I am trying to tune my coupe (ca18det autronc smc and cdi unit) the engine breaks down at 6000 rpm. I have done 3 hill climbs since buying the car in nov (it hammers even if it only goes to 6000). So I booked it in for a tune because of the missfire

the first dyno run (2 weeks ago)sure enough it breaks down at 6k the tuner tells me to put in 4 new coils (to do it my self I'll save money). We need to start somewhere.

Coils done, I dropped the car of this morning. in the arvo I get a phone call, engine is still breaking down and on the last run the oil filter blew and made a massive mess. S%*& did that stress me out. I went to the work shop to help clean up turns out the filter worked its way undone and luckily only lost about 1.5 litres.
so now I have to replace oil filter and oil, and take the car back to the tuner to find problem with breaking down. I have been told now (by the autronic dealer)to check the crank angle sensors.

hopefully the 3rd time lucky all will go well, its putting out 230 hp at 6k and 14psi now, so with 18psi and 7.2k (my aim if all goes well next time) the car should put out some great power and will be a force to recon with on the track.

any ideas why it might be breaking down?


my a14 was so easy, but I had to have more power ( it seams to come at a cost)

Oh I forgot to mention that i am still lucky to have a coupe as the oil ignited on the exhaust an there was a little fire in the engine bay. it could have been a lot worse and luckly no on was injured during the dyno run.

Its not running out of fuel at high rpm? ie. not enough fuel from the pump/s?

Air fuel ratios are fine. I am sure the tuner will sort it but time is money. any ideas might help.

Does anything else change at 6K, like boost pressure??

If nothing else changes I would test what Autronic recommends.

Are the wires from the CAS properly shielded??? You may be getting interference into the RPM signal.

Maybe the rev limiter has been set at 6K ??

nothing changes when it hits 6k, when in lower gears 1st and second it gets up to 7k as soon as it loads up 3rd, 4th and 5th the engine starts to break down.

like you said do as the dealer said it will be one thing at a time.

I feel your pain, diagnosing a problem like this is usually a bit of trial and error. I would have expected your tuner to be giving you more info then they currently are though.

What do the plugs look like after it breaks down. I.e is one cylinder acting up or do all look the same? Igniter failure should result in one plug looking different.

I've seen injectors fail to work under high fuel pressure, although this has been well above 14psi boost pressure (Around 60psi fuel pressure). Are you using a raising rate pressure reg?
Earthing is one of the most common causes of retrofitted EFI system problems. Make sure you have proper earthing. You will be surprised what a few earth leads here and there will do, particularly if you have the battery relocated to the boot/tray.

That's my two cents anyway.

is the autronic a piggyback or full control stand alone?
if its piggyback then the revlimiter or speed limiting will cut it at the higher speed in the higher gears.
probably it is under more load at those revs in the higher gears and some link in the electrical or ignition system breaks down under the heavy load, its then just a process of elimination, plugs, gaps, heavier leads, coils u have already done, all electrical contacts and so on.
but yeh, another dyno run expense on top of the other parts expenses sucks.

All sorted it was the cas. Can't wait to race it now, with an extra 1500rpm and 25hp than when it had the miss. I now have more hp in the 4000 to 5500 range as well so it will be fun.

The turbo is runing 15.5 psi after 4300 with the rev limiter set at 7500.

That is a nice figure Have you done anything to the motor? Ect...?