A/F going way rich under boost, not boost leak.

[Kei]

So, finally got the fresh motor in my gen1. It's great. Love it to bits, as I always have. No major hiccups, other than an axle being stuck in the hub and getting in the way a bit. Thermostat is also stuck open, but it's summer and I'll get to it soon.

Have about 600 miles on the motor so far, did a 500 mile oil flush and then out the good stuff in there.

I'm a paranoid type, and yes I know the car has a wideband in it stock, but I have another just so I can watch it. The previous motor ran around 12 under hard load if I remember correctly, and was pretty stable. Now, under hard load (4th, scared to truly lay into it still) it drops real low. Into the 10s. I can feel it, there's a slight drop in power. Scares me pretty bad, I cleaned the MAF, checked for leaks, haven't found a thing.

Bonus images of the 3 (or 6, if you count it) holes in my old motor included below.

[LenSpeed6]

my afr goes as low as 8.7 when I first go wot, I'm not nervous at all

[Jeff23spl]

that was a carnage!

for your AFR, how did you checked leaks ? Unless you did a complete boost leak test under pressure you won't really know if you have a leak. Some won't be seen.

[MSMS3]

Agree about going super rich when first going WOT. As long as AFRs settle into the expected range, I'd not worry about it. The stock tune and many aftermarket tunes are deliberately super rich under WOT, even all the way to redline.

The purpose of that is to provide cylinder cooling from the extra fuel. This allows more timing advance.

There is honest debate about which tuning philosophy works best on forced induction direct injection engines.

What may be concern is whether this represents a change in AFRs and logged data in general compared to the same tune on your other engine. If the setup is the same, mod for mod, identical fuel and identical ambient temps, and you are suddenly running much richer, then maybe something is amiss.

But, just because your AFRs are in the 10s under load is not, in itself, anything to worry about. What does the rest of your WOT log look like?

[Jeff23spl]

I though about it once more and It could depend if you look at a linear data log or you just look at the AP peak values? the second can record low values between shifts... if you have a bov or a valve that don't work perfectly.
But as other said, it won't harm the motor unless you try to extend the oil change for very long and it is rich to the point to have fuel to dilute your oil...At worst you may need to replace colder plugs more often.

[Kei]

It settles very rich. The only reason I'm anxious over it is because before the swap it would settle in a different spot. I don't have a way to datalog currently- haven't decided to go AP or Versatuner yet. I haven't done a full pressure leakdown alongside other tests, I'll see if I can't do that today.

Wouldn't the ECU see how rich the thing is running, and try to correct or something?

Originally Posted by MSMS3 Agree about going super rich when first going WOT. As long as AFRs settle into the expected range, I'd not worry about it. The stock tune and many aftermarket tunes are deliberately super rich under WOT, even all the way to redline. The purpose of that is to provide cylinder cooling from the extra fuel. This allows more timing advance. There is honest debate about which tuning philosophy works best on forced induction direct injection engines. What may be concern is whether this represents a change in AFRs and logged data in general compared to the same tune on your other engine. If the setup is the same, mod for mod, identical fuel and identical ambient temps, and you are suddenly running much richer, then maybe something is amiss. But, just because your AFRs are in the 10s under load is not, in itself, anything to worry about. What does the rest of your WOT log look like?

Yup- same exact setup, way more fuel. When first on boost, it starts to settle at a spot (11.5 or so) closer to normal, then a few seconds in it'll have a noticable drop-off and even barely break up.

I do know about cylinder cooling and such, avoiding detonation, etc. Have turbo rotary stuff. This is definitely on the problematically rich side.

[Jeff23spl]

Oh well, no tuning device but a gauge... I hope you still have factory intake and exhaust or i probably know why you had to replace the engine....

You could at least get an obd dongle and torque pro + mazdaspeed add-on until you get decided on the tuning device (total cost of about 25$) or VT has a free version for monitoring, you just need a compatible dongle.....
There could be more stuff to look at to be worried about than just AFR.

