knock at all.
Plugs dont have any fine metal fused to them, as generally when they knock they blow off very small particles of piston which generally fuse to the electrode of the sparkplug, pistons are nice and flat from what i can see through the plug hole to.
Im nearly out of fuel so im gonna hit it with some 98 and octane booster and see how i go
Saturday, September 05, 2009 - 05:19 pm, by: Daniel Clarke(Dieseltrain)
Up here Normal Vortex is only 94-95 octane rating . Maybe It was a bad batch of fuel and has detonated and hurt the plugs as well ? so new batch of fuel and some new spark plugs may be in order Scott.
Saturday, September 05, 2009 - 07:45 pm, by: Scott Wilkes(Scottywilkes)
yes it is, i was stuck in a pickle, closest gas station is caltex, only place to get 98 is 15 minute drive, and well, sister borrowed the car and fuel guage was under 5L so didnt trust it HAHA. I should of just topped it up and went and got 98, o well.
Its got 98 in it now with some nulon octane booster.
First time using octane booster, so see how it goes, ive never been told good stories about it though.
Saturday, September 05, 2009 - 08:30 pm, by: Daniel Clarke(Dieseltrain)
Ive always used the NUlon Pro Strength ... Years ago it was tested as the Best on the market . Should bump the 98 up to 100 RON AMazing how much mroe timing can be put into a tune compared to regular pump 98 when using it Scott.
Sunday, September 06, 2009 - 07:56 am, by: Scott Wilkes(Scottywilkes)
changed the fuel filter last service, serviced the car yesterday and pulled it, still flows well, so its not that.
When i put the plugs in i gapped them to .7
Pump im not sure how that is, might be worth bypassing the fuel pump relay and flow testing it, anyone know how much it should flow per minute?
Also no luck with the fuel and booster, its still doing it unfortunately , which leads me to something else, il drive into the workshop and put some new plugs in today
Scott Wilkes DieHard Tasmania 92 TT Factory Manual
Sunday, September 06, 2009 - 09:17 am, by: Scott Wilkes(Scottywilkes)
well put some iridiums in it just now, there not brand new, when i got the car i pulled them out and put coppers in, but for the purpose of narrowing down my problem they are good enough.
Took it out the highway and it seems good now, its not popping and goes nice and hard .
Sunday, September 06, 2009 - 03:37 pm, by: Scott Wilkes(Scottywilkes)
i still think theres an underlying problem somewhere, it seems to have a flat spot before it really starts to go, so i reckon the plugs were part of the problem but not all of it.
Monday, September 07, 2009 - 05:54 pm, by: Scott Wilkes(Scottywilkes)
well all seems good
Last couple nights ive taken it out the highway and done a few high gear full throttle runs, boost up to 1.1 bar nicely and keeps pulling hard to redline.
I reckon the plugs have been stuffed for a while, but suddenly completely shat them selves haha, as it seems to pull alot harder than when the plugs were acting fine