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DIY Fuel injection thread.


yoeddynz

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Is your Avatar from Interstate 76? :) Yeah I've heard good things about the HP Academy.

 

I've been having a hell of a time trying to tune my engine, just nothing was making sense.

 

So I decided to take a step back and check some physical things like spark plug condition... Found cyl 1 and 2 spark plug holes full of oil, was intermittently running on 3 or 2 cylinders. So a whole afternoon's worth of trying to fix up AFRs was for nothing... But glad to have found the problem and fixed it.

 

Although I was having exactly the same symptoms when trying to tune my twin injector thingy, so it turns out that might be good afterall!
 

I'll reinstall it and give it a round 2 hoon some time after nats.

I also wired in an accellerometer, my laptop battery died before I could have a good play but this is AWESOMELY sensitive.

I can see it being very useful for tuning and also measuring cornering etc at trackdays.

 

So you'd start a run on a flat piece of road, datalog it. Loop back around, advance ignition a few degrees and datalog same again at same place.

 

then overlay the two runs and compare which gave the highest accelleration rate at each rpm. Then combine the two to suit the best values.

Then iteratively fine tune it from there to find the point of minimum timing that gives best accelleration.

Only really works for WOT though I guess, unless you put a stopper on the throttle body to limit it's travel to 50% or something to tune some midrange bits.

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I datalogged a trip home from Hampton today - datalogging 10 ballzillion variables at 40hz makes for a big file! About 250mb for an hour's drive.

 

However I've been looking into coming up with a fairly robust way to analyze log files for things which need complex calculations like fuel consumption.

I think all of my maths works but I'll have to datalog a few more runs and see if it stands up to scrutiny.

The Litres per 100km values are about on par with what I was seeing with the factory ECU on long trips, so that's a good start I guess.

The following was running closed loop with 14.7 goal AFR, so it will be interesting to lean out the goal AFR and see if it actually improves the litres per 100km figure.

5sbuk5er.z2e.jpg









 

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Is your Avatar from Interstate 76? :) Yeah I've heard good things about the HP Academy.

 

It's a high pitched sound
Hot rubber eternally pressing against a blackened pavement
A wheel is forever
A car is infinity times four
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Yip understand the theory Cheers, his table is showing -8% at 60 degrees which seemed a bit too much to me.

Its probably ok only way to really check it is to hook up a wide band and get intake temps to 60deg and have a look. It could have been tuned at 30degrees or so.

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Cool thats the answer then add some fuel in at that temp to solve problem. Also check water temp as thatll add fuel if motor gets hot etc so its a fine ballence at different ratios or air and water temp. If it idles at 14.7 check it at 60deg then dial up untill you reach 14.7 again then intopolate to where its at 0

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Wait, iat should only ever get that high if you are thrashing the shit out of it for ages and its heatsoaked everything.

Under normal driving if it's that high move air filter

Try making 28psi boost for extended periods without making serious heat.

Car is a borg warner equipped 2j making a touch over 540 wheel kw. Im not sure air filter location is likely to do much.

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Since it's a car with big HP and so obviously grunty fuel pumps etc. Does it have any fuel cooling?

If the fuel rail is getting ballzillions of heat into it, and it was tuned on cold fuel it might make it run a little leaner only when the motor gets super hot perhaps?

http://www.linkecu.com/support/glossary/fuel-temp-def

Fuel temps are being monitored and logged in the return line and after a track beating only shift about 5 degrees hence my like for the post above.

EDIT : fuel temp is just an offspin of the eflex sensor not a dedicated input.

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