o2 trim stuck, with new 560's and 2g mas?

[spartan]

Hey guys, I just got done installing my 560 cc's and a 2g mas in my galant. After I got done I went out to log some low throttle stuff. I was noticing that everything was looking good at first; all around 100%. After some driving, the low fuel trim went to 81% and the o2 trim was doing crazy stuff. Some times it would sit right at 100%, then I would touch the throttle and it will drop all the way to 32.8% and just stay there? How is that even possible? Also, when I am giving it a little throttle while driving it drops below 60% also. Another question, how long is id supposed to take the o2 volts to go from .1-.9? Cause it was taking my car about 2 minutes to make 1 cycle. I have a new o2 sensor sitting in my garage, but I want to put it in with my ported o2 housing, and I haven't had that much time lately. Anyways, any advice that you guys could give me would be appreciated.

Thanks,
Travis

 

[DSM90AWD]

A good O2 sensor should cycle freely around .5V during closed loop (idle or low speed cruise). Installing an O2 sensor is a 10-15min job with the proper O2 socket or crow-foot.

BTW, do you have a SAFC or eProm to compensate for the 2G MAS (~30% leaner) and 560s (~25% richer) ?

 

[spartan]

yes right now I have an safc 2 that I have leaned out 10% across the board because of the 81% low trim. Do you think that it is the o2 sensor that would cause the o2 trim to stick like that?

 

[LessIsMore]

I know some of the earlier ECU's only have a 19% range of adjustment on the fuel trims (81%-119%)

If this is the case sounds like you're dead rich and need to pull more signal to get your trims back in wack.

 

[dsmsucks]

Im havin the same problem with the low trim and I have the same combo. I dont even worry about it, its only idle. I only concern myself with the mid and high trim!!!
I did everything
ecu rebuild
o2 sensor
boost leak test
coolant temp sensor
Nothing works

 

[DSM90AWD]

yes right now I have an safc 2 that I have leaned out 10% across the board because of the 81% low trim. Do you think that it is the o2 sensor that would cause the o2 trim to stick like that?

The LTFTs are average stored readings of the STFT which on the datalogger is OxyFeedback. Whenever start to tune a new setup I log OxyFeedback at different RPMs while parked and adjust my SAFC until it centers around 100% for each specific RPM (usually just 1K-3K) and then reset my ECU to clear the trims and see where the end up and fine tune from there.

If the OxyFeedback does not oscillate smoothly and/or does not react to adjustments to the AFC, then likely the O2 sensor is bad

 

[DSM90AWD]

I know some of the earlier ECU's only have a 19% range of adjustment on the fuel trims (81%-119%)

I know this is the case for the 1990 T/E/Ls, not sure of the Galants

Im havin the same problem with the low trim and I have the same combo. I dont even worry about it, its only idle. I only concern myself with the mid and high trim!!!

And your mid + high trims are at near 100%

 

[GVR4592]

The Galant maf sensor is not the same as the 1g sensor. It reads about the same as a hacked 1g sensor. Your o2 should be cycling much faster, I would replace it and reset the ecu, and see if that helps.

 

[spartan]

Well I finally got around to replacing the o2 sensor, in fact I removed and ported the turbo, o2 housing and installed a 2g exhaust manifold as well as a new o2 sensor. I am still having the same problem however? The low fuel trim is still at 81% and the o2 trim although it is moving more, still likes to stay at really low values when I am idling (like 32.8-44%). I am getting my chip put in as soon as I can so that I don't have to try and tune the car twice, so I don't know. I guess I have kinda given up until then.

 

[GVR4592]

Did you reset the ecu?

 

[tom04841]

Spartan.....i have the same setup. I had to have my lo throttle 1k setting at -16 to get my low trim in the 90's...think it was 96%. Just keep leaning it out until you get there....as long as you have a GOOD O2 sensor, you won't do any damage.

I have an eprom now, and when i burned the chip for it, i coded it for 560's, but it still wasn't enough. So i went back into it, and finally settled for the code for 580's and still have my safc at -3 which gave me a 99% low ft. These evo 8 injectors seem to flow more than what they are rated for

 

[dsmsucks]

I know this is the case for the 1990 T/E/Ls, not sure of the Galants

And your mid + high trims are at near 100%

Yeah the mid is at 96 and the high is at 110!! The low is stuck at 81.2

 

[DSM90AWD]

Yeah the mid is at 96 and the high is at 110!! The low is stuck at 81.2

Could be overrunning your stock FPR. Have you tried pulling fuel at 1K and 2K on the S-AFC and watching your oxy-feedback's reaction?

 

[spartan]

OK well it looks like it is going to be a while before I can get the chip burnt so I will have to try and get this thing worked out. I hope that I don't have the same problem with the chip that you did. Was your chip from keydiver? Anyways, I will go out and try and do some tuning today, wish me luck since this is my first time! Oh yeah I don't know if this will help but I will list my mods in case anything sticks out:

-buschur racing stg 1 (2g pistons, no b/s)
-2g mas
-walbro 190 fp
-dave brode fmic kit
-evo 560cc injectors
-safc2
-2g manifold
-ported 14b
-ported 1g o2 housing
-leaky 2.5in turbo back exhaust
-brand new denso o2 sensor

I also have a new fuel filter sitting in the garage, anybody think that would help at all?

 

[dsmsucks]

Could be overrunning your stock FPR. Have you tried pulling fuel at 1K and 2K on the S-AFC and watching your oxy-feedback's reaction?

Wow you think so??? I was told by MANY people it wasnt possible to overrun since Im using a unwired 190lph I have to remove a much a 24 to get the low fuel trims to move.
As for pulling fuel and watching oxy feedback reaction what do you mean
thanks
rep points

 

[DSM90AWD]

Wow you think so??? I was told by MANY people it wasnt possible to overrun since Im using a unwired 190lph

I was probably one of them as my 190 worked fine on my setup, then again I'd bumped base FP up to 42psi via my B&M Modifier so did'nt have to bypass as much fuel at idle than if was at the stock 37.5psi base pressure (I'd also compensated for this via my S-AFC).

Base pressure can also be affected if you were to of plugged the fuel tank vapor line (that hose that connects to the evap canister) as pressure in the tank has no where to go.

I have to remove a much a 24 to get the low fuel trims to move.
As for pulling fuel and watching oxy feedback reaction what do you mean

OxyFeedback represents your Short-Term Fuel Trims (STFTs) which is driven by your ECUs comparison of the fuel it sends to the engine to maintain a 14.7:1 AFR and the AFR your O2 sensor reads after combustion and +/- fuel adjustments the ECU makes to maintain 14.7:1 AFRs. This information is then used to update the LTFTs if adjustments were needed.

Datalogging OxyFeedback at Idle, you should see a smooth oscillating plot with a midpoint at 100%. If its' below 100% then subtract fuel at that RPM (S-AFC Low Setting), if above 100% add fuel.

If OxyFeedback does not move at all, then the O2 Sensor is bad or you are beyond the adjustment range of the S-AFC

 

[spartan]

Does it make sense that I would not be able to get my o2 trim to get above 60% while using my evo injectors. Even if I take out like 30% it will only move a very slight amount?

 

[DSM90AWD]

In your first post you mention your current O2 sensor is slow to cycle. Replace it, reset your ECU and see where you stand

 

[spartan]

Yeah I already have replaced the o2 sensor, but my o2 trim, and low fuel trim are both still maxed out rich at idle. This is with a -25% correction also?