Jaycar Boost and Fuel Control

[AlexCim]

I dont see any difference in operation between a 10psi spring and a 20psi spring. Infact, the way i see if, if you have a 7psi spring with a 10psi map, and then you replace with a 20psi spring, and used the old +3psi (10-7) map, you would boost 23psi

I dont really know how to explain why i think that, but with a bigger spring, bigger boost, more pressure at the same duty cycle on the spring so it all stays in proportion...

Would i be right to think like that?

With this IEBC, there is no overboosting, boost drop etc, you map that all into the map. Part throttle works like any other boost controller...

[mokompri]

I dont see any difference in operation between a 10psi spring and a 20psi spring. Infact, the way i see if, if you have a 7psi spring with a 10psi map, and then you replace with a 20psi spring, and used the old +3psi (10-7) map, you would boost 23psi

I dont really know how to explain why i think that, but with a bigger spring, bigger boost, more pressure at the same duty cycle on the spring so it all stays in proportion...

Would i be right to think like that?

With this IEBC, there is no overboosting, boost drop etc, you map that all into the map. Part throttle works like any other boost controller...

<{POST_SNAPBACK}>

just had a long think about this and this is what i came up with,

it shouldnt boost 23psi, what happens on the wastegate line is basically an amount of pressure exists which is related to the duty cycle of the solenoid, the boost pressure in the plenum (or input to solenoid) and the size of the restrictor, and from experience of tuning my IEBC, it works out something like this (i didnt use restrictor in formula because it gets overcome at pretty low pressures and becomes part of the solenoids operation/purpose):

boost ~= [7 (wastegate spring) ] / [.5 (duty cycle which .5 = 50%)] = 14psi

so with 20psi actuator boost ~= 20 / .5 = ~40, so it takes 40psi in the plenum to reach 20psi in the wastegate line at 50% duty cycle and thus open the wastegate right ? in practice it will probably be less, because the venting of the restrictor at that sort of boost levels will be overcome too much and wont be able to vent enough to keep the wastegate line regulated to 50% of its input pressure

so from that i'll need to run around ~77% duty cycle for 18psi with 14psi spring

in regards to overboosting and dropping i was referring to what is documented in the book, where by say if your running 0% duty cycle all the way to load point 20, then on 21 give 30% duty cycle, it will cause it to drop boost and load point down, onto 0%, which will make it go up again, then down etc.. sort of cycles itself. then it goes on to say thats why you have to progressively build up duty cycle. my initial thought was is this going to happen with a higher spring rate actuator, because as your progressively building up duty cycle the actuator is still closed because of its higher spring rate, then suddenly pop open and cause a drop in load point - but then i realised it wont make a difference it seems, as long as you load up the actuator progressively.

OK, my head well and truly hurts now, so i'll leave it at that. post up some thoughts and if ive got it all wrong let me know

[AlexCim]

Well,

Try and see. I am sure you could still control boost no issues, just a bigger minimum boost.

With overboosting, the one issue i had was this. I had my map set up like, 0 0 0 0 0 0 50 80 80 etc. I found that like this, when it could hover between the two load points of 0 and 50, the boost could be very "jittery" and the car felt as if it was about to stall or had a flat tyres.

To overcome this, i just leveled it out a lot more, so like 0 0 0 0 0 15 30 50 70 etc

Now i dont get this issue any more. If your EBC does spike, i guess you could just shift the map down a few load points to catch the spike out before it happends.

[chrissso]

I got all my car back together today (well most of it) and tried out the IEBC. It's setup with 0% to load 10 and then 100% up from there, 1mm bleed hole. I immediatley noticed a difference in the spool speed. Realquick! Even when off the boost for 2 sec and then back on - even quicker! I will tune it on the weekend and tell all. I got the wife to check ot the max duty cycle. It was 52 at 6700ish. Seems high for 8psi. I haven't tuned the DFA yet so this may come down. Probably not much though.... What a heap of FUN!

[chrissso]

I tuned, well started tuning the ebc today, what a bastard! Boost was going up and down like a camels back! Me and 2 mates took a while to get our heads around it. Works pretty well though. I'm having trouble getting a flat boost curve. I think I read somewhere in another post that a 1mm vent size might be to small and causes symptoms like this. Anyone share this experience? My map start average is at load 21 and 10psi is achieved at about 35-40% solenoid duty thoughout the higher loads. This seems low in comparison to other maps posted on this thread. . Should I drill a 1.5mm hole?

