Badog

Had a couple of great conversations with Ray concerning Nocab's engine(tuning, the state of engine building for the 3rd gens, future projects, and advanced ignition setup & tuning) while it was getting installed. He had some really postivie things to say. I just forgot who he was talking about! Now I know...again.

twokrx7

iTrader: (1)

Just relocated my intake air temp sensor to the Greddy Elbow(nice to have some time off from work!). I'll post impressions when the weather clears up and I can put some miles on it.

pp13bnos

iTrader: (1)

Baddog, I don't mean to be a jerk....but its Rob@pineapple. CJ

Badog

Typo. Good catch. No jerkiness noted!

twokrx7

iTrader: (1)

The relocated intake air temp sensor works much better than the stock location. The sensor heats up less when the car is parked and it cools faster once underway. Still has the potential to lean out the car quite a bit after letting a hot car sit for awhile then starting it up and getting on the boost. Definelty need to let the sensor cool down to realistic intake air temps.

Brentis

Ok - rx7 & pfc noob here. I just installed my pfc last week and noticed the exact same thing. I also installed a greddy smic and felt either the fmic guys were completely right about heat soak or the gauge is incredibly slow to react...

So - anyone car to give me a "how-to" on where the sensor is and the best way to move it?

Another observation i had was - is it the sensor is "slow" due to heat soak/etc. or is the sensor sample speed frequency need adjustment?

Thanks for your patience.

twokrx7

iTrader: (1)

Sensor is under the UIM. Pull it out, plug the hole, and relocate the sensor by drilling and tapping a hole plus lengthening the harness to wherever you like, preferably away from the heat of the motor. Mine is now in the elbow just upstream of the TB. If you have a front mount I suggest mounting it in the IC outlet tank.

Observed heat soak is not a function of sample rate (not adjustable). The sensor is physically threaded into the UIM which is a bolted to the LIM which sits adjacent to the header/turbo/downpipe. Since the LIM/UIM are metal the net effect is a btu highway pumping the heat to the sensor anytime you stop the flow of air through the engine compartment and slow the flow of air through the motor ... stop and go traffic or parking a hot motor. It may sound funny, but it appears the sensor is reading the temperature of the UIM instead of the air flowing through it. Poor design.

Xcessive

Hey CJ
We are opening a new shop, combined well have 12000
sq ft so I have been reeeeel busy. I relocate all my air temp sensors out of the engine compartment area, example on the outlet of a front mount intercooler in front of the radiator. But when you do this the air temp drops a ton to approx ouside temp plus boost temp.
With a T72 my incoming air temp at cruise is outside ambient air temperature and the correction factor in the pfc must be leaned out or it will be real rich on cold days.
example air temp before 30c to 65c
after move 0c to 25c
Ralph

Badog

Ralph,

I would have said that the temperature correction factor needs to be tweaked. The stock temperature correction is woefully inadequte for a modded car. Even after moving my temperature sensor, I had to tweaked the corrections factors to ADD MORE fuel. I just don't want people to assume that the stock factors are overly rich or anything.

Congrats on the new shop! I wish I was closer to you to come out for a visit. It's always nice hearing about people supporting the modding community so well.

Tony K.

forcefed1

I would like to do this change. Would anyone tell me what size tap I'll need?

Badog

While it hasn't been that long ago, I've tapped so many things since then they all run together.

Wife disclaimer: Honey, I was talking cars again. Nothing to do with all those fine young thangs always calling "from work" and all.. You just keep your panties unknotted. :End Wife disclaimer

cewrx7r1

iTrader: (2)

I just moved my temp sensor to the outlet of my Blitz FMIC.

Went driving with an outside air temp at 58F and climbing, at noon. Had checked the local temp on TV before going out for this 1/2 hour test.

Stopped a couple of times while running to play with the Blitz controller(new toy). My air temp went to a high of 19C which equates to 66F. If the outside temp was still 58, that is only 8 degrees hotter doing multiple 14PSI runs. That front mount and new location are soooooooo great!!!!!!!!!!!!

jeff48

Ok guys, I am now totally confused by the interplay between this thread and a couple of others. Really I probably have no business even asking these kind of questions because we all know that if lawyers could actually do math, they would have gone to med school instead.

