I have a 2003 WRX, and I got a ProTune by Doug from Topspeed in January. It was relatively cool in the shop when he did the tune (around 55 F). It's now around 70 F outside while I've been driving.

At first, things were good. No knock and smooth power. As the outside temperatures increase, I've noticed knock. Whenever I roll into full throttle in second or third gear from 2500 to 3000 rpm, I get audible knock.

I did some datalogging, and I'm curious about A/F ratios. When Doug tuned the car, he commented that Kansas gas is really bad. He added fuel and pulled timing basically everywhere. For example, my final dyno plot shows an A/F ratio of 11.6:1 at 2850 rpm and WOT. A datalog I captured today shows .87 lambda (or 12.79:1 A/F) at 2850 and WOT. Doug used an O2 sensor at the tailpipe, and I'm using my OEM sensor with ecuExplorer.

Should I be concerned about the difference in A/F ratios, and could it cause the knocking? Any ideas on what's causing the difference? Is it possibly a combination of warmer temperatures and winter gas? Would winter gas affect A/F ratio? Ultimately, what can I do to try to correct this?

Thanks for any help...

The front O2 sensor is not as accurate as a wideband, so I don't know how much faith to put in those readings.

Can you post up some logs showing the problem?

Thanks,
Mike

How much boost at that rpm point? Also what's your timing values?

Sure... here are a couple of log files. They're both third gear transitions to WOT. In the first one, I heard one or two "clicks" of knock. In the second one, I heard more sustained knock, so I didn't stay at WOT long (or not at all, according to the log). Do the really fast IAM changes seem odd also?


"Time" "Engine Speed (RPM)" "Manifold Absolute Pressure (PSI)" "Air/Fuel Learning #1 (%)" "Air/Fuel Correction #1 (%)" "Throttle Opening Angle (%)" "Mass Air Flow (g/s)" "Ignition Timing (°BTDC)" "Knock Correction (°BTDC)" "Primary Wastegate Duty Cycle (%)" "Fuel Pump Duty (%)" "Air/Fuel Sensor #1 Current (mA)" "Air/Fuel Sensor #1 (Lambda)" "Knock Signal #1 (On/Off)" "Advance Multiplier (020124) ()" "Coolant Temperature (°C)"
0 2569 14.51 3.13 2.34 20.78 37.79 34 1 0 66.67 -0.25 0.99 0 16 83
15 2568 15.09 3.13 3.13 21.96 40.08 33 3 0 66.67 -0.25 0.98 0 16 83
78 2592 15.525 3.13 2.34 23.53 41.17 32 4 0 66.67 -0.375 0.99 0 16 83
296 2592 16.541 3.13 -0.78 35.69 45.78 27 7 18.82 66.67 -1.875 0.95 0 16 83
515 2618 17.847 3.13 -0.78 54.12 49.68 28 9 28.24 66.67 0 1 0 16 83
734 2631 18.427 3.13 -6.25 67.06 50.58 27 9 37.65 66.67 -3.625 0.9 0 16 83
953 2676 19.008 2.34 -2.34 94.12 53.09 25 9 50.2 66.67 0.5 1.02 0 16 83
1171 2715 19.443 2.34 0 98.82 56.35 24 9 59.61 100 -8.375 0.8 0 16 83
1390 2744 20.024 1.56 0 100 58.63 22 9 69.02 100 -5.75 0.86 0 16 83
1609 2771 20.459 1.56 0 100 61.88 21 9 81.57 100 -7.5 0.83 0 16 83
1812 2825 21.039 0 0 100 64.87 21 9 90.98 100 -5.5 0.87 0 16 83
2015 2840 21.62 0 0 100 68.06 21 9 96.86 100 -5.625 0.86 0 16 83
2234 2908 22.2 0 0 100 70.47 18 7 96.86 100 -5.625 0.86 0 12 83
2453 2929 22.925 0 0 100 75.19 18 7 96.86 100 -6.5 0.85 0 12 83
2656 2986 23.651 0 0 100 78.91 18 7 97.25 100 -7.625 0.82 0 12 83
2859 3047 24.376 0 0 100 82.58 18 7 97.25 100 -9 0.81 0 12 83
3062 3091 25.102 0 0 100 85.67 17 6 97.25 100 -11.25 0.79 0 12 83
3265 3146 25.537 0 0 100 89.55 17 6 97.25 100 -13.5 0.76 0 12 84
3484 3177 25.973 0 0 100 91.56 17 6 97.25 100 -13.75 0.76 0 12 84
3703 3237 26.263 0 0 100 94.24 16 6 97.25 100 -15 0.76 0 12 84
3906 3295 26.408 0 0 100 96.27 16 6 97.25 100 -13.75 0.76 0 12 84
4109 3363 26.553 0 0 100 96.74 16 6 97.25 100 -14.125 0.76 0 12 84
4328 3426 26.698 0 0 100 101.71 16 6 97.25 100 -14 0.76 0 12 84
4531 3488 26.553 0 0 30.2 101.95 16 6 97.25 100 -14.625 0.76 0 14 84
4734 3511 18.863 0 0 10.59 54.39 29 6 18.43 100 -8.75 0.8 0 14 84
4937 3516 10.592 0 -12.5 1.57 19.96 42 0 8.24 66.67 -2 0.93 0 14 84
5156 3519 8.416 0.78 -5.47 1.96 21.42 42 0 12.55 66.67 0.75 1.03 0 14 84
5375 3456 7.4 0.78 -3.91 1.96 20.01 42 0 19.61 66.67 -0.125 0.99 0 14 84
5593 3463 6.82 1.56 -3.91 1.96 18.35 41 0 19.61 66.67 -0.375 0.98 0 14 84
5812 3429 6.239 1.56 -3.91 2.35 16.37 41 0 19.22 66.67 -0.125 0.99 0 14 84
6031 3388 5.804 3.13 -5.47 1.96 14.7 40 0 19.22 66.67 -1.25 0.96 0 14 84
6234 3354 5.369 3.13 -5.47 2.35 13.25 39 0 19.22 66.67 -0.375 0.98 0 14 84