[Kei]

Originally Posted by Jeff23spl Oh well, no tuning device but a gauge... I hope you still have factory intake and exhaust or i probably know why you had to replace the engine.... You could at least get an obd dongle and torque pro + mazdaspeed add-on until you get decided on the tuning device (total cost of about 25$) or VT has a free version for monitoring, you just need a compatible dongle..... There could be more stuff to look at to be worried about than just AFR.

Previous motor was surrounded in super stock bits. I do have a little obd dongle thing, I'm not that bad.

[Jeff23spl]

ok lol
What do you mean by: ''surrounded in super stock bits'' google traduction doesn't return anything useful with this...

[Kei]

Originally Posted by Jeff23spl ok lol What do you mean by: ''surrounded in super stock bits'' google traduction doesn't return anything useful with this...

It was totally stock. I need to get out of the habit of using my super nervous speak.

Ordering an AP for it tonight when I get off work, I really want datalogs out of the car.

Seriously though, thanks for the active conversation.

[Jeff23spl]

I'm a french Canadian, my English is just enough to understand a bit. For jokes or second degree speaking, i started learning here lol...

Just be aware with AP about the training fee and time to get ATR.

[MSMS3]

This may be of help. If you are on stock tune and stock intake, you will be super rich under load. That's Mazda's philosophy.

Below is a Boost v. AFR chart from my MS3 as modified in my signature. I did sort of roll into the throttle, so you see boost rise a bit more gently than might otherwise be the case. This was a fourth gear pull. It probably would have gone rich right at WOT had I gotten on it lower in the power band. I don't like to go WOT in fourth gear at much lower rpm. Rods tend to bend when doing that.

But, as you can see, it drops below 12 and stays down there all the way to redline. I drove it safely that way, making 300 whp for all but the first year of my ten years of ownership. Other tunes take different approaches. All I can say is that you need to be able to log someway and see what is going on, and that rich AFRs are not, in and of themselves, dangerous. Something else must be going on.

BTW, if you are on stock tune, it starts closing down the throttle body at 5,500 rpm and power declines substantially at that point. You can feel it. Good aftermarket tunes maintain power all the way to redline.

On this tune and with these mods, AFR almost immediately drops to 12 at full boost and dropped to 10.5 at 6,000 rpm and as low as 10 afterward until I let up on the throttle between 6,100 and 6,200 rpm and AFR's climbed back up. This is typical for that tune and those mods.

[Kei]

Originally Posted by MSMS3 This may be of help. If you are on stock tune and stock intake, you will be super rich under load. That's Mazda's philosophy. Below is a Boost v. AFR chart from my MS3 as modified in my signature. I did sort of roll into the throttle, so you see boost rise a bit more gently than might otherwise be the case. This was a fourth gear pull. It probably would have gone rich right at WOT had I gotten on it lower in the power band. I don't like to go WOT in fourth gear at much lower rpm. Rods tend to bend when doing that. But, as you can see, it drops below 12 and stays down there all the way to redline. I drove it safely that way, making 300 whp for all but the first year of my ten years of ownership. Other tunes take different approaches. All I can say is that you need to be able to log someway and see what is going on, and that rich AFRs are not, in and of themselves, dangerous. Something else must be going on. BTW, if you are on stock tune, it starts closing down the throttle body at 5,500 rpm and power declines substantially at that point. You can feel it. Good aftermarket tunes maintain power all the way to redline. On this tune and with these mods, AFR almost immediately drops to 12 at full boost and dropped to 10.5 at 6,000 rpm and as low as 10 afterward until I let up on the throttle between 6,100 and 6,200 rpm and AFR's climbed back up. This is typical for that tune and those mods.

I'll watch my wideband and see if it follows something similar. I'm thinking the p/o might have had a tune on it, and sometime during the swap it might have been lost? Weird.

Thanks a ton for that chart, that's awesome.

Originally Posted by Jeff23spl I'm a french Canadian, my English is just enough to understand a bit. For jokes or second degree speaking, i started learning here lol... Just be aware with AP about the training fee and time to get ATR.

Ooo, yeah. Didn't know there was a training fee. Cobb seems to like to add fees to anything they can

[I<3Groceries]

Damn.

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