Timing Retardation with Intake Temp

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Timing Retardation with Intake Temp

Postby chaloux » Mon Jun 02, 2014 10:23 pm

So in my journey to lower my intake temps, I've been trying to read up as much as possible about WHEN and HOW MUCH ignition timing one should take out of their base timing table with an additional MAT/IAT timing retard table.

Why do you take timing out when IATs climb? So your engine doesn't detonate and blow up the nice shiny stuff inside your long block. This is obvious, right? Okay, but at what point should we start removing timing due to IATs, and how much timing do we remove? The downside to retarding timing is higher EGTs and less power. Go too far one way (advance) and you detonate, go too far the other (retard) and you melt stuff.

At least with VEMS, this table is very simply laid out:

iatret.jpg
iat ign retard
iatret.jpg (124.28 KiB) Viewed 4613 times


This is how I used to have my 30r setup. I was very weary of intake temps and have a feeling it contributed to my last engine's detonation problems. Since upgrading my intercooler and intake setup, I've reduced my IATs and have subsequently adjusted the amount of timing the ECU will pull from the base timing map.

New Treadstone vs old CXRacing intercooler:
iattrvscx.jpg
iattrvscx.jpg (99.79 KiB) Viewed 4612 times



I recently found a table from the Evo guys, this is how their stock ECU pulls timing:
EVO ignRtd_vs_airTemp.gif
EVO ignRtd_vs_airTemp.gif (4.39 KiB) Viewed 4613 times


This is clearly where dyno tuning helps the calibrator in that he can see MBT (or as much timing as possible before MBT due to knock) and hear detonation/preignition. If det, pull timing. It may be that one just cannot run over a certain amount of boost - Marc tuning the billet k26 on the small #6 hotside, for example. If I recall, intake temps went off the "acceptable" limit at a certain boost regardless of timing. But what if you're unable or don't have the funds to get on the dyno right away? Suck it up, gotta pay to play? Or are there some very general guidelines out there?

So at what temperature do YOU start pulling timing, and how much? How high of temperatures is too much? What is simply too little timing? Is there a certain number or range that there is no point in pulling MORE timing than?

For example, based on that IAT timing retard table I posted above that I used to use on my 30R, my VEMS was pulling 6 degrees out of my timing table on a regular basis. My base timing table was only ~12-15 degrees in the upper RPM range. 6 degrees of timing is NOT a lot, one could say effectively *too little* timing to even be worth it. BUT, that was my old intercooler and I felt it was worth it to save the motor. Sure, "turn down the boost yadda yadda" but I wanted to be able to push the car and let it figure out when/how to pull timing.

This is my current IAT retard table. As you can see, it is much less conservative:
new iat timing ret table.jpg
new iat timing ret table.jpg (67.45 KiB) Viewed 4613 times
Matt

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Re: Timing Retardation with Intake Temp

Postby loxxrider » Tue Jun 03, 2014 10:36 pm

TLDR :D

Just kidding. I skimmed it. That is more timing than I pull here in FL on 95 F days. I will see if I can pull a map for how much timing I pulled. The only thing I can tell you about mine is that when I took it apart there were no signs of det whatsoever.
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Re: Timing Retardation with Intake Temp

Postby SEStone » Wed Jun 04, 2014 10:55 pm

Out here in blazing hot AZ weather, where IATs are sitting in the 50-60C range during normal driving/use and we run 91 octane, timing pull is not that aggressive. I would have to look at the ME maps we do, but figure 5-6deg in the 70-80C range if you let things get that hot, relative to 25C. A dyno is the best place to find out. Remember, physics works in terms of Kelvin, so just because things are hot to you and I doesn't mean they are that radically different in terms of how the reactions go down.
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Re: Timing Retardation with Intake Temp

Postby chaloux » Thu Jun 05, 2014 7:44 am

Sorry for the long winded post Chris, lol, just trying to be clear.

Thanks guys. This is why we need to have this discussion! I feel like this is a big part in preserving motors. The more info and experience we have here will only help reduce the number of melted motors. Those are some good concrete numbers Sam. Anyone else? Brady? Marc? Hank? Etc
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Re: Timing Retardation with Intake Temp

Postby EDIGREG » Thu Jun 05, 2014 10:01 am

MAT/TPS retard is a safety feature - nothing more. Why do you want to reduce the table's ability to provide that safety?

In my opinion, leave it alone, let it do its thing. Remember, MAT/TPS retard, along with any other ignition retard tables, use the ignition map as a base. So if you tune ignition appropriately (with a good set of knock ears), then you've adapted the ignition table to reference the MAT/TPS retard table's values. In other words - let's say you've dyno tuned the ignition map with 60* MAT...you detected some slight detonation so you backed the timing off 2* to be safe. But the MAT/TPS table was also pulling 3* at that point. By reducing the values in in the MAT/TPS retard table, you're now back ON or PAST the detonation threshold at that load cell.

