Timing question

[WildHorse]

3600 - 4100 added 3 degrees
4200 - 7300 took away 4 degrees

Bad gas or false knock ? I'd figure bad gas would take away timing from everywhere. Fuel trims are spot on. Thanks.

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[Bluemustang]

3600 - 4100 added 3 degrees
4200 - 7300 took away 4 degrees

Bad gas or false knock ? I'd figure bad gas would take away timing from everywhere. Fuel trims are spot on. Thanks.

Not necessarily. On pump gas mine starts to pull timing at about 6000 rpm and then tries to add it back but by then its too late.

Only way to know for sure is to try higher octane fuel or E85 and see if it still pulls timing. If not then its false knock.

 

[WildHorse]

On pump gas mine starts to pull timing at about 6000 rpm and then tries to add it back but by then its too late.

You remember your total timing ? Mine was 21.5-22 degrees from 6000-7300 RPM on 94 pump.

 

[Bluemustang]

You remember your total timing ? Mine was 21.5-22 degrees from 6000-7300 RPM on 94 pump.

You should see around 26-27.5 peak timing on pump 93. Mine will typically rise to 26-27 before falling. That seems a little low, making me think it's false knock. I would try running that tank out and find another station with 94 and fill up - run the test again. You should see at least 26-27 assuming you're NA. On E60 - flex tune - for instance I will see 29.5 and it stays there. E85 tune I will see 30.5 max.

Who's your tuner, Lund? I presume the tune is setup to advance timing to 30* if knock sensors allow. Unlikely you'll get there on pump gas, but 26-27 seems to be pretty normal/typical.

 

[WildHorse]

You should see around 26-27.5 peak timing on pump 93. Mine will typically rise to 26-27 before falling. That seems a little low, making me think it's false knock. I would try running that tank out and find another station with 94 and fill up - run the test again. You should see at least 26-27 assuming you're NA. On E60 - flex tune - for instance I will see 29.5 and it stays there. E85 tune I will see 30.5 max.

Who's your tuner, Lund? I presume the tune is setup to advance timing to 30* if knock sensors allow. Unlikely you'll get there on pump gas, but 26-27 seems to be pretty normal/typical.

Thanks for the info Sir. No LUND doesn't tune me. Tuner just got back to me and said the same, either false knock or bad gas. But he can't see it being bad gas cause it added timing in the beginning. High load, low RPM is the recipe for knock haha. Oh well, guess the hunt begins. Thanks.

 

[Bluemustang]

Thanks for the info Sir. No LUND doesn't tune me. Tuner just got back to me and said the same, either false knock or bad gas. But he can't see it being bad gas cause it added timing in the beginning. High load, low RPM is the recipe for knock haha. Oh well, guess the hunt begins. Thanks.

No problem. You'll find it.

I'd say it's unlikely to get knock down low with 94 octane, unless your tuner is shoving in gobs of timing down low. The tune should be pretty safe that you can't hurt it by stomping on it at 1500 or 2000 rpm. In any case, I would follow your tuners advice.

 

[WildHorse]

No problem. You'll find it.

I think I seen what's going on. Seem on the 'hit' it went +3 and timing dropped to 21.5 Tried to add -3 for a few hundred RPM, then went back +4 above 5000. So that means bad gas if I'm reading it right ?

 

[Bluemustang]

I think I seen what's going on. Seem on the 'hit' it went +3 and timing dropped to 21.5 Tried to add -3 for a few hundred RPM, then went back +4 above 5000. So that means bad gas if I'm reading it right ?

Hard for me to say definitively. How long did you do the pull, what did it do past 5000, it stayed at +4? Do you have any exhaust mods or anything that could trip the knock sensors? Vibrations resonating at a certain frequency could certainly do that and also change with rpm. If it was something hitting or rattling that could cause an issue on the "hit" and possibly again at higher rpms when vibrations increase.

Then again if it is indeed bad gas i.e. it has degraded or was tampered with, etc. Hard to say what it would do to the timing.

I am assuming you have a Gen 2 like me. Some limits of max timing is normal with pump gas, even 93 or 94. So some timing will get pulled up top inevitably. But what you are describing doesn't sound like normal behavior on pump gas i.e. timing pulled for real knock prevention.

 

[WildHorse]

I am assuming you have a Gen 2 like me

Yea Gen 2. And what I mean is that the timing is taking a nosedive as soon as I go WOT from 3000 rpm in 3rd gear. Tries to add some back, say's fuck it, and stays at 21.5-22 degrees right through to 7 grand.

 

[Grimreaper]

Usually false knock on my gen2 will yank chunk of timing and then it's a pretty steady add back in. Usually happens on a hard shift. If it's a roller coaster of adding and subtracting it may be real unless your setup has something causing vibrations/rattles through the pull. Additionally when I've seen what I'd consider a real octane issue on my logs, heavy part throttle tells the same story as wot in the consistency in timing being pulled

There is plenty of head room in the fuel trims to throw 1/3 tank of e85 in to bump the octane. Or boostane.

27.5 degrees is usually tops like mentioned depending on cam timing and what the tuner did with the mbt lambda adjustment. If you can choose the channels to log, watch timing, borderline, and mbt timing channels. It will show how far off the mark it is.

What do you load tunes with? Post a log

 

[WildHorse]

What do you load tunes with? Post a log

Diablo.

 

[Bluemustang]

That's... going to be hard to read LOL

 

[Grimreaper]

Lol need a magnifier for that legend

The ECU pulls based on severity. Stepping from small correction to larger happens. Takes more removed to stop the detonation than if you never detonated at all. The adding back in portion is very mild in stock settings and often doesn't get back to normal by redline. Ruins a whole gear

The false knock events I've seen (based on running e85 and stock timing) is usually a small reduction or blip on the line or a massive one that maxes the reduction allowed. You can feel the last one pretty easily. Either way extra octane will confirm. Costco gas cost me 3 degrees during wot and 4 in certain part throttle spots. Quick Trip and its perfect.

 

[K4fxd]

"There is plenty of head room in the fuel trims to throw 1/3 tank of e85 in to bump the octane. Or boostane."

So it is safe to use 5 gallons of E85 with the rest being 93 E10?

I've experimented with 3 gallons of 85 with no issues, commanded lambda = measured, and was totally blasted on this forum for trying.

 

[Torinate]

Stoichiometric air fuel ratio is different from e85 to straight 93 octane. 14.7:1 for gas, 9.8 for e85 and ~14.2 for e10. So you may think you’re doing a good thing by adding e85 to 93, however, if the car is not tuned for the increase in fuel needed, you will run lean. You may have higher octane, but not enough fuel. I’m not sure how much your tune will compensate for the reduced total fuel flow. Good question for your tuner. This is why e85 and flex tunes work so well. They adjust total fuel needed to burn at the correct stoic and benefit from the increased octane and cooler burning that comes from e85. One reason fuel mileage on e85 is way worse - need to burn more fuel. If e is available to you, the biggest benefit is a true flex tune or straight e85 tune. No more knock and all the timing.

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