Having problems with 02 readings after 3500 to 4000 rpm

[Generation X]

The problem that I'm having is, that everytime I go to log a run on my logger, the 02's will register fine up to about 3500 to 4000 rpm, and then it just goes to 0.00 for some unknown reason. It even does the same thing on my S-AFC.

Also... at idle it cycles like it should, so I don't know if it's a dead 02 sensor or not, even though I have run leaded race gas before, maybe a couple of times at most. The 02 sensor is only about 3 to 4 years old now, but I've only put about 10,000 miles on it at most during that time. If any of you guy's could help me out, or help me to understand why this is happening I would be greatly appreciated. Thanks!


Here is a recent log of one of my runs.


RPM 2408 Timing 27 02 0.19 Air Flow 4.13
RPM 2536 Timing 25 02 0.14 Air Flow 4.89
RPM 2660 Timing 24 02 0.20 Air Flow 5.56
RPM 2808 Timing 22 02 0.74 Air Flow 6.46
RPM 2976 Timing 20 02 0.68 Air Flow 7.52
RPM 3160 Timing 18 02 0.71 Air Flow 8.56
RPM 3356 Timing 14 02 0.56 Air Flow 10.80
RPM 3592 Timing 11 02 0.91 Air Flow 13.41
RPM 3868 Timing 6 02 0.91 Air Flow 16.35
RPM 4164 Timing 5 02 0.23 Air Flow 19.59
RPM 4472 Timing 5 02 0.03 Air Flow 21.86
RPM 4836 Timing 1 02 0.00 Air Flow 23.82
RPM 5084 Timing 2 02 0.00 Air Flow 24.70
RPM 5420 Timing 3 02 0.00 Air Flow 25.49
RPM 5612 Timing 7 02 0.00 Air Flow 25.25
RPM 5860 Timing 9 02 0.00 Air Flow 25.56
RPM 6132 Timing 11 02 0.00 Air Flow 25.54
RPM 6356 Timing 11 02 0.00 Air Flow 25.76
RPM 6552 Timing 12 02 0.00 Air Flow 25.71
RPM 6736 Timing 10 02 0.00 Air Flow 25.90
RPM 6832 Timing 11 02 0.00 Air Flow 25.92
RPM 6956 Timing 12 02 0.00 Air Flow 25.83

I'm running about 23psi, and by redline I'm at about 19psi on a ported FP B28, with supporting mods. I'm also running HKS 264/272 cams, 550's, walbro 255lph, FullThrottle AFPR set @ 46 to 47psi with vacuum line attached. I'm running pump 93 gas as well.

Here are my HI settings on my S-AFC

1K-23 2K-22 3K-21 4K-21 5K-21 5.5K-21 6K-21 7K-21

 

[Generation X]

If no one can answer my question, can you atleast tell me what you think of my logged run. Thanks!

 

[spyderturbo007]

Careful......bumping a post will most likely get it locked. Not that it bothers me, but I don't want to see you left out in the cold with your tune. I know that some people, like myself, are never on at night. I'm only online when I'm at work, as bad as that sounds. Suprised I still have a job.

Anyway, down to business.

Holy crap that log is horrible. Sorry to be so blunt, but it definately needs some work. Don't worry, we'll get it fixed up. The O2 voltage isn't effecting the ECU's fuel delivery / timing / etc, as the ECU doesn't care about O2 voltage at WOT. So that's not the problem.

Your timing is really low and needs to be corrected. Have you done a leak check? Does your TPS read ~100 at WOT? What are your TPS trigger points set at?

Go ahead and add back 3% to the SAFC and make another pull.

One other thing....Thank you for being so thorough in your post. I.E. posting up your SAFC-II correction factors and your mods. That really makes it easy to go through.

 

[Generation X]

Careful......bumping a post will most likely get it locked. Not that it bothers me, but I don't want to see you left out in the cold with your tune. I know that some people, like myself, are never on at night. I'm only online when I'm at work, as bad as that sounds. Suprised I still have a job.

