yoeddynz

DIY Fuel injection thread.

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10 hours ago, Testament said:

 

I dunno, I think if you counted your time it would be easily cheaper to just buy the ecu with more I/O to start with. It's one of those things where when you have don't it and your more or less repeating a setup you have done before you might say yeah I can make a saving this way plug it together and know it will work easily. but when you haven't done it before and you have to spend several full days (when you add up your research time etc.) not a chance. I mean if you want to learn canbus stuff then that's the learning budget so maybe fine. but people sure love to say oh you can do it this way and save so much and 99.99% of the time its a load of bollocks.

 

my experience is that its not tuners not wanting to tune megasquirts, its tuners not wanting to deal with dodgy installs that have all sorts of other problems when you taken them to the dyno. been there done that and seen mates setups have the same issue.

on top of that, just being less familiar with them it will invariably take more time vs using software or doing troubleshooting on something they work with very often.

to be fair the prices have definitely come closer with the link atom and monsoon now, when you factor in shipping GST and customs plus the additional features the links have in some cases you are talking a few hundred dollars. if that means your car gets started and tuned in half the time that's probably worthwhile.

this is really the case, provided you are so inclined and interested in learning this kind of stuff.

because of the diy nature of megasquirt its all about the installation being done well and troubleshooted well on setup/startup. which you have to do and fuck up a few things to learn how to do it right really.

there a are a few naff things about them but none that make them dangerous to your engine any more than other potential failure modes

A+ rant. 


 

6 hours ago, ajg193 said:

Still waiting on the chinese oxy sensor.

 

Meanwhile, BNT reckons they provide a 1yr/30000km warranty on the LSU 4.9 sensors. But they do cost significantly more than from NZefi ($210 for 0.85 m cable sensor vs $160) - NZefi provides no warranty.

 

No idea if BNT would be able to honour the warranty or if Bosch would just tell them to bugger off though.


Probably only for factory fitment?

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Literally every modern car runs at least two widebands, and if they're less than 5 years old they'll most likely be a 4.9.

I replace the cunts all the time.

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I have a link atom 2 and the wiring is doing my head in. Is somebody in auckland able to help me finish it/finish it for me. It is the last thing to do to have my car running. @Roman? @Stu

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On 06/12/2018 at 08:31, Testament said:

 

I dunno, I think if you counted your time it would be easily cheaper to just buy the ecu with more I/O to start with. It's one of those things where when you have don't it and your more or less repeating a setup you have done before you might say yeah I can make a saving this way plug it together and know it will work easily. but when you haven't done it before and you have to spend several full days (when you add up your research time etc.) not a chance. I mean if you want to learn canbus stuff then that's the learning budget so maybe fine. but people sure love to say oh you can do it this way and save so much and 99.99% of the time its a load of bollocks.


Great point Tom! Fair call.

However also, even if you dont DIY your canbus stuff (which is becoming increasingly easy) canbus based stuff in general is just becoming a lot more common and commercially available too. 

There are heaps of options for can based wideband now for example, race dashes are canbus based, I've seen some EGT setups being canbus too. In every instance you get a better quality of information than analog. Even if you can only offload 1 or 2 things to canbus, on the likes of an Atom that's freeing up a big chunk of your IO.

But, similarly, on principle I'd also be inclined to go for a surplus of IO rather than just scraping in or being short.

Log all the things! haha.

Hows the Fiat tune going? Running good? 

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23 hours ago, bigfoot said:

I have a link atom 2 and the wiring is doing my head in. Is somebody in auckland able to help me finish it/finish it for me. It is the last thing to do to have my car running. @Roman? @Stu

Also can you give us a bit of an idea of where it's at currently, and what needs doing? 
Does it need an entire loom made? just a few things finished? 

This could be several days work.

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All the engine side is done, just trying to get my head around the relays/power supply

I had it running 6 months ago, then had a small engine bay fire so pretty much started it again from scratch

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32 minutes ago, bigfoot said:

All the engine side is done, just trying to get my head around the relays/power supply

I had it running 6 months ago, then had a small engine bay fire so pretty much started it again from scratch

man some of thoes fire extinguishers cause some major damage to electrical wires. Worse than the actual fire in some cases. 

dry powder me thinks 

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22 minutes ago, scooters said:

man some of thoes fire extinguishers cause some major damage to electrical wires. Worse than the actual fire in some cases. 

dry powder me thinks 

It was dry powder. It was definately the fire that killed the wiring though

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11 hours ago, Roman said:

Hows the Fiat tune going? Running good? 

