low fuel trim not staying put?

[sidewaystsi]

Ok i just got an safc and i been having a hard time getting the low trim to stay in one place. I have a 2g mas with evo 560's. When i put those in the low trim went rich,81.2. Now i got the low setting on the safc at -12% at 1k and zeroed out the rest of the way. That seems to get it back right between 101 and 103% while driving, but as soon as i come to a stop and idle for a minute it drops right back to the 80's%? Also i know your supposed to set the lows by just free reving but the trims dont seem to change unless i drive the car. I heard the 1g take a while to change but i sat there for 15 minutes and they wouldn't move. Anyone have an idea why this happens??

 

[sidewaystsi]

No one else's car does this?

 

[91tizzy]

I had the opposite problem a while back with my low trims pegging lean but that was due to some pre 02 sensor turbine/exhaust housing leaks skewing the readings. I was kinda hoping to offer you that advise but you seem to be having the reverse problem....I have a similar fuel setup (550's, 2g maf) but with keydiver setup and since I fixed the exhaust leaks everything has been looking good. How does your mid trim and high trim look? Factory 2g mas? Unhacked?

 

[->PrOjEcTGS<-]

Try logging your O2 trim while trying to setup your tables. The O2 trim is what the ECU is currently trying to do. It will give you a better sense as to which way to go.

Example: if your Low trim is 81 and the O2 trim is fluctuating around 100 where it should be. then you know you need to take a little bit more away so that the low fuel trim will come back up a little bit. Now, if the Low trim is at 81 and the O2 trim is also really rich (in the 90's or 80's) then you know that the low trim is maxed out and the ECU is trying to lean things out even more. Thus, you need to take fuel away. Now, if your low trim is 81 and the O2 trim is high (130-140) then it evens each other out and eventually the fuel trim should come back to around 100.

Any changes you make to the SAFC while logging the O2 trim should give you instant feedback at the logger.

Make any sense?

 

[sidewaystsi]

How does your mid trim and high trim look? Factory 2g mas? Unhacked?[/QUOTE]

Yea its unhacked and mid is perfect at 99-100% and high is 114%. Should i take some pulls and try to richen the high a bit or is 114% within reason?BTW this is at 17psi on the 14b.

Try logging your O2 trim while trying to setup your tables. The O2 trim is what the ECU is currently trying to do. It will give you a better sense as to which way to go.

Example: if your Low trim is 81 and the O2 trim is fluctuating around 100 where it should be. then you know you need to take a little bit more away so that the low fuel trim will come back up a little bit. Now, if the Low trim is at 81 and the O2 trim is also really rich (in the 90's or 80's) then you know that the low trim is maxed out and the ECU is trying to lean things out even more. Thus, you need to take fuel away. Now, if your low trim is 81 and the O2 trim is high (130-140) then it evens each other out and eventually the fuel trim should come back to around 100.

Any changes you make to the SAFC while logging the O2 trim should give you instant feedback at the logger.

Make any sense?

Ok that is info is i think i was looking for so i shouldn't worry to much when it drops that at idle as long as it goes back aroung 100% while driving and it evens out with the o2 trim?

 

[toofast82]

How does your mid trim and high trim look? Factory 2g mas? Unhacked?

Yea its unhacked and mid is perfect at 99-100% and high is 114%. Should i take some pulls and try to richen the high a bit or is 114% within reason?BTW this is at 17psi on the 14b.
[/QUOTE]

The joys of tuning without a wideband
Are you getting any knock when doing your pulls?
What are your idc(injector duty cycle)?
I'm assuming at 100% on the high fuel trim it is targeting the very rich factory 9.3:1 fuel maps. If thats the case 114% maybe something like 10-11:1, but not sure? Thats why I ask about the knock. Obviously if you had a wideband, you would know your exact a/f ratio and it would be pretty simple to tune.

 

[->PrOjEcTGS<-]

Toofast, the high fuel trim doesn't have anything to do with the Open loop maps. All the trims are for closed loop operation to help the ECU target 14.7:1

 

[toofast82]

Toofast, the high fuel trim doesn't have anything to do with the Open loop maps. All the trims are for closed loop operation to help the ECU target 14.7:1

I know low is for idle and mid is for very light load, so is the high just a little more load than the mid while still in closed loop?

 

[sidewaystsi]

I do have a wideband. WOT a/f is 10.9 with which from what i gather is a good ratio for 93 pump gas right? As for the log timing drops to 15 at 4000 the slowly climbs to 22 at 6500 so that seems good right? The o2v are .80, unfortunatly i forgot to log idcI was just wondering if it would be worth it if i leaned the high table out a hair ### this is my dd and im new to tuning so im not trying to live to dangerous haha.But yea my biggest concern was getting the low map dialed in first. Otherwise is there anything else on the logger i should keep an eye on?

 

[sidewaystsi]

Oh yea i probably have the worst case of phantom knock ever(lifters)it seems to be good for a while then comes back with a vengence even just crusing. When i took that pull timming was 22 at 6500 but knock was also at 26? If im knocking that bad why would the timming still be getting advanced?.I would assume timming should be way retarded? Just to be sure i pulled the plugs but those have good color on them.

 

[->PrOjEcTGS<-]

I know low is for idle and mid is for very light load, so is the high just a little more load than the mid while still in closed loop?

Yes, exactly.

 

[sidewaystsi]

Alright i got it now, i was looking at the LFT instead of the o2FT when trying to adjust the low map haha DUH. Thanks for the help guys.

 

[jrohner]

Toofast, the high fuel trim doesn't have anything to do with the Open loop maps. All the trims are for closed loop operation to help the ECU target 14.7:1

The high fuel trim DOES effect open loop operation. That's pretty much the only reason to care about getting your trims really close to perfect.

The low trim is kinda weird even stock on a 1G, so I wouldn't worry about it too much.

I look at the o2 trim mostly when tuning rather than the LTFT's.