Anyway, down to business.

Holy crap that log is horrible. Sorry to be so blunt, but it definately needs some work. Don't worry, we'll get it fixed up. The O2 voltage isn't effecting the ECU's fuel delivery / timing / etc, as the ECU doesn't care about O2 voltage at WOT. So that's not the problem.

Your timing is really low and needs to be corrected. Have you done a leak check? Does your TPS read ~100 at WOT? What are your TPS trigger points set at?

Go ahead and add back 3% to the SAFC and make another pull.

One other thing....Thank you for being so thorough in your post. I.E. posting up your SAFC-II correction factors and your mods. That really makes it easy to go through.

Yeah... thanks for reminding me of that dude. You have been a great help to me already as it is. I wasn't thinking about it when I posted again. My bad. I'm actually trying to kill two birds with one stone without having to start another thread.

Anyways... yeah I was thinking my logs were out of whack. This colder weather has really made it difficult for me to tune. It was just bugging me why my 02's weren't registering, because I didn't want to have to go out and buy a $70 or $80 dollar 02 sensor if I didn't need one.

I have done a boost leak test and everything seems to be OK for the time being. As for the TPS, it doesn't read exactly 100% at WOT. It's around 98 to 99%, but I have heard that is OK. My TPS trigger points are set at 30% and 80% if that's what your referring to.

I probably wont do another run until Friday or Sat, for I don't drive my car everyday. I car pool with my wife during the week to try and save a little money on gas, and wear and tear on my car. When I do another run I will add back 3% and I will keep you posted. I truely and dearly appreciate your help.

 

[Generation X]

Ok spyderturbo007.... today (Friday) on the way home from work I did another pull in third gear. I added about 3% back in, but this time I started from scratch and set my base FP back to stock levels 43.5 to 44psi with vacuum line attatched.

I don't know if it makes a huge difference or not, but it was about 40 degrees outside, which is a little bit colder than usual, and I'm about 2800ft above sea-level. The results are still not to promising IMO.

Here they are:

RPM 2708 Timing 27 Air-Flow 5.15
RPM 2836 Timing 21 Air-Flow 6.59
RPM 3012 Timing 15 Air-Flow 8.76
RPM 3220 Timing 10 Air-Flow 11.35
RPM 3488 Timing 9 Air-Flow 14.17
RPM 3788 Timing 8 Air-Flow 17.50
RPM 4088 Timing 6 Air-Flow 20.63
RPM 4444 Timing 7 Air-Flow 22.79
RPM 4768 Timing 5 Air-Flow 24.83
RPM 5092 Timing 4 Air-Flow 26.32
RPM 5416 Timing 5 Air-Flow 26.76
RPM 5660 Timing 6 Air-Flow 26.88
RPM 5932 Timing 10 Air-Flow 27.05
RPM 6092 Timing 10 Air-Flow 27.29
RPM 6312 Timing 11 Air-Flow 27.14
RPM 6508 Timing 12 Air-Flow 27.28
RPM 6676 Timing 12 Air-Flow 27.21
RPM 6700 Timing 10 Air-Flow 26.78
RPM 6880 Timing 10 Air-Flow 26.78

My S-AFC settings were:

1k-22 2k-21 3k-19 4k-18 5k-18 6k-18 7k-18


I think I need to richen her up a wee bit more, what do you think, maybe add another 2% back in, and try another run? Thanks bro!

 

[spyderturbo007]

Looks like we are getting somewhere.

The only thing that colder air will do is require more fuel. The colder the air, the more densely packed the molecules are, resulting in a higher mass of air.

Let's do this, go ahead and add back 2% and make another pull. If we don't see a nice jump in timing, I think we should start dropping the boost. The reason I say that, is because you are at around -18% on the SAFC-II. 550cc injectors are 18% larger than stock and the ECU normally runs a pig rich tune. This results in needing to go leaner than normal (-18%) with the Hi Throttle map. Mostly because the whole point here is to lean out the ECU's rich AFR and compensate for the larger injectors.

