Unstart on first key turn + pull timing on hot days

[BARMYMX5]

Is there any way the Interceptor on my modified MX5 with factory turbo can be made to:

1. Stop the car starting on the first turn of the key so the new race bottom end gets lubed before starting?

2. Pull timing on hot days or when detonation is detected so I won't need to rebuild the bottom end again?

3. Cope with the 1000cc injectors I'm being recommended to get so there's less risk of running lean - also to avoid having to rebuild the bottom end?

[Donn29]

1. I'd assume you could just unplug the coils, or Injectors, or the ecu itsellf while cranking. Sparkplugs out will make it easier on the battery and starter motor.

2. That is was ATS and CTS corrections are for.

3. 1000cc seems like a lot, what fuel and boost?

[BARMYMX5]

1. Was hoping for a better way as it'll also be a road car.

2. So an Interceptor can recognise detonation?

3. 98 for starters, E85 later. 14psi. The existing 440s may have contributed to the blow up by leaning out the AFR too much - along with the high ambient temp, not enough cooling, maybe a lazy injector, etc etc.

[Donn29]

1. You could probably set up dual tables, and have one table set to 0 fuel pulsewidth.

2. Don't think so, but when the air intake temp rises you can add fuel and pull timing. Same with coolant.

3. There should be a value you can datalog that will show you the duty cycle the injectors are being run at. Keep it under 80% is safe.

[Donn29]

Oh, and I know with the Plat Sport, the harness has relays for the injectors, power to the ecu, etc. You could put a switch inline with on of the relays to disable the engine from stating.

[BARMYMX5]

Oh, and I know with the Plat Sport, the harness has relays for the injectors, power to the ecu, etc. You could put a switch inline with on of the relays to disable the engine from stating.

It's just an Interceptor, from about 2007.

[Donn29]

It should still have relays to power it, just put a switchh inline with one of the trigger wires of one of the relays. Or you could even put a switch on the relay for the fuelpump.

[HaltechMatthew]

The Interceptor is not designed for large scale modifications.

1) The Interceptor will not do this, it only intercepts the factory load signals and crank sensor. I would put a momentary switch on the dash that cuts power to the injectors that you hold down while cranking.

2) It can adjust timing based on temperature inputs, but definitely does not do knock control. The factory ECU should be doing this.

3) No. Your factory ECU is running the injectors, and will not handle being tricked from having ~260cc injectors up to having 1000cc injectors. It means you need to fool the factory ECU into believing you have 1/4 of the engine load it really has. That means it will try to give timing values that reflect this. It has disaster written all over it!

My advice, put a Sport 1000 on it with a patch loom to suit. It will plug right in and give you full control to run whatever you want.

[BARMYMX5]

Thanks for the responses. They explain why people with factory turbo MX5s with mods or with ones with turbos added later tend to go a different direction.

The Interceptor was great for when the car was used on the road and for my first couple of seasons of sprints, but now I'm using more throttle more of the time it seems I'll need to go Megasquirt like nearly everyone else, if only because there's so much support for MS in the MX5 community.

[BARMYMX5]

The Interceptor is not designed for large scale modifications.

1) The Interceptor will not do this, it only intercepts the factory load signals and crank sensor. I would put a momentary switch on the dash that cuts power to the injectors that you hold down while cranking.

2) It can adjust timing based on temperature inputs, but definitely does not do knock control. The factory ECU should be doing this.

3) No. Your factory ECU is running the injectors, and will not handle being tricked from having ~260cc injectors up to having 1000cc injectors. It means you need to fool the factory ECU into believing you have 1/4 of the engine load it really has. That means it will try to give timing values that reflect this. It has disaster written all over it!

By disaster, do you mean the injectors being unable to provide enough fuel at 14psi and the tune having too much timing for a 40 degree day plus maybe a dodgy batch of fuel, all combining to cause detonation being reported by spectators and a (stock) rod deciding to redesign the block and sump? Unfortunately it seems the stock ECU wasn't doing anything about knock control.

[Donn29]

He meant the ecu will run too much timing advance, causing detonation. You need the right amount of fuel injected to run an engine, but how much ignition advance at any given time is just as imporntant. Sorry to the OP and Matt about the miss information! The PS1000 sounds like a great idea for full control!

[BARMYMX5]

Maybe a week from the motor being back in the car. Now going to run max 10psi, way more cooling, hi-flowed IHI turbo, bigger than the present 440cc injectors, 98 octane and planning to find a Haltech expert who'll tune it for no detonation even with loads of heat sink and while running rubbish 91 octane.

Will the Interceptor be ok for this?

How big injectors will the Interceptor handle?

Haltech tuner around SE Melbourne or Mornington Peninsula?

[BARMYMX5]

Found a local supplier - George Voutsas at Pro Flow Fab & Dyno in Seaford. He's going to remove the existing Haltech Interceptor and install the PS1000 along with flex fuel sensor, bigger fuel lines, 1000cc injectors etc. I've sold the existing setup to someone who'll only use his SE on the road and George will get the work installing that too.

Because of delays with other work on the car this won't get done until after the Winton 6 hour (regularity) so that'll be done very gently with maybe 6psi on the existing kit to run the motor in.

Thanks for the advice from various people.