those using 72pph injectors...

[mcglsr2]

...i need some help. i've got my own custom cal, and i went with a set of 72pph injectors. i'm currently having some trouble.

the car idles very rich, as soon as i start it my wideband AFR drops down to 11 or so and stays there. the car also idles fast like it has a vacuum leak, except that during idle i'm pulling close to 20" vacuum. if i blip the throttle, the AFR dips even more rich and the car stumbles. i can smell gas the whole time the car is idling.

i have recently learned that the 72's are rated at 43.5, i'm running the stock 55psi with the stock FPR. which means the injectors are really like 81pph. i created a cal for 83pph injectors. car behaves the same exact way as before.

can someone please help me with why the car is running way too rich? is anyone here running 72pph injectors with no issues? if so, can you send me your cal so i can compare? i'm running out of ideas, please help!

[ShelGame]

How'd you adjust the cal?

[mcglsr2]

i adjusted the cal by using the scale injectors in zChem. i originally scaled for 72pph. the next time i scaled for 83pph. each time i compiled a new bin file.

[ShelGame]

Which codebase?

[mcglsr2]

TLM version 9, compiled from source

[ShelGame]

OK, I'd say you probably need to adjust the BATOFF table. This is the injector latency table. It really doesn't change with flow rate, it's simply different for each injector. More than likely, the 72's are much lower latency than our older stock injectors. I'd scale that table by 50% and see if it helps.

I think Geoff has it scaled with injectors. Which, though not accurate, probably gives a decent approximation for the big aftermarket injectors.

[Shadow]

Are you not running o2 correction? Even when my 72's were pig rich down low, the o2 would still correct when it was warm.

[mcglsr2]

OK, I'd say you probably need to adjust the BATOFF table. This is the injector latency table. It really doesn't change with flow rate, it's simply different for each injector. More than likely, the 72's are much lower latency than our older stock injectors. I'd scale that table by 50% and see if it helps.

I think Geoff has it scaled with injectors. Which, though not accurate, probably gives a decent approximation for the big aftermarket injectors.

okay, so to make sure i totally understand, when you say scale it by 50%, you mean for each datapoint, use a value that is 1/2 of the previous value. i will give that i shot when i get home. also, i can't scale for 72pph in zChem, as i'm running 55psi FP and not 43.5. the other other choice i have is to scale for 83. would it be possible to create a selection for 81 (what the 72's flow at 55psi), or even better allow the user to enter any value he/she wants?

Are you not running o2 correction? Even when my 72's were pig rich down low, the o2 would still correct when it was warm.

as far as i know i am. before, the car would try to idle around 14.7:1. in the cases i have tried, the car wasn't warm, it was cold, but it should still shoot for 14.7:1.

Rob, i have a separate question about one of the tables in the cal - i'm not sure it's scaling correctly. the table is the FuelStartDecayIntoRun (or something like that, i don't have it in front of me, but it's in the Starting grouping). it deals with the amount of pulsewidth to TAKE OUT as the car transitions from starting into running. correct? last time i checked this table, it was adjust lower (meaning less pulsewidth) when i scaled for larger injectors. shouldn't it actually add MORE pulsewidth - the y value is tagged as pulsewidth REMOVED. since the injectors are larger, don't i want to remove more pulsewidth, otherwise i would be on the rich side? am i misunderstanding this?

[ShelGame]

okay, so to make sure i totally understand, when you say scale it by 50%, you mean for each datapoint, use a value that is 1/2 of the previous value. i will give that i shot when i get home. also, i can't scale for 72pph in zChem, as i'm running 55psi FP and not 43.5. the other other choice i have is to scale for 83. would it be possible to create a selection for 81 (what the 72's flow at 55psi), or even better allow the user to enter any value he/she wants?

Only if Geoff re-writes CheM to work that way. wowzer's new editor will allow you to use any value, but I don't think it has too much support for T-LM. I'll try to re-work T-LM for it as much as possible, though.

Rob, i have a separate question about one of the tables in the cal - i'm not sure it's scaling correctly. the table is the FuelStartDecayIntoRun (or something like that, i don't have it in front of me, but it's in the Starting grouping). it deals with the amount of pulsewidth to TAKE OUT as the car transitions from starting into running. correct? last time i checked this table, it was adjust lower (meaning less pulsewidth) when i scaled for larger injectors. shouldn't it actually add MORE pulsewidth - the y value is tagged as pulsewidth REMOVED. since the injectors are larger, don't i want to remove more pulsewidth, otherwise i would be on the rich side? am i misunderstanding this?

You know, that's a very good point. It really should be the other way (that table should be scaled up, not down). But, it's only a transition adjustment. So, once you are up to temperature, that PW is subtracted out until the result is less than the running fuel, then it switches to running fuel. So, it shouldn't have a huge impact. If you're running really rich right from startup, this table probably isn't why. But, you are right I think, it should be scaled the other way...

