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PostPosted: Thu Feb 09, 2006 10:36 am 
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Group N
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Joined: Tue Oct 18, 2005 8:07 pm
Posts: 384
Car Model: None
hi :)
i was thinking about the fuel maps in the standard ecu, particularly the behaviour shown by the injectors when the boost is turned up past the mapped level of 12psi.

i have been running my car with the turbo pressure sensor blanked off (so no fuel cut) and at roughly 15psi for around a year, with no problems whatsoever. this includes the rather abrasive haynes track and a visit to the nurburgring, so i am reasonably confident in the safe power level of my car at the minute.

i have plumbed an AFR gauge into the narrowband O2 sensor and it shows full rich when going on boost, and holds full rich right up to the redline. i know all about the fallacies of using a narrowband to monitor the AFR, but at least this is better than nothing ;)

i would also like some way of monitoring injector duty cycle, i know i am pushing the injectors pretty hard (stock 440cc/minute). is there a cheap and dirty way this can be done? even if its as simple as plugging a multimeter into the ecu and reading off bare voltages, then looking up the corresponding flowrates on a table. mind you, i have a feeling i need to look at the number of pulses/sec so an oscilliscope type device would be required

im interested in your thoughts on this. just a geeky little device would be cool, even if its just used once or twice when setting up boost levels when the fmic is welded in.

cheers

andy :)

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Sprint ST165 aka "The 500BHP Sledgehammer" #6 in the Toyota Sprint Series. GT3071 1.9bar


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PostPosted: Thu Feb 09, 2006 2:05 pm 
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Club Staff
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Joined: Wed Jul 13, 2005 5:10 pm
Posts: 1953
Location: Sunny Fareham, UK
Car Model: ST205
Andy - think this pretty difficult to do with a stock ECU.

My thoughts would be that the duty cycle is going to alter boost vs rpm - a direct function of the amount of fuel required.

As the rpm increases the time available for the injector to get enough fuel in decreases.

I suppose measuring the duty cycle would have to take into account the available time to inject, against the length of time the injector is open?

Therefore both the time available to inject needs to be measured against the time the injector is open?

The pulse for the injector can be measured with a scope, (digital storage might be best), but Not too sure about measuring the time available for injection?

Measuring this on an aftermarket ECU is a LOT easier though!

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