Point is - that table can be whatever you want it to be, but it should be tuned before the ignition map, then left alone. I prefer leaving the values there on the higher side, so that it can more effectively help protect your motor.

Referencing something from another platform, on a completely different ECU, is useless. That is a completely different motor, head, compression ratio, etc - and the ECU was designed specifically for that motor. Factory ECUs have hundreds, if not thousands, of tables - and you don't know anything about the other tables that are also effecting the spark event on that platform.
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Re: Timing Retardation with Intake Temp

Postby turboskipper » Thu Jun 05, 2014 11:32 am

Every engine is different, some are highly knock sensitive and others are not. The base data might be ok but the only real way to calibrate is finishing you base table map at a nominal IAT with no IAT offset. Then adjust IAT (on a nice engine dyno with controlled combustion air or through varying weather) and find the knock limits at various IAT's. I've done it many times on dyno, this is a fairly easy curve/map to calibrate.

Also keep in mind that as IAT goes up your air mass goes down. This is simply defined with the ideal gas law. So the reduced air mass slightly offsets the increased knock sensitivity from temp.

Hope that helps
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Re: Timing Retardation with Intake Temp

Postby loxxrider » Thu Jun 05, 2014 7:20 pm

For what it's worth, the number Sam quoted is what I remember mine being. Let's pull it up to see how good my memory is...

Here we go. This is the table I used for MANY a hot (90-95F) day at about 25psi in FL with 56mm turbo. I can't take credit for making this. I just left it as is because it was working well. Also used in conjunction with a base timing map from Marc (no dyno time).

MAT vs Timing Table.PNG
MAT vs Timing Table.PNG (17.49 KiB) Viewed 4494 times
-Chris

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Re: Timing Retardation with Intake Temp

Postby audifreakjim » Fri Jun 06, 2014 12:32 pm

That looks about right, 6 degrees of adjustment across the board is close to what I am running.
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Re: Timing Retardation with Intake Temp

Postby Hank » Sat Jun 07, 2014 10:43 pm

It really depends on the setup. On a meth setup, ignition advance can be increase on pump gas but if there is a pump error, or a plugged jet, you are screwed. IAT's are what will be the tell-tale of a faulty meth setup, so that table is where the "safety" is built in. If I see 80C on meth, it aint working and timing needs to be pulled significantly.
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Re: Timing Retardation with Intake Temp

Postby ChrisAudi80 » Thu Feb 23, 2017 2:05 am

loxxrider wrote:For what it's worth, the number Sam quoted is what I remember mine being. Let's pull it up to see how good my memory is...

Here we go. This is the table I used for MANY a hot (90-95F) day at about 25psi in FL with 56mm turbo. I can't take credit for making this. I just left it as is because it was working well. Also used in conjunction with a base timing map from Marc (no dyno time).

MAT vs Timing Table.PNG


Would this table be any different if running E85?
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Re: Timing Retardation with Intake Temp

Postby loxxrider » Thu Feb 23, 2017 8:28 am

Yes, that table is for 93 octane only with that particular turbo.
-Chris

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Re: Timing Retardation with Intake Temp

Postby ChrisAudi80 » Thu Feb 23, 2017 9:57 am

loxxrider wrote:Yes, that table is for 93 octane only with that particular turbo.

I see. My IATs are currently 45-48c when cruising at 100-120kph. Temps are rising over here again. Le sigh...

Would water only injection make any difference on E85?
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Re: Timing Retardation with Intake Temp

Postby loxxrider » Thu Feb 23, 2017 9:20 pm

I'm not sure to be honest, but I'm inclined to say it couldn't hurt and would probably help a bit. I'm also inclined to say that you really shouldn't have a problem on e85 even at high temperatures. I'd be more concerned about boiling than anything.
-Chris

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Re: Timing Retardation with Intake Temp

Postby ChrisAudi80 » Fri Feb 24, 2017 4:21 am

loxxrider wrote:I'm not sure to be honest, but I'm inclined to say it couldn't hurt and would probably help a bit. I'm also inclined to say that you really shouldn't have a problem on e85 even at high temperatures. I'd be more concerned about boiling than anything.

Boiling? Where? In the fuel rail? I have fixed the hot fuel tank issue. My wiring to the pump was bad. Blew a fuse. Re-soldered it and the pump and tank are much cooler. I also have the little fuel cooler with fan in the trunk.

Also have the Zeitronix ECA-2 flex fuel set up on my list to monitor eth content and fuel temps, but 349 bux is a lot.

