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Old 04-01-2010, 06:01 PM   #1
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Default Retarded detontaion!

Hey guys,

I'm still trying to tune out some detonation that I am getting. I am so fed up reducing my ignition advance - it's getting so gay.

I'm getting knock around 6300-6500rpm while MAP is between 145-156kpa. Ignition advance is 12-14*. AFR is 12.3 at this point

Can anyone give me some pointers on what I am doing wrong?

My timing map below has a retard of 5* all around. Whatever you see also has 5* trimmed in real time.

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Old 04-01-2010, 06:07 PM   #2
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Add fuel. At that boost level you should be tuning for 11.5:1.
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Old 04-01-2010, 06:07 PM   #3
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Youre ignition advance shouldnt be anywhere near that low

are you 100% sure its detonation?
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Old 04-01-2010, 06:12 PM   #4
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Quote:
Originally Posted by Jeff_Ciesielski View Post
Add fuel. At that boost level you should be tuning for 11.5:1.
11.5:1 is really conservative for 7 psi...
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Old 04-01-2010, 06:16 PM   #5
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when i'm driving, there's always a retard on the throttle
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Old 04-01-2010, 06:19 PM   #6
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I'm definitely feeling the reduction in power. I was getting signs of detonation on my spark plugs, I have black and silver specs on the porcelain. I am going to aim for a lower AFR without so much ignition retard and see how that goes. I hope these are not famous last words

I'm starting to feel impatient as I just want to drive my car hard again. I want to avoid a tuner if possible.

And I know this is a bit of a vague n00b question, but is there a general amount of fuel I could try adding? For example, 10% addition across my detonation cells? Is there any general correlation between additional fuel percentage and AFR reduction?
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Old 04-01-2010, 06:24 PM   #7
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Quote:
Originally Posted by Full_Tilt_Boogie View Post
11.5:1 is really conservative for 7 psi...
I'm willing to bet if the car were on a dyno, he would make just as much, if not more power at 11.5:1 @ 7psi. The "I can run my car insanely lean" mentality on this forum gets to me. No doubt you *can* run your car that lean without destroying it (hopefully), but whether or not you *should* is debatable. For most of us these aren't race cars, they're street cars, so why run it on the edge?
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Old 04-01-2010, 06:34 PM   #8
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$0.34 cents says your pulley timing mark is no longer accurate.
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Old 04-01-2010, 06:34 PM   #9
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Your spark numbers should be OK, but you are way to lean. AT 7psi you want 12.0:1. Make sure your WB gauge is reading correctly.

I lost power but torque stayed the same when fattening to 11.5:1.
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Old 04-01-2010, 06:34 PM   #10
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It's definitely not a race car, and I'm not aiming for the best fuel economy. I've set my AFR targets a bit lower as well as raised up the fuel values in my problematic areas.

I re-calibrated my LC-1 just last week and haven't driven anymore than 100km so far.

fooger03, it's still on the original timing belt so unless something has slipped on it's own.... I'm just coming up on the first timing belt service interval.

Now I'm jealous of you guys with Megasquirt and the multitude of AFR target cells.

Would you guys mind posting your 3D fuel map image? I want to see what sort of slope I should be aiming for once into boost
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Old 04-01-2010, 06:37 PM   #11
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Quote:
Originally Posted by dgmorr View Post
And I know this is a bit of a vague n00b question, but is there a general amount of fuel I could try adding? For example, 10% addition across my detonation cells? Is there any general correlation between additional fuel percentage and AFR reduction?
Well you're dealing with a mass ratio. 14.7 pounds of air to one pound of fuel would be stoich. So if you're at 12.3:1 now and you want 11.5:1, that's an increase of 0.8 out of the original 12.3 or about 6-7%. I'm sure there are dynamic factors coming in play that might make the relationship not totally linear, but you could start by adding 10-12% and then pulling fuel from there if you're richer than 11.5:1. You can redo the math for 12.0 or whatever AFR you decide on and it should get you in the ballpark.
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Old 04-01-2010, 06:38 PM   #12
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Old 04-01-2010, 06:50 PM   #13
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There is a reason that Savington, snowboarder, myself, and the multitude of other have put AFR at 11.5:1, then added spark. That reason is because we can add significantly more spark angle to make lots more torque, and run cooler cylinder temps, and due the the advance significantly cooler EGT. I can't speak for everyone here but the 3-of us spent a lot of time on the dyno getting the tunes right independantly and we all came up with the same conclusions.

Running 11.3:1 seems to be the limit on cylinder wash, you get lots more torque, lower EGT, and you might even get laid out of the deal.
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Old 04-01-2010, 06:56 PM   #14
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Quote:
Originally Posted by fooger03 View Post
It could be possible, but it doesn't seem too likely. All my timing values seem to make sense when going over the log data....so far
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Old 04-01-2010, 07:04 PM   #15
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do I need to point out the 10:1 pistons in the motor?
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Old 04-01-2010, 08:08 PM   #16
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do I need to point out the 10:1 pistons in the motor?
Is this too much timing for stock compression?

I just raised all the fuel values up about 10-15% and I'm getting the same AFRs and knock counts. I'm starting to think these stock injectors are near their max. Are the 265cc injectors not enough for 7psi of boost?

I've got my 550cc injectors ready to go in once I put in the new clutch.
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Old 04-01-2010, 08:23 PM   #17
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Quote:
Originally Posted by dgmorr View Post
I just raised all the fuel values up about 10-15% and I'm getting the same AFRs and knock counts. I'm starting to think these stock injectors are near their max. Are the 265cc injectors not enough for 7psi of boost?


Do you think that might be an important detail to leave out?
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Old 04-01-2010, 08:25 PM   #18
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Old 04-01-2010, 10:27 PM   #19
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yes, I forgot to mention that, lol. I've seen a couple other people running the 265cc injectors at 7psi with no issues.
Apologies for the n00besity, lol

Thanks for the help
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Old 04-01-2010, 10:52 PM   #20
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Are they running a standalone ecu or a rising rate fuel pressure regulator that raises the fuel pressure significantly when in boost? Are they making the [email protected] injectors run 350+cc @ a lot more than 43psi? Just an idea.
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