It's Alive - Delco 173

[stevemc32]

Thanks guys, such a difference now.

I ended up with an injector flow rate of 0.1244 and running backwards on the kinjflow spreadsheet indicates 15 lb/hr injectors. As far as I know they are just standard VK units as I got them off a VK motor that appeared to be complete.

The VK manual says 185cc/min which I believe works out to 18lb/hr using petrol at 0.737kg/l.

The log looks alot better now so time to start working on making something happen when I open the throttle...

[Holden202T]

i get a result of .104 with your engine and injector size!

[stevemc32]

Yeah 0.104 was my first change, it was originally set as .1002 as per your loaded bin for the 173.

I ran it again after cooling down yesterday again it was lean even after warming up at 0.1244 so might even need to go higher.

[Holden202T]

you might need to change the VE table too, i've never run a motor as a 173 so anything in the tunes is based on a 202 and usually with worked heads and cams, so anything for the 173 is going to be a bit of trial and error. try and bring the revs up a bit with some load on the motor and see if it goes lean still, if not it might just be the idle area of the ve table that needs changing.

the ultimate dictator of the injector rate will be what your peak VE number is and weather its in the right range (80-90%) if its not then its probably the injector rate that needs to change.

[Holden202T]

i've just had a look at your logs, particularly the last one you posted looks like its rich enough at idle, but then as the revs rise its going really rich, i'd say you need to lean out the injector rate and change the ve table for idle.

can you post up your current bin file so i can take a look see ?

in the last log too it looks like the iac is getting closer! might need to just slightly back off the throttle stop screw to get a few more IAC steps!

another thing you can do too, try and increase and decrease the spark in the idle areas and see which number gives you the lowest map sensor reading, you might find that tune is commanding more spark than you need for your combo.

[stevemc32]

Here's the bin and the last run that I did the other day. Won't have a chance to play again for a few days but you've given me some good things to have a think about before then.

A quick bit of info on the engine for reference. It's a stock worn red 173 block and cam with the VK black injection head and manifold so with the 202 chamber head it's like the old low compression 173. It's unlikely to be the final motor that goes into the car but will probably be the engine that is used for initial registration so it does need to be driveable. That said there's no great rush as it won't be registered for some time and that severely limits my ability to do any logs on the run.

Around 2 minutes into this last log I stab the throttle a few times and if I'm reading it correctly we see a hesitation of about 1 second before the rpm changes, a fairly big lean spike then followed by an extended rich condition as the IAC brings the rpm slowly back down to idle.

Thanks again for the help, I know I won't be able to get it anywhere near fully tuned without being able to drive it around but if I can get it capable of a run up and down the street than I can keep going on the build and keep learning about the tuning.

[Holden202T]

well i think i've found at least one thing that might be contributing to your lean idle!

with my motors most of them having mild cams in them, they idle with far less vacuum than your motor ... so much so in fact in your logs im seeing map readings in the high 20's! now if you have a look at the ve table the 30 column is a fair bit higher than the 20 column, so the issue is as it pulls over into the 20 kpa column its leaning it out a far bit .... most of my motors idle in the 50-65kpa area!

also not sure if your aware, the tune is running in MAP A tables, you have .1244 in the map A injector rate and .1002 in map b ?

anyways, try this tune, i've increased all the areas i mentioned above in the VE table, it will be a fair bit richer, so get it going and then adjust the injector rate closer to the .104 we worked out above till the idle mixture is as close to commanded as you can get it.

LJ_Startup0214-holden202t-1.bin

i've left the injector rate as you had it set, so just try slowly decreasing the value from .124 -> .104 and see how it goes.

also in your logs you can see that lean spike on throttle crack, then goes really rich after it .... i believe the richness is the different areas of the VE table, and possibly the throttle crack leanness is accelerator enrichment, but worry about that table after you have sorted out the injector rate and see how it is.

also if you want to try and put some load on the motor to see how higher areas of the VE table are looking, you can always support the diff with jack stands, and then drive it with the brake on to simulate load! if you do this though make sure its nice and smooth throttle applications and stead state, anything jerky will likely give you in-accurate results.

[stevemc32]

Fantastic, thanks for doing an update to it. Hopefully get a chance to give it a go today.

I haven't touched anything in Map B as I was just going to leave it as it was loaded for a reference.

For my education were the updated VE numbers calculated using the calcVE or a similar spreadsheet from the logs or where they an adjustment made from tuning experience?

[Holden202T]

yeah just me changing them as i saw fit

really 90% of tuning is experience and knowing what to change and how much effect it will have. if you compare my ve table with your original you will see there is not a huge amount of change, but 20kpa column there is somewhere in the order of a change of 10-15% more fuel. the difference i saw was your .124 -> .104 which if you divide these is about 15% difference..... at the end of the day you'll probably find .11 is going to be about where you'll want it to make everything right.

other than that i just increased everything in a smooth fashion to get the VE table nice and flat so theres not massive changes from one cell to the next like there was in the 20kpa column!

it will be a fair bit richer when you start it with the .124 still in there but rich is safe and easy to fix once you have it running .....

with the map a & b stuff, i get what your saying but i would recommend keeping all changes made the same between map a & b ... it saves on confusion and hassles later, if you want to keep records of differences, just save the file as a new name everytime you change something, then you have plenty of previous tunes to go back to if the latest change is no good.

for example, when i start with a new car tuning, i'll select the right base file for that motor, then make all the changes needed specific to that setup, like injector size, cylinder size, etc, throw that in the car and see how it goes, then if im tuning from a log i'll normally analyse the log and then save as a new name and / or date ... i generally prefix my tunes with "2014-02-27 - 1 - xxxxx" where 1 is the first tune for that date and x is the specifics, like changes you've made or something like that to help you find the file you want later.

also prefixing with the date reversed as above means that all your tunes will display in windows in the order they were created which makes things easier in the long run!

at the end of the day personal preference will prevail and you'll work out what you need to be sane while tuning!

on the map switching stuff, i use the dual maps for my race car when staging at the drags i press the button on the shifter, this switches to map b for everything, sets 3000rpm rev limiter, retards timing, richens up fuelling and stuff like that so i can stage with full throttle and build boost, then when i let the button off, back to map a and full power up it

obviously this is individual stuff, but you might want to have two maps for switching high/low octane fuel or similar ... i guess what im trying to say is i personally think its better to change all map a and b things the same as you go along to save issues later

[stevemc32]

Great info, the concepts are finally starting to fall into place for me and I'm getting a much better understanding of what's actually happening and how to change it. Keeping the map A and B changes in line seems like a good idea.

Ran the new tune and settled on an injector rate of 0.112 which looks to have sorted out the idle quite nicely. Gave it a quick run up and down the street but the log isn't real useful as I was concentrating more on holding the laptop and stopping my new fuse block from wedging itself under the brake pedal than smooth throttle work. I'll post it up anyway for a look.

It occurred to me that a misfiring cylinder would likely produce a lean condition at the WB sensor and this is something I haven't checked yet. Next run I'll pull each injector plug in turn and check if there's anything amiss. It's certainly running rough enough to have a dropped a cylinder so I might find something interesting...

Where would be the best place to start on addressing the big hesitation on throttle opening?