Well aftter a long nigth last night trying to tune the datto we are still trying to find the problem
It runs fine new turbo making 8psi at only 3000rpm revs sweetly to 8000rpm BUT!!! as soon as load on the dyno it missfires at about 8psi all signals to computer are fine plugs and gaps are fine we changed a few. We tested the spark even with 30mm gap we had a bright white fat spark!!
WARNING never touch the positive of coil while car is running (very painfull shock)
so what I have to try and do now is source the problem I have 4 new bocshe coils that have run fine with 20psi. the MSD Dis 4 is reasonable new im going to try and borrow another and plug it in to see if that the problem if so Ill replace it for the R500 autronic model.
Does anybody have any other ideas as to what may be going on??
Cheers Andrew

You say that its fine just running from 3000rpm to 8000rpm at 8 psi but as soon as it the dyno puts load on the new donk missfires. You also say that you got bright fat spark even over a large gap (and the positive hurts when touched I ALSO KNOW YOUR PAIN - OUCH EEY MUMMA). Hows your fuel delivery system? its not missfiring due to running lean when loaded up or is the computer overcompensating when loaded and putting in too much fuel. If you can hook up a inline fuel pressure gauge near the fuel reg you could see if pressure drops/rises when loaded up. Can also watch the exhaust for excessive black smoke. But in saying that the dyno should be able to pick this up. It is quite possible for the coils to lack punch with crap loads of fuel/air in the chamber so your 4 bosch coil idea will eliminate that possible course. Let us know how you go.

Bugger on all counts..

I'm starting to consider going to SR20

Did you change anything electrical from last time?

You really need to see if the pulses from the mdis to the coils are keeping nice and consistant throughout the revrange. Using a CRO is the way to do that. Using the dwell reading on an auto multimeter would also work. Doing a simple swap of the mdis unit is a good idea, especially if it's a plugout/plugin setup.

Would be good to check the dwell on the coils to check that each of them are getting the same love.

After installing the Autronic CDI, I haven't had a moment of ignition problems..except for the Bosch plug I fried after only 1 hour of driving. I've never worried about gaps, and it ran fine at 18psi boost.

Hmm. For my spark plug incident, maybe that wasn't a plug....maybe that was the Autronic injector driver failing, even back then. It was on the same cylinder..Hmm

I hope it all goes well. I would suspect an MDIS problem. Be sure that you have a good earth for the coils, and a good earth for the MDIS unit.

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I'll give ya $50 for that crusty old CA and running gear to help the project along if you like

Bundy fuel pressure and AF ratio was perfect I have a Fuel pressure guage mounted and it rises as boost does its working as its supposed to be.
Chris how much was the R500?? Ive been told close to $1k I havnt made any electrical chages except for new injectors.
I see that craigs 1200 is mighty close to be ing finished too. I really do hope i get this sorted before too long.
Cheers Andrew

Good news on the fuel side of things - 1 less thing to eliminate.

Silly question but are the injectors the right 'impedience'(I think thats how you spell it) for the CA. I heard there was 2 types.

Check the earth wires and solder all the connections... the factory crimping is useless... also clean all the contacts with sandpaper....

if they are detoriated u will be suprised on what a difference it can make...

Tappet The wiring should be fine although I will be double checking it again its all been soldered and shinkwraped. All the engine bay was rewired by myslef in the rebuild.

Hey Andrew, you are one post away from becoming a dattomaster!!

You didn't tell me that you rewired the engine bay since the engine rebuild.

I guess it could be wiring.

Nah mate not the engine rebuild the car rebuild a few years back now

YAY for me 1000 posts its taken how long?? LOL
just imagine how many posts id have if I got involved with all the arguments