I thought I would create a thread here for the purpose of educating others including myself about the basics of timing and how it effects your performance. I do not have a complete grasp on timing myself, so I leave this up to very experienced people to chime in. I will start of with a few basic questions that I'm sure many people would like answered and also need to know anyway.

1. Base timing at idle when checked with a timing light is 5* btdc. How come in a datalogger you usually see 8-10* btdc? What is happening here? How is the timing light showing the timing being fired at 5* when the datalogger is showing 8-10*? Where is this 3-5* of extra timing come from?

2. Advancing of timing creates more power and torque right? Does retarding timing at low rpms equal faster spool?

3. There is a point where advancing timing so much that it does not yield any more power. What is the average of this point? Can this be reached on pump gas (91-93)?

4. What affects the limit of your peak timing you can get? Is it air temperature?

5. What affects the limit of your peak timing you cant get? airflow or level of boost?

6. What is a good overall peak timing with pump gas (91-93) on a certain boost level? What about a certain airflow level? For example only: 25-30 lbs/min = 19* peak, 30-35 lbs/min = 15*

Those are just a few questions I have in mind at the time. Please feel free to chime in with legitimate/experienced advice. Also, I know I left out many more great questions. So please step up and ask for the benefit of all tuners.

Thanks.

1. DSMLink shows 5 degrees for me, not sure what the issue is there.

2. yes, yes, depends a lot on the rest of the tune though

3. Ideally, I'm sure there is a limit, but cars will never reach it, because of knock.

4. knock, if your car senses knock, it pulls timing

5. again, knock, although higher temperatures do correlate to lower timing, both by higher intake temps and the ecu will retard timing if things are too hot

6. at least for 2g's , 16 or so is fine, doesn't really depend on boost levels, but often the more you boost, you'll have to lower some timing, again, because it will knock.

You have to find a good balance between timing, knock, and a/f

one thing for sure though, our cars like more timing much more than a lean mixture, at least in my personal experience anyway

crunchymilk said:

1. DSMLink shows 5 degrees for me, not sure what the issue is there.

2. yes, yes, depends a lot on the rest of the tune though

3. Ideally, I'm sure there is a limit, but cars will never reach it, because of knock.

4. knock, if your car senses knock, it pulls timing

5. again, knock, although higher temperatures do correlate to lower timing, both by higher intake temps and the ecu will retard timing if things are too hot

6. at least for 2g's , 16 or so is fine, doesn't really depend on boost levels, but often the more you boost, you'll have to lower some timing, again, because it will knock.

You have to find a good balance between timing, knock, and a/f

one thing for sure though, our cars like more timing much more than a lean mixture, at least in my personal experience anyway

Click to expand...

thanks for your reply. but i think you took it the wrong way in a few questions. i know knock is caused by too high of cylinder pressure from .... boost, high timing, high air temperature. but what i was getting at was what cause this knock to come on...? do you know what im saying? im sorry if im being confusing.

crunchymilk said:

1. DSMLink shows 5 degrees for me, not sure what the issue is there.

Click to expand...

hmmm, well i heard that from the factory 2g should have 5* btdc and i know i have seen more than that a few times in my logs. maybe im mistaken? but i would like someone to step in if they have the same issue. i could have sworn i have seen some one say that base timing is different from a datalogged timing at idle. again, maybe i am mistaken.

1: Timing being checked with a timing light and the datalogger simultaneously is impossible. If you have the datalogger connected you are in idle adjustment mode, not timing adjustment mode, unless you're using Dsmlink.

2: You want to advance timing to the point of best torque (you won't get that far on pump gas). The goal is to create the highest possible cylinder pessure at 16 degrees ATDC, this creates maximum torque. Lowering timing will rasie EGT's and may improve the spool but in some cases it's not worth it. You can gain torque by advancing the timing in "spoolup" area, sometimes this will get you past the laggy point in the powerband much quicker than lowering timing will. Try both methods and see which one makes the car quicker.

3: That point is usually beyond the detonation threshold in a turbocharged application. With a N/A engine, torque will usually start to fall off before detonation occurs, this is not the case with a F/I engine. In a F/I engine without knock control, the pistons will usually become damaged before power starts to fall off when advancing timing.