I don't want to get to the point of dumping a crap load of fuel in there just to drop the knock counts.

Enjoy!

 

[Generation X]

Hey man hows it going? I'm glad you posted back, I appreciate that!

This past Saturday I did do another run. I just wanted to wait and post it when ever you replied back. I did add back in another 2% and I didn't bother logging O2's because they just don't register. Here are Saturdays results.


RPM: 2548 TIMING: 23 AIR-FLOW: 5.14
RPM: 2644 TIMING: 20 AIR-FLOW: 6.11
RPM: 2808 TIMING: 16 AIR-FLOW: 7.50
RPM: 2976 TIMING: 11 AIR-FLOW: 9.40
RPM: 3184 TIMING: 8 AIR-FLOW: 11.43
RPM: 3404 TIMING: 7 AIR-FLOW: 13.60
RPM: 3628 TIMING: 6 AIR-FLOW: 15.77
RPM: 3916 TIMING: 6 AIR-FLOW: 18.66
RPM: 4204 TIMING: 4 AIR-FLOW: 21.12
RPM: 4480 TIMING: 5 AIR-FLOW: 22.51
RPM: 4768 TIMING: 4 AIR-FLOW: 24.59
RPM: 5032 TIMING: 5 AIR-FLOW: 26.00
RPM: 5340 TIMING: 5 AIR-FLOW: 26.72
RPM: 5572 TIMING: 6 AIR-FLOW: 27.14
RPM: 5756 TIMING: 7 AIR-FLOW: 27.32
RPM: 5980 TIMING: 9 AIR-FLOW: 27.44
RPM: 6172 TIMING: 11 AIR-FLOW: 27.51
RPM: 6376 TIMING: 12 AIR-FLOW: 27.48
RPM: 6528 TIMING: 13 AIR-FLOW: 27.39
RPM: 6620 TIMING: 12 AIR-FLOW: 27.53
RPM: 6724 TIMING: 13 AIR-FLOW: 27.40
RPM: 6856 TIMING: 9 AIR-FLOW: 26.76
RPM: 6832 TIMING: 5 AIR-FLOW: 27.29

Temps were about 45 to 50 degrees via the logger. I don't know what exactly happened after 6724 RPM but it felt like my timing was being pulled like crazy.

My S-AFC settings were: 1k - 19 2k - 18 3k - 16 4k - 16 5k - 16 6k - 16 7k - 16

I also went ahead and did another run on Sunday, and I added another 2% more back in, just to see what would happen.

Here are the results for Sunday.

RPM: 2572 TIMING: 20 AIR-FLOW: 5.87
RPM: 2744 TIMING: 17 AIR-FLOW: 6.92
RPM: 2924 TIMING: 14 AIR-FLOW: 8.45
RPM: 3116 TIMING: 11 AIR-FLOW: 10.28
RPM: 3336 TIMING: 9 AIR-FLOW: 12.44
RPM: 3592 TIMING: 7 AIR-FLOW: 14.96
RPM: 3860 TIMING: 7 AIR-FLOW: 17.61
RPM: 4152 TIMING: 6 AIR-FLOW: 20.63
RPM: 4428 TIMING: 7 AIR-FLOW: 22.49
RPM: 4756 TIMING: 7 AIR-FLOW: 24.53
RPM: 5064 TIMING: 7 AIR-FLOW: 26.19
RPM: 5368 TIMING: 6 AIR-FLOW: 27.21
RPM: 5612 TIMING: 8 AIR-FLOW: 27.57
RPM: 5852 TIMING: 10 AIR-FLOW: 27.79
RPM: 6072 TIMING: 12 AIR-FLOW: 27.68
RPM: 6272 TIMING: 12 AIR-FLOW: 27.80
RPM: 6472 TIMING: 14 AIR-FLOW: 27.65
RPM: 6688 TIMING: 13 AIR-FLOW: 27.40
RPM: 6748 TIMING: 12 AIR-FLOW: 27.35

I stopped at 6748 RPM because I once again felt it pull timing or something, so I let off. I still left my base fuel pressure at stock levels, even though I can raise them. I haven't tried turning up the fuel pressure a little, except for the very first pull that I posted in this thread.

