very nice view of warm up ... looks like the afr is only recorded with a resolution of 0.1 afr. not that this is any type of issue just curious.

First, I respect your opinion here.

Take a look at these runs http://911chips.com/dyno.html on Steve's web site and you will find many of the runs have a very flat AFR=13.0 or so for WOT runs across the RPM range. In general the target is in the 12.8 to 13.1 range but I do tend to agree that in certain parts of the RPM range at WOT you may want to go richer. The only way to know what works is to test on a load dyno.

Correct! I record .1 resolution for AFR and I can easily record .01 if I wish. I just figured .1 was good enough for my purpose.

Sal,

In your logging, have you noticed a certain AFR pattern in the 5-6.6K (while running the engine in one gear from 2K to redline, WOT) , where the mixture tends to go a point or two richer?

Regards,
jp

JP,

I tune my AFR at WOT and can make it look anyway I wish but to your question I have noticed and seen other runs that tend to put more fuel into the engine at max torque (5-5.7K) range. In this area right around 5K I have seen folks bring the AFR richer about .2 points. I think this is not a bad idea because more fuel reduces cyl head temps as well as detonation. Keep in mind that max torque is the most stress on the engine.

In my car right now I run about 13.0 on cold low humidity days and tend to run in the 12.8 range for hot humid days. The motronic has this built into the system via the Air Temp Sensor on the AFM, by default the maps for this sensor tend to richen the fuel with hotter air temps. This is why you MUST take into acount the air temp and humidity on the day of the tune.

With that said I have toyed with AFRs that tend to richen in the 5-6K range or simply above 5K but I have not had any dyno time yet so I'm not sure if this makes any diffrence?

Sal,

My first chip had a slight dip (rich) in the 5-6K range, after submitting AFR logs to SW, I found the tuned chip had a slightly more pronounced dip, which also went a little farther 6.6K rpm. I didn't get a chance to do back to back tests between the two, and I don't think the difference is noticeable by the butt dyno. My final AFR readings are very similar to yours 12.8-13.1. I tried experimenting with the DME fuel/timing pot, but didn't find any discernible difference aside from the AFR readings.
I'm very impressed with your logging data, it gives excellent feedback to what is going on within the engine.
It's interesting how you see the temp changes while operating the engine under less than optimal conditions; it confirms that the engine works best in the "sweet spot" of the rpm range. I don't understand how some people operate the engine in 5th under 4K rpm???

Regards,
jp

Sal,

Do you adjust the DME mixture/ignition pot depending on ambient temps? I know the Motronic adjusts for temp fluctuations during the part throttle maps, but during WOT, the mixture is set by the chip's burn. It would seem that ambient temps would have an affect on the AFR in WOT mode.

Regards,
jp

I never move the fuel quality switch on the DME, I leave it set in Pos 0. I have toyed with this switch in the past with no real good results.

Then, the AirFlowMeter has a built in Intake Air Temp Sensor this helps the DME calculate/adjust fuel based on intake temps. This must be done because the Barn Door AFM is NOT a MassAirFlow sensor it is only a simple air flow sensor and does not measure mass of the air (density) so air mass must be calculate from air flow and air temp. There are maps in the chip that use intake air temp and adjust fuel based on the combination of air flow measured by the barn door and air temp measured by the sensor. Simply cold air is more dense than hot air so this means cold air requires more fuel to achive target AFR than hot air needs. Simply as air gets colder fuel needs to go up. The required fuel difrence is not much but does need to be adjusted. If this adjustment where not done and the car was tuned at WOT for 13.0AFR on a 90 deg F day then the same car would lean out at WOT on a very cold 20 deg F day, I would suspect it could lean out as much as 13.5AFR which would not be good.

In contrast the new style Hot Wire MAF devices truely measure air mass and don't need to be corrected based on Air Temp. But even with a MAF you often still see a Intake Air Temp Sensor because in general you want to add a little extra fuel on very hot days. For example; at WOT on a 20deg F day a AFR of 13.0 may be a good choice but the same car on a very hot 100 deg F day is also under higher stress and higher CylHeadTemps at WOT and it's just a good idea to add some fuel under these conditions just to be safe I'd bring the AFR to 12.8 under these very hot days.

This idea of brining AFR richer on hot days is already pre-built into the DME maps via a special fuel trim map that richens mixture as air temps get colder based on the IntakeAirTempSensor.

