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View Full Version : Got 550s but low trim maxed lean...


94EclipseGST
09-17-2004, 07:22 PM
I'm using 2.01 MAFT. Mods are: K&N, Dejon Tool UIP, Autometer Boost Gauge, TurboXS HPBC, TurboXS H-34 Racing BOV, Apexi 2.5" catback, 2.5" Magnaflow High Flow Cat, RNR 2.5" downpipe, 2G Exhaust Manifold, SBR B16G Turbo, ACT 2100 clutch and XACT flywheel, datalogger w/MMCd, 3G revised lifters, 3" GM MAF/MAFT, FIC 550cc injectors

I have the following setting:

Aux=0
Base=C
Idle=8

I can't richen the idle anymore. What should I do? So far, the Mid and High trims are 100%, but I haven't done a steady state drive yet. I'm trying to get the low trim off maxed lean, because it knocks like crazy under even minimal boost.

HELP!

Thanks,
Steve

98spydert
09-17-2004, 07:38 PM
i had that problem and ended up switching to dip switch settings for the 3.5 MAF. That sent me extremly rich rather than extremly lean. There's more room to lean out the base settings than richen it so that worked better for me. I still run 3.5 MAF settings for my 3" MAF.

94EclipseGST
09-17-2004, 09:17 PM
i had that problem and ended up switching to dip switch settings for the 3.5 MAF. That sent me extremly rich rather than extremly lean. There's more room to lean out the base settings than richen it so that worked better for me. I still run 3.5 MAF settings for my 3" MAF.
I moved the settings to:

Aux=0
Base=A
Idle=8

This worked a little bit, and brought the trim to 120 range. I'll try what you said. When you switched to 3.5, did you leave the base setting:

Aux=0
Base=C
Idle=0

Thanks.

98spydert
09-18-2004, 05:25 AM
No when you switch at 3.5 settings, it sends you to the other end of the spectrum. Instead at starting out at extremly lean, you start out at extremly rich. You need to adjust the base to lean it out. When you start lean, you've only got 2-3 clicks before you're maxed out on the base knob while going rich. When you start rich, you've got like 10 clicks lean before maxing out the base knob in the other direction... maybe I don't make sence :(

Talon91
09-18-2004, 01:34 PM
Mine is RC550. I've tried to use Aux=0, Base from 5 to A. Idle always need to be 7 or 8. Low trim is still > 100%. That's very ridiculous. I'm still trying error.

kpt4321
09-19-2004, 03:53 AM
The low trim is only active at idle, so it has nothing to do with knock at part throttle. That's going to be the high trim, into the open-loop range controlled by the mid knob on the MAFT.

Talon91
09-19-2004, 01:05 PM
:confused: So if I have a low trim like 120~140% and keep mid and high trims to 100%, it would not hurt my baby?

My part throttle knock often occurs at the 180Hz, O2 trim > 100%. But before 180Hz, O2 trim is <100%. After 180Hz, O2 trim would also be < 100%. It seems that 180Hz is a lean point. Is that because I set Idle to 7 or 8 (too rich)?

kpt4321
09-19-2004, 02:49 PM
:confused: So if I have a low trim like 120~140% and keep mid and high trims to 100%, it would not hurt my baby?

My part throttle knock often occurs at the 180Hz, O2 trim > 100%. But before 180Hz, O2 trim is <100%. After 180Hz, O2 trim would also be < 100%. It seems that 180Hz is a lean point. Is that because I set Idle to 7 or 8 (too rich)?

Are you saying that the car is lean only at 180 Hz, and nowhere else? That's just weird.

Talon91
09-19-2004, 03:04 PM
Are you saying that the car is lean only at 180 Hz, and nowhere else? That's just weird.

What I mean is that occasional part throttle knock is at that point. But there's no knock at WOT. Just hate that part throttle knock.

I just would like to know if it is ok to let low trim between 120~140%?

kpt4321
09-19-2004, 03:15 PM
What I mean is that occasional part throttle knock is at that point. But there's no knock at WOT. Just hate that part throttle knock.

I just would like to know if it is ok to let low trim between 120~140%?

It's fine to leave the low trim at 120, even 130. At that point, the ECU still has control over the mixture, so you're probably fine.

