How do I tune AFR's safely?

I'm using the LOG function w/ a wideband 02 sensor for the ATP input, but my readings kind of seem all over the place, and the car will boost, but then kinda falls on its face. too much fuel it seems...

I have 680 pri and 1000cc sec (550,720 setting)w/ hybrid to4 turbo. I've done some tweaking but I'm getting some sputtering/hesitation at higher rpms under vac also...

I'm going to set the secondary point at about 3200, and try use that as a transition point on the fuel maps.

Settings are like -30% under vac all rpm...

-20ish% at 2-4psi -18%ish 6-8psi... still seeing afrs in the 10's...

Basically I'm trying 3rd gear pulls on the street, boost on stock wastegate should be at ~7.5psi max.

Cruising seems fine.

Any suggestions or information are appreciated... I'm doing this myself, so don't suggest I take it to a tuner...

 

You need to keep pulling more fuel. You are giving the car a lot more fuel than it is expecting with those injectors but it sounds like you are on the right track. Don't try to do everything at once. Get the WOT area of the map tuned, and work backward to handle the driveability area of the map. When I first started tuning cars, the 3d map helped me visualize what I was doing.

Figure out where your boost hits, lets say 2000 RPM. From 2000 to redline add 10% (using that as an example) fuel from 60% load to 100% load. Do a pull and see where you are at. Keep doing that WOT pull and adjust as necessary.

Don't be afraid to make a near 10% change if you are seeing 10:1 AFR. 10% of 10 is roughly a full point of AFR, and subtracting 0% fuel should put you close to 11:1 which is where you need to be. Obviously if you are close to your target, you will need to adjust in smaller increments.

Also, your wieband may not read below 10:1. Some don't, so you could be richer than that.

 

Update: its getting a lot better now. -24% 0-6psi and -20ish at 8 and up. Still hitting 10 afr's though. Yea, the WB only reads to 10's so who knows how low its going... getting wheel spin in first now. weee!

I only take it out when its dry... so tuning is going kinda slow.

I'm going to input the timing map this weekend, maybe...

Anyone else want to share they're RTEK tuning experience(s)?

 

Update 2: pulled yet more fuel, but found out I have it on the 550,500 setting... So... I might start over using the 550,720 setting as I thought I was. This might help with idleing and low rpm/vacuum operation. Any input is appreciated?

Arghx, turbo2liter, njgreenbud, 95nracer, I know you guys got some info/tips!?

 

Going from the 550/550 to 550/720 won't change anything down low since it only effects the secondaries..

 

Yea, I was thinking that on my way home, I'll just continue to pull fuel, I hope I'll be able to get to 11 afrs with 1000cc's as 550's.

Yesterday morning I was doing a 3rd gear pull in the morning like 40 degrees out and it hiccuped or something and I thought it was over. I just don't want to blow my ****. I've never done or seen tuning before so I'm out on a limb here and just looking for info on how others are doing it.

Is the stock timing too aggressive?

Can now spin in second and its sounding better, but still in the 10 afrs...

 

That hiccup was more than likely a result of still being so rich .id keep pulling till u see some kind of movement in your afr

 

I would switch to 550/720 preset, it would help with secondary transition.. and do your runs in low gear until you start seeing the AFRs you are looking for, like 2nd gear. If it happens to detonate, it is easier on your engine under less load


also stock timing is too aggressive imo, before you do any more tuing, you may want to take a look at it and retard it more. Use 20degrees at 10psi and 15 at 15 psi to start with. I think the stock map has it advanced like 35 degrees at full stock boost. I think the stock timing map is why turbo rx-7s have a bad rep for blowing engines.

 

Ok, I didn't get the timing in, but I removed a little more fuel yesterday -3 clicks from 2psi-8psi above 3200, and it felt a lot better. Didn't run any logs, thought I was, but you can't use the alarm function and the log function at the same time. 7.5-9 psi felt as fast or a little faster than the stock turbo at +12psi... Still pig rich probably too.
On the way home was having issues though... NB o2 was reading lean intermittantly in vacuum/low load operation... the meter would go lean and it seemed to be low on power, then it would jump back to rich and run fine. I verified that it was lean on the palm 15-17afr... stayed out of boost. Fuel pressure was good and didn't drop, but I wasn't getting fuel or something... It was fun though and my brother in law got to go for a ride.

 

Wow, so much clearer to see on the PL Viewer and I see what you mean about the timing... This was before the last run, so before I pull anymore fuel and do more runs I need to get that timing in....
Thanks!

 

I saw the exact same thing. seems like if you take out ANY fuel out in the cruising area of the map (higher vacuum, >10inHg), it starts doing this weird super-lean hesitation crap.

There was a thread about it a while back, others were seeing teh same thing. I opened a trouble report about it on pocketlogger, but no solution was ever found. I ended up leaving the cruising area of the fuel map alone and it was super rich at times, but no more hesitation. i think its just a quirk of the stock ECU

but yeah change your timing map before doing any more runs

 

I have experienced that same lean spike condition on several cars including 2 of my own.

I never found a pattern for it when i tried to duplicate the condition when testing. I was only successful 3 times out of 12. But since gxl90rx7 mentioned that it could just be a ECU thing, that got me thinking.

Looking at that log nick i see how your timing might very well be affecting those lean conditions as soon as you let off and cruised around 3500rpms while still in gear. Did you manage to record your split?

