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Old 06-12-2013, 02:47 PM   #1
gtx matt
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Default Can't Get Rid of Detonation

This car is driving me insane, I can not get it to stop detonating around 1 g/rev in the 3000ish rpm range, I keep pulling timing and it keeps feedback or fine learning correcting. It corrects -2.11, I pull four, it still corrects -2.11. I even richened it up to around 11.5-12:1 AFR in this range, and have a total timing of roughly 20 degrees in this range. Its usually in open loop when this occurs. WHAT GIVES? I noticed from my logs its always when I'm around 20-50 % throttle, never more, and my boost targets are very high at low throttle imput (12-13 psi @ 49.4 %, 9-10 psi @ 36.1 %). Do I need to aim for less boost at low throttle opening?

This is an 02 WRX, VF39, no cat, turbo back, 565 cc pinks, front mount intercooler. In fourth gear I can spool 19 PSI around 3300-3500 RPM.

I don't have a catch can yet, but the thing doesn't seem to use excessive oil, has around 100K on the short block. I'm thinking of trying a seafoam cleaning too. This is driving me insane.
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Old 06-12-2013, 06:10 PM   #2
Concillian
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Do you have a wideband? Have you verified the fuel is actually richer? Have you logged OL / CL state to see that you're open loop in these conditions?

To me it sounds like you're getting boost, but load is low enough it's staying closed loop.
In which case you could correct it via less boost or by changing the CL / OL parameters until you're going into open loop when you need to.
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Old 06-14-2013, 09:39 AM   #3
wgr73
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What fuel are you on? Assuming pump and not E85 (injectors). Try a higher octane and see what happens....if this is possible.
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Old 06-15-2013, 08:55 PM   #4
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Originally Posted by wgr73 View Post
What fuel are you on? Assuming pump and not E85 (injectors). Try a higher octane and see what happens....if this is possible.
Me on e85 on 565cc

OP could possibly have something resonating/rattling at 3k rpms? Make sure all heat shields are tight.
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Old 06-15-2013, 09:07 PM   #5
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Im at like 30-35* in that area, try adding timing. I had a knock problem I couldn't get rid of until I increased timing in that area.
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Old 06-16-2013, 02:54 PM   #6
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i have had a problem in the same are, to the extent that the iam was going down to 8. i pulled about 15% timing in most of the mid range through the top end. still iam is going down to about 14 and pulling about -2. log your iam also because if it is a lower value then 16 you are pulling -2.11 and then some. looking to the internet for the easy answer is usually every ones first instinct but i think it would be worth it to rent a little dyno time and take out some timing and then slowly add it back in and look for the torque gain to level off or fall off then back up a few degrees and call it good. you cant successfully set timing on the street, best torque can quite often occur well before theknock sensors set off the iam or knock learning. that being said if you have an iam value of 16 and are logging values around -1 to -2.5 that is perfectly normal and you dont have much to worry about. -4 or better then you should retard the timing or add fuel.
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Old 06-17-2013, 09:29 AM   #7
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Quote:
Originally Posted by Andrewxxcarlson View Post
Me on e85 on 565cc
Hahahaha
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Old 06-22-2013, 03:49 PM   #8
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lowering the timing like that will cause teh egts to rise and make the car more knock prone.
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Old 07-16-2013, 01:48 AM   #9
gtx matt
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Sorry for the delay guys, ran into some other issues and distractions (clutch started slipping under power, not bad for the original clutch with 102k on it).

Anyway, I do have a wideband but don't have the plug set up to log it yet. So I set my CL/OL to 0 which helped pretty much eliminate my problems. However, of course I'd prefer some perimeters for delay.

IAM is always 16. Is the consensus generally that to have the car pull 2.11 degrees is ok? I have no knock at WOT/higher loads, just under/around 1.0 g/rev. I'd really prefer it didn't pull anything, but I'm used to my carbed/NA engines where we tune for audible knock. I just hate the idea of it pulling timing here since so much of the time I spend driving is in this area. I don't like climbing a hill with it pulling 2.11 degrees all the way up it.
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Old 07-19-2013, 09:01 PM   #10
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Yay, I was right!

Pulling 2.11 degrees is likely the minimum step at that load. It's not a huge deal to have a small subset of load areas pulling 2.11 degrees, but it usually indicates some knock has triggered that to happen, and the ECU will occasionally put that timing back and try again. The knock is very small and probably of no major concern, but as you say, it's better to have no knock at all, and the good news is that it's really easy to solve the problem (you already did.)

You asked about CL / OL parameters. I'll explain them in some detail, but there is much more in-depth discussion and detail in this thread: http://www.romraider.com/forum/topic1603.html

In the 02 ROM the important delay is either B4 (MT fully warmed @ high altitude) or D4 (MT fully warmed @ low altitude). I'm guessing you're at low altitude, since the default value there is much higher... 3662 (the number is approximately msec delay, so ~3.6 second delay to switch to OL... however if you pass multiple triggers, this delay value will essentially get cut in half or 1/3rd).

A zero in that cell will de-activate all other CL / OL parameters. Then you tune the ability to go open loop with the parameters in the Open loop section. This is adequate tuning for most people.
- Min active AFR -- whenever the OL AFR is below this, it will immediately switch to the OL fuel map when the OL/CL delay is zero. This will allow you to tune for your knock issue. You can enrich the cells of interest causing knock, so that these automatically cause it to switch OL.
- Throttle map allows you to set the leanest AFR it can run at a given throttle position. For example, if you want WOT to never be richer than 12.5:1, then you set the last two throttle % cells to read 12.5 It can run leaner than this at partial throttle if the open loop map tells it to, but at WOT it would always immediately drop to 12.5:1 unless the OL MAP calls for richer fueling.