"Time" "Engine Speed (RPM)" "Manifold Absolute Pressure (PSI)" "Air/Fuel Learning #1 (%)" "Air/Fuel Correction #1 (%)" "Throttle Opening Angle (%)" "Mass Air Flow (g/s)" "Ignition Timing (°BTDC)" "Knock Correction (°BTDC)" "Primary Wastegate Duty Cycle (%)" "Fuel Pump Duty (%)" "Air/Fuel Sensor #1 Current (mA)" "Air/Fuel Sensor #1 (Lambda)" "Knock Signal #1 (On/Off)" "Advance Multiplier (020124) ()" "Coolant Temperature (°C)"
0 2906 17.702 2.34 0 25.88 56.18 27 8 7.45 100 -0.125 1 0 14 86
219 3004 17.847 2.34 0 25.88 56.99 27 8 0 100 -2 0.94 0 14 86
438 3102 17.847 1.56 0 26.27 58.46 28 8 0 100 -2.375 0.93 0 14 86
641 3211 19.008 0 0 38.43 66.28 25 9 15.69 100 -0.625 0.98 0 16 86
860 3271 20.169 0 0 47.45 72.73 24 9 25.1 100 -2.75 0.93 0 16 86
1063 3375 21.184 0 0 61.96 80.54 25 9 37.65 100 -8.625 0.8 0 16 86
1266 3528 22.345 0 0 74.12 86.72 24 9 47.06 100 -5.75 0.88 0 16 86
1469 3651 23.361 0 0 86.67 99.29 21 8 56.47 100 -11.75 0.77 0 15 86
1688 3772 24.667 0 0 93.33 110.03 19 8 65.88 100 -14.25 0.76 0 15 86
1891 3925 25.537 0 0 96.08 118.34 18 8 75.29 100 -16 0.76 0 15 86
2094 4056 26.553 0 0 96.86 125.92 17 8 84.71 100 -15.625 0.76 0 15 86
2297 4197 27.133 0 0 97.65 131.01 17 7 94.12 100 -14.25 0.76 0 15 86
2500 4378 27.133 0 0 99.22 137.02 14 5 97.25 100 -14.125 0.76 0 15 86
2719 4507 27.133 0 0 91.76 146.23 14 5 97.25 100 -14 0.76 0 15 86
2938 4664 23.651 0 0 0 123.59 17 0 23.92 100 -14.25 0.76 0 15 86
3157 4221 7.545 0 0 0 17.75 12 0 0 66.67 11.875 1.75 0 15 86
3375 3852 6.384 0.78 0 0 19.13 12 0 0 66.67 10 1.63 0 15 86
3594 3539 6.529 0.78 0 0 19.05 12 0 0 66.67 9.75 1.66 0 15 86
4047 2988 6.094 3.13 0 8.24 15.51 17 0 18.04 66.67 9.625 1.64 0 15 85
4047 2988 6.094 3.13 0 8.24 15.51 17 0 18.04 66.67 9.625 1.64 0 15 85
4250 3197 9.286 3.13 0 13.73 31.33 39 0 19.22 66.67 -1.375 0.96 0 15 85
4469 3161 10.882 3.13 6.25 14.51 34.37 35 0 20 66.67 -1.125 0.97 0 15 85
4688 3079 11.318 3.13 6.25 14.9 34.84 34 0 20 66.67 -2.375 0.94 0 15 85
4907 3095 11.608 3.13 6.25 15.29 36.04 34 0 18.82 66.67 -2.5 0.93 0 15 85

How much boost at that rpm point? Also what's your timing values?