Terrible lol

I need to spend a day with a clear head just tuning it to minimise some of the strange misses and stumbles at small throttle movements as best as I can, but haven't had the luxury with whats been going on at work lately so barely managed to jam it back together to drive up on Saturday.

but pretty sure a bunch of it is down to the log inlet manifold causing uneven airflows between the cylinders, resulting in significantly different air fuel ratios. So actually have bought a monsoon to put on it so I can get full sequential with cylinder trimming, and umming and ahhhing about wire transferring money to Poland to get an ecumaster can-egt box haha.

the other thing I was discussing with rookiedave was going from speed density to dual table alpha-n and speed density boost compensation/reference, which should give more resolution with throttle movement, as with the supercharger running speed density/map only it goes from vacuum to boost so quickly you end up in the same cells all the time even with different throttle openings and driving conditions.

only thing is not sure how to tune that with the supercharger, as you need to tune the alpha-n with no boost first. not so simple as taking the wastegate springs out. maybe I can take the belt off the supercharger and cable tie the bypass valve open or something.

at least the bypass valve works though, inlet temps cruising on the open road have gone from 80+ to around 50 now

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Sounds like full sequential will make a big difference! 
Will be interesting to see EGTs if you go down that path. But yeah might not even be necessary once you can fire injectors evenly.
Keep us posted sounds cool.

What other factors affect how much boost the engine sees?
Is your bypass valve triggered by the ECU?
If your ECU knows if its open or closed perhaps you could use that as the basis for a compensation table.

Also if monsoon has a lot faster processing speed (dunno?) maybe some of your weird transient stuff will go away anyway.

 

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Just thinking about the setup some more 

So you have an air inlet on the supercharger. Supercharger moves a volume of air thats fixed with RPM. 

But then after that a bypass valve lets some of the volume of air back out, essentially in reaction to throttle position.

To deal with varying throttle positions the pre throttle pressure rises until spring pressure of the bypass valve lets air out (?)

Sooooo you have different high pressure situations pre and post throttle body and they both affect VE of the engine.

Efficiency of the throttle is affected by variables of both pre and post throttle changing a lot so maybe not a stable variable for a load axis

What could be interesting would be to hook up a second map sensor between the throttle body and the supercharger.

Because that effectively represents both your throttle position and how well the bypass valve is working. It's really a combination of these two things that affect your map readings in the plenum not just throttle angle itself. Because a mechanical bypass valve will have some latency that isnt represented by throttle angle alone, but pre throttle pressure will change when this happens.

Otherwise if you fit a type of bypass valve that you can control with PWM then you can play with the curve to a really nice linear throttle response and also use that pwm% as the load axis on a compensation table.

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bypass valve is a factory thing off a late model supercharged mini. It has a vacuum operated actuator, so purely mechanical. it runs off the vacuum in the supercharger inlet  elbow and closes when that drops as the throttle opens. the bypass loop is entirely downstream of the throttle plate so don't think bleeding off boost is the right way to explain it but whatever.

my feeling is the full sequential will help a bunch, and getting the  air fuels evened out will be mostly a fixed offset that maybe tapers off with boost and gets worse a little with speed. but yeah latency in the bypass valve response and whatnot, I dunno. I think some factory supercharged setups have multiport solenoid valves to supposedly make better driveability but I have also heard its a thing to just rip those off supercharged mr2s and stuff like that too and not even worry about it

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Oh yeah true first things first.

I forget there's so many ways you can plumb up a supercharger, like throttle ahead, before, etc.

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nah you are right, logging map ahead of the supercharger could be quite useful too.

the throttle body is on the large size which amy not be helping either, 65mm off an EL falcon or similar which works out for the power level but maybe with the lighter car could do with a more progressive bellcrank, as at low engine speed 1/4 throttle is basically 100%. once throttle opening area is gets close to the 35mm bypass valve area its going to lose vacuum, shut and go straight to more or less full boost.

do you know what clock speed the link ecus run? it's weird their website doesn't seem to list it

the microsquirt runs at 24mhz

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