4:The limits to maximum timing advance are varied. You want the minimum advance for best torque. Ultimately it is detonation limited due to heat, octane, cylinder pressure and other variables. On pump gas you probably won't reach mean best torque without experiencing detonation.

5:All else being equal (air temp, coolant temp, A/F, timing, etc), the onset of detonation will come much sooner with higher boost due to cylinder pressure.

6: Too many variable's to give an accurate answer.

You will find that tuning is a huge compromise between power and reliability. Making your setup efficient is the key to both.

GVR4592 said:

1: Timing being checked with a timing light and the datalogger simultaneously is impossible. If you have the datalogger connected you are in idle adjustment mode, not timing adjustment mode, unless you're using Dsmlink.

Click to expand...

im sorry, i didn't mean for you to think i was doing it at the same time. what i meant was that all 2g have 5* base timing right? and this cannot be adjusted without some sort of ecu control. so if you had 8* timing shown on your datalogger, what should you do?

8 degrees is normal. If you have an adjustable CAS and you ground the timing connector under the hood, timing will attempt go to 5 degrees. There is no way to monitor this with a datalogger because the car won't be in timing adjustment mode. When you go out of timing adjustment mode after setting the timing to 5 degrees, it would be back around 8-10 degrees.

The only time you actually have 5 degrees is then your setting the base timing and the ECU isn't applying any timing correction for RPM, load, temp, and altitude. When we talk about setting the timing on the car what we are really doing it synchronising the engine with the position sensors to that they match what the ECU is expecting.

Like GVR4592 is saying a normal timing reading for a 4G63 at stock idle speed, temp and sea level is 8-10* BTDC.

Steve

I'll go a little further into it becasue I'm at work and it's reallly slow.

95-96 have brown grounding box next to the battery that will force the ECU to goto base timing at idle. 5deg. 97-99 do not have this box so the ECU need to be forced manualy. The 8deg timing when it is not grounded comes from the CAS. You can advance or retard timing by loosing the bolts and twisting it. Vfaq.com has more info on it..

The max timing curve on a stock ECU 2g is around 16-17 deg. Intake Temp, Coolant Temp, Knock values all play contributing factors in Timing. Intake temps above 84 deg will loose 1deg timing. Coolant temps below 206 get full timing, between 206-224 loose 1deg timing, above 224 loose 2 deg timing. I honistly forgot what the knock/timing retard timing tables are. I'll look when I get home if no one posts them.

Just reamber your shooting for airflow above 2.1g/rev and timing to steadly climb up to 16deg. Fuel enrichment is the biggest area of enprovment you have right off the bat when it comes to MAF tuning. You're goal is to lean the AFR out at WOT closed loop becasue of the factory ecu's massive 55% enrichment above 4500rpm/2.1g/rev. But that really has nothing to do with your question so I'll leave that for another time.

steve said:

The only time you actually have 5 degrees is then your setting the base timing and the ECU isn't applying any timing correction for RPM, load, temp, and altitude. When we talk about setting the timing on the car what we are really doing it synchronising the engine with the position sensors to that they match what the ECU is expecting.

Like GVR4592 is saying a normal timing reading for a 4G63 at stock idle speed, temp and sea level is 8-10* BTDC.

Steve

Click to expand...

ahh, i see now. so you set the base to 5* and the ecu takes it from there. kind of like setting it to a "zero" point so it knows where its at.

scottsee said:

I honistly forgot what the knock/timing retard timing tables are. I'll look when I get home if no one posts them.

.

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that would be great if you can find out those tables are. i think it would be good to know how many counts of knock cause the ecu to pull 1* and so on....

both the 1G and the 2G, every 3 knock counts translate directly into about 1 degree of timing retard.

scottsee said:

both the 1G and the 2G, every 3 knock counts translate directly into about 1 degree of timing retard.