These are my ign timing and retard tables.
Attachments
MAT TPS IGN RET.jpg
MAT TPS IGN RET.jpg (422.13 KiB) Viewed 2031 times
igntiming e85.jpg
igntiming e85.jpg (451.36 KiB) Viewed 2031 times
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Re: Timing Retardation with Intake Temp

Postby chaloux » Fri Feb 24, 2017 7:16 am

That seems like a lot of iat retard and not a lot of timing in general. I was running more timing and less iat retard on pump which... Won't make much power for you on e85. 0 signs of det when the engine failed due to oil starvation.

Edit, see my revised table and the table that Chris posted. I can also post my timing table, I have it somewhere.
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Re: Timing Retardation with Intake Temp

Postby ChrisAudi80 » Fri Feb 24, 2017 8:18 pm

chaloux wrote:That seems like a lot of iat retard and not a lot of timing in general. I was running more timing and less iat retard on pump which... Won't make much power for you on e85. 0 signs of det when the engine failed due to oil starvation.

Edit, see my revised table and the table that Chris posted. I can also post my timing table, I have it somewhere.

Keep in mind that the tables are for my AEB.
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Re: Timing Retardation with Intake Temp

Postby mushasho » Sat Feb 25, 2017 12:28 pm

ChrisAudi80 wrote:
loxxrider wrote:
Also have the Zeitronix ECA-2 flex fuel set up on my list to monitor eth content and fuel temps, but 349 bux is a lot.



Do what I did and just get the same sensor they use have VEMS decode it... GM Part #13577394 (Cheap) ... Frequency Output determine E content , amplitude determine temp. Though I don't measure temp.

Description Calibration Conversion Formula

Ethanol Content
(%)
50 Hertz = 0% ethanol
150 Hertz = 100% ethanol
ethanol % = [ Frequency (Hz) - 50 ]

Fuel Temperature
(degC)
1millisecond pulsewidth = -40
degC
5milliseconds pulsewidth = 125
degC
degC = [ 41.25 * Pulsewidth (ms) ] - 81.2
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Re: Timing Retardation with Intake Temp

Postby ringbearer » Sat Feb 25, 2017 12:41 pm

Wish it did pressure too!
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Re: Timing Retardation with Intake Temp

Postby mushasho » Sat Feb 25, 2017 12:50 pm

ringbearer wrote:Wish it did pressure too!


I did that cheap enough as well... albeit with another sensor

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Re: Timing Retardation with Intake Temp

Postby ChrisAudi80 » Sat Feb 25, 2017 9:54 pm

mushasho wrote:
ChrisAudi80 wrote:
loxxrider wrote:
Also have the Zeitronix ECA-2 flex fuel set up on my list to monitor eth content and fuel temps, but 349 bux is a lot.



Do what I did and just get the same sensor they use have VEMS decode it... GM Part #13577394 (Cheap) ... Frequency Output determine E content , amplitude determine temp. Though I don't measure temp.

Description Calibration Conversion Formula

Ethanol Content
(%)
50 Hertz = 0% ethanol
150 Hertz = 100% ethanol
ethanol % = [ Frequency (Hz) - 50 ]

Fuel Temperature
(degC)
1millisecond pulsewidth = -40
degC
5milliseconds pulsewidth = 125
degC
degC = [ 41.25 * Pulsewidth (ms) ] - 81.2

Cool! A few questions:

How did you wire it in? Like whatVEMS pins.
What config settings in VEMS?
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Re: Timing Retardation with Intake Temp

Postby ChrisAudi80 » Sat Feb 25, 2017 9:56 pm

mushasho wrote:
ringbearer wrote:Wish it did pressure too!


I did that cheap enough as well... albeit with another sensor

Image


Got a link or other information about that sensor? The fitting you put into too, if possible.
TIA.
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Re: Timing Retardation with Intake Temp

Postby mushasho » Mon Feb 27, 2017 12:30 pm

ChrisAudi80 wrote:
mushasho wrote:
ringbearer wrote:Wish it did pressure too!


I did that cheap enough as well... albeit with another sensor

Image


Got a link or other information about that sensor? The fitting you put into too, if possible.
TIA.


I used a raw input / wheel speed 2 ... not a 0-5v pullup

http://www.vems.us/node/51

http://www.technafitstore.com/FP193-p/fp193.htm
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Re: Timing Retardation with Intake Temp

Postby ChrisAudi80 » Tue Feb 28, 2017 3:27 am

Thanks for the links.
I think I will have to modify something on my VEMS ECU. I don't have a PS2 input. PS2 does not plug into the ECs, right?
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Re: Timing Retardation with Intake Temp

Postby mushasho » Thu Mar 30, 2017 8:28 am

ChrisAudi80 wrote:Thanks for the links.
I think I will have to modify something on my VEMS ECU. I don't have a PS2 input. PS2 does not plug into the ECs, right?

This is a 0-5v pullup... No mod needed for fuel pressure sensor.

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