My old 300hp 4g93 needs some lovin!

Yes. I have downloaded the manual, and bought a wideband sensor, and I have been studying it all. At the moment, there seems to be an issue with the TPS and it had a split hose at the BOV, so Im assuming all this has increased the imminent demise of the engine. My only concern is knowing where the cam should be set, as that is what triggers the timing. It also doesnt idle, I think the stepper motor is kaput. The software for the 8860 is quite old, so I might try to find some tutorials and go from there.
Any help would be greatly appreciated.

Thanks. Ben.
 
the tps doesn't do much on the microtech, only idle and transient ie pump injection. the boost leak will generally result in higher exhaust pressures which can push the motor into detonation.

the ecu uses the crank sensor for ignition timing not the cam sensor, so i would think setting the cam timing to 0 should be a safe bet.
is the idle stepper motor connected to the 8860 or std ecu?

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Ok. That makes sense, the car would still run, but the TPS signal would drop out and in all the time.
The stepper is through the 8860. The only reason I say the cam sensor, is the trigger on the cam has been modified with a hacksaw to make it work with the 8860. So I does something.
 
the cam sensor is usually there just so the ecu knows if it should fire cylinder 1 or 3 but in a wasted spark setup it makes no difference. at least to the microtech not sure about yours. it might get confused seeing two pulses.

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So, a bit of an update for anyone who cares.
I have installed the new pistons. See pics. Woo Hoo.
I am in the process of fixing the head myself, as it has been at a reputable head repair shop in Newcastle for nearly 4 weeks and they put it in the too hard basket and wanted me to do all the research and get the new valve springs and then charge me $1000 to swap a cam and put new springs in! So I turned up this morning and took the heads back.
When I got the heads home, I realised how much time and effort someone has put into the original head and decided to fix it myself. Just like the pistons. So at the end of the day, I have basically had to rebuild the motor myself.


Bore honed, new Cosworth pistons in.
IMG_0367.JPG


Intake manifold gasket on the head I got
IMG_0378.JPG

Same gasket on Std head
IMG_0376.JPG

I was going to swap the cam over to the standard head because of the slight damage (detonation)to No 4 Ex port on ported head, but I figure Ill keep it as there is a lot of hours put into porting and polishing it.
The casting numbers are different too, so Im not sure if they are the same head.
The intake manifold has also been ported to suit, so someone has spent some serious time on this motor.
 
You will need to get the head welded then machined to remove the porosity in the alloy. The valve seats will need to be removed. it might be cheaper to use another head and port depending on the quality and extent of the porting.
 
I'd just clean it up with a die-grinder. Looks like the gasket surface might have been spared so you might get away with it. but I'm a bit of a hack.


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Thanks for the feedback guys.
Yeah, I just cleaned it up with the die grinder. Im lucky to have access to an endescope with a motorised head that can look back up at the valves through the spark plug hole. If it gets worse, Ill do the other head.
Valve springs just turned up. Woo hoo, might be running on the weekend.
Wish I knew how to take some timing out of the tune, just to run around and bed the rings in.
Cant get it on the dyno for a month or 2, as Justin who tuned it originally is very busy and no one else wants to touch the dirty old EMS 8860.
 
if your not sure about the setup pull the plugs and have a look at them and inside the cylinder with your scope after each run.

Looks like the ems has a ignition trim just pull some timing out or just stay off boost. ;)

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can't really read it properly but is the timing map hitting 35 degrees at some points?
What load point is that?

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couple of points,
1. i am not a professional tuner! but I've seen pros do damage like this before(not to my car) hence why i just diy and can only blame myself. lol
2. don't belive the Internet!
3. timing needs to be done on a dyno and/or with an in cylinder pressure sensor(pretty much no one has) and good knock sensing.
4. the overall trend across the revs seems peculiarly flat.
is it on boost at 3krpm?


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1. I understand and appreciate the help. I also want to diy.
2. You got that right!
3. I agree, thats why Im happy just to detune the car for now, collect data and knowlege of tuning with the EMS, and maybe get some dyno time with another tuner I know.
4. Not sure how much boost at 3000, if any, full boost at 4500.
 
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