Turbo + irtb's tip-in problem
 

Car specs:
european 1.8 NB
T25 s13 turbo
adapted fuji-racing irtb's
rx8 injectors
adaptronic 420c v10 firmware

The car runs well when steady throttle is applied but tip-in is almost impossible to tune. No matter how much or less fuel the injectors sprays, the engine reacts the same way, it bogs down and shows a lean spike. Adding more than ~8ms to off-idle and the engine dies filled up with unburnt fuel after a huge lean situation.

I'm using MAP x TPS x RPM (dual tables) tuning method with TPS-based accel enrichment

List of things I've tried, unsuccessfully:

-Move the injectors from the irtb location to the stock location on the head.
-Relocate the injectors wires as described in this thread: https://www.miataturbo.net/adaptroni...sitions-65816/
-Switch from full sequential to batch firing in pairs with divided pulses

I think it can be related to injection timming but the 420c ecu uses a fixed injection angle, so I can't change it.

https://www.miataturbo.net/attachmen...ine=1348785122

https://www.miataturbo.net/attachmen...ine=1348785122

:vash:

Pics please.

;)

https://www.miataturbo.net/attachmen...ine=1348790716

https://www.miataturbo.net/attachmen...ine=1348790716

Now the car has installed an external IAC valve and a few vaccum lines more

well isn't that some shit

Holy crap....1st person I've seen yet (iirc) with IRTB'S+BOOST

You sir, are awesome

:party:

Thanks! It's a friend's car, i'm helping him to tune it.

Mine's a '01 with a much bigger turbo and a "simple" square-top intake manifold.

Gawdam you are Man.

That shiz needs to be on the home page of this site. Reporting that post for going to 11 in awesomeness.

Regarding your problem, is overrun turned on? Or off.

Thanks for the compliments!

Overrun turns on at 60ºC but iirc it's only applied when rpm is greater than 1500-1600 or something

Just a noob throwing out an idea. Does the adaptronic do anything equivalant to MS EAE? that might negate the need for so much normal AE perhaps?

Also how long is the lean spike? its hard to tell from the pic if its only 0.2 or 0.3 seconds it might just be a case of thats as good as it gets with an aftermarket, i know Brain ( i think ) has said before that u will never 100% get rid of lean tip in with MS since its reacting to changes after they happen.

Scott

Be careful. You may actually be too rich. When you kill the engine with fuel, you don't consume the oxygen and the WBO2 reports lean.

Have you tried reducing the acceleration enrichment?

I've tried from 0 to big numbers and it reacts the same way. Bigger pulses only makes the AFR richer after the lean spike. The only way to make the engine rev without hesitation is running 10'xx AFR at idle with nice black clouds coming out the exhaust.

The AE in adaptronic are not as complex as in MS. There is no fancy algorithms for fuel in walls, but is much more than capable to do the job.

The lean spike is almost 1 second and the car is undriveable.

I'm almost positive we had these lean tip in issues when we were screwing around with the early adaptronics years ago. You already probably checked the adaptronic section, but I'd look through there again. Something about asynch pump settings and "predictive throttle" if I remember correctly.

In fact, I'm almost positive that by messing with those 2 settings I actually got mine to do EXTREMELY rich tip in, which ironically enough, was just as terrible as your lean tip in. I remember the car bogging like crazy then lurching forward.

Sorry I can't be of more help and post actual discussion threads, but I'd browse that section more if I were you.


*edit: then again, none of us had IRTB's so maybe that wouldn't help you.

Thanks Vlad. I think your talking about the "predicted MAP" option that was introduced in the firmware when a lot of users were having problems dialing the transient throttle.

This car is a pain in the ass to tune because you need to think in 4D instead of the traditional 3D fuel and spark tables. The theory says that acceleration enrichments are not very important when tuning using a TPS x RPM method. The ecu is configured to use a primary table to determine fuel and spark values based on TPS position, and a secondary table used as a multiply factor to attend for changes in manifold pressure, this indicates that the change in fuel values is going to happen faster based on a TPS table rather than using the traditional MAP x RPM method, so once the tables are correctly tuned, the transient throttle settings become less important.