The Bosch engineers really did there homework here.

Sal,
Is the intake temp sensor in the AFM "active" during WOT? I was under the impression that these sensors were bypassed when the TPS clicks the WOT switch??
Is just the O2 sensor ignored during WOT?
Regards,
jp

There is much mis-undertood info on the WOT mode of these DME boxes. From my personal research I have found that even in WOT mode the AFM signal is used and so is the AirFlowSensor. However, one truth is that the AFM barn door is for the most part fully opened at about 5200RPMs under WOT conditions, you can find some graphs I posted earlier in this thread that show this, this means that after 5200RPM the DME calculates fuel based mostly from RPM.

Then, you are correct that the O2 sensor circuit is completely ignored as it must be because if it where not the closed loop mode would try to bring the AFR back to 14.7 and this is not the case. I know for sure that the AFR at WOT is in the 13.0 range.

Sal,
just asking... do you think the stock DME outputs 13.0 at WOT all the way up to ~6300?
if yes, then does this somewhat discount the discussions of the AFR dropping to way rich at the higher rpms? E.g. I saw my AFR drop close to being in the 10's at higher rpms..and WOT.

I really can't comment much on the stock setup since the car I bought is not stock. But I suspect that maybe the AFR at WOT that came from the factory may not be a pin straight line of 13.0 across the RPM range. I have heard that the stock chip setup does actually run slightly rich in the 12.5 to 12.8 range but I have no way to verify this.

But I can tell you that if you are seeing AFR in the 10s anywhere in the RPM range at WOT you are WAY rich and will never produce max power with AFR in the 10s. The only time I have ever seen AFRs in the 10s in my car is at very Cold initial startup on days where temps are below 50deg F. Something is very wrong with your setup if you are seeing AFRs in the 10s at WOT. You can see plenty of dyno runs with AFR values on Steve Wong's site http://911chips.com/dyno.html you will also note that most of the tuned runs have very straight flat AFRs in the 12.5 to 13.0 range. I suspect your Cyl Head Temp Sensor could be bad and indicating that CHT is much colder than it really is, test the CHT sensor.

Stock chip programming on 911 motors are far from optimal at WOT. They are mapped to be lean at low and mid rpms for emissions, and very rich at upper rpms to a)keep the cat cells from melting down on extended WOT runs on the autobahn, and b) for the worst of conditions with low octane fuel to minimize warranty claims. This is especially true with the 3.2s and 993s. As you know Porsche has to warranty emissions systems including the cat for 10 years. The following dyno data is very typical of a stock 3.2 motor showing the AFRs of the stock programming, and the AFR and power gains after AFR optimization and reprogramming for 93 octane fuel.

Steve,

Nice graphs. I would never had thought the stock setup dips close to 11.0 AFR at high RPMs, nice to know.

Thanks for your input here, glad you pitched in on this topic.

I know the thread is old but here's my entire WBO2 system in action along with my EPROM emulator working hand in hand:
https://www.youtube.com/watch?v=OYgYEoQkjT8

I've been using this setup to live tune for a few years now.

Thought I'd post an update.

Sal, that was a nice video. I like where TunerPro shows what area of the table it accesses in real time. It makes tuning a lot easier. It reminds me a little bit of the Megasquirt setup.

Does TunerPro support self-optimization of part-throttle maps? In Megasquirt you can create a part throttle A/F map. Then you drive around and MS will log A/F data as you drive around. After enough driving it will suggest changes to the PT fuel map to meet the target A/F ratio table. With that you can tune to maximize fuel efficiency at lower RPM ranges and then gradually step up to optimum power in the higher load/RPM areas all the way to WOT where all you want is maximum power.

Ingo

Ingo, the emulator can only do hit trace it can not do any self tuning. But I use the setup often for dyno steady state tuning and it works wonderfully.

Nice work sal didnt realise it was so cheap and easy to interface the stock ecu. I have an 84 carrera as well and will look at this shortly seems quite cost effective.

This thread is a few years old and the WideBand I used 2J1 is no longer available but the best unit for the money now is the 3A2, it has a ton of inputs and supports the better LSU 4.9 wideband sensor that needs no free air calibration. The 3A2 also has a native built in true USB port.

http://wbo2.com/3a1/default.htm