94EclipseGST
09-19-2004, 11:10 PM
Hey, you guys hijacked my thread!:p

So, knock at part throttle is in the Mid knob range. My mid and high trims are at 100%, so I thought it had to be the low trim because that was the only one lean. Hmm. I'm confused again.:confused:

Today, I moved the dip switch to 3.5 and then started leaning out the idle. The car runs much slower than it did when set to what I said in the first post. Also, fuel cut sets in. I'm going to go back to my first setting. The car ran really strong with the low trim about 120. It was getting high knock at partial throttle, even with the other trims at 100.

Could it maybe be a timing issue? I reset it to 5* before I reinstalled the MAFT and put the new injectors in, though.

Kyle, HELP! :eek:

kpt4321
09-20-2004, 02:57 AM
The low trim is in effect at idle. The hi trim is in effect at highway cruise, up to about 3-4 psi of boost. In between the two is the mid trim (and you can see that you're actually usually in the lo (idle) or hi (cruise) range).

If you're knocking before the car goes into open loop, then you might want to check the mid trim.

The mid knob on the MAFT is for tuning the boost transition. It will effect the hi trim, but only at higher throttle angles so it probably won't show up in the trim much. If you're knocking at boost onset, try richening the mid knob.

Talon91
09-20-2004, 03:09 PM
Well, today I reset for the test as below; My related mods are RC550, 255L fuel pump (38psi), and base timing is 5*.
Aux=0, Base=5, Idle=5, Mid=0, Wot=0.

The results of Fuel trims are Low=140%, Mid=98%, High=100%.

:mad: Still got the partial throttle knocks between rpm1500~3000.

Should I try to set Aux=0, Base=4, Idle=5, Mid=0, Wot=0 to rich low fuel trim?

94EclipseGST
09-23-2004, 01:25 AM
Well, today I reset for the test as below; My related mods are RC550, 255L fuel pump (38psi), and base timing is 5*.
Aux=0, Base=5, Idle=5, Mid=0, Wot=0.

The results of Fuel trims are Low=140%, Mid=98%, High=100%.

:mad: Still got the partial throttle knocks between rpm1500~3000.

Should I try to set Aux=0, Base=4, Idle=5, Mid=0, Wot=0 to rich low fuel trim?I switched to:
AUX=0
BASE=D
IDLE=8
MID=1
WOT=0

I noticed that my partial throttle knock has gone down to no more than 3 counts in any of the gears. However, my low trim is still maxed out at 140.

I put the scanmaster 3 in today, and made a run. Car pulls hard and hardly any knock but that dang low trim makes me nervous. My midtrim is 98 and high is at 91. No fuel cut like I used to get, but I cannot get the low trim off maxed lean.

Anything else I can try or should I just not worry about that low trim if I'm getting almost no knock in all gears?

Kyle, as always, your expert opinion is greatly appreciated.

94EclipseGST
09-23-2004, 01:28 AM
Well, today I reset for the test as below; My related mods are RC550, 255L fuel pump (38psi), and base timing is 5*.
Aux=0, Base=5, Idle=5, Mid=0, Wot=0.

The results of Fuel trims are Low=140%, Mid=98%, High=100%.

:mad: Still got the partial throttle knocks between rpm1500~3000.

Should I try to set Aux=0, Base=4, Idle=5, Mid=0, Wot=0 to rich low fuel trim?
Wait, you are leaning out your base instead of richening it up. I think if you are getting partial knock, you might actually want to richen the base knob (remember, base knob is opposite--to the right is lean, left is rich). But hey, what do I know, I'm in here asking for help too!!!:)

Talon91
09-23-2004, 02:22 PM
I switched to:
AUX=0
BASE=D
IDLE=8
MID=1
WOT=0

I noticed that my partial throttle knock has gone down to no more than 3 counts in any of the gears. However, my low trim is still maxed out at 140.

I put the scanmaster 3 in today, and made a run. Car pulls hard and hardly any knock but that dang low trim makes me nervous. My midtrim is 98 and high is at 91. No fuel cut like I used to get, but I cannot get the low trim off maxed lean.

Anything else I can try or should I just not worry about that low trim if I'm getting almost no knock in all gears?

Kyle, as always, your expert opinion is greatly appreciated.
:) Great, I'm glad that you made it under 3 knock counts. I never tried to set Base to D since I was afraid to make it too lean. I'll try to set Base=D to check the results. I'll let you know.......