I received my ECU a few months ago and promptly took it over to have it installed and tuned. Since getting the car back from the tuner, it's has been getting horrible gas mileage. I attributed it to going into boost more often and playing with the new power until recently. I have been diving the car more and even when driven conservatively on flat freeways it's still going thru gas very quickly. During tuning my AFR sensor got fouled and until recently I didn't have the time to fresh air calibrate it, so I didn't know my AFR. Calibrated the o2 sensor yesterday and drove 50 miles each way to a friends house to see how much fuel I'm using over a 100 mile trip and to watch the AFR.

Over the trip the car used about 6.5-7 gallons of gas and ran 11.5-12 AFR most of the time. Also while coasting down hills the injectors no longer shut off and max out the AFR gauge which is very strange since the car has always done this.
My question is, should the car be running this rich outside of boost.
When I had the car tuned I think Rodney told me to have it at 11.2-11.7 going
into boost but I'm not sure what AFR it should be at in non boost conditions. Pushing the car I used closer to 9 gallons to make the same 100 mile trip all freeway.

 

in for answers. my AFR is high 11's from the base map tune sent to me. I know I'm running super rich and my gas mileage is horrible.

hopefully someone will chime in with answers. my AFR gauge should be installed within the month so I can monitor at all times.

good thread idea, Hi Speed.

 

who did the tuning for your car in san jose?

 

Other than AFR, the car is running amazing, which explains why it's taken 5000 miles to really come to grips with the fuel consumption issue. With no more rev hang or reduced power in 1st and 2nd gear and the electronic boost control it drives like what I think a factory turbo car would feel. Very smooth and less all or nothing than the manual boost controller. The IAT sensor is also reading 14 degrees below ambient from the start and 8-9 below while driving so I have full timing most of the time, making the car that much more responsive.

 

Ryan at Tech 3 performance.

 

Dead/shot o2 sensor??? You may have to order a new one to get those AFR accurate and may see your fuel economy freashened up again. The reason why sensors are bad can relate to incorrect fuel mixture, heat, and general wear. So if you've been running the car untuned, spark plugs and sensors would be the first to go.

 

What do your plugs look like?

 

I haven't pulled the plugs to look at them yet. The AFR sensor used by my wideband was fouled by the extra fuel of tuning, but once fresh air calibrated it seems fine. In speaking to the tuner I did discover the ECU is not connected to my wideband, so the ECU is getting AFR info from the stock ECU. This might be where things are going wrong.

 

Hi Jack, If your wideband isn't connected to the MS3, then whoever installed it didn't do it correctly. The wideband and boost solenoid were the two things you had to connect on your own aside from power and ground. The rest was done through the piggyback harness.

Do you have TunerStudio and a laptop to connect to your ECU? If you have the same map I have, 12.x dominates the picture. There is small region for cruising that is in the normal 14-16 area. But if you are like me, you live in the 12's a lot.

 

^so what is the correct way to install the wideband sensor and connect it to MS3?

 

All of the wires are labeled. The documentation says it's a purple wire but the email that Rodney sent me said it was pink. Depending on the W/B there is an analog output wire that you connect to it. Then you have to change a setting in TunerStudio under Tools/Calibrations to match the specific controller.

 

thanks for that response. when i get mine in, i'll post some pics here and hopefully you guys can help me/us figure out the easiest way to do this.

i'll be relaying all this good info to whomever is welding in the sensor and wiring everything up.

 

I haven't installed tuner studio yet, I was watching the videos to get a better sence of the system before messing with the ECU I think my map is slightly different from the one you got but it's good to see 12 is where I want to be. As far as the AFR not being connected I don't know what is going on but I will have to fix it. I thought the ms3 was using my AFR sensor to figure AFR, not the stock computer which has it's o2's connected to defoulers. Guess I need to find a new tuner.

 

i feel like i've asked this before, but i don't remember getting a response.

where should the AFR be set to once everything is tuned?

 

I was thinking about this. It's is impossible that there is nothing going back to the MS3. There would be no basis for it to make any of the A/F adjustments. Ask Ryan how he knows the W/B isn't connected.

If you connect up a laptop, you'll be able to tell if the MS3 is reading the W/B right off. There is no real chance of screwing anything up as long as you keep the controller settings.

And as you said, I don't think the stock sensors are even going to give you an accurate reading. The connection to the MS3 is impossible since they are proprietary W/B in design.

There is no magic number. You want good gas mileage then a higher number is your number. What the most performance, then 12's might be it. Then gas mileage sucks.

The tune I have is supposed to in the upper 300's so I expected my gas mileage to suck.

 

Surely the tuning map is using the MAP (vacuum reading) as a mapping variable, right? If so, then you can have leaner AFR for economy and then have richer AFR for performance based on MAP. Would this work?

 

I figured that since my AFR gauge was not displaying correct, the sensor had to be out of whack and couldn't be giving a good signal to the ECU. The shop I was using just were not getting it done so I think they may have slammed it together at the end to get rid of me. I called about the AFR gauge not working right and how it might be effecting the tune and was told the AFR and ECU are not connected. Which made sence because of how well the car is running, but thinking back I think you are right that the ECU couldn't run from defouled o2 sensors.

 

Yeah, you could have an tune that has less performance or even in our case no boost. But I am pretty sure you'd need TunerStudio to do the swap.

I'm trying to wrap my head around the fuel load to MAP correlation with the MS3. The VE Analyze map uses this and Rodney has mentioned that this somehow relates to the MAP readings. Each cell in the table below also has a target AFR and the auto tune feature uses this to adjust on the fly.

 

Followup:

I did some checking. You can do various things:





The more you look, the cooler this thing becomes.