Sounds like replacing the corroded coil lead might cure your rough running.

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_________________
Don
GT4DC Chairman
1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
1994 Toyota Celica GT-Four Special GT 590bhp @ 1.8bar
1989 Van Diemen RF88/89 Formula Ford 1600
2008 Nissan Patrol GU 3.0L ZD30DDTi 154bhp

Picture of corrosion in cap connector from coil

http://s284.photobucket.com/user/Kjetil_Gout_Eriksen/media/20150205_155806_zpscquhcqx0.jpg.html?sort=3&o=2

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I tried to turn the bad coil lead around so the red plug is in the cap instead of on the coil (just in case this cord is ment to be directional). This also made the lead slightly "longer" so it also hangs less exposed.Making me think this is how its supposed to be mounted.

This made a slight improvement and the car is now idling properly again when hot and no engine stalles when returning to idle from revving.
The rough running is there but less noticable now.
I cross my fingers that this lead is struggling to deliver enough voltage to get consistant sparks.

Because if the lead does have 1000 times more resitance than it should, according to my calculation the voltage reaching the cap Would be redicilously low. To low to even for the electrons to make the jump on the sparkplug to create a spark.

Maybe it takes higher voltage to make sparks in brand new plugs, and thats why It got worse after my plug change.


The original leads are very fragile and the harness it stupid.
I will go for 8 mm or 8,5 mm leads next time.

If the new cord fixes the issue im gonna have it tatooed on my right shoulder.

It was not the cord

Could it be a vacum problem? When Idling it makes -0,5 bar. Previous owner thinks he remembers it beeing as low as -0,67
Does anyone know if this could cause rough running?

I also noticed both my vacuum gauges is showing way to low pressure when compared with the pressure measured by my power fc.
On my gaugepod there is a thin plastic hose, is the dash turbogauge also connected by hose or is it a electric gauge with signal from the map sensor? Does anyone know where this hose is connected? The dash gauge has been off a little since I bought the car, but now it barely registers.
And the gaugepod that have been correct earlier is now showing 0,4 to low.
If its leaking somewhere on the line to the gauges, would this affect how the engine runs?

You need to make sure your boost gauge hose is connected to one of the take-offs on the plenum NOT via a T-piece in the hose to the MAP sensor mounted on the firewall. Any leaks or modifications to the hose to the MAP sensor can cause all sorts of problems with idle, slow running etc. Don't rely on the OEM boost gauge on the dash, it's pretty useless and is only a very rough relative guide to turbo boost pressure. I ran a good quality Greddy electric boost gauge where the pressure sensor/transducer was plumbed in to one of the plenum take-offs. A decent quality direct reading analogue boost gauge plumbed into the plenum should also give you a reliable reading. One thing we have found over many years is that the aftermarket silicon hose used for vacuum lines is nowhere near as good quality or as reliable as the OEM vacuum hose. It tends to split quite easily and sometimes this can be hard to spot.

_________________
Don
GT4DC Chairman
1994 Toyota Celica GT-Four ST205WRC JDM 269bhp @ 0.9bar
1994 Toyota Celica GT-Four Special GT 590bhp @ 1.8bar
1989 Van Diemen RF88/89 Formula Ford 1600
2008 Nissan Patrol GU 3.0L ZD30DDTi 154bhp