So I went to start tuning the ecu and...

[Keyan]

my front Low fuel trim is at +12.5%, and my rear low fuel trim is at -12.1%.

um, LOL.
*throws in the towel*

i can supply a log but this forum doesnt allow .csv files to be uploaded.


not sure what to do. if i increase the fuel, it'll fix one bank but make the other worse. and visa-versa.

the weird part is that it seems to idle just fine at 14.7.


where the heck do i even start with that?

[Greg E]

FPR over run. It does that to your trims.

[futurevr4man]

i have almost the exact same problem except im adding fuel, and its not changing the values at all. i do not have any overrun, i can guarantee that. suggestions?

[Keyan]

i have an aftermarket regulator.

[futurevr4man]

i have an aftermarket regulator.

as do i. an aeromotive, about 42 - 43 psi base

[Rom3BreaK]

Similar over here, aem fpr.

Sent from my Motorola Atrix

[Keyan]

oh good, its not just me. lol

[futurevr4man]

i need to figure this out asap. need to get the car tuned today. i change fuel and reflash, but its not changing the fuel trims

[Greg E]

i change fuel and reflash

What do you mean by this exactly? You're changing the fuel table?

I always assumed this happened in my car due to FPR over run, but it appears that's not the case with all you guys.

[Greg E]

Also, it takes 16min for the long term trims to update. Make sure you're changing the MAF comp values with-in the correct HZ range of the trim you're trying to adjust.

[futurevr4man]

yeah i changed fuel values and then reflashed. i have done it 3 times now, and the trims are still stuck at 12.5

on top of that, arent the values supposed to zero out and reset themselves everytime you do a reflash? because mine have not done that

[futurevr4man]

Also, it takes 16min for the long term trims to update. Make sure you're changing the MAF comp values with-in the correct HZ range of the trim you're trying to adjust.

are you referring to the VE table? do you recommend we tune off that still, or should we change the big fuel table like the evo guys?

[Greg E]

yeah i changed fuel values and then reflashed. i have done it 3 times now, and the trims are still stuck at 12.5

Adjust the MAF Comp (VE) tables to get your trims back with in spec.


on top of that, arent the values supposed to zero out and reset themselves everytime you do a reflash? because mine have not done that

No. Where did you read that? The only way to reset the trims is to reset the ECU. There might be a MUT command to reset them but I haven't figured that out yet.

[futurevr4man]

so i just need to make an adjustment, then go out for a long drive every time to let the ecu properly adjust everything then?

would you say that the VE table is for the big changes, and the fuel table is to get the fine tuning perfect?

[Greg E]

so i just need to make an adjustment, then go out for a long drive every time to let the ecu properly adjust everything then?

would you say that the VE table is for the big changes, and the fuel table is to get the fine tuning perfect?

The fuel table is more like your target AFR table. The MAF Scaling table is for fine tuning. The MAF Comp (VE) table is for big changes.

[futurevr4man]

The fuel table is more like your target AFR table. The MAF Scaling table is for fine tuning. The MAF Comp (VE) table is for big changes.

that makes perfect sense. the maf scaling table is what converts from hz to actual amount of air (grams/second) from what i can tell. i have never even looked at that table before.

the only thing that doesnt make sense to me is still why my fuel trims havent changed. i have gone up about 3% across the lower Hz area of the VE table, and then driven for at least 20 minutes and they didnt change a bit. not even .1%...

[Greg E]

Just curious. You didn't disable any of the bits in periphery 0 did you?

Are you trying to tune the low long term trim? That one only adjusted at idle.

[futurevr4man]

Nope, didn't disable any of those bits. And I know the low fuel trim is tuned out at idle by the oxygen sensor feedback.

My mid and low fuel trims are at 12.5 and my high is at zero. My afrs sit perfect sometimes then like hitting a button go real rich (high 12's) or lean (high 15's).

I am having a REALLY bad lean spike that happens as soon as boost is coming on. The lean spike is my biggest concern and I'm having a real hard time getting rid of it. The wideband usually hits about 18.0 then it more or less gets past a point (I can't seem to find a common denominator on what that point is) then it's fine and the car pulls either partial throttle or wot with no issue.

I know these are noob questions and I'm sorry :/

[Greg E]

Add more % to the Accel Enrichment TPS Delta Multiplier table. The white numbers on the left hand side correspond to the difference in your TPS % from how far you push the pedal. It won't fix the cause of your lean accel, but it'll help cover it up.

...remind me again. Are you running an open atmosphere BOV?

[futurevr4man]

Yes I am but I am also running a blow through setup. I also have the 3.75L engine so I expected a lean spike or two

[futurevr4man]

one more question, greg. my maf hz signal is maxing at 1600 now even though its scaled for 2800. any thoughts on that?

[Greg E]

one more question, greg. my maf hz signal is maxing at 1600 now even though its scaled for 2800. any thoughts on that?

You're logging the wrong request. Read up about the 2-byte stuff in the chrome thread.

What's funny is in chrome 2.1, i'm getting rid of the 2-byte stuff and redoing the MUT with all new 1 byte variables that can read double what they can now.

[Keyan]

i have the same lean spike with a 3.0 engine with blow-through.

i have turned up the delta multiplier a good 6 points across the board and i still havent seen any change to my lean spikes. I gotta play with it some more.

[futurevr4man]

You're logging the wrong request. Read up about the 2-byte stuff in the chrome thread.

