AaronL

iTrader: (1)

Hi all,

My max (2001, 180k km) has quite different fuel trims on the each bank:
Bank1- short term fuel trim 4.6%
Bank1 - long term fuel trim 3.1%
Bank2 - stft - 2.3%
Bank2 - ltft - 8.5%

The engine definitely seems to be running rich (strong smell in the exhaust). I've also got an intermittent (a couple of times in a few weeks) misfire in bank 2 - I think I've isolated it to a bad coil, but it's hard to be certain with it being so intermittent.

Do those fuel trim values seem reasonable? From what I've read it seems like bank 2 is borderline- could it be due to a failing upstream O2 sensor?

My fuel economy sucks, but it always has - about 17 mpg city.

MadMax SE

You can test the resistance of the coils to see if they are going bad, those fuel trims look ok for the mileage your getting. My bank 1 sensor 1 was OEM at 220k and was causing me to get 11 mpg highway with a stft of 7% and a ltft of almost 10%. I'm guessing my sensor died and was giving just enough of a reading to not throw a cel. The same sensor failed the diagnostic check in torque pro app.

AaronL

iTrader: (1)

What OBDII device are you using? And what year is your car? I bought a cheap ELM 327 and I can't get it to work with my max. (I pulled the fuel trim values from my dedicated reader which can pull freeze frame data- it can't read fuel trim on it's own though).

(Edit: The ELM doesn't work with my 2001 Max but does work with my wife's Mazda 3. I think the device just doesn't support whatever protocol the 2001 ECU uses)

MadMax SE

i have a 2000 se and a cheap flea bay elm327 adapter so i dont see why it wont work. certain apps dont like certain cars. give torque app a try.

AaronL

iTrader: (1)

Hmm... I've also got an elm327. I've tried torque (and a bunch of other apps) but can't get it to work. Maybe I'll try ordering another one, but this does remind me how much I hate working with crappy tools

MadMax SE

Mine in finicky aswell, you have to select it from the Bluetooth menu and connect before you start torque everytime. The key has to be on acc2 or running. If you can get it to work torque can rest your sensors for you and tell which one fails its accuracy test. My adapter Was about 10 dollars

ManualMaxima

iTrader: (10)

My ELM27 has worked perfectly with my 01 Max for years. I run an app called DashCommand.

Derrick2k2SE

iTrader: (3)

I had to try a few ELM adapters to find one that works. The diagnostic apps work great with a good adapter.

Derrick2k2SE

iTrader: (3)

There's a whole lot more to fuel trims than high or low and you'll have to view them live. There's not much that can be learned from one static reading.

This guy does a very good job of explaining fuel trims in a way most people can understand.

MadMax SE

I thought torque displayed live readings? I know it has graphs for the o2 sensors because I used them to see my lazy o2's. One had a steady .2v and the 2 a/f ones wouldn't go past .5v at all. After I replaced them the readings looked like most videos I've seen. I would watch my fuel trims for both banks while I would drive normaly.

AaronL

iTrader: (1)

Thanks, that's a really good video! I especially liked the 'quizzes'

I've ordered another adapter, once I got my new coil installed I'll test it out and see if I can find anything of interest with my fuel trims.

Derrick2k2SE

iTrader: (3)

Yes, Torque can do all that. You can make gauges for the STFT and LTFT for each bank all on one screen. You can chart the voltages as well.

I have Torque Pro and Car Gauge Pro.

IMO, Torque has more and better gauges and is easier to set up. You can create a gauge for practically any sensor on the car.

Car Gauge Pro is much faster to read and clear codes. It also allows you to adjust the timing, RPM, shut down individual cylinders and do several relearns.

The two apps plus a good ELM adapter make a powerful tool that's always with you and still costs less than a cheap reader.

AaronL

iTrader: (1)

I picked up a another cheap ODB2 adapter (VeePeak) and this one works nicely.

I used Torque Lite to look at my fuel trims and I get conflicting values from the graph display and the dial display (not just blips where the dial reacts faster than the graph). I consistently see the STFT graph looks to be -6 % while the STFT dial shows only -3%. Anyone else see this? It's going to be hard to figure out what's going on if I can't get accurate values!

AaronL

iTrader: (1)

I think I figured this out - "Torque Lite" is garbage (apparently). I was seeing consistent -30 LTFT with no codes (or driveability issues) - suspcious right? Upgraded to "Torque Pro" and things look normal now.

Aleiben

What's the avg MPG City for 5th Gens anyways?