Here are my problems understanding the justification for moving the sensor. Is it your contention that the actual intake air temps when measured by the sensor at the OEM location are incorrect (way lower than reported) because the sensor is acting as a heat sink and reporting some of the sensor body temperature and the actual IAT to the ECU? If so I understand the theory behind moving it. However, when you move the sensor to either the elbow or outlet for the IC aren't you discounting the rise in IAT caused by the air flowing past the rest of the intake system but before it hits the chambers? It seems to me there could be a real rise in IAT attributable to the intake air traveling through the heated aluminum. If it is a negligible rise, then no problem but if significant, it would appear that it would be better to leave the sensor in the stock position and, using the standard AIT v INJ tables, adjust for the differences due to ambient air temp.

That last sentence brings me to my other question which actually references the thread on Air temps and datalogit
https://www.rx7club.com/forum/showth...hreadid=154640 .

That thread references some conversion factors and Badog's graph in an earlier thread
https://www.rx7club.com/forum/showth...hreadid=137398 .

Now my question here stem from the theory that the conversion factors need to be applied when the actual IAT differs from the IAT at which the engine was originally tuned. That part makes sense. The engineers created a table for those conversions and built the ability to use those conversions into the ECU. Now first assuming that we are tuning a stock engine (although I don't see why this theory would change at all in a single conversion highly modded engine system) , I don't understand the idea that the slope of the curve is going to change as a result of tuning at a different reference IAT temp. In other words my question is why does the slope of the correction factors have to change if you tune at say 60 degrees C rather than 40 degrees. It makes sense to me that although the conversion factors for each IAT will change, the percentage difference + or - between them will not. I have included a chart and graph representative of my thinking on this. Can someone tell me why I don't get it.
That being said, I agree that in a heavily modded engine there may be some requirement to change the percentages of + or - to the injectors, but once that relationship is established at any tuning temp, wouldn't the slope hold true for all tuning temps? HELP, my brain is going to explode. I should have bought a YUGO!!!!


Here are the table and graph for my understanding





Tuned at-----30c---------40c---------50c--------60c

Actual___________________________________
IAT_____Recommended INJ adjustment_____________
80----------0.948-----0.957------0.966-----0.975
70----------0.957-----0.966------0.975-----0.984
60----------0.966-----0.975------0.984----- 0.998
50----------0.975-----0.984------0.998----- 1.012
40----------0.984-----0.998------1.012------1.034
30----------0.998-----1.012------1.034------1.055
20----------1.012-----1.034------1.055------1.079
10----------1.034-----1.055------1.079------1.102
0-----------1.055------1.079------1.102-----1.125
-10---------1.079------1.102-----1.125------1.148
-20---------1.102------1.125-----1.148------1.171
-30---------1.125------1.148-----1.171------1.194

jeff48

For some reason I can't get the graph to transfer. If you want it PM me with an email address and I will get it to you via email attachment.

coop

Do you guys have some pics of where you moved the IAT sensor? You don't have a write up on what you did? and what worked and what didn't?

coop

Never mind on the writeup...I missed that previous post...sorry,
but one question, if planning on running Water injection, I want the IAT sensor after the WI nozzle to pick up the cooling effects of the water...right?

cewrx7r1

iTrader: (2)

Why it makes a difference for a modded engine and or relocate.

I am going to make up a new term. The air velocity to surface area ratio encountered by air flowing through through a stock IC is smaller than that when using a large IC for a modded engine. Large ICs are designed to transfer more heat away even at the same flow rate than the stock IC. That is the reason the bigger ICs cool better.

The air flow through the normal IC piping, UIM, and LIM is very fast with almost no surface area and very very small air velcoity to surface area ratio. Thus the air is not affected by the temperature differential.

After heat soaking, the UIM has a lot of mass to cool off with poor air flow around it. The Greddy elbo is more removed from the heat soak. The FMIC is even further away.

After moving the sensor, the PFC correction factors still will need to be changed with a datalogit for optimization.

jeff48

Thanks Chuck, this part I get. To use my words from my earlier post, the negligible rise between the actual intake air temps and those measured at the elbow or IC outlet are insignificant as far as the establishing a baseline tuning temp (i.e. the temp just prior to entering the chamber is not going to be significantly higher than what it is at the TB or elbow or IC output).