Any non-zero values in the delay cell will tell it to use the OL/CL delays. As mentioned, this number is roughly time in ms. These tables are a lot more complicated, so most simply set this to zero.
There's an RPM table, so above a certain RPM you can force the delay to start.
There's a throttle table so you can force the counter to start at a certain throttle% open too.
The last table is an injector pulse width table... this table is the primary reason why people get knock in the 2.0L ROM when they don't zero the CL / OL delays
This is essentially the load table... at a given RPM x milliseconds injector pulse width = a specific amount of fuel, and since AFR is always stoich in closed loop, this also dictates g/rev. Unfortunately, this scales the wrong way with bigger injectors. You put in big injectors and this load to switch to OL goes up the same percentage. So you popped in 565cc injectors and didn't zero the delays and you are running stoich at higher loads than you were with the stock injectors.... recipe for knock.

Your trigger loads for Open Loop @ part throttle are nearly 30% higher just because your injectors are nearly 30% higher flow than stock. Now imagine someone with 750cc+ injectors... yikes... it will try to stay Closed Loop at nearly double the stock trigger to switch.

Even if you are WOT, with large enough injectors, if you don't trigger this value too, then you're delaying your switch to the OL map longer than the stock setup would, since this trigger isn't made, it won't decrease the timer as rapidly as the proper load values will.

So most people will reset the delays to zero and just tune the AFR and throttle position for switching OL. You can put a delay there and tune the CL / OL tables, but the base pulse width table is not the most intuitive way to set load values. You could tune the CL / OL tables and run a delay, but there isn't really a huge reason to, IMHO. The fuel economy gain is negligible and the OL triggers are adequate to maintain safety for the engine.

Last edited by Concillian; 07-19-2013 at 09:24 PM.
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Old 07-19-2013, 10:47 PM   #11
Andrewxxcarlson
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Quote:
Originally Posted by Concillian View Post
Yay, I was right!

Pulling 2.11 degrees is likely the minimum step at that load. It's not a huge deal to have a small subset of load areas pulling 2.11 degrees, but it usually indicates some knock has triggered that to happen, and the ECU will occasionally put that timing back and try again. The knock is very small and probably of no major concern, but as you say, it's better to have no knock at all, and the good news is that it's really easy to solve the problem (you already did.)

You asked about CL / OL parameters. I'll explain them in some detail, but there is much more in-depth discussion and detail in this thread: http://www.romraider.com/forum/topic1603.html

In the 02 ROM the important delay is either B4 (MT fully warmed @ high altitude) or D4 (MT fully warmed @ low altitude). I'm guessing you're at low altitude, since the default value there is much higher... 3662 (the number is approximately msec delay, so ~3.6 second delay to switch to OL... however if you pass multiple triggers, this delay value will essentially get cut in half or 1/3rd).

A zero in that cell will de-activate all other CL / OL parameters. Then you tune the ability to go open loop with the parameters in the Open loop section. This is adequate tuning for most people.
- Min active AFR -- whenever the OL AFR is below this, it will immediately switch to the OL fuel map when the OL/CL delay is zero. This will allow you to tune for your knock issue. You can enrich the cells of interest causing knock, so that these automatically cause it to switch OL.
- Throttle map allows you to set the leanest AFR it can run at a given throttle position. For example, if you want WOT to never be richer than 12.5:1, then you set the last two throttle % cells to read 12.5 It can run leaner than this at partial throttle if the open loop map tells it to, but at WOT it would always immediately drop to 12.5:1 unless the OL MAP calls for richer fueling.

Any non-zero values in the delay cell will tell it to use the OL/CL delays. As mentioned, this number is roughly time in ms. These tables are a lot more complicated, so most simply set this to zero.
There's an RPM table, so above a certain RPM you can force the delay to start.
There's a throttle table so you can force the counter to start at a certain throttle% open too.
The last table is an injector pulse width table... this table is the primary reason why people get knock in the 2.0L ROM when they don't zero the CL / OL delays
This is essentially the load table... at a given RPM x milliseconds injector pulse width = a specific amount of fuel, and since AFR is always stoich in closed loop, this also dictates g/rev. Unfortunately, this scales the wrong way with bigger injectors. You put in big injectors and this load to switch to OL goes up the same percentage. So you popped in 565cc injectors and didn't zero the delays and you are running stoich at higher loads than you were with the stock injectors.... recipe for knock.

Your trigger loads for Open Loop @ part throttle are nearly 30% higher just because your injectors are nearly 30% higher flow than stock. Now imagine someone with 750cc+ injectors... yikes... it will try to stay Closed Loop at nearly double the stock trigger to switch.

Even if you are WOT, with large enough injectors, if you don't trigger this value too, then you're delaying your switch to the OL map longer than the stock setup would, since this trigger isn't made, it won't decrease the timer as rapidly as the proper load values will.

So most people will reset the delays to zero and just tune the AFR and throttle position for switching OL. You can put a delay there and tune the CL / OL tables, but the base pulse width table is not the most intuitive way to set load values. You could tune the CL / OL tables and run a delay, but there isn't really a huge reason to, IMHO. The fuel economy gain is negligible and the OL triggers are adequate to maintain safety for the engine.
Ahhhhh my godddd! So much for my brain!!!!!!!! *poof*
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Old 07-25-2013, 05:36 PM   #12
Concillian
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What? It's not like I said "infinity times infinity"

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Old 10-08-2013, 04:24 PM   #13
gtx matt
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What? It's not like I said "infinity times infinity"

Concillian,

I appreciate the time you spent to type that out and wanted to let you know I read it! Thanks for the explanation, unfortunately I ran into more problems with this car (took out second gear) but I'm finally getting around to fixing that now, so will be back to tuning it again... 2 and a half months later haha
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