IAT tricker + sd tune + nitrous = potential boom.
10-27-2010, 06:14 PM
#1
IAT tricker + sd tune + nitrous = potential boom. I am posting this here in an effort to spread knowledge.
Since the beginning I have ran into stupid issues with my nitrous, and I think I just solved it. This goes all the way back to my dry shot halo bar and my stock motor blowing within the first bottle. My setup has since changed to a wet shot and a nozzle, but I have always had issues. I think I found the constant here...the IAT tricker.
Recently I deleted my maf and cats from my car and went with a SD tune. Ever since this I have not been able to successfully spray the car. Prior to this I could spray it, but always ran into strange issues. It always seemed like I had to jet the car a little richer than what others did to get similar AFR's. I also never really picked up the power I thought I should have on spray. This issue has stumped me and last night while laying in bed trying to sleep (I know obsession right) it came to me. With my car and other cars that I have tuned I have always seen small changes in the AFR as the IAT would go up 20 degrees or so, but this just hadn't dawned on me yet.
Up until now I have been a strong supporter of the IAT tricker to pull nitrous. I have always suggested this to people, and know of at least one person running a setup like this based on my recommendations (don't worry I am going to contact them)
So, what is the IAT tricker and what does it do?
Nitrous requires timing to be pulled from your NA tune. You only spray a fraction of the time, so why pull timing all the time. Some timing pull devices cost a lot of money, the IAT tricker can be made for dollars. Here is how it works.
A resistor wired up to a relay. Wire the relay up so that it sees power when your solenoids do. Cut your appropriate IAT sensor wire and splice in the relay. When the relay sees power current passes through the resistor making the IAT sensor believe the intake air temp is higher than it actually is (this depends on the resistor used, 201 degrees in my case). Then in the tune you go into your IAT timing tables and set the appropriate column to pull the amount of timing that you want. You now have the best of both worlds...or do you. Based on my findings today, this also DRASTICALLY alters the fuel.
My findings.
Today I unhooked power from my nitrous and fuel solenoids. I changed my IAT timing table in the tune so that no timing would be pulled with the 201 degree IAT's. I made a baseline 3rd gear pull with the nitrous off just to get an idea of the AFR error and actual AFR. Things looked fine this pull (see attached screenshot below) For those of you not familiar with hp tuners here is what you are looking at. The red line in the top row of the graph is rpm. What you need to look at here is the overlapping white and green lines in the second column of the graph. This is actual AFR vs commanded AFR. Also, note that the IAT of this run is 68 degrees.
Now this next run is with the nitrous armed (remember no power to the solenoids I am not spraying, also remember no timing is pulled in the 201 degree column for this demonstration). So to be clear here I am not spraying. The bottle is shut and there is no power to the solenoids. Just want to make sure we are clear here. Anyway, you can see that the system activates and the IAT goes up to 201 (red gauge lower right hand corner). Also note the rise in the green line (actual afr) at around 4200 when the IAT tricker sees power. You will see the actual AFR shoot up to mid 15's. THATS RIGHT 15.5'S AFR UNDER WOT ON MOTOR. Notice the commanded AFR is the same mid 12 as above. Once I saw how lean this was I killed the system and continued the run thats why at the end you see the actual AFR drop back down. No changes to the tune were made between these runs. Approx 6 min of time passed between the first and second run. Both were 3rd gear pulls.
Now this final run shows what I had to do in the tune to get my actual AFR back where it needed to be. Notice I did pull 7 degrees in the 201 degree column this time. It took me about 6 runs to get this dialed in. Remember, there is still no power to the nitrous or fuel solenoid on this run, and the bottle is still shut. What I did was add fuel in the POWER ENRICH FUEL ADDER VS IAT TEMP table in the tune under the 194 and higher column. As you can see here I am commanding a 10.5 AFR to reach my actual mid to high 12 AFR. Also notice the RICH SPIKE I now have when the system activates.
Now like I said, I have used this IAT tricker since the beginning. I always noticed issues even with the maf but nothing this severe. I am guessing since the maf reads airflow it was somehow partially making up for this. Who knows though, this could have been part of the reason I lost my stock motor on the dry shot a few years back. There have to be some tables somewhere that control all of this that I do not have access to in HP tuners.
So what am I going to do? I am going to ditch the IAT tricker. I have HP tuners, and I rarely race on the street anymore. At the track I always have my laptop, and if I am going to be playing around on the street I will have my laptop. I will just flash to a tune with less timing if I am going to spray.
Before I pull off the IAT tricker, if I can find the motivation I am going to put the maf back on and repeat this test to see how much of an effect it actually is with the maf there to compensate.
Since the beginning I have ran into stupid issues with my nitrous, and I think I just solved it. This goes all the way back to my dry shot halo bar and my stock motor blowing within the first bottle. My setup has since changed to a wet shot and a nozzle, but I have always had issues. I think I found the constant here...the IAT tricker.
Recently I deleted my maf and cats from my car and went with a SD tune. Ever since this I have not been able to successfully spray the car. Prior to this I could spray it, but always ran into strange issues. It always seemed like I had to jet the car a little richer than what others did to get similar AFR's. I also never really picked up the power I thought I should have on spray. This issue has stumped me and last night while laying in bed trying to sleep (I know obsession right) it came to me. With my car and other cars that I have tuned I have always seen small changes in the AFR as the IAT would go up 20 degrees or so, but this just hadn't dawned on me yet.
Up until now I have been a strong supporter of the IAT tricker to pull nitrous. I have always suggested this to people, and know of at least one person running a setup like this based on my recommendations (don't worry I am going to contact them)
So, what is the IAT tricker and what does it do?
Nitrous requires timing to be pulled from your NA tune. You only spray a fraction of the time, so why pull timing all the time. Some timing pull devices cost a lot of money, the IAT tricker can be made for dollars. Here is how it works.
A resistor wired up to a relay. Wire the relay up so that it sees power when your solenoids do. Cut your appropriate IAT sensor wire and splice in the relay. When the relay sees power current passes through the resistor making the IAT sensor believe the intake air temp is higher than it actually is (this depends on the resistor used, 201 degrees in my case). Then in the tune you go into your IAT timing tables and set the appropriate column to pull the amount of timing that you want. You now have the best of both worlds...or do you. Based on my findings today, this also DRASTICALLY alters the fuel.
My findings.
Today I unhooked power from my nitrous and fuel solenoids. I changed my IAT timing table in the tune so that no timing would be pulled with the 201 degree IAT's. I made a baseline 3rd gear pull with the nitrous off just to get an idea of the AFR error and actual AFR. Things looked fine this pull (see attached screenshot below) For those of you not familiar with hp tuners here is what you are looking at. The red line in the top row of the graph is rpm. What you need to look at here is the overlapping white and green lines in the second column of the graph. This is actual AFR vs commanded AFR. Also, note that the IAT of this run is 68 degrees.
Now this next run is with the nitrous armed (remember no power to the solenoids I am not spraying, also remember no timing is pulled in the 201 degree column for this demonstration). So to be clear here I am not spraying. The bottle is shut and there is no power to the solenoids. Just want to make sure we are clear here. Anyway, you can see that the system activates and the IAT goes up to 201 (red gauge lower right hand corner). Also note the rise in the green line (actual afr) at around 4200 when the IAT tricker sees power. You will see the actual AFR shoot up to mid 15's. THATS RIGHT 15.5'S AFR UNDER WOT ON MOTOR. Notice the commanded AFR is the same mid 12 as above. Once I saw how lean this was I killed the system and continued the run thats why at the end you see the actual AFR drop back down. No changes to the tune were made between these runs. Approx 6 min of time passed between the first and second run. Both were 3rd gear pulls.
Now this final run shows what I had to do in the tune to get my actual AFR back where it needed to be. Notice I did pull 7 degrees in the 201 degree column this time. It took me about 6 runs to get this dialed in. Remember, there is still no power to the nitrous or fuel solenoid on this run, and the bottle is still shut. What I did was add fuel in the POWER ENRICH FUEL ADDER VS IAT TEMP table in the tune under the 194 and higher column. As you can see here I am commanding a 10.5 AFR to reach my actual mid to high 12 AFR. Also notice the RICH SPIKE I now have when the system activates.
Now like I said, I have used this IAT tricker since the beginning. I always noticed issues even with the maf but nothing this severe. I am guessing since the maf reads airflow it was somehow partially making up for this. Who knows though, this could have been part of the reason I lost my stock motor on the dry shot a few years back. There have to be some tables somewhere that control all of this that I do not have access to in HP tuners.
So what am I going to do? I am going to ditch the IAT tricker. I have HP tuners, and I rarely race on the street anymore. At the track I always have my laptop, and if I am going to be playing around on the street I will have my laptop. I will just flash to a tune with less timing if I am going to spray.
Before I pull off the IAT tricker, if I can find the motivation I am going to put the maf back on and repeat this test to see how much of an effect it actually is with the maf there to compensate.
10-28-2010, 08:46 AM
#4
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this is exactly why i didnt use a IAT timing tricker with my setup... because the air temperature is very important for speed density. The temperature of the air determines how dense the air is.... If the computer thinks the air is 200 degrees then when it does it calculations and references the VE table it THINKS there is less air going into the engine and therefore adds less fuel. Im glad that you figured this out now its just too bad you didnt post this idea before you lost the first motor so someone could have told you then 
. Although if you had the MAF on then like you already said i dont know how much of an impact it would have had... but on speed density its a big deal. You have only the MAP pressure and air temp.... Nothing else.
on a side note i cant seem to find that table you modified in my hp tuners under the fueling table at all
. Although if you had the MAF on then like you already said i dont know how much of an impact it would have had... but on speed density its a big deal. You have only the MAP pressure and air temp.... Nothing else.on a side note i cant seem to find that table you modified in my hp tuners under the fueling table at all
Last edited by got-a-ls1; 10-28-2010 at 08:57 AM.
10-28-2010, 11:07 AM
#5
this is exactly why i didnt use a IAT timing tricker with my setup... because the air temperature is very important for speed density. The temperature of the air determines how dense the air is.... If the computer thinks the air is 200 degrees then when it does it calculations and references the VE table it THINKS there is less air going into the engine and therefore adds less fuel. Im glad that you figured this out now its just too bad you didnt post this idea before you lost the first motor so someone could have told you then . Although if you had the MAF on then like you already said i dont know how much of an impact it would have had... but on speed density its a big deal. You have only the MAP pressure and air temp.... Nothing else.
on a side note i cant seem to find that table you modified in my hp tuners under the fueling table at all
. Although if you had the MAF on then like you already said i dont know how much of an impact it would have had... but on speed density its a big deal. You have only the MAP pressure and air temp.... Nothing else.on a side note i cant seem to find that table you modified in my hp tuners under the fueling table at all
http://www.ls1gto.com/forums/showthread.php?t=388218
Yeah I do not know what effect this would have with the maf intact. I always noticed I had to jet higher than I felt I should have. I might throw the maf back on and repeat the test.
10-28-2010, 11:08 AM
#6
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IAT is a key factor in speed density air mass calcs and
tricking that might not be so good an idea. Not unless
the bottle so dominates true air temp & mass that the
environment is never a factor. Not at all true when
your shot is a fraction of NA HP.
If you're going to play tricks, best one trick at a time.
IAT for timing has that air mass consequence on a SD
tune.
tricking that might not be so good an idea. Not unless
the bottle so dominates true air temp & mass that the
environment is never a factor. Not at all true when
your shot is a fraction of NA HP.
If you're going to play tricks, best one trick at a time.
IAT for timing has that air mass consequence on a SD
tune.
11-01-2010, 12:35 PM
#7
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I have always just cut the IAT wire and ran it to a toggle switch. Flip the switch to open the ciruit and it defaults to -40. Then go subtract your timing in that column....no need for relays and all that complexity.
With that said, I agree with the others-its best just to flash the proper tune when you want to spray.
With that said, I agree with the others-its best just to flash the proper tune when you want to spray.
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11-01-2010, 06:11 PM
#8
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I have always just cut the IAT wire and ran it to a toggle switch. Flip the switch to open the ciruit and it defaults to -40. Then go subtract your timing in that column....no need for relays and all that complexity.
With that said, I agree with the others-its best just to flash the proper tune when you want to spray.
With that said, I agree with the others-its best just to flash the proper tune when you want to spray.
i think the safest(?) thing to do (and what i might try)would be to set the resister to simulate 40º or so... because that would run slightly richer if the temp was say 80-90º... Also if your actual intake air temp is 40º who cares if your running less timing in those cells when your not spraying because honestly the tires arnt gonna grip for crap anyways...
11-02-2010, 01:02 PM
#9
I'm on SD also, but my tuner pulled timing from the cts (coolant temp sensor) wire from the ecm. He modified the wot timing tables from his software, so it takes out a certain amount of timing from a flip of a switch. It's also wired, so the nitrous will not arm unless the timing switch is on.
