Timing Advance

[KeltonDSMer]

Why is my ECU slowly pulling timing at high RPM, I have no knock right now at 17-18psi?

I was thinking at first it is because my O2 signal is obviously messed up, it is almost always 0.00volts at WOT, but I'm not running lean! I know this can't be it because the ECU doesn't even take the O2 value into account in closed loop.

At 3500RPM, the advance is in the mid 20's, and it keeps getting pulled untill it is 17 or 18 by redline, WTF? Again, there is no knock at all, the sensor itself is only about 10K old.

I thought it was suppossed to keep advancing until it sees knock, damn.

I can show a log if you all want, but it is only 2nd gear because of me not having a licence yet, (circling the block).


I wish I had control over the timing as well as fuel.........comon DSMLINK!

[XakEp]

Step 1) Get your license.

Step 2) Replace your O2 sensor.

Step 3) Go do pulls on the on ramp to the highway so you can top out in 3rd gear.

Step 4) Come back and report your findings.

[v413nc3]

That's actually quite standard of our cars. If you want to hold 22* or so to redline you better look into management.

[KeltonDSMer]

It is a new O2 sensor, it was replaced when the knock sensor was. I don't know why it doesn't register at WOT, but it seems to work just fine after it warms up at low throttle.


That is way bitch if it is normal, because I already have the weak '90 exhaust cam. After 6K, it just isn't as beastly as from 4-6K.


I have done a 3rd and 4th gear pull when my bro was driving, but that was at 14psi and is not really significant anymore.


I just checked the 2nd gear log and it is exactly how I described it. It actually starts about at an advance of 30 at 3K and then slowly drops to 17/16 at 7K even though there is no knock.




I think if I got some even bigger injectors and pulled fuel from the AFC it would give me better timing, what do you all think? I ask this because I have a 2G MAS and just 550's, so all my values at WOT are positive on the AFC.


I'm suprised I haven't hit fuel cut because my logger maxes out the airflow number right when the turbo fully spools, and I have high, positive values on the AFC at 5K+ RPM.

[DSMtuned]

Carl explained this to me one time.

The stock ECU timing map decreases timing after about 6500 rpms. There is nothing you can do unless you get an engine management system, a programable ECU, or a chip.

-Craig

[KeltonDSMer]

Shit, it looks like I'm going to need some cams to get the top end I want.

[psychlow]

Also, the more airflow the ECU sees, the more it'll pull timing. I don't know if you're on stock injectors, but if you are, that's probably why. That's one reason why AFCers with large injectors have to be careful - the ECU thinks you're pulling in 30% less air with 660's, so it adds more timing.

[KeltonDSMer]

I actually have 550's, and a 2G MAS which reads much leaner than the stocker.


I am flowing a good amount of air right now, so maybe bigger injectors would make the ECU give me more timing if it thinks there is less air entering the motor.

Otherwise, it looks like I might just wait for the 1G DSMLink.

[evildsmr]

dude it's for sure your tuning... i have an afc-2 2g mas and stock injectors and i get 23 degrees of timing at the top of third even at 8k.... on good days i get 25.... so myabe you need to tune somemore..... my values are negative on my afc with the 2gmas and injectors....


Josh
93 TSI AWD

[Hal]

never mind

[KeltonDSMer]

There is NO KNOCK, how else could the timing be pulled unless I am flowing more air than the ECU wants to see?

I think I am just flowing a lot of air and my ECU knows it. That isn't good that you have negative values on your AFC with stock injectors and a 2G MAS. The MAS alone would cause you to run dangerously lean without adding at least 15% on the AFC, and you are in the negative values.

What are your mods? Boost? Turbo?

What kind of frequency is your MAS putting out max? I hit the max on the logger (1606) as my turbo is spooling, before the WG opens.

My computer thinks even more air is entering the motor because I have releatively high values on the AFC by redline in order to have no knock, (18psi and pump gas).


I do need to get on a dyno with a wideband, but I don't see how timing can be pulled unless there is knock or if the ECU sees too much airflow.

[Mirage]

I think I am just flowing a lot of air and my ECU knows it. That isn't good that you have negative values on your AFC with stock injectors and a 2G MAS. The MAS alone would cause you to run dangerously lean without adding at least 15% on the AFC, and you are in the negative values.



I would love to agree with the airflow compensation thing. But I must be an exception.

When I installed my larger injecters (FIC 780's vs. ND 660's), I still had to give positive values (like +25%) on my AFC in order for the thing to even idle right and under certain conditions. Even with different kinds of air metering (unhacked, moderate, and severely hacked 1g MAF, 3" and 3 1/2" GM MAF's with and w/out the HC's).

On more than one occasion have I had to give it odd correction numbers for the setup or for what "seemed right".

Also, For some reason, I almost always have at least 21-23* across the board for timing under WOT conditions on pump gas. I don't have any timing control other than an AFC either. I do, however, have an old-ass TMO stage 3 chip. This *could* have some sort of extra timing burned to it, but I'm doubting it. Is my good timing because I just made a really good match injector-wise? Maybe. I can't explain it otherwise...

Marcus Martinez

[evildsmr]

well iforgot to say i have a chip configured for a 2gmas.. sorry if i got your panties in abunch hal....