This makes me think that there is some physical problem with fuel delivery or triggering.

It's not anything to do with this is it?

https://www.miataturbo.net/adaptroni...sitions-65816/

Also tip in is effected by the VE table, look at the cells you hit when you stab the throttle and try playing with those.

With just your fueling scheme you should be to about 80% of the fuel you need on tip in with no stomp comp, at least for the rpms where you cant build boost, thats the nature of tps based fueling. I bet you need a fuck of a lot less fuel at that RPM level of tip in, and its showing lean on the wideband because you're actually making it misfire with all that fuel.

Also, did you change your injection angle? The injectors are further from the head than stock so you need to have the injectors inject sooner.

Guessing you didn't read the OP's posts.

He tried from zero fuel to lots.

You can't adjust the injection angle on his ECU.

I missed where he didnt try any comp. This sounds exactly like an injection angle problem. Putting the injectors back to the stock location would theoretically fix that.

The injectors are placed in the stock location.

no way, my tip-in enrichments go fat as what. and it shows up as so...you'd have to go 100%dc for something like you're saying to happen.





so the adaptronic might not be great at tps enrichments, but at least the adaptronic can do tip-in retard.

Yup, sorry, re-read the op. The first two times I read the things tried unsuccessfully as things I'm going to try.

What doesn't make sense is that your lean spike is corresponding to exactly where the o2 should be seeing the fuel injector spike? How much exactly did you increase the stomp comp by? Last time I had to tune transients from scratch the default values in the ecu was like 6 and it needed to be like 30 (cant remember which value it was). When I first stared adjusting it I though it wasn't doing anything. What exactly can you adjust on your transients? Amount of asynchronous pulses and pulse width right?

I don't know how your adaptronic blends the tables together, but running alpha-N with boost is generally a bad idea. Why not run speed density?

As long as you can choose the blend and run alpha-n for idle and low rpm and then get to complete map by the rpm the turbo spools its ok. I've tuned boosted cars on straight tps, and it sucks a massive taint, even when they're blower cars with airflow more or less always being equal related to tps. But I refuse to ever do it again unless a large stack of bill are placed in my hand, because it takes forever, and makes you want to bunch babies holding kittens.

you cant tune a tps-based turboed car?

You can. But if you dont have some sort of MAP compensation its going to be tuned to have a rich spike when you first get on it if you're above the boost threashold. It works, but its a terrible idea. :fael:

It uses a table for TPS x RPM with direct msec values or VE scaling if you want, and a second MAP x RPM table where a 1.000 means 100% fuel value in TPS table, 1.200 = 120% and so on. You can leave the under 100kpa area almost at factor 1.0, because there isn't a big change in manifold pressure but a big change in air mass, more related to TPS position. Over 100 kpa the MAP x RPM table do the trick for increased manifold pressure with increased air mass at the same throttle apertures.

i see what youre saying.

This sounds exactly like how I had to tune, except you have a 3d table for your map compensation because you have rpm I only had the ability to skew vs map. How I managed to make it work somewhat well was making the table compensation map look like a good ve table (vaguely) and then fine tuning it in with the tps main fueling table. You've got a better setup there and it sounds like how you have it is the best setup for itbs. I still would make the in boost part of the map based table look like a generic ve map though and then tune in the tps map for fine tuning of it. Course during spool up you'll have to fiddle with the two to make it work right. This is making be remember the days of.

:vash::vash::vash::vash::idea::vash::vash::vash: :crx:

Itb tip-in has a LOT more throttled volume than single throttle body. People have a tough time as it is when n/a going by tps and not map based enrichment... Turbo+itb is like a 9.5 of 10 on difficulty comparatively. It's going to have a VERY narrow window where it will work correctly. That's Also why you see progressive throttle linkages.

The two pics of your engine bay just gave me a migraine...thanks a lot asshole!:giggle: