Mat vs Timing table in chips....

[TType85]

Does anyone know if this can take timing out or just add to the timing?

 

[ijames]

I know it can subtract and I'm 99% sure it can add, but I'll check tonight and post if it can't.

 

[dennisL]

I'll take this one Carl so you can rest tonight.

Yes, you can add or subtract advance by using the MAT table. The code only adds the MAT table value to other values it has for spark advance calculation. However, there is a bias value for the MAT table ($160) that gets subtracted. So, if the table # is greater than the bias #, the advance is added. If the table # is less than bias, the advance is subtracted.

("advance is subtracted" - sounds retarded)

Example: $160 = 20 (hex)
- if table value = 23, 1 degree is added
- if table value = 20, nothing is added
- if table value = 1D, 1 degree is subtracted

 

[bruce]

Originally posted by dennisL
I'll take this one Carl so you can rest tonight.

Yes, you can add or subtract advance by using the MAT table. The code only adds the MAT table value to other values it has for spark advance calculation. However, there is a bias value for the MAT table ($160) that gets subtracted. So, if the table # is greater than the bias #, the advance is added. If the table # is less than bias, the advance is subtracted.

("advance is subtracted" - sounds retarded)

Example: $160 = 20 (hex)
- if table value = 23, 1 degree is added
- if table value = 20, nothing is added
- if table value = 1D, 1 degree is subtracted

FWIW, you'll do better to be in the habit of using 15d or more for the bias values in any spark timing situation. And also avoiding 0's in the table entries. If you don't you can see some ocassional silliness in your dataloggings.

 

[bruce]

Originally posted by TType85
Does anyone know if this can take timing out or just add to the timing?

Also, remember it's just for the higher LV8s, and that you add timing as it raises, up until your turn off level.

Lots of folks think you should add timing when it's cold out. not true. Dave Vizard covers the reasons pretty well in his books.

This is again one area where using a Translator shines. The new MAFs do their own temp correction, so then you can 128 the MAF to fuel table, and then really properly use the MAT for accurate timing.

If you're running a translator then you can mount the MAT sensor in the plenum and get accurate about your timing corrections.

YMMV
Not to be attempted without acult supervision,
be careful and read the plugs often
A WB makes this all much easier.

 

[BoostKillsStres]

Re: Re: Mat vs Timing table in chips....

Originally posted by bruce
Not to be attempted without acult supervision,

aaahhaaa!!! I always knew bruce was into the acult How else could he spew so much TR tuning knowledge J/K

 

[TType85]

My thought is to use the MAT Timing table for somthing a bit different.

It looks to not be used in a stock prom.

If i'm right thinking the way the MAT works, if you have a resistor there you can basically tell the ecm that its xx temp and it will add or subtract timing according to the table.

What i'm looking to see if its possible is to say have a some sort of setup where you can set the resistance to a value (one on either end of the scale) on say a switch and tell it to pull some timing while thats on... sort or a retard switch.

I had real good luck with my friends car pulling about 4-6deg of timing out when spooling up at the line.

Or to take this further (I don't know a whole lot about electronics) but how about somthing to vary resistance (a pot of some type) to take out or add a bit of timing (not a whole lot, don't want to go to 27deg of timing w/o adujusting fuel delevery)

basically tune the timing with a nob

 

[bruce]

Originally posted by TType85
My thought is to use the MAT Timing table for somthing a bit different.

It looks to not be used in a stock prom.

If i'm right thinking the way the MAT works, if you have a resistor there you can basically tell the ecm that its xx temp and it will add or subtract timing according to the table.

What i'm looking to see if its possible is to say have a some sort of setup where you can set the resistance to a value (one on either end of the scale) on say a switch and tell it to pull some timing while thats on... sort or a retard switch.

I had real good luck with my friends car pulling about 4-6deg of timing out when spooling up at the line.

Or to take this further (I don't know a whole lot about electronics) but how about somthing to vary resistance (a pot of some type) to take out or add a bit of timing (not a whole lot, don't want to go to 27deg of timing w/o adujusting fuel delevery)

basically tune the timing with a nob

Just remember that changing the MAT changes the fuel calculation!!!!! ! !!!! ! ! ! !!!!
If you want an in cab way to change timing get the Translator Plus.

The reistance vs degree mat is not linear, if you want to build an ecm bench to see what you really have, OK, just installing a variable resistor and willy nilly changing the timing IS NOT the way to go.

Please, study the fuel correction before getting in there with your dial a timing stuff. You'll see how the fueling changes.

 

[bruce]

Re: Re: Re: Mat vs Timing table in chips....

Originally posted by BoostKillsStres
aaahhaaa!!! I always knew bruce was into the acult How else could he spew so much TR tuning knowledge

Naa, just a poor typist.
Gads, of all the typos.......

 

[Eric Stage I]

ATR made a box that changed timing and plugged into the MAT some years ago. It does work. However, like Bruce said, you'll probably want to zero out the MAF vs airtemp correction table. So there is a trade-off (unless you have a new style maf that does its own correction).

Regards,
Eric

 

[TurboJim]

Originally posted by TType85
.