[AlexCim]

Well, my stagea vent was 1.25mm and it worked well

Then i got a 1.5mm vent and i couldnt boost below ~13psi

Then i soldered up my vent and drilled it to 1mm and it boosts ~7psi

I can get a perfectly stable boost curve, you just have to do heaps of fine tuning. Dont forget that you want to be in the same angle/location all the time because it could be different up hill compared to flat areas.

[chrissso]

Well, my stagea vent was 1.25mm and it worked well

Then i got a 1.5mm vent and i couldnt boost below ~13psi

Then i soldered up my vent and drilled it to 1mm and it boosts ~7psi

I can get a perfectly stable boost curve, you just have to do heaps of fine tuning. Dont forget that you want to be in the same angle/location all the time because it could be different up hill compared to flat areas.

<{POST_SNAPBACK}>

Thanks alex - I am still tuning it slowly. I got it flatish from slow start but then when I booted it in higher revs, it would spike to 15PSI!! I think the map started to high. I brought the map start average down to about 18 - much better. What duty cycles are you using with a 1mm vent? Mine go:-

13-8

14-12

15-16

16-20

17-24

18-28

19-32

20-36

21-40

22-40

23-40

etc.

I think that i could probably make the map steeper and I might even change the 40s to 36's as boost hits 10 and drops back to 9-9.5. Then I'll fine tune it some more.

I can't easily find a location under the skyline dash to fit both the IEBC and the DFA. Found room for one only. I don;t really want them in the globox - they don't fit that well in there either!

[PJ]

Thanks to everyone who has posted really helpful info, solutions and fixes in this thread. I have an r33 auto, decided to get the fuel controller after reading sidneykids comments. Put it together, tested the fuel controller box voltages and everything was fine. I have one problem, my screen doesn't light up on the hand controller. Like the earlier posts I turned up the conrast level to full, half, and minimum and nothing comes up. Voltage is getting through to it, but no display. Have checked every component on the multimetre and they seem within specs.

The only conclusion I could draw was that I have used a parrallel cable (yes they do fit) instead of a serial. Would that have blown the screen on the hand controller?

I have tried another actual serial cable, and still nothing. Any suggestions?

Edited November 20, 2005 by PJ

[chrissso]

Thanks to everyone who has posted really helpful info, solutions and fixes in this thread. I have an r33 auto, decided to get the fuel controller after reading sidneykids comments. Put it together, tested the fuel controller box voltages and everything was fine. I have one problem, my screen doesn't light up on the hand controller. Like the earlier posts I turned up the conrast level to full, half, and minimum and nothing comes up. Voltage is getting through to it, but no display. Have checked every component on the multimetre and they seem within specs.

The only conclusion I could draw was that I have used a parrallel cable (yes they do fit) instead of a serial. Would that have blown the screen on the hand controller?

I have tried another actual serial cable, and still nothing. Any suggestions?

<{POST_SNAPBACK}>

I tried 3 cables lying around the office until I got one that worked, so I don't think that you have blown it...

[AlexCim]

You have to get the cable which they jaycar people suggest to buy from them

I bought a paralell cable from dick smith and it didnt work.

The cable needs to be omni direcional in transmitting data, where serial cables are just in one direction (to printer)

Just get the right cable, its $10

[xRHETTx]

The display will only work if it is plugged in before the main unit is powered up.

I nearly had a heart attack when i finally plugged mine in and it didnt light up, so i turned the car off and back on again and it worked.

Hope this is the case for you too...

[chrissso]

It has to be a 25pin RS232 serial cable.. I think it says this in some of the earlier posts.

[PJ]

That makes me feel a bit better, thanks. Ill head to jaycar, get the cable and see what happens.

[benl1981]

Hey Sydneykid - you said....

"Suggestions to your questions follow;

1. There should be no difference, the engine should run exactly the same. I strongly suggest you check the input and output voltages across the whole range of AFM voltages"

I assume you were just doing the test with the car sitting in neutral. Comparing reading at idle then say 2000rpm, 3000rpm and up to 5000rpm etc.

This still will only give you comparison from 1v up to about 3v right?

How did you calibbrate the fuel adjuster for the higher volatages? (Not on the dyno right) mine seems to be within about 0.1v at the higher end and about 0.01 v at low voltages. Using the crappy trimpot though. I find as you measure input voltage when you take the multimeter off the load point changes about 4 points, then I go to adjust and it goes from 4v to 8v!! I guess with a more stable signal such as from the AFm you won't get this problem.. Still not sure do you just calibrate from 1-3v and assume it to ber gith for the rest. you really wasnt to have load point 128 whenAFm reads about 5.2v right? As the AFM can read this high if enough airflow.

