Injector dead time and pulsewidth

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Alex DTA
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Joined: Fri Feb 28, 2014 1:03 pm
ECU Model: S40 Pro
Distributor: DTA
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Re: Injector dead time and pulsewidth

Post by Alex DTA »

You can always fudge the MAP compensations in this case. As you know the only time you're getting there is in very rare cases, just reduce the MAP corrections.
You may need to turn on Overrun Cut Off, otherwise you may end up with unburnt fuel in the exhaust on overrun. Flames look cool, but aren't great for the surrounding bits.
craig903
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Joined: Mon Apr 03, 2017 12:45 pm
ECU Model: S80 Pro
Distributor: ebay
Firmware Version: 73.01

Re: Injector dead time and pulsewidth

Post by craig903 »

So it seems I’m making some progress. There’s conflicting information on the dead times but most sources are saying 0.409 at 14volts. I can’t run the dead time test with two stoke mode as the pulse becomes well too small and the engine dies instantly. I’ve now set the dead times to 0.409 and corrected the fuel tables and idle is a now stable too within 20 rpm. When switching between 0.71 o 0.40 dead time my pulse has gone from 2.55 to around 3.7 huge jump in the fuel table but it calculates correct. Still have the lambda shoot up when the RPMs dropping back to idle but for now I have a heat soak issue, air temp sensor is reading 40-50 c when idling for 5 minutes after a drive and fueling is being reduced from the compensations. I happened to noticed that earlier the temp compensations where reducing 7% fuel and then the lambda correction was adding a 7% compensation. Hmmmmm. I’m going to move the Air temp sensor tomorrow to the opposite side as it’s currently is close to the radiator. Never thought of that when I fit it lol
katana
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ECU Model: S60 Pro
Firmware Version: 29

Re: Injector dead time and pulsewidth

Post by katana »

Surely AT sensor should be located where air intake into airbox / plenum is - whether it is pulling rad heated air or cooler air via ducting - its the temp of air that the engine gets that's important. Can't figure the AT fueling reduction together with Lambda increase - seems to be a no-win fight!
craig903
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ECU Model: S80 Pro
Distributor: ebay
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Re: Injector dead time and pulsewidth

Post by craig903 »

Well its a turbo car so it needs to be after the intercooler. Its currently placed between the throttle body and the intercooler but on the front side of the pipe in front of the rad. I think the rad is heating the pipe and sensor up. I will spin it 180 degree so its hidden behind the pipe. Its a silicone pipe.


I've had a look over my log that I had done and it confirms that when coming down from around 2,200rpm my map sensors reading 23kpa(lowest my sensor is configured for
) and fuel pulse is around 1.15 and lean lambda's. The rpm drops below target for idle and then the pressure raises to mid 30 kpa and pulse raises to 1.5/1.6 and steadies for idle. When the map is around 33kpa the pulse is at around 1.6 Now my throttle body is permanently closed on idle and it uses a bosch pwm valve to control idle air. If I was to open the throttle body a bit and then adjust the idle pwm's Would this create less off a vacuum in the manifold when coming down to idle. I haven't adjusted the bosch valve at all so when the idle controller is off its around 15% open.
Rob Stevens
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Joined: Thu Jul 28, 2011 4:10 am
ECU Model: S100 Pro
Distributor: None-Coil On Plug :)

Re: Injector dead time and pulsewidth

Post by Rob Stevens »

As Alex suggest just try flattening the <35kpa fuel corrections?
stevieturbo
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Location: Norn Iron

Re: Injector dead time and pulsewidth

Post by stevieturbo »

Close the idle valve, or at least a very low duty, maybe 10-20%

As said before, use the throttle blade to give yourself a good hot idle at a sensible rpm.

Then idle control will only ever really be used to increase rpm when cold. never to reduce rpm, which will far lessen any tendency to want to stall because idle control is trying to reduce rpm.

OEM's may often use a closed throttle.....aftermarkets...just never seem to manage.
craig903
Posts: 18
Joined: Mon Apr 03, 2017 12:45 pm
ECU Model: S80 Pro
Distributor: ebay
Firmware Version: 73.01

Re: Injector dead time and pulsewidth

Post by craig903 »

Okay, I have a few things too try tomorrow. Shall keep me busy for a little bit. Thanks
craig903
Posts: 18
Joined: Mon Apr 03, 2017 12:45 pm
ECU Model: S80 Pro
Distributor: ebay
Firmware Version: 73.01

Re: Injector dead time and pulsewidth

Post by craig903 »

So, Today I have relocated the air temp sensor.

Its now taking longer to heat soak but it does. again I have witnessed the compensations as air temp raises its pulling fuel and the lamda controller is putting straight back in. In the end I zero'd the air temp corrections at10/ 20/30 degree's and when I went on a run and got the temps down I pull over and fuel is spot on +-0.5% as soon as the temps creap back up it pulls fuel and the lambda increases full lol.

I have also changed the map compensations low down as suggested by alex. So now at 10kpa/75% 20kpa/75% 30kpa/70% 40kpa/60% etc etc and the lean lambdas on run down have vanished.

So we have had success but that damn heat soak. all I can think off is keeping the fueling zero'd at 20,30,40 range so no compensations there.
Rob Stevens
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ECU Model: S100 Pro
Distributor: None-Coil On Plug :)

Re: Injector dead time and pulsewidth

Post by Rob Stevens »

Do you have one of the solid type at sensors or one with a little blob in a cage. I imagine the latter would be best. Can you put it some where else perhaps if the rad is heating it up?
SMR
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Joined: Tue Jan 16, 2018 9:38 am
ECU Model: S100 Pro
Distributor: DTA
Location: Aberdeen

Re: Injector dead time and pulsewidth

Post by SMR »

As Rob said - I'd see if you can get one of the plastic "blob" type air temp semsors as the solid brass ones do get serious heat soak.
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