The advantage to moving the sensor farther from the thermal mass of the UIM, LIM and piping is that the resultant IAT used by the ECU is closer to the real temp of the air. When unaffected by the thermal mass the sensor reacts more accurately and faster.

That part is the easy part. My tougher question focuses on the slope of the correction. If there are additional variables or constants I am missing that would change the slope of the graphs for each test temp, what are they? If not, wouldn't the table that I included above, indicate the corrected numbers to input to the datalogit for the IATs when the car was tuned. (e.g. if the IATs were around 30c when you tune the car, you would use the 30c column for the corrections to be input to the datalogit)?

twokrx7

iTrader: (1)

The thread is a 10mm, 1.25 pitch.

Badog

Dave,

I would think that you would want the H20 to have full effect on the other gases, get a full mix and give it a little time before measuring the effect. Where are you plumbing in your nozzle? Do you have mixture/flow numbers and which unit are you using?

I am guessing the nozzle will have most impact pre-IC, and the IAT should be pre-TB, post IC. I can do the math to support it but my gut tells me that is pretty close.

Tony K.

Badog

I enjoy (1) my family (2) my car (3) and being validated by equations or smart people...sometimes with better equations!

Hello Fuel Temperature correction. I don't scream about this one, because I don't think it's region of influence is but a lost shadow of air temp.

Should I start a new thread on ignition correction factors and their influence to tuning?

coop

I think I too may be diverging from the original topic, but it is related...here is my question.
With Water injection, do you want to use the cooling ability to cool the air charge, or to cool the combustion chamber?
It could seem like the same thing...and I guess either way the same about of heat energy is pulled out of the process if the water is vaporized.
but I was wondering if I inject the water before the IC, then don't I risk contestation inside of the IC...?
I would agree that the longer the water mist is in the air the more it will be able to cool it down, but if I inject closer to the TB then won't I have less contestation loss, and therefore have more water to cool per spray cycle.
As for amount of water, I am still debating, but it will depend on boost levels. I will have two nozzles each will be actuated at a different boost level (they are the aquamist .9 nozzles). I am going to try to run the configuration like the fuel system; I have a tank (the windshield washer fluid tank for now) and a pump that will pump the water though a loop. The nozzles will be controlled by solenoids; each opens at a different pressure. I am going to have a circuit to keep the pump running for 10seconds or so after the boost level falls below the trigger level, so the system is running and ready to spray, if the level isn't met, then the pump turns off. I am shooting for about %15 water to fuel. I have a book about water injection and the systems design, so I am not going to do much until I have that read.

Badog

Dave,

If you tune FOR the H20 spray, what happens when you don't run it?

I would tune WITHOUT it, and add it as a safety feature for high boost.

Have you ever taken surface temperatures of the fins on your IC and relate that to IAT changes? I think the finely atomized H20 will stay in suspension is the intake air is high enough velocity. After that, do you really care? If there is condensed (state change from gaseous/finely spread droplets to larger globlets in more of a liquid?...I think it's still a liquid throughout and never a gas) H20 on the intake it will simply cool the IC inside, and evaporate into the intake air (true gas now?) which means it's still ingested, right? Just not when you want.

What I am trying to say is that the atomization keeps it from condensing too quick, and the air velocity aides in that. Hitting more surfaces will increase the likelyhood of condensing, but how much does it matter? I don't know.

I have done nothing with H20 injection, nor do I claim any insight into it.

twokrx7

iTrader: (1)

I run WI and inject after the IC. There are split opinions on the optimal location to inject. My Aquamist supplier is adamant that it's best to have tiny droplets of water entering the engine meaning it's better that not all of the water be vaporized. He suggest to inject close to the motor.

I inject into the outlet tank of my IC, directly opposite of the of the outlet tubing, so it's basically injecting straight down the middle of my IC outlet tubing. This is about 20" upstream of my IAT sensor that resides in the Greddy elbow. I feel better with this arrangement than injecting after the sensor or injecting upstream of the IC. IC should work better with the WI post IC but YMMV.

coop

I see how the debate could easily go either way.
So TwoKrx7, did you tune your car using IAT's with the WI or without?