Click to expand...

awesome dude, thanks

What's the max you want to run on 93 pump gas and 20 psi with a 50 trim in a 2g? I know every car is different but theoretically speaking. I am getting the full 16 degrees of timing advance right now and i am still rich but should i also think about advancing timing or just stick to going lean since i'm on pump?

scottsee said:

both the 1G and the 2G, every 3 knock counts translate directly into about 1 degree of timing retard.

Click to expand...

That's not completely correct. The 1g and 2g interpret knock in different ways. Neither will retard timing at 3 counts of knock. On a 1g at anything less than 3 counts the ecu will keep advancing timing, between 3 and 7 counts it will hold timing steady and above 7 counts it will retard timing at a rate of 1 degree per 3 counts of knock. I don't know if 2g's are the same.

olmytsi said:

What's the max you want to run on 93 pump gas and 20 psi with a 50 trim in a 2g? I know every car is different but theoretically speaking. I am getting the full 16 degrees of timing advance right now and i am still rich but should i also think about advancing timing or just stick to going lean since i'm on pump?

Click to expand...

Tune for no knock. That will give you the best results. There's no specific number that you should be shooting for. Start a new thread if you want to discuss A/F and timing tuning on pump gas.

both 1g's and 2g's are the same the way they retard timing. I should have been more specific on the KnockSum values.

Amazing what can happen with the use of a search button!

Knock(degrees) = KnockRetard(raw) / 2.84.

One thing to add. Displayed "knock" value is the amount of timing retarted, not the actuall seen value of knock.

scottsee said:

One thing to add. Displayed "knock" value is the amount of timing retarted, not the actuall seen value of knock.

Click to expand...

Only with Dsmlink. The other dataloggers display knock in raw form. 0-43 counts.

i know all engines are different and all but i think it would be helpful if people posted what timing they were running with a certain airflow. that way it can give other people an idea of what to shoot for. if i knew someone with the same setup running more timing, then i would start double checking everything to at least get close to their setup.

like i said, my point is that posting your timing with a given airflow and boost will give people an idea whats being done out there and something to shoot for.

Yeah they do, sorry about that, thanks for point that out.

PS. You can't upload excel files or I would post up the 1g/2g tables.

scottsee said:

both 1g's and 2g's are the same the way they retard timing. I should have been more specific on the KnockSum values.

Amazing what can happen with the use of a search button!

Knock(degrees) = KnockRetard(raw) / 2.84.

One thing to add. Displayed "knock" value is the amount of timing retarted, not the actuall seen value of knock.

Click to expand...

GVR4592 said:

Only with Dsmlink. The other dataloggers display knock in raw form. 0-43 counts.

Click to expand...

I run Dsmlink and did not know that; THANKS.

Good info!

IIRC I ran around 20* peak timing at 21ish psi on a 16g with a 11.3 afr. I think around 23-24* with 110 race gas with a 12.5:1 tune at 30 psi dropping to 24 (damn 16g )

For an answer to question 2. I would just let the motor breath. If you want more heat for spool up try running it lean pre boost and then bringing down your afr's as boost starts to rise.

GVR4592 said:

That's not completely correct. The 1g and 2g interpret knock in different ways. Neither will retard timing at 3 counts of knock. On a 1g at anything less than 3 counts the ecu will keep advancing timing, between 3 and 7 counts it will hold timing steady and above 7 counts it will retard timing at a rate of 1 degree per 3 counts of knock. I don't know if 2g's are the same.

Click to expand...

The admin of the dsmlink forums spoke with Todd from TMO and they came to a conclusion that timing is being pulled immediately once knock is detected.

GVR4592 said:

On a 1g at anything less than 3 counts the ecu will keep advancing timing, between 3 and 7 counts it will hold timing steady and above 7 counts it will retard timing at a rate of 1 degree per 3 counts of knock. I don't know if 2g's are the same.

Click to expand...

This would be true if you were talking about the Octane feature in the ECU. Think of octane as a long term trim applied to ignition timing. At 1 to 3 counts of knock octane is increased slowly. From 3 to 7 counts of knock octane holds steady. Above 7 counts of knock decreases octane quickly. This is why it's nice to get the 'octane reset' mod done to eprom chips.

I got the information from here: http://www.vfaq.com/TMO/

After doing some research I found that information is not accurate.