DIY Fuel injection thread.

[downtrail]

Youll probably find it does that to get some heat into the cat when its cold to prolong its life etc.

[Lith]

Only got a moment so this might not be nicely worded, sorry... hopefully this is on track and gives something to ponder on in regards to warm up tuning (inc. target rpm).

 

Wall wetting in general is substantially worse with a fully cold motor, I tend to think of it that the whole warm up process is generally less efficient as the fuel is pretty content to condense with far less provocation and the air/fuel mixture won't mix as evenly etc etc.  Everything is far from ideal.  

I guess unless you want to get into it further, the way I tend to think of it to not get into a mindf*ck is that you have to generate a minimum amount of torque required to maintain a given stable idle speed.  As your engine warms up it's BSFC (ie, ability to make a given amount of power from a given amount of fuel) is greatly reduced and typically this means you often also need more air to make a given power level.  What you'll find with a colder motor is you'll need more input from your IACV (/ more airflow) to hold a stable 1000rpm - but you can technically still hold those rpm, which if you have an already nicely set up closed loop IACV setup may hide from you a bit the fact that you're actually using more air to make the same torque.

 

The trick here is that you can probably make most warmed up engines idle smoothly and happily at 800rpm, but what if when they are operating at this reduced state of efficiency they don't actually have enough efficiency to generate the torque to maintain a nice happy idle at 800rpm?   Like maybe it CAN idle at 800rpm but realistically you get to the point where you either add no more air and have an engine which is putting it's back into it to just manage 800rpm, or it will suddenly start revving higher.  

 

I tend to choose ALL of my idle conditions (including warm up) such that at all points the engine has a reasonable amount of "spare torque" (ie, will rev up cleanly from) those points at MBT and then have the timing control set up to having it idling at 90% of that, for sake of argument.  What that means is the engine is moving more air than it actually needs to idle and warms up quicker (where relevant) but also if the throttle is leaned on then I can reintroduce the full timing for MBT and create the torque the engine CAN make there - results in a far more authoritative idle and also a very response/smooth to drive car.  

 

If you have it at max torque just to maintain an idle you can get a bit of a hesitant or generally not very nice car to drive.  More rpm naturally get all the lubing stuff etc moving quicker too, I tend to think of a higher idle at warm up full of positives    I am guessing the OEM are using similar logic, though 2000rpm seems excessive.

 

Hope that makes sense, sorry it was a bit rushed so feel free to correct me if I've said something dumb or unclear or even not answered the right question!

[mjrstar]

I like to use more air and less timing to get a sweet torquey idle, but idle control thingees are too flash for my cars.

/ling out.

[eke_zetec_RWD]

My v6 navara nearly hits rev limiter when you start it lol. Bloody thing not very low key.

E85 cold start-don't get me started on that! Nearly need a petrol injector as well on freezing mornings. It's weird shit, crank crank crank with like 300% cold crank then boom boom starts and runs perfect with no plug fouling.

[Roman]

Youll probably find it does that to get some heat into the cat when its cold to prolong its life etc.

Oh yep good point! Although the strategy for getting the cat working well is to keep the right AFR as soon as possible so it's possibly still a relevant strategy for nice cold start.

 

Although, at this stage it's all delusions of grandeur to have a smoothly improving idle after yesterdays tests haha.

 

I think I've got a vaccum leak, which isnt helping things.

But when using e-throttle for idle control. It's like 4.1% throttle opening does nothing to change idle and then 4.2% throttle and you're doing 4000rpm heh.

 

I think it'll take a bit of mucking around to find the range of throttle angles that actually do something useful for idle, but looks as though it'll be spanning across percentages of a percent. No dramas to hook an ISCV up again if it's not working, but would be nice to keep it simple, should be able to get it working.

 

Thinking about it now, I might have set a higher deadband for FPS/TPS angles as one of the things to get it working when I was having TPS trouble.

Will check this afternoon and look for leaks at the same time.

[Lith]

My v6 navara nearly hits rev limiter when you start it lol. Bloody thing not very low key.

E85 cold start-don't get me started on that! Nearly need a petrol injector as well on freezing mornings. It's weird shit, crank crank crank with like 300% cold crank then boom boom starts and runs perfect with no plug fouling.

 

Have you tried adding pre-crank priming (if you have the option)?  Freezing condition cold starts are always going to be a prick and there will be a point where it's impossible to make it start perfectly, but thought I'd throw that in there as it definitely helped those kinds of starts a lot for me.

[Roman]

Speaking of pre crank priming...

 

After changing nothing but a firmware update on ECU and finishing testing some sensors/wiring. I started the car again and then it was running like complete crap. Sounded like running on 2 or 3 cyls and would stall without foot on the gas.

 

Ran around checking everything on the ECU seeing what's changed, double checked wiring etc.

 

Then I realised that I'd had the key off and on a bunch of times since the last time I started the motor haha.

 

So pre crank prime was tipping a bunch of fuel in that wasnt going anywhere until the first time I started it.

 

Cleared spark plugs and once it cleared out it now runs great.

 

Idle control with the E-throttle is friggen marvelous so far!
I could never cure the stalling issue with the ISCV because I think the hoses were too small.

Now it cranks and fires into life awesomely without the foot on the pedal, and when up to temp holds a nice 850rpm idle awesomely.
Currently aim for 1200rpm when colder than that but I've still got to datalog from the Echo and see how that compares.
But I'm pretty happy that I can give it a big rev and then when it drops back it doesnt stall anymore.