I was running about 46 to 47 psi base fuel pressure on my very first log, and the rest were all on stock 43.5 to 44 psi fuel pressure.

My S-AFC settings were: 1K - 19 2K - 18 3K - 14 4K - 14 5K - 14 6K - 14 7K - 14

I may have to turn the boost down a couple psi like you mentioned. Just let me know what you think?

One more dumb question: Does air-flow #'s translate to HP #'s? Like does 32 or 33lbs of air-flow equal about 320 to 330 hp or am I way off thinking that way? I really appreciate your help bro.

 

[spyderturbo007]

I would leave the FP where it is. There are some issues with your log and nothing is jumping out at me.

Your timing should be peaking around 20 degrees, as the ECU is only "seeing" 1.98 g/rev of airflow. Anything over 2.1 g/rev and the ECU locks down the timing map to a max of 17 degrees. This is telling me that you are knocking somewhere.

Couple of suggestions / things to try:

Drop the boost to 18 or 19 psi, lean out the SAFC-II to around -18% and make another pull. I'm just courious to see what happens with the log. If you drop the boost and lean out the SAFC-II and see an increase in timing, go ahead and yank out another 2% and make another pull. You really should be around -20% or more on the SAFC to compensate for the 550cc injectors and for the ECU's rich AFR.

What is the gap on your plugs? What plugs are you using?

As far as the HP correlation.....There is some "relationship", although mostly unproveable, between airflow and HP. I did a post on this awhile ago, which had my opinions of the relationship, but I would have to look for the post. I'll see if I can dig it up.

EDIT -> I found it for you, post #29

http://www.dsmtuners.com/forums/showthread.php?t=189412&highlight=chp

 

[Generation X]

Ok cool dude, I will keep you posted within the next few days. I will give you a break for a little while.

So... you think I should be around the -20 on the S-AFC even with my cams? I always thought that you should be seeing around 16 degrees of timing on the topend at the least. I guess I thought wrong. Thanks again for your time and patience.

O' yeah... my plugs are NGK BPR7ES and there gapped @ 28. Maybe I should try gapping them down to 26?

 

[spyderturbo007]

So... you think I should be around the -20 on the S-AFC even with my cams? I always thought that you should be seeing around 16 degrees of timing on the topend at the least. I guess I thought wrong. Thanks again for your time and patience.

I didn't even notice that you have cams.

I don't have any first hand experience with cams, so I really shouldn't comment on their effect. I wouldn't think that they would screw up the tune, as they are designed to increase airflow. The SAFC-II is really there to compensate for the injectors, so it shouldn't matter if you are flowing 3 or 4lbs more than someone without cams. The SAFC is still doing the same thing.

But I will let someone with cams comment further.

As far as the gap is concerned. I am pushing about 33lbs (max) and my gap is 0.026". There is a wide variety of opinions on gap vs. flow, but 0.026" is working for me.

You are correct in saying that you "should" be seeing at least 17 degrees of timing, but that is under ideal conditions on the ECU's highest airflow map. Anything over 2.1g/rev and the ECU places you on that particular map, using a maximum timing value of 17 degrees. But, like I said, that is ideal. IAT over 84 degrees and you loose 1 degree of timing. Coolant temp over 210 and you loose 1 degree.......etc.

With your setup, you will not be pushing over 2.1 g/rev, so the ECU will not place you on it's highest airflow map (i.e. lowest timing map) so you should be seeing timing over 17 degrees. Normally with 550's and your setup, you should be in the neighborhood of 20 degrees.

Actually, I need to rephrase the above statement. The ECU needs to "see" 2.1g/rev. Don't forget that the SAFC modifys the airflow signal, so the ECU isn't being provided with the whole picture. You might be flowing over 2.1g/rev, but the ECU doesn't know that. It becomes a vicious cycle.