I am really curious how your timing tuning is coming now. Please keep us posted!

 

Are you guys running stage 2.0 or 2.1?

 

Stage 2.1

Drove to work this morning and it only went lean a few times, I've upped the fuel in the vac area, so we'll see how it does on the way home this evening.

Thanks

 

Switch to MAP based timing. In that particular log you posted, it doesn't look like the stock timing is all that advanced if you are in fact on 93. 19 degrees at 9psi and 4500 rpm or so... i mean from there on I wouldn't advance it further than that much. I'm pretty sure from the factory FD's run about 17 degrees at that same rpm and boost level, and they have 9:1 rotors. That is based on supposed stock FD maps I have for my Power FC. I think I posted shots of some of them in another thread.

Here is a MAP based timing chart. It is not the same map that I posted in the other thread, it's got a bit less timing.

You are running 93 octane correct?





the problem with load based timing is that there is hardly any information out there about it. every other EMS for this car uses rpm vs boost.

As far as AFR's go, you really can't go wrong with 11.0:1 once you really get into boost over say 5psi. I've always found Rx-7's (2nd and 3rd gens) run a lot worse when you get richer than that, and they can misfire. But nobody is gonna say "11:1 ? wtf too lean" either.

 

Yea lead timing on that map looks ever so slightly more retarded than the one I was going to use, which I'll be putting in this weekend when its raining. Since I don't want to have the car running I'm going to disconnect a few things to keep the amp load to a minimum for the 1 hour or so its going to take to put these tables in there. I've heard you can burn up the coils when the ign. is in the run position, but with engine not running for a duration of time? Or kill my battery...

I get premium (93 I believe) and run premix.

This is Rtek tuning business seems to be cake. I'm very happy with it. Easier than I thought, but I do see how you could easily go in there pull way too much fuel and pop your motor.

This is the map, I might get access to a dyno in the next few months which will give me time to finish my tune and finalize and see what she's putting down...

Map
https://www.rx7club.com/showpost.php...4&postcount=30

 

Ok, so I've got the Lead timing map in. One question tho. The maps you have shown, only have 18 rows, on the palm there are 19?

The cells on the palm are actually in-between all the psi's that are listed on the table.
(one above 16psi and one below -19.4in/hg)

I started from the top. ended up with 5 rows on the bottom the same. But thinking now I'm a little advanced in the boost areas?... So should I err on the safe side and move the rows down?

Thanks... now onto the split map...

 

I got the timing maps in, added a little fuel to be safe and here's what I saw.

Seems more torqey on the bottom, but she's running good.

I've also attached the log file for you with the PLViewer.

What do you guys think?

 

..

 

you can smooth your boost signal out by putting a restrictor pill in the boost sensor line.. if you dont already have it installed, take a small piece of plastic or something that will fit in the line and drill a 1/32" hole through it, should smooth out the boost signal and timing will be a lot more smoother also

 

I'm looking at the log right now. What is your AFR-to-voltage scaling for the wideband input? I can't see your AFR's right now because I don't have the wideband input set up, but you could lean it out to 11.5:1 , at least up to 10psi. people would run that on an FD all day long and those cars have horrible intake temps and higher compression rotors.

As far as inputting the timing map rows, I just took somebody else on here's chart file and changed the values. so I can't speak for the way he arranged it. I don't have an Rtek 2.1 , I had a 1.7 and now have a Power FC.

just get the restrictor pill from the dealer. it's like a dollar or something. use the one mazda designed specifically for that purpose.

 

Will get the restrictor pill. Input 1 (WB) Scaling is 0v=10afr and 5v=20afr

Yes the map is ok, but it does have another row at the bottom -21in/hg or something, I just pulled the timing back a little and it looks like the other map you posted above. I'll post it up when I have time to put it in excel.

"people would run that on an FD all day long and those cars have horrible intake temps and higher compression rotors" Would? But don't??

Yea, thats about what I'll be shooting for 11:1ish, it is running pretty good now, no hesitaion, or cutting out. Idles nice and smooth... need to add some fuel in a few spots but should be able to do full 3rd(4th?) gear pulls now. Still getting a little boost creep, but I ported the WG so its way better than before.

How do I know what my Injector duty cycle is? The RTEK spits it out in ms(milliseconds) and how does that translate to max duty cycle %????

Thanks

 

a -21 row would have more or equal timing, technically (more vacuum = more advance), although you would only be in that row on deceleration.

what I meant is that 11.5:1 should be safe at 10psi as long as the leading and trailing split timing maps are fine and you are on premium fuel.

Now this is the first time I've used the pocketlogger viewer, but I just right clicked on the graph you sent me, went to parameters, and clicked INJ D/C . highest I saw it get was 66% .

 

To find out your injector duty cycle use this forumla if you somehow cant find the % on the Palm or software.

RPM x PW / 1200 = %DC

heres an example:: 7000rpms x 10ms / 1200 = 58% Duty Cycle

 

I ran a few logs of the 'lean issues' I've been trying to work out.

I'm going to bring the lower vac areas up to -10ish and see if it changes anything, I've added a little, Could this be a bad primary injector? Or something else?

Just cruising it goes lean once I step on the gas under vac -15 to -5in/hg at 2500-3000rpm.

Also my WG actuator rod fell off... I thought my clutch was starting to slip. It was just the little c-clip that fell off.

Thanks...