deceleratoin high afrs

[kurt fuhlbrigge]

When I do my 3rd gear pull and let off at the end , my wideband will read 18:1 from 70-40 mph is this normal or lean ? I know ecu shuts of fuel when you let of the gas . Is 18:1 ok for a couple seconds under deceleration ? If not would you richen it by adding inj deadtime or raising the maf settings at idle .Thanks

 

[Calan]

It's normal. With no fuel being injected on deceleration (and the throttle blade shut), it's gonna run about as lean as it can get.

Once you get down to a certain range of RPM and load, the ECU will start injecting fuel again to maintain idle.

 

[kurt fuhlbrigge]

Ok ,Thanks .I think I'm getting close . How about my idle . It's around 14.7-15.3 ( ltft is -.8 combined ft 1.4 stft 2.1 inj dt 165 ). Does the computer set that ? I cant seem to make it change . I'll post a new log soon . Thanks Calan you're a big help .

At the end of the run my ltft -1.4 stft +1.4 cft 0.0 They bounce around a little

 

[Calan]

It's around 14.7-15.3 ( ltft is -.8 combined ft 1.4 stft 2.1 inj dt 165 ). Does the computer set that ? I cant seem to make it change .

That is called closed loop operation, and the ECU tries to maintain an AFR of 14.7:1 using feedback from the O2 sensor. CombinedFT and LTFT are a way of indicating how hard the ECU is having to work to do that...in a matter of speaking. When accelerating or going WOT, the ECU goes into open loop mode and tries to hit a target AFR based on the DA table and fuel sliders...but it doesn't use any feedback to see if it hit it or not.

You should probably do some reading on the ECMLink wiki pages. There is a lot of good information up there on all of this. Here are a couple of good pages to start with:

Basic Engine and ECU Operation
Fuel Trims

Thanks Calan you're a big help .

NP

 

[turboglenn]

untill around 1700 - 2kRPM on decell the AFR's should go to nothing on an AEM wideband as the injectors should shut down completely. If they are staying showing a reading then you ptobably have a TPS outof adjustment

 

[kurt fuhlbrigge]

Always looking for good reading mat thanks . Wideband pegs on decel but reads 18:1 on laptop ,which I believe is maxed out . Looks like everything is normal . Good ,some more tweeking and I'll be on the road . Got a good laugh from my neighbor doing a 1 wheel power brake burnout in front of my house last night . I told him my ford f150 will do that .Ha , Ha . That boy don't know what he is playin with . Mitsi is FAST . With a half as**ed tune .

 

[-red97rum-]

ptobably have a TPS outof adjustment

Or the brittle little wire might have come off the closed throttle switch.

 

[kurt fuhlbrigge]

No closed throttle switch wire ,I'm using the 2g tps . And that is adjusted . I think everything is ok . I'll post a log tommorrow .I have one now but I think the adjustment that need to be made are obvious . I just needed to understand a little better .I'm on track . Thanks