More air = more fuel.
More fuel = larger injectors.
Larger injectors = Lower SAFC correction
Lower SAFC correction = Less air at the ECU
Less air at the ECU = Higher timing

Blah, blah. Piggyback tuning sucks!

 

[Generation X]

Thanks dude! I'm gonna turn the boost down a little, and then do a few more runs over the weekend, and I will show you a few more logs. Thanks once again!!

Oooooh yeah... I checked my plugs and they are gapped at .026 and not .028 like I said earlier, sorry about that. I just checked them with my feeler gauge. Laterz!!

 

[Generation X]

I didn't even notice that you have cams.

I don't have any first hand experience with cams, so I really shouldn't comment on their effect. I wouldn't think that they would screw up the tune, as they are designed to increase airflow. The SAFC-II is really there to compensate for the injectors, so it shouldn't matter if you are flowing 3 or 4lbs more than someone without cams. The SAFC is still doing the same thing.

But I will let someone with cams comment further.

As far as the gap is concerned. I am pushing about 33lbs (max) and my gap is 0.026". There is a wide variety of opinions on gap vs. flow, but 0.026" is working for me.

You are correct in saying that you "should" be seeing at least 17 degrees of timing, but that is under ideal conditions on the ECU's highest airflow map. Anything over 2.1g/rev and the ECU places you on that particular map, using a maximum timing value of 17 degrees. But, like I said, that is ideal. IAT over 84 degrees and you loose 1 degree of timing. Coolant temp over 210 and you loose 1 degree.......etc.

With your setup, you will not be pushing over 2.1 g/rev, so the ECU will not place you on it's highest airflow map (i.e. lowest timing map) so you should be seeing timing over 17 degrees. Normally with 550's and your setup, you should be in the neighborhood of 20 degrees.

Actually, I need to rephrase the above statement. The ECU needs to "see" 2.1g/rev. Don't forget that the SAFC modifys the airflow signal, so the ECU isn't being provided with the whole picture. You might be flowing over 2.1g/rev, but the ECU doesn't know that. It becomes a vicious cycle.

More air = more fuel.
More fuel = larger injectors.
Larger injectors = Lower SAFC correction
Lower SAFC correction = Less air at the ECU
Less air at the ECU = Higher timing

Blah, blah. Piggyback tuning sucks!

Ok bro.... I finally did another run last night. I know it's been awhile, sorry about that.

I'am now running 20psi according to my new autometer boost gauge, and I'm running stock 43.5 base fp, so here are my results for this run.

RPM 2700 Timing 19 Air-flow 4.94
RPM 3048 Timing 24 Air-flow 6.44
RPM 3272 Timing 20 Air-flow 8.14
RPM 3476 Timing 15 Air-flow 10.41
RPM 3744 Timing 11 Air-flow 13.24
RPM 4028 Timing 7 Air-flow 16.08
RPM 4340 Timing 7 Air-flow 18.17
RPM 4660 Timing 6 Air-flow 20.83
RPM 4920 Timing 6 Air-flow 22.85
RPM 5296 Timing 7 Air-flow 23.87
RPM 5564 Timing 12 Air-flow 24.01
RPM 5868 Timing 14 Air-flow 24.42
RPM 6092 Timing 15 Air-flow 24.74
RPM 6356 Timing 16 Air-flow 24.98
RPM 6552 Timing 17 Air-flow 25.15
RPM 6772 Timing 18 Air-flow 25.10
RPM 6956 Timing 18 Air-flow 24.25


I started to lift at around 6700 to 6900 rpms.

HI settings on my S-AFC were 1k-24 2k-23 3k-22 4k-21 5k-19 5.5k-19 6k-19 7k-19

I think my #'s are looking somewhat better considering I'm at 2800ft above sea-level. I sometimes forget about that making a big difference.

If you have any more suggestions I would be greatly appreciated.