Josh
93 TSI AWD

[KeltonDSMer]

I really do think it is pulling timing because of airflow, but why would I not hit fuel cut?

My ECU advances the timing to about 25 or 30 by 4K, but it slowly drops to about 17-20 by 7K. This is really confusing to me because I thought it was supposed to start concervative with the timing and then continue advancing it if there was no knock.



If a log would help you guys figure out what is going on, I can post a 2nd/3rd gear pull.

Thanks a lot everybody.

[DSMtuned]

I'm telling you, this is normal for the stock ECU. The timing maps in the ECU decrease timing between 6k and 7k rpms, even if there is no knock. I lean my SAFC out significantly after 6k and it makes no difference. I cannot get the timing back up to where it is between 5500rpms and 6000.

Where's Carl? He can layout the timing maps for us.

-Craig


I really do think it is pulling timing because of airflow, but why would I not hit fuel cut?

My ECU advances the timing to about 25 or 30 by 4K, but it slowly drops to about 17-20 by 7K. This is really confusing to me because I thought it was supposed to start concervative with the timing and then continue advancing it if there was no knock.



If a log would help you guys figure out what is going on, I can post a 2nd/3rd gear pull.

Thanks a lot everybody.

[DSMtuned]

Here is my post and Carl Morris' response. He has been making his own chips, and so he know the different maps in ECUs well. Here it is:

Date: Tue, 29 Jun 2004 09:47:59 -0600 (MDT)
Subject: RE: [CoDSM] Timing & cruise map??
From: "Carl Morris" <cd2@cdmorris.com>

> Craig Adams asked:
> Also, does anyone know which parameters make the biggest difference with
> the 1g ECU adjusting timing? Do greater injector duty cycles or airflow
> affect timing the most? It seems like these would cancel each other out
> when someone is tuning with an SAFC.
>
>>I am getting 26* timing advance on the logger at 6000rpms with no knock.
>>Timing drops to around 21* by 7000rpms. Others have told me that this is
>>too high and that the 1g ECU will go into a "cruising map" with this much
>>timing. The thing is wouldn't that lead to knock?
>>
>>Should I decrease the base timing a bit to compensate?
>>
>>EGTs and FP are normal. I am running a bit rich for around town driving
>>and could probably lean the SAFC out a bit for the track.
>>
>>Is 25-26* of timing too much at 6000rpms? Is the 21* too much at
>> redline?


Craig,
The stock timing map looks like this (may be just slightly
different because this is from my GVR4 image):

12 17 1C 22 28 2F 30 34 34 34 34 34 34 34 34 34
12 17 1D 23 27 2D 30 34 34 34 34 34 34 34 34 34
12 18 1F 25 28 2B 2E 32 32 32 32 32 32 32 32 32
12 1A 22 26 28 29 2B 2F 2F 2F 2F 2F 2F 2F 30 30
18 1E 25 26 29 28 28 2B 2B 2B 2B 2B 2B 2B 2D 2E
15 1C 21 23 26 23 26 28 28 28 28 28 2A 2B 2C 2E
11 18 1D 1E 1F 22 26 25 27 27 27 27 28 2B 2C 2B
0F 16 17 1A 19 1B 1E 25 27 26 27 25 28 2A 2A 27
0D 14 15 18 13 17 19 1F 23 23 25 23 28 2A 28 26
0B 12 13 16 11 15 17 1C 1F 1F 20 1F 24 27 26 23
09 10 11 14 0F 13 15 1A 1A 1D 1E 1E 23 23 24 1F
07 0E 0F 12 0D 11 13 19 19 17 1B 1C 1D 21 22 1D

The number are in hexadecimal, and are in the units
of degrees BTDC + 10. The columns are in
rpm, 750,1000,1250,1500,1750, and then by 500s to
7000. The bottom rows are the highest loads. So,
if you're making at least 280hp or so, all you really
care about is the last row when you're at WOT. From
your description of the timing that you are seeing,
I'd say that you're not on the bottom row, either
because you're not making that much power yet, or
else because you're fooling the ECU with an AFC or
equivalent. 26*@6k puts you between the 10th and
11th rows (out of 12), and 21*@7k puts you right at
the 11th row. So you're not falling off to a lower
load level above 6k, you're just seeing the timing
fall off because that's what the table is set up to do.
Airflow and injector duty-cycle are directly proportional,
so for all practical purposes when you're talking about
one, you're talking about the other as well. Adding
airflow with the AFC moves you down the rows, and pulling
fuel/airflow with the AFC moves you up in rows, which adds
timing, as you can see. There's nothing wrong with the
timing that you are running...but you'd be able to run more
boost on pump gas if it weren't for that big peak in the
table at 6k. That made sense for a stock configuration
where the ECU wasn't being fooled, but causes a lot of
premature detonation issues for modified people. There
is no "cruising map" so I'm not sure what people were
trying to say. If you're not seeing detonation don't worry
about it. If you want to go as fast as you can, get an
EPROM ECU and change this map, or get a 1g DSMlink when they
become available. Until then you're stuck with not being
able to lean out your fuel without adding timing.

--
Carl Morris

[KeltonDSMer]

Thanks so much, that was exactly what I wanted to know.