Idle quality vs fuel pressure

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BennVenn
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Idle quality vs fuel pressure

Post by BennVenn »

I've just dropped a set of remanufactured VT (0280 155 777) injectors into my N13 pulsar for a little extra fuel for the turbo and potentially better economy with the better spray pattern.

The pulsar runs a 2.5bar reg, the VT runs at 3bar.

I was expecting to have to adjust the tune but I guess at 2.5bar they flow exactly the same as the stock injectors.

Cold start AFR's were spot on though when it came up to temp the engine really didn't want to idle at 13.8 where it was happy idling previously. Anything over 13.0 would cause it to hunt and miss.

BPW at idle before and after the swap was 1.88mS and the same reported AFR but it does not run well at 13.8.

I pulled the plugs after 20min idling at 12.8 expecting fouled plugs but they were still bright white (new plugs).

I'll pull the wideband and recalibrate this morning just incase it's a little off but it was fine the day before (A couple hours of VE learn tuning).

So, what is going on?!!? Could the low fuel pressure be causing a stream instead of a spray giving an incomplete burn requiring more fuel? I've got an adjustable reg I can install to bump it up to 3bar to see if that helps. Has anyone ever seen something like this?
BennVenn
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Re: Idle quality vs fuel pressure

Post by BennVenn »

Pulled the wideband, recalibrated in free air, back in, same readings.

I pulled the vacuum reference off the regulator, this would boost the idle pressure approx .5bar, matching what the VT would run at idle. After adjusting Kinjflow, no change to idle quality at 13.8

Set the Single Fire flag - The idle cleared up at 13.7. Any leaner and a slight miss can be felt.

I guess its just a compromise with accuracy at a smaller BPW on a larger injector? I'll take it for a spin into town today and see if l/100km improves at all.
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Re: Idle quality vs fuel pressure

Post by vlad01 »

Have you entered all the injector calibration data for the 777s?
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
BennVenn
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Re: Idle quality vs fuel pressure

Post by BennVenn »

Yeah, pulled from 12P APNX V6 bin. That should get me in the ballpark?
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Re: Idle quality vs fuel pressure

Post by vlad01 »

Nah the 777s are way different. You need to pull the offset and adder tables from a VT tune.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
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Re: Idle quality vs fuel pressure

Post by BennVenn »

Ahh thanks, I'll pop those in and see how we go. Will a stock VT (CJKU) bin be OK or should I get them from a 12P VT tune? edit: 12p is not suitable for vt?
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Re: Idle quality vs fuel pressure

Post by BennVenn »

Is there a tool or spreadsheet that'll approximate the values for 12p? Vastly different scalars in 12p vs VT tune
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Re: Idle quality vs fuel pressure

Post by vlad01 »

Just copy the rows that have same or similar voltage and for the adders the ms rows that are close or the same. IIRC, VS onward had the same tables just rounded slightly different and more rows (larger tables)
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
BennVenn
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Re: Idle quality vs fuel pressure

Post by BennVenn »

New values in, Kinjflow adjusted, still a not so great idle. A close look at the injectors and there's no bosch logo on them. I suspect chinese rubbish... I'll put my old ones back in and send these back to where they came from.

Should 4cyl Memcal be set under Message Lists? 4cyl is set and it's a pulsar 1.8L memcal but it looks like the ecu isn't detecting it?
memcal.JPG
memcal.JPG (21.89 KiB) Viewed 4325 times
note, this isn't from my tune, just an example
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vlad01
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Re: Idle quality vs fuel pressure

Post by vlad01 »

yeah those China copies are horrible, straight in the bin they should go.

Not sure about the cylinder select. Never had to play with that as I am always working on 6 cylinders and it's always been the default on my NVRAMs and 12P tunes.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
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