Can someone explain why my AFRs don't seem to match my fuel maps? Here are the details:

I am using a Zeitronix wideband to log AFR and boost (peak of 24 psi and tapering to ~21.5 at redline). My AFRs are too lean (~11.9 - 12.4) from 3500 upto 7781, but I dont see any knock until 6800 / 7000 (timing 15*) and AFR 12.4. Like I said, I know this is too lean and will richen the maps up a bit, but what I don't understand is that in the load target area my fuel maps are as rich as 9.3 up to 10.0, but nothing close to 12. Why is the actual AFR so off from the ECU map??? Should I just bump everything by .4 pts? Have I maxed out my fuel injectors?

My wideband sensor is on the downpipe right before my catalytic converter.

Mods are:

3" TBE w/ hiflo cat
Nisei LICP
HKS Super Hybrid filter
Modified airbox lid
Walbro fuel pump

 

because those targets are based on a completely stock car and you have several mods that will affect it. you just use the AFR target number as a reference point for changing it.

 

Numbers on the fuel map between cars are not always comparable, and as hondafan explains there is usually an offset anyway on the standard car. This is due to lean spool. However, at similar boost to you with similar mods (but IX JDM/UK), I find that 9.6 just before 4000 gives mid-high 11s:1, at 4000-red line 10.2 gives mid 11s richening just into the very high 10s at red line in a high gear with lean spool disable set to 7500 RPM. At the red line in intermediate gears I only run about 19-20 PSI on datalogs and have about 95% IDC with the mentioned AFRs. At this point they are about static anyway and the precise AFR control has gone.

You can calc IDC on your log by multiplying IPW and RPM and then dividing by 1200 to see if you're maxxed out or not...

Don't know about your fuel, but if I force it to 21.5 PSI at red line I get it back in the low 11s again with 100% IDC, but I have to retard a lot of ignition and the car is I think slower. This is 99 RON which is probably about 94 PON.

 

They are theorectical A/F figures. Not actual by any means

 

Thanks JCS...As you can tell, I bought the air filter you were (are) using as well as swapped the airbox lid for one with similar cutouts..

My IDCs seem to be a bit high -- @7000 rpm they are 95% and then at 7281 rpm they are 101% and then at 7781 rpm they are at 106%. I am not sure how technically it can go over 100%, but I believe I read that max is 120%. Thoughts??

I should be hitting 16* + at redline (that is what I was hitting before at least) once I get the AFRs worked out.

 

They are not even close in the higher load cells on a completely stock car.

 

It can't go over 100%, and even at 95% it probably never has time to close the injector before the next pulse. If it shows a higher pulse width it just means that the ECU has calculated that it needs a higher pulse width. So in this case increasing the fuel map number will not make it richer once you're already at 100%.

Might be worth checking your fuel pressure at high RPM since usually the stock injectors will keep up with the stock turbo on pump fuel with a fuel pump.

 

I was afraid of the injectors being maxed out...

Is there an easy way to log fuel pressure or are we talking about putting a in cabin display and have someone monitor it?

Also, I am wondering if I should just decrease the top end boost a bit or put the stock airbox lid back on. Thanks

 

Depends how accurate your boost gauge is as to whether to reduce at the top. It is normally quite difficult to hold 22 PSI at 7000 RPM on the stock actuator, and IMHO loses power on pump fuel if you do because of knock requiring ignition retard. I tend to go off a MAP sensor datalogged with RPM to be sure.

I would not restrict your inlet to reduce your injector duty cycle, I would reduce the boost level if you have to do anything.

Fuel pressure check would be from a gauge and tested at high RPM where it runs lean.

So we don't know if you're car is a freak car making oodles of power and overwhelming the injectors or if you have a fuel supply problem.

 

FWIW I found I made the best power at lower boost levels and more aggressive timing.. Sure there was a bigger torque peak if I let it spike, but if I kept a 20psi or so boost curve, and kept things fairly lean with fairly aggressive timing, I made more power than much higher boost levels (on pump gas that is)

 

One possibility that was not mentioned is that your sensor might be giving you the wrong data.

Try re-calibrating the sensor or get a new. IIRC, a dying sensor give lean readings. But the ZT2 controller should give you an error message if your sensor is fading, shouldn't it?

 

Thanks guys...I believe it is the IPW cutoff set at ~7K that is causing the problem (spoke to John this AM). I need to increase this (although it is greek to me)...

That said, boost is logged with Zeitronix and is very accurate. I have also logged boost in the past with Innovative.

I cannot wait to be able to take my AFR and boost logs and incorporate them into either Mitsulogger or Evoscan ....

 

If you're logging it with the Zeitronix and it shows 22 PSI at 7000 RPM then I'd believe it.

I put my IPW step (lean spool disable) at 7500 as I keep the stock rev limiter at 7606 RPM and usually shift at 7000.

Your IDCs will come down by moving it, but if you are lean with 100%+ IDC then you'll only get leaner.

You might have a stiffer than average wastegate pre-load which gives you more top end boost. As discussed though you need to know that the extra boost is winning you extra power, or are you just heating up the EGTs by running more boost and more retard at the top where the VE is low because the exhaust manifold pressure is so much higher than the inlet manifold pressure? Engine becomes like a pressure cooker, or a big constipated man that can't fart if you prefer

 

Download Mitsulogger 1.5 alpha, Zeitronix support is in there, it incorporates all of the zeitronix data into the MUT logs, I only added the AFR information to the Data Log Lab definition, but its all in there.

 

I thought that IDC could actually go above 100% on the IX since the fuel injectors are bigger than what the ECU thinks they are. (ECU thinks they're 513cc/min but they're actually 560cc/min). Or am I talking out of my ***?!