Mazda 6 Forums banner

1 - 11 of 11 Posts

·
Registered
Joined
·
578 Posts
There is a thread on 6tech discussing manifold restrictions where mike2005 was kind enough to post his short term fuel trims for idle, 3k RPMs and at WOT. Give it a read (3/4 down the page)-> Here.

Maybe not exactly what you are looking for, but it's a place to start.
 

·
Registered
Joined
·
1,906 Posts
Doesn't really matter what the fuel trims are. Individual differences in the engine will probably cause cars to each have their own trim characteristics.

Ideally, you want each bank to be as close to the other as possible.
 

·
Registered
Joined
·
578 Posts
^ Excellent point.

There are so many factors that go into determining fuel trims that you almost can't compare one vehicle to another to gain an understanding of what normal is. Only way to know is to log your car.
 

·
Registered
Joined
·
981 Posts
Fuel trims should be as close to 0 as possible.

If they're negative, you're running rich which means the car is putting more fuel in because of some imbalance.

If its positive, you're running lean where its putting less fuel in and allowing more air, this could cause engine detonation if it gets out of control.

I scanned Mike2005's car a wihle ago, his long term trims were about -10%. Mine on the other hand, were about -24% which caused me to get CELs due to running too rich. I have since gotten a tunable MAFci from CPE and I tuned it down so its closer to 0, no more CELs.

Also, running rich will produce extra soot to show up on your tail pipes, so check for that.

What kinds of problems are you having?
 

·
Registered
Joined
·
1,302 Posts
Discussion Starter #6
At idle, my short terms are at 0, same as when I'm at speed. Long term trims on the other hand, are +20.3 at idle, and between +5-10 at speed.

I'm just trying to figure out why my Catalyst Monitor is showing as Not Ready. It's the only emissions monitor that shows as Not Ready. My cat temps are around 1500 degrees, and I read that they're supposed to be around 1200. I thought maybe my car was running rich, and that's why the cats were hotter, but I guess not.

I think I need to use a visual oscilloscope thing to read the O2 voltage, 'cause it's hard to visualize it just using an AutoXray. My downstream sensors seem to fluctuate at the same speed, or slightly slower than the upstream ones, and I read that the Catalyst Monitor uses a cross check ratio b/w the up and downstream sensors to determine the cat's efficiency.

I don't understand why the cat's wouldn't be working, I just got my y-pipe replaced by Kooks at the end of August.

Anyway, I'm slightly intoxicated right now.
 
1 - 11 of 11 Posts
Top