Damn fuel trims, guys I searched!

[dsmsucks]

Yeah like the title says my trims seem to stick at 100%. So I seached and decided to reset the ecu. I left the - post unhooked for a day and that did nothing? Any input would be great!

 

[92awddsm]

100% is where they are supposed to be. And 100% is the default setting after you reset the ecu. Just drive it a little and give them a chance to change. Also, the car needs to be running at least 185-190* before the ecu starts correcting fuel trims. If they stay around 100%, that usually means that your tune is pretty good and no need for changes.

 

[steve]

If they stay around 100%, that usually means that your tune is pretty good and no need for changes.

Or that things are out of whack and your ECU is never going into closed loop. Check and make sure the O2 sensor is cycling at idle and cruise.

Steve

 

[dsmsucks]

Or that things are out of whack and your ECU is never going into closed loop. Check and make sure the O2 sensor is cycling at idle and cruise.

Steve

Thanks for the input guys. o2 sensor cycling? The # doesnt change unless I step on the gas
Btw Im looking at o2r and o2f.

 

[steve]

Yes, cycling. The voltage should cycle back and forth between say 0.3v and 0.7v (your numbers will vary) at idle, low throttle driving and cruising.

If it's not then you have a problem and the ECU isn't going into closed loop and won't update the fuel trims. When using MMCd the 1G DSM O2 sensor is O2-R.

Steve

 

[dsmsucks]

So if I dont see cycling the o2 sensor is dead?
Also is it safe to let my car idle? I know the car is running rich because its spitting out gas from the tail pipe

 

[dsmsucks]

Yeah guys the o2 is gone.
1. The car runs rich at idle no matter what I do. I backed the screw on the 2g mas all the way out and took as much as -14 out on the safc. Nothing changed!
2. The o2r reading on the logger reads 2.50v???
thanks guys for the input

 

[steve]

2. The o2r reading on the logger reads 2.50v???

You sure your looking at O2-R and not O2-F? O2-R is the correct one.

Steve

 

[1stGenRocks]

sorta off topic but just a quick question about fuel trims. on a 1g low is up to like 1500, mid is up to 3000 and high is above that? and if my trim is at 114 does that mean i need to add or subract fuel for that range?

 

[dsmsucks]

Yeah steve Im looking at the o2r. It stays at 2.50vlts

To firstgenrocks, your fuel trim is fine. Remember you want to get at lease 10% of 100. 100 perfect fuel trim in a 1g. You could add fuel to lower it

 

[steve]

sorta off topic but just a quick question about fuel trims. on a 1g low is up to like 1500, mid is up to 3000 and high is above that? and if my trim is at 114 does that mean i need to add or subract fuel for that range?

The fuel trims are airflow based. The low trim is up to 113Hz, mid from there to 182, high from 182 until you go open loop. So the RPM will vary depending on with gear your in.

Yeah steve Im looking at the o2r. It stays at 2.50vlts

Sounds more like a short or a ECU problem. What does it read when the largest connector of the three is pulled. You still be able to turn the ECU on but the car won't start.

Steve

 

[dsmsucks]

The fuel trims are airflow based. The low trim is up to 113Hz, mid from there to 182, high from 182 until you go open loop. So the RPM will vary depending on with gear your in.



Sounds more like a short or a ECU problem. What does it read when the largest connector of the three is pulled. You still be able to turn the ECU on but the car won't start.

Steve

Ecu problem, I dont think so. I would hope not! I had the caps in the ecu replace! Larget of the 3 connectors? I will try this tomorrow. You wouldnt happen to know the color or what wire it is?
thanks

 

[steve]

Larget of the 3 connectors? I will try this tomorrow. You wouldnt happen to know the color or what wire it is?

I'd just unplug the whole connector but if you want to release just the O2 sensor, it is the white wire on pin 4 of that connector. That would be the top row fourth from the left as your looking at it plugged in. Don't get it mixed up with the knock sensor on pin 9 also a white wire in the top fourth in from the right.

The white O2 on pin 4 will have a black/red wire in pin 3 and yellow/black in pin 5.

Steve

 

[kraka]

Yes, cycling. The voltage should cycle back and forth between say 0.3v and 0.7v (your numbers will vary) at idle, low throttle driving and cruising.

If it's not then you have a problem and the ECU isn't going into closed loop and won't update the fuel trims. When using MMCd the 1G DSM O2 sensor is O2-R.

Steve

Just a side question: If the mmcd software reads the 02 data using the rear sensor, what would happen if you have a testpipe or cat eliminator and the 02 is not hooked up anymore...

Or am I just confused

Sorry bout that....

 

[steve]

Am I just confused

Your confused.

MMCd only supports OBD1 ECUs like the 1G DSM. As you should know the 1G DSM only has one O2 sensor. It just happens that MMCd calls it O2-R because that same command when sent to a OBD1 V6 ECU happens to outout the rear bank O2 sensor.

Steve

 

[92awddsm]

Just a side question: If the mmcd software reads the 02 data using the rear sensor, what would happen if you have a testpipe or cat eliminator and the 02 is not hooked up anymore...

Or am I just confused

Sorry bout that....

The cat has nothing to do with it on a 1g dsm. The reason the software has o2-f and o2-r is for logging 3si cars with a 6g72. The 6 cylinder has an o2 sensor on each bank so the software designates them as front or rear. We only have 1 sensor and it is desingnated as o2-r on 4 cyl cars.

 

[dsmsucks]

Hey Steve I did what you said. The car started right up with the o2 sensor unpluged. The car ran the same way. The voltage still read 2.50volts

 

[steve]

That would suggest that the ECU has a problem.

I've seen that a few times now where the EMI filters on the signal inputs go bad and develop resistance between the pins coupling a voltage from one pin to another.

Steve

 

[dsmsucks]

That would suggest that the ECU has a problem.

I've seen that a few times now where the EMI filters on the signal inputs go bad and develop resistance between the pins coupling a voltage from one pin to another.

Steve

Damn
I just replaced this thing last year and changed the caps. Reason I was leaning towards the o2 sensor because at idle the car runs rich. I backed the screw out of the 2g mas all the way and took as much as -15 out of the safc and still no difference. Gas was still coming out of the tail pipe.
thanks steve

 

[oldman]

why not send the ECU to steve and ask him to check it out for you, he's one of the best I know.

 

[kraka]

The cat has nothing to do with it on a 1g dsm. The reason the software has o2-f and o2-r is for logging 3si cars with a 6g72. The 6 cylinder has an o2 sensor on each bank so the software designates them as front or rear. We only have 1 sensor and it is desingnated as o2-r on 4 cyl cars.

Thanks, that sounds better

But, you say we have only 1 sensor..I know there's one in the 02 housing(obviously), but what about the one that is by the catalytic converter?? <---or is that only for 2g's??

I always thought all dsm's had the one important 02 tapped in the 02 housing, and the other rear one tapped in the stock cat which can trigger a CEL when you disconnect it (for instance if you eliminate the cat)

Thanks for your help, I feel odd for not knowing this already...Apparently I was mistaken...

 

[oldman]

1g = 1 o2
2g = 2 o2

 

[steve]

or is that only for 2g's?

Yes, only on 2G's.

Steve

 

[dsmsucks]

Hey guys I will let you know by this saturday what happened

 

[kams1gsx]

1g = 1 o2
2g = 2 o2

my o2 has been bouncing around from like 0 to.37 to.6 and only gets to .89 at full spool,also turbo light comes on and off,what the hey?