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Discussion Starter · #21 ·
This was helpful. The timing curve is higher on the scale, but still low for just Map 1 on 93 Octane. What brand of fuel are you using? I would try another brand and see if you can get some improvement. I just did a Map 5 pull. You see my Ign1 field stays between 5 and 10. Yours even on map 1 is going down into the 3's. I use 93 pump gas and stick with a brand that works consistently for me. My signature shows I have Water Meth injection also, but it is not on the car right now.


View attachment 113740 Map 5 log
This was a pull I did yesterday, it shows me going into the 15s
 

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The concern is more on the low end of the curve where it went down to between 3 and 4 it appears.

Not familiar with HEB gas, but I did not see it on a Top Tier Gas listing. If you are planning on running your Q hard on a regular basis, days of bargain gas shopping should be over. Find the brand that works best in the car and stay with it. Also DI engines should run top-tier fuel anyway IMO. Owners manual may even recommend/require it...don't recall..

 

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Discussion Starter · #23 ·
The concern is more on the low end of the curve where it went down to between 3 and 4 it appears.

Not familiar with HEB gas, but I did not see it on a Top Tier Gas listing. If you are planning on running your Q hard on a regular basis, days of bargain gas shopping should be over. Find the brand that works best in the car and stay with it. Also DI engines should run top-tier fuel anyway IMO. Owners manual may even recommend/require it...don't recall..

I'll get her to empty today and fill her up with some Quick Trip 93
 

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I realize QT is on the list for top tier, but I would suggest going with a station named for the gas, not as a convenience store. P66, BP, Mobil, Sunoco, etc. Top Tier designation is more for the cleanliness of the gasoline....not sure what it means for variation to octane rating.
 

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Newport, Oregon
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HEB sells "generic gas" which is not Top Tier gas, so it doesn't have the additive package that Top Tier gas has. I wouldn't use it.
 

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Newport, Oregon
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I realize QT is on the list for top tier, but I would suggest going with a station named for the gas, not as a convenience store. P66, BP, Mobil, Sunoco, etc. Top Tier designation is more for the cleanliness of the gasoline....not sure what it means for variation to octane rating.
Not cleanliness but the addition of detergents and other additives to reduce buildup on valves, injectors, etc.. The EPA set minimum standards for detergent additives many years ago, but the auto industry didn't think that standard was adequate for their increasingly sophisticated engines. So in 2004, Top Tier gas was developed to contain additive packages that exceeded EPA's standards. All octane grades must adhere to the Top Tier standards, not just premium.

From CR:
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I've never heard of any of this. Is CostCo Top Tier gas?
 

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Map2 using Sunoco
That does look a little better...the timing curve bottoms out at 5 instead of below and this is Map 2 vs your Map 1 on the HEB gas. One thing that still sticks out at me is that you ECU PSI is very low and builds slowly. At full throttle you should see that value go to 8's and 9's much quicker and stay there until you reach high RPM (5800 and up it should start to taper back to about 7). Yours seems to hang in the 5's for a bit then slowly increase until its peak and then immediately starts to taper back down. It should be a much flatter curve so not sure what is causing that...its not JB4 related...its your car. If you want to prove it out, do a pull on Map 0 and log that.

Regarding next JB4 steps, I would say you can try maps 3 and maps 4. I think one of those will be your max setting based on what we have seen so far.
 

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Unfortunately, I have similar trends on my Q50 as OP, and I have been concerned for a while. I suspected fuel at first, but then I noticed that lean AFR, maxed-out trims, and very low ign timing can occur or not occur on the same tank. turning the car off for a couple of minutes and then starting again sometimes makes the issue disappear. My car currently has 44k miles on it, and I didn't do the maintenance scheduled services for the last 10k miles (only been doing filter and oil changes lately). That's why I'm starting to think maybe I should do some major maintenance before doing any more hard runs.

Advice is appreciated! 😆
 

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Here is an easy run log on my car. pedal at ~60%, and ign timing is as low as 0 at some moments (map 0). Lately, the issue has been showing up consistently (not like before where it was less frequent). Any advice on what the issue could be?
I'm planning on checking the spark plugs and maybe cleaning the fuel filter.

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