Injector minimum mS time setting?

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Injector minimum mS time setting?

Postby LaNcEGT4 » Tue Mar 07, 2017 1:42 pm

A bit of background

Haltech Elite 2500
1550cc xspurt injectors@43.5psi base
98 pump
Air intake sensor mounted in manifold

I've spent a lot of time to sort through my idle stability issues, and I believe I have it down to the fact that I can't idle these injectors much below 1.5ms. Similar injectors on the market and the feedback I've seen is these injectors still have good spray properties around the 1.5-1.6mS mark.
In the target map, I've had to richen up the idle zones to around 13.5:1 to account for a very hot ambient idle (60+ intake temps)

But, in cold ambient idle (20-30 intake temps) i can get the engine to idle clean at 14.7:1

I can comfortably cruise the car at 14.7-15.7 ratios with no surging/missing regardless of conditions.

I don't want to reduce my base pressure, as need the overhead for when I do switch to E85.

The lambda Air Temp adjustment seems like the wrong place, as it would affect the entire map. As well as affect the target once I switch to E85.
O2 Control is still working hard, but still want the ability to at least hit target (say 14.7:1)when it can, but not go below a certain mS when air temps start rising and pulling fuel out.

There isn't anything obvious under the fuel tables either. And then when you consider that whatever changes i do here, may affect the flex capability down the track.

EDIT: add, yes, i've got injector size and dead times bang on, as can change them in the target and they are reflected in the Wideband output within .1 afr
EDIT2: add, yes have fiddled with the whole range of injector firing angle, everything from 270->450*+, no real difference

Any thoughts on how I could make this happen?

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Re: Injector minimum mS time setting?

Postby HaltechMatthew » Mon Mar 27, 2017 4:51 pm

There is no need for a minimum injection time as this would only serve to force it to run richer than it needs. It is not something we do.

This could be anything, but more likely it will be the load on the engine cold versus hot. It just plain may not be happy with those injectors under that condition. Retard timing to allow more time for squish and it can allow you to run leaner.

You mentioned injection time. This will be around 345 to 365 in a very narrow band at idle where it is happiest, depending on the cam and overlap of when the exhaust valve shuts.

The target lambda correction tables are 3D capable.

Posts: 32
Joined: Mon Jan 09, 2017 12:08 pm

Re: Injector minimum mS time setting?

Postby LaNcEGT4 » Mon Mar 27, 2017 7:52 pm

Thanks matt, will try less timing.

Otherwise have compromised and just run it rich at idle :)

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