What i'm looking to see if its possible is to say have a some sort of setup where you can set the resistance to a value (one on either end of the scale) on say a switch and tell it to pull some timing while thats on... sort or a retard switch.

Thats what ATR's EMC10 did, and yes, you can do that

 

[TType85]

ATR made a box that changed timing and plugged into the MAT some years ago. It does work. However, like Bruce said, you'll probably want to zero out the MAF vs airtemp correction table. So there is a trade-off (unless you have a new style maf that does its own correction).

I'm more looking to do it where on a switch I can pull some timing to spool the car at the line. It would not really be needed beyond that. I am running a 3.5" MAF with a regular Translator.

Originally posted by bruce
Just remember that changing the MAT changes the fuel calculation!!!!! ! !!!! ! ! ! !!!!
If you want an in cab way to change timing get the Translator Plus.

The reistance vs degree mat is not linear, if you want to build an ecm bench to see what you really have, OK, just installing a variable resistor and willy nilly changing the timing IS NOT the way to go.

Please, study the fuel correction before getting in there with your dial a timing stuff. You'll see how the fueling changes.

If the info is correct from this page I should be able to get what I want with some experimenting. I don't know about the variable part as, like you said its not linear but if I say have it at one end of the scale and thats all where the change is in the table? I think it could be done, but how well it will work? I dunno.

Does the Translator/LS1 maf do the temp corrections already?

http://www.diy-efi.org/gmecm/component_info/sensors.html

 

[TType85]

Just remember that changing the MAT changes the fuel calculation!!!!! ! !!!! ! ! ! !!!!
If you want an in cab way to change timing get the Translator Plus.

What happens when someone uses the boost sensing harness with turbo link?

Its using the MAT input connected to a MAP sensor.

Does that affect fueling?

I'm going to have to get chip burning stuff again so I can play with this stuff..... sorta wish I never sold it....

 

[TurboJim]

Originally posted by TType85

Does the Translator/LS1 maf do the temp corrections already?

Yes, the LY/LS1 MAF does temp correction inside it. Usually Set corrections to 80h (+/- 0) with a translator.

 

[bruce]

Originally posted by TType85
What happens when someone uses the boost sensing harness with turbo link?
Its using the MAT input connected to a MAP sensor.
Does that affect fueling?
I'm going to have to get chip burning stuff again so I can play with this stuff..... sorta wish I never sold it....

The inner workings of the Boost sensing cable are different from just using a variable resistor. It just so happens to correlate to reality.

Yes, it does slightly change the fueling, but it's in the correct direction.

You already had the chip burning stuff, and then wanted to do this?. Arrgh.

 

[Donald McMullin]

Bruce:

If you're running a translator then you can mount the MAT sensor in the plenum and get accurate about your timing corrections.

Do you mount the MAT sensor in the "Up Pipe" or directly in the TB plenum?? This is in the case of having the MAF in the stock location not in the "Up Pipe" like in your case.

If it is mounted directly in the plenum, do you have any pictures??

Deep Enough
Donald McMullin

 

[dennisL]

TType85 - just to give you a feel for how the MAT sensor works, I looked up some resistance values from the service manual. The first thing to note is, as the temperature goes down, the resistance goes up.

Here are some sample numbers:
275 degF - 100 ohms
100 degF - 1.6 K ohms
70 degF - 3.4 K ohms
20 degF - 13.5 K ohms
-40 degF - 100.7 K ohms

The stock MAT table is setup for the range of -13 degF to "hot as hell". You can change the minimum temp if it makes it easier (smaller range of resistance values needed). But like Bruce said, it's not linear so think about a multi-position switch with fixed resistance at each position.

 

[TType85]

Originally posted by dennisL
TType85 - just to give you a feel for how the MAT sensor works, I looked up some resistance values from the service manual. The first thing to note is, as the temperature goes down, the resistance goes up.

Here are some sample numbers:
275 degF - 100 ohms
100 degF - 1.6 K ohms
70 degF - 3.4 K ohms
20 degF - 13.5 K ohms
-40 degF - 100.7 K ohms

The stock MAT table is setup for the range of -13 degF to "hot as hell". You can change the minimum temp if it makes it easier (smaller range of resistance values needed). But like Bruce said, it's not linear so think about a multi-position switch with fixed resistance at each position.

Thank you for the information. Last night I was thinking of using a multi-position switch

The problem is, how much timing should I play around with when i'm not doing anything with the fuel? i'm thinking maybe +-4 or 6 degrees since I'm really just wanting to retard a bit to spool faster at the line.

 

[Donald McMullin]

Bruce: Found your pictures of the relocated MAF and liquid cooling which shows your MAT in the side of the TB plenum.

Great work on the liquid (fuel) cooling.

Good enough for now.

Donald McMullin

 

[bruce]

Originally posted by Donald McMullin
Bruce: Found your pictures of the relocated MAF and liquid cooling which shows your MAT in the side of the TB plenum.
Great work on the liquid (fuel) cooling.
Good enough for now.

Got to do some driving today, and it was 50dF.
Even with the MAT reading 100dF, the Upipe was signifigantly cooler then that. Just proves that at low speeds, the manifold warms the air in the manifold to above Uppipe temp..

Curious, said Alice