Should AFR be constant?

[keslerkaiyu]

I've been trying to tune with my DSMlink for a few days now. Is it supposed to be exactly 14.7 when idling, because mine is changing all over the place. I just can't seem to adjust it to stay put.

 

[robbo185]

I've been trying to tune with my DSMlink for a few days now. Is it supposed to be exactly 14.7 when idling, because mine is changing all over the place. I just can't seem to adjust it to stay put.

define all over the place

i would think anywhere from 14.5-15.2ish would be acceptable

It wont stay at 14.7 constantly. It should be changing.

 

[keslerkaiyu]

At first it was between 12 and 15 but now with me trying to get it to stay at 14.7 it will only go as high as 13.5 or so. I will change it back to how I had it.

thanks for your input

 

[turboglenn]

The stock sensor won't stay put, and even teh NTK/NGK wideband sensor oscilates heavily with the operation of closed loop (a.k.a. it's doing what it's supposed to) it this reason i use a wideband that uses teh bosch LSU4 sensor because it switches slower and maintaines a better steady reading at cruis and idle.

under WOT your reading should go to whatever AFR you set for and stay ther through the RPM range

 

[keslerkaiyu]

The stock sensor won't stay put, and even teh NTK/NGK wideband sensor oscilates heavily with the operation of closed loop (a.k.a. it's doing what it's supposed to) it this reason i use a wideband that uses teh bosch LSU4 sensor because it switches slower and maintaines a better steady reading at cruis and idle.

under WOT your reading should go to whatever AFR you set for and stay ther through the RPM range

When you say "whatever I set it at" you're talking about the global and deadtime setting or something else?

 

[redline2k6]

well if those are right...your cruise should be close mine was like 14.5-15.1 in that general area, at wide open is where you make your fuel and timing adjustments, as far as cruise go in to your air flow and you can adjust the 50Hz slider to get it more in tact.

 

[turboglenn]

When you say "whatever I set it at" you're talking about the global and deadtime setting or something else?

NO, i mean at wide open , the afr should go to say 11.4:1 ( you adjust the sliders for that load an RPM to where you floor it and it goes 11.5:1 and stays there through reline..you will have to slightly adjust it at eveery RPM going up till about 6500 PRM then is starts to fall off a good VE and you have to use less fuel to get the same AFR.

 

[420a-t]

at wide open is where you make your fuel and timing adjustments

Timing adjustments are always on, weather it be at cruise, or WOT.

Mine did that for a long time, then I man'ed up and got a new o2 sensor, works fine now.

What is your front o2 voltage at wot and cruise?

 

[Calan]

I've been trying to tune with my DSMlink for a few days now. Is it supposed to be exactly 14.7 when idling, because mine is changing all over the place. I just can't seem to adjust it to stay put.

At idle, the computer is trying to maintain the AFR based on fuel trims and the O2 sensor reading. In a nutshell, it thinks it needs more fuel, and adds some... then it sees that it added a bit too much and pulls some. It's oscillating like this every time it gets an O2 sensor sample, so you will see some variation. It should be around an average of 14.7 though.

How do your fuel trims look? Have you calibrated the MAF?

 

[BoostFrenzy]

Well, since a wideband is in your wish list, the narrowband O2 sensor will always be oscillating like it is at idle. Thats why I call my current Autometer a "light show" because thats pretty much all it is good for. If you are using a narrowband sensor to tune with, don't trust the number it throws out to you. Only trust it if it goes really rich or really lean. There is no medium.

Are you using the estimated AFR in DSMLink to tune? I can't find anything else in your profile that could double as a NB.

Next purchase: WB

 

[keslerkaiyu]

Well, since a wideband is in your wish list, the narrowband O2 sensor will always be oscillating like it is at idle. Thats why I call my current Autometer a "light show" because thats pretty much all it is good for. If you are using a narrowband sensor to tune with, don't trust the number it throws out to you. Only trust it if it goes really rich or really lean. There is no medium.

Are you using the estimated AFR in DSMLink to tune? I can't find anything else in your profile that could double as a NB.

Next purchase: WB

Yes, right now I'm only using link to tune to get it running so I can get to work. The car had not seen WOT since the 6 bolts. I want to take it easy so I don't blow anything.

 

[keslerkaiyu]

At idle, the computer is trying to maintain the AFR based on fuel trims and the O2 sensor reading. In a nutshell, it thinks it needs more fuel, and adds some... then it sees that it added a bit too much and pulls some. It's oscillating like this every time it gets an O2 sensor sample, so you will see some variation. It should be around an average of 14.7 though.

How do your fuel trims look? Have you calibrated the MAF?

My fuel trims are all within 1 of the "0", and I'm pretty sure I haven't calibrated the MAF yet since I have no clue as to what you're referring to I am still reading though most of the wiki trying to figure this thing out.