[mcglsr2]

Only if Geoff re-writes CheM to work that way. wowzer's new editor will allow you to use any value, but I don't think it has too much support for T-LM. I'll try to re-work T-LM for it as much as possible, though.

i think it would be pretty useful, at least for me in the meantime, i can scale for 83pph which is slose to my actual and adjust manually from there, once i get the car idling good.

You know, that's a very good point. It really should be the other way (that table should be scaled up, not down). But, it's only a transition adjustment. So, once you are up to temperature, that PW is subtracted out until the result is less than the running fuel, then it switches to running fuel. So, it shouldn't have a huge impact. If you're running really rich right from startup, this table probably isn't why. But, you are right I think, it should be scaled the other way...

i didn't think it made that much of a difference, but when i was looking through tables i noticed that and it seemed opposite to what i was expecting.


so when i get home, i am going to use the 83pph cal that i created. i haven't adjusted anything other then scaling through zChem. i will adjust the BATOFF table by 50%. any other tables that i should pay attention to? what table(s) control idling?

[turbovanman²]

Turn the fuel pressure down to 43.5 psi, easier on your fuel pump too and see what happens.

[mcglsr2]

Turn the fuel pressure down to 43.5 psi, easier on your fuel pump too and see what happens.

i don't have an adjustable FPR

[ShelGame]

i think it would be pretty useful, at least for me in the meantime, i can scale for 83pph which is slose to my actual and adjust manually from there, once i get the car idling good.

wowzer's new editor will allow you to use any flow rate you wish...

any other tables that i should pay attention to? what table(s) control idling?

Do one at a time. If the BATOFF doesn't help, then maybe go to the PumPEff table in the low RPM's.

Idle control is a whole big mess of stuff...

[mcglsr2]

wowzer's new editor will allow you to use any flow rate you wish...

where can i get that bad bay?

Do one at a time. If the BATOFF doesn't help, then maybe go to the PumPEff table in the low RPM's.

Idle control is a whole big mess of stuff...

okay. i'm sure my pump eff is off too, as i've got a ported head and ported exhaust man. on the car. regarding idle, is there any reason the car should idle fast? usually that says vac leak to me, but as i might have mentioned earlier, i'm pulling like 20" of vac...

[turbovanman²]

i don't have an adjustable FPR

It might be easier to get one and try it.

I am glad you posted this up as I'll be going 72 lb injectors next year.

[mcglsr2]

It might be easier to get one and try it.

yah, but i would like to try to fix this without spending more money...

I am glad you posted this up as I'll be going 72 lb injectors next year.

what are you talking about, move to 72's now! we need another guinea pig besides me! the thing is, i'm for sure not the first to do this. where are all those successful 72pph users at!?! they got to have some advice for those poor sods like myself that can't get this working...

[turbovanman²]

what are you talking about, move to 72's now! we need another guinea pig besides me! the thing is, i'm for sure not the first to do this. where are all those successful 72pph users at!?! they got to have some advice for those poor sods like myself that can't get this working...

I have to buy some first,

Engine rebuild is high on the list, then injectors.

[quantum]

Try manualy scaling FuelStartDecayIntoRun at 20% less than the rate you scale the injectors. For 72# scaling the FuelStartDecayIntoRun table to the +40's (52#) level is about right. To find out the proper number here is the math: Take the current injectors (33 stock) and divide by the new injector size, subtract .2 from the answer, subtract the result from 1, and then multiply that by the current "out" number at that point, the answer is what the new out # should be. So that's (1-((oldinj/newinj)-.2)) x "out" = new "out". For example the first point for stock injectors is 24 out at 63.4 degrees; for 72# injectors you would take 33/72 (assuming going from stock), to get .45833333, then subtract .2 to get .258333333, subtract from 1 to get .741666666, then times the 24 to get 17.8 at 63.4 for the new point.

[mcglsr2]

well i think i am on to something. i have a rough idea of what i need to accomplish, now i just need to do the work of tweaking until i get it right. what's killing me right now is the FuelStartFromCoolantTemp (STRTFL) table and the FuelBatteryOffset (BATOFF) table, and the relationship between the two. I can adjust my cal such that i can keep the BATOFF table unchanged and account for the injector size completely in the STRTFL table - but this has an effect on transitioning into running and running itself. likewise, i can adjust BATOFF completely and leave STRTFL unchanged from the initial scaling. both situations allow the car to start, however do not mean that the car will run well. so i need to find the correct balance between the two tables (and possibly a few others). so i'm going to be making a lot of tweaks and reburning a lot of chips in the next couple of days. i need to think more on the relationship and my expectations so that i am sure to approach the tweaking from the right angle. but i do think the solution is here in front of me.

i've got some thoughts on the FuelStartDecayIntoRun table, and it's a little different then what quantum says. but i will hold off until i can get the car to start reliably and then do some testing before i talk about it. and of course i could be completely wrong...

[mcglsr2]

I have to buy some first,

Engine rebuild is high on the list, then injectors.

well i'll try to get rid of as many gremlins as i can for you. i hope your transition to 72pph won't be as painful