Don't know ifI got an overly bad trim pot...

I'm selling it to someone so I'm just trying to give it to him calibrated to the best of my ability...

Edited November 25, 2005 by benl1981

[sl33ek]

Hi guys,

I bought Ben's ^^ DFA already assembled - Thanks Ben, i know how tedious it is to put together kits. I'm certain my car is running too rich because of the poor fuel economy (350k's to a tank) and exhaust dust on my rear.

Its all working and calibrated now but there were alot of soldering problems, mainly alot of dry solder joints and some pins with not enough solder. The capacitor near 12V input was very dry and as a result it needed over 20V+ just to light up the red LED hehe.

Its all kewl though I've gone through and resoldered every pin.

I got a constant 5V signal too from a voltage machine I borrowed which had the ability to vary the voltage. I found the supplied tuning test pot to be extrememly sensitive and crap as you mentioned so I binned it. At the moment it is fully calibrated ready to go.

I tested it by varying the 5V input signal, and the load points changed correspondingly on the hand controller from 1-128 and any adjustmenst made from the hand controller reflected in the output voltage too.

I'm looking forward to installing it in my car this weekend, drive it around for a week and get it tuned the weekend after by Bel. I'm not game enough to tune it myself.

I'll post my results in th near future!

Cheers

[benl1981]

Hey Gengis - It booted up on mine no problems with 12.6v from that battery (i.e without car running) I find that very odd that you needed 20v.

I made sure every pin wasn't dry - some had more solder than others I guess but I wouldn't have thought you'd call them dry...

Anyway glad you got it calibrated well. Sorry you had to fiddle with it a bit...

Hey Gengis...that sensor check on your consult isn't good enough to tell you if your 02 sensor is ok or not. When you get on the dyno to tune the DFA get them to check your Air to fuel ratios at idle and at low low points. These should be 14.7 as the 02 sensor if its functioning properly will be varying the injector duty cycle to maintain this. I.e. ECU will be in closed loop mode using feedback from 02 sensor.

P.s Yeah the pot was crap for calibration...wonder if I got a bad one

Edited November 29, 2005 by benl1981

[sl33ek]

Ben, thats just what I found, it wouldnt boot (Red LED Lit) on in my car which had around 13 volts and on the bench it wouldnt light up too unless i gave it heaps of volts. Tuning the VR4 pot all the wayclockwise didnt help too, it was only when I removed the capacitor and resoldered did it boot up OK every time at 12V.

The other joints looked like the pins were not heated enough to allow the solder to flow smoothly onto the pad.

Thanks for the tip at idle, I'll see if I can get them to check that. I had an idea the consult cable alone wouldnt be good enough to tune this. I'm getting readings from my 02 sensor with it though, does it mean that it could still be faulty? I'm not sure myself.

I'm really looking forward to this tune! Thanks again for the DFA man.

Edited November 29, 2005 by Gengis

[benl1981]

Thats cool man - sounds like your pretty good with the soldering wand, glad you were able to fix up the things you thought were a bit iffy.

Just make sure you get the DFA doing what it should b4 you take it the dyno. Like you're doing check on the bench when you add + or - that the output voltage changes.

Yeah but if the 02 is incorrectly sensing the 02 level you may be getting AFR of 13:1 or something.. Do you drive it hard - 350km per tanks is pretty low.

If you are running 10psi on stock ECU then you are probably riunning very rich if you are pushing it. Hopefully DFA will help.

What was your fuel consumption before on stock boost?

[sl33ek]

Yeah the consult doesnt tell me what my AFR is unfortunately, at least I dont think it does. I dont really drive it that hard but I like to get to the speed limit at the click of the finger lol

I can't remember my mileage before I increased boost to 10psi (just a bleed valve) but I got the exhaust dust on the bumper from the start. Not a good look on white paint

[Sydneykid]

My observation;

1. As soon as I increased the boost on the Stagea to 10 psi the A/F ratios dropped into the 9's, that's 33% more fuel than 12's you need for best power.

2. Due to the increased airflow (via the AFM) at boost build time the standard ECU was into rich (hence the 9's) and retard mapping. This means you need more throttle opening to compensate for the loss of power from the retarded igntiion timing.

Double whammy, 1/3rd more fuel than the engine needs and more throttle to achieve the same acceleration or to hold the same speed.

cheers

Edited November 29, 2005 by Sydneykid