What's funny is in chrome 2.1, i'm getting rid of the 2-byte stuff and redoing the MUT with all new 1 byte variables that can read double what they can now.

i will do this and report back! i didnt even see that... i am wearing the dunce hat, i swear

[Greg E]

i have the same lean spike with a 3.0 engine with blow-through.

i have turned up the delta multiplier a good 6 points across the board and i still havent seen any change to my lean spikes. I gotta play with it some more.

I wonder if your BOV is opening during the transition from negative to positive pressure. This will change the air turbulence inside the y-pipe and screw with the GM MAF readings. Are both you guys running your BOVs set to the tightest setting?

[futurevr4man]

mine is an hks, so i have no tightener screw.

also, i just did a datalog and hit 2575hz, so the 2 byte thing worked much better. i am still on wastegate boost haha

[Greg E]

mine is an hks, so i have no tightener screw.

also, i just did a datalog and hit 2575hz, so the 2 byte thing worked much better. i am still on wastegate boost haha

Holy shit! That's pushing some air! What load numbers are you seeing?

[Chris@Rvengeperformance]

FPR over run. It does that to your trims.

I do not see this problem. drove for a week and I am at -4.2 on low and -4.8 on mid. That is before upping the scaling any in the last week or so, installing some stereo crap at the moment.

[Chris@Rvengeperformance]

The only time I have had the trims peg like that is when my scalings or latencies were stupidly off or I had a broken o2 sensor wire. I have never seen this opposite trims you guys are seeing.

[futurevr4man]

i dont have opposite trims, chris... but mine were at 12.5; i am going to reset the ecu. I think that my oxygen sensors are no good. may invest in some new ones in the very near future.

greg, i am seeing around 200 on the load side of things. im curious to see what happens when i start turning up the boost past wastegate haha

and just as an update: the 2 byte airflow really helped a lot more. i got the tune reasonable up top (11.5 afr) by messing with the VE table, but that dang lean spike is awful. having a hard time figuring out how to tune that out.

and when i went to take the car out to turn up the wick, one of my oil return lines gave out. im not sure if it was the fitting or the hose itself, but it started spewing oil and i was done. so i will fix that when i come home from texas, then tune it some more. hoping for some big results!

[Greg E]

Keyan, getting back to your issue with the trims, what's the history of your fuel injectors? Did you purchase them new or at least get them flow tested before installing them?

How old are your narrowbands?

[Keyan]

they are newish sensors. the front bank is an OEM replacement and the rear bank is a bosch universal kit (with the water tight crimps).

it is only my low fuel trims that are weird.

My trims look like this, currently:
Front Low 12.5+ .......Rear Low -12.1
Front Mid 9.57+ ........Rear Mid 1.17+
Front High 1.95+ .......Rear High 1.95+


history of the fuel injectors is nothing crazy, bought them new and have been using them for 50,000 or so miles. PTE.

narrowbands are only about 2 years old, only 60,000 miles or so on them.

i have an fuellab reguator, this one specifically 3SX Custom Fuel Kits - Fuel Pressure Regulator FPR Kits*-*Mitsubishi 3000GT*/*Dodge Stealth Parts (http://www.3sx.com/store/comersus_viewItemBundle.asp?idProduct=26350). with the fuel pressure set to stock 44 wi@ 0vac. I also am running a simple walbro 255, that is very old. but it seems to be running fine.

[Keyan]

also here is a log from my drive home from work (20 min drive)

https://docs.google.com/file/d/0BxXvnQJNC-9iV1g1bEloVDVCNjQ/edit?usp=sharing

you can see around row 6131 that the ecu tried to adjust the trims by pulling the front bank leaner (from 12.5+ to 11.9+), which forced the rear bank leaner than that (from 12.1- to 12.5-). and then quickly reverted what it did.

[Chris@Rvengeperformance]

I'm not saying this is your problem, but you could certainly eliminate one possibility switching to these

Bosch 13807 Oxygen Sensor, OE Type Fitment : Amazon.com : Automotive (http://www.amazon.com/gp/product/B000BZEIWU/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1)

Bosch 13808 Oxygen Sensor, OE Type Fitment : Amazon.com : Automotive (http://www.amazon.com/gp/product/B000BZI2TU/ref=oh_details_o00_s00_i01?ie=UTF8&psc=1)

[Chris@Rvengeperformance]

ok I double checked a log. My front and rear lows are a little different, but nothing like you see:

Front Low Trim -4.6056
Rear Low Trim 0.6891

The mids are exactly the same: -4.2134

I am running the o2 sensor above with my 1050s scaled to 1003. I had planned to up to 1035 to get the trims down a little bit closer to zero.

[Greg E]

Keyan. Are you absolutely 100% sure that your front manifold isn't cracked?

[striker2]

I took a log today and noticed something similar to the OP. my front low LTFT is stuck at 12.5 while the rear is at 7.4. O2 sensors have about 10k on them so I dont think thats the problem. I have noticed some back fires out the exhaust during shifts lately and can smell the car running rich. I know that when I rebuilt the engine the front manifold was cracked but I had it welded up. Im suspecting that it cracked again and its causing the rich condition, (which in turn is causing the back fires when the extra fuel hits the oxygen from the crack) along with the stuck low LTFT on that bank.

Keyan, have you had a chance to check your front manifold for cracks? Ill try to check out mine in the next day or so.

[Keyan]

its not cracked, but ill be replacing it soon with a gctech one soon anyway.

ill let you guys know when i yank it this week.

[J-Groove]

Scott, Iceman back in the day on 3Si, had a very similar situation with his AEM setup. I can't remember what the cause was. But he is active on the Facebook boards. Scott Humpert.

Shoot him a message on there.

-John