[Roman]

Oh so after some blathering about idle speed, I datalogged the Echo tonight.

 

20 deg is about 2200rpm!

An engine that happily idles at 630rpm when warmed up starts out at nearly 4x that.

 

A graph, because Roman:

 

 

I've set the Carina to same goal RPMs in the Link so tomorrow I'll adjust idle throttle angle targets to match those above and see how it goes.
 

[Lith]

 

I've set the Carina to same goal RPMs in the Link so tomorrow I'll adjust idle throttle angle targets to match those above and see how it goes.

 

Nice work with the start up/idle stuff, can be some of the bigger headf*cks when tuning at times      It's strangely rewarding tuning something that just runs and drives like a normal car, haha.

 

 

 

I have been having a complete nightmare of a time with tuning lately, so far over half of the cars I've tuned in recent months have had fuel delivery issues and I am getting over it.  

 

People, don't skimp on fuel system parts.  Buy "genuine" injectors and ideally make sure they all flow evenly, same goes for good fuel pressure regs, use suitable hoses and whatever else you have involved in fuel transportation, if you can get a fuel pressure sensor and wire it into your ECU for logging/warning lights, and make sure the fuel system you have chosen is suited to the application.   If there is ANYTHING you spend the money on with a build you want to not have problems with, get the fuel system sorted.   

 

<deep breath>

 

Yay after this rant I ended up tuning a mate's Skyline which had a nicely setup fuel system (yay, ID1000s etc) so I was cautiously hopeful that things might go nicer than some of the recent outings I've had have gone. 

 

This tune was EASY, biggest stress was that it's a stock and already pretty well used RB25 and the owner wanted pretty serious solid power considering it's used exclusively for track racing.  Everything went pretty smoothly and settled on 21psi on E85, and I'm pretty impressed with the power delivery:

 

This is with a pretty cheap Masterpower R595 turbo with a .63a/r hotside on knock off intake and exhaust manifolds and the thing was still happily picking up more power with additional boost (17-21psi went from 326kw to 368kw), the gate was opening at ~.9bar at comfortably under 3500rpm and 21psi it was still opening by 4000rpm so very decent performance for the price - well impressed and would seriously consider these things as a viable budget option after this performance.

[Yowzer]

Shit that's some decent grunt. Must be fun

[Lith]

Yeah it's pretty hearty power, though not really anything too unheadrd of - the thing which really impressed me most is a cheap basic turbo like that being able to supply 200kw @ wheels as early as 3700rpm while also being able to make 368kw - with change.   Not street legal so rolled straight off the dyno onto the trailer, and it's next track outing is next month so going to have to be patient

[cute wee gem]

So the new MP turbo are pretty good? Been looking at em for the 2jz

[Rookie]

Masterpowers have been a good cheapish turbo for a while now, long gone are the days of glued compressor housings and catastrophic failures. I guess the reason you dont see them used more is that they are twice the price of China turbos and half the price of Garrett, so dont suit cheap or rich people, which are basically the only two types of car guys hahaha.

[mjrstar]

I have a MP turbo on my starlet, still in one piece, it's an older version pretty basic wheel design but seem ok.

[Lith]

Yeah as far as I know they had always been solid, I think there was a period a few years ago where they got lumped in with the XSPower turbos of the world if not actually had a cheaper knock off copy made of them but I haven't heard of anyone having any issues with the legit Brazilian ones.

Their range used to just be T-series Garrett copies which meant nothing special performance wise but this thing with their own wheel designs seems good so far. It has already been running with it for a couple years or so and I know a few others running them without issue so guessing they must be ok

[Roman]

I've been playing around with Virtual Dyno a bit, it's a struggle finding a 100% flat road but it seems pretty consistent between runs anyway suprisingly.

Cant wait to use it at the drag strip / compare to actual dyno.

 

Says it should be in the region of 170-180hp atw which sounds about right. and tapering off a little towards 8000rpm but still making power which makes it worth holding each gear longer.

 

Which correlates with how the car feels too.

 

 

[Rookie]

Wind that timing into it Roman.

[Roman]

Yeah a few issues with knock sensing at the moment that I want to resolve first.

 

Currently I've got a bolt wound into the old knock sensor hole, that I flattened off and tapped a thread into. Then another bolt holds the 'donut' knock sensor in place.

However I've got my suspicions that this is making it less sensitive to knock / less than ideal as the sensor is maybe 20-30mm away from the block, on an upstand because of bolt height.

 

I've found a part number for the correct tapered stud that threads into the block for holding a knock sensor, so it will hold the sensor directly against the side and give me some peace of mind that it's working correctly.  Waiting for that to turn up before I spend more time on the knock sensing which is what I want to do before advancing timing some more.

 

Off topic but out of interest I setup a catch can that goes

 

Engine breather > catch can > line back into throttle body just before throttle plate

Slipped the line for my second map sensor into the catch can to see what happens, I thought it would pressurize at high rpm/load.

 

But regardless of RPM / load / etc it just stays at 1kpa above atmospheric pressure.

 

I guess that means my piston rings are still doing something, haha. (And the lines aren't too small)

[yoeddynz]

You have a second pressure sensor?!  SLUT.

[Roman]

MUST USE ALL INPUTS / OUTPUTS

 

haha