Looks like boost was approximately +7 psi and timing was 21 degrees BTDC at that point. I'm comparing the rows at 2825 and 2840 in the first of the two log files above, by the way.

It happens to be a point where the ECU dropped IAM from 16 to 12 in the log file, and it's a labeled point on my dyno graph from the ProTune. On that graph, A/F ratio was 11.6:1 at that point. Admittedly, the OEM O2 sensor isn't the greatest for this, but I'm surprised it would deviate by this much without something else chaging.

11.6:1 @ 7psi and 2900RPM is plenty safe (rich). 21 degrees BTDC at that spot should be fine as well.

I would suspect your gas is crap. REALLY crap. What brand is it? I am assuming 93 octane.

No temperature change of 20F should be causing this.

11.6:1 @ 7psi and 2900RPM is plenty safe (rich). 21 degrees BTDC at that spot should be fine as well.

I would suspect your gas is crap. REALLY crap. What brand is it? I am assuming 93 octane.

No temperature change of 20F should be causing this.


93 isn't available in Kansas. We only get 91 except at BP stations which often sell 92. I have my doubts about whether it's really 92 or not, though. I'd love to have some sort of "pocket octane tester".

My last full fillup was 91 from a Phillips 66. That's when the temperatures increased also, and I started noticing the knock. I switched to a "stock mode" realtime map and tried to stay off boost until around half the tank was gone. I then filled up with BP 92.

Could oxygenated or "winter" gas cause this? If I had something like StreetTuner, could adjust fuel or timing to avoid the problems?

Wish I could help you out more, man. Maybe someone else can chime in from other octane-challenged areas :(

I only know that it's crazy for you to be knocking under those engine conditions, so have to suspect your gas as a first guess.

I don't believe oxygenated/winterized gas could be the only cause for that, even on 91.

If you had StreetTuner, you could certainly pull 2 degrees of timing in that area and it would likely stop.

ecuExplorer can pull timing out across the entire map so it's not as precise, but if it's any consolation... this isn't the first crappy running car I've seen from TopSpeed. On a side note, you could always invest (only $150) in a custom PDX map for your AP/car. Even though those maps are mailorder rather then tuned on a dyno people seem to be very happy with them and from the logs I've seen the outcome is good. Of course the final decision is yours... it must be hard to find good tuners in your area, but getting a protune is not always the best answer. (Tuners tend to max out power on a ProTune and sometimes forget about that safety window they need to leave in and inturn make that window smaller and smaller.) Of course, this is all dependant on the tuner themselves.

Hope things improve for you...

I would hazard a guess on bad gas and to much timing. A/f and boost are ok for those areas.

I would hazard a guess on bad gas and to much timing. A/f and boost are ok for those areas.

After thinking about it more, that's what I'm hoping. I hadn't thought about pulling a few degrees of timing with ecuExplorer as a test. I'll try that... and probably try to find some better gas.

Yeah... so, if anyone's still interested, I ended up pulling 4 degrees of timing with ecuExplorer.

I initially tried 2 degrees, then 3 degrees... and increasingly long pulls at WOT. The knock was nearly gone, but I thought I heard a faint "click" or two, so I backed off to -4 degrees. IAM is holding steady at 15, which seems better too... or perhaps the car is doing less "coarse learning" because it's been a day or two since an ECU reset.

There's no harm in running like this for a few days, right? I suppose really low timing values could result in high EGTs, but I don't think I'm anywhere close to that...

I did some datalogging, and I'm curious about A/F ratios. When Doug tuned the car, he commented that Kansas gas is really bad. He added fuel and pulled timing basically everywhere. For example, my final dyno plot shows an A/F ratio of 11.6:1 at 2850 rpm and WOT. A datalog I captured today shows .87 lambda (or 12.79:1 A/F) at 2850 and WOT. Doug used an O2 sensor at the tailpipe, and I'm using my OEM sensor with ecuExplorer.

Should I be concerned about the difference in A/F ratios, and could it cause the knocking? Comparing the stock A/F sensor's numbers to a proper wideband is not wise. Check out this example of how BAD the calibration is on the stock O2 sensor:

http://www.iwsti.com/forums/showthread.php?t=36914

The thing to note is that the farther away from 1.0 lambda you get, the worse the accuracy is.

Now, another thing to consider, if you are looking at logs of the tune and then logs later, you have to make sure that EVERYTHING is the same to make direct comparisons. If the boost at 2850 in Doug's log is higher than the boost at 2850 in your log (because you rolled into throttle later or whatever), then the AFR won't be the same either.

With all that said, the stock sensor tends to read richer (up to the point of maxing its range) than a real wideband does.