Relocating the IAT sensor to lower intake runner on 1994 mustang?

[ramonspeed]

Hey guys, I was wondering what you think about relocating the Intake Air Temperature sensor on my 1994 mustang from the intake tube to the lower intake manifold on the engine . I have changed my lower intake manifold to a ported one from a fox mustang and I have the threaded hole available to relocate the sensor in the runner, I just have to extend the harness. Also, should I run a fox mustang sensor instead of the sn95 plastic unit I have.

BTW I have a Kenne Bell 1500 running at about 10 psi (2" pulley I think) with ought a bypass and the air charge sure gets hot with the small pulley on the supercharger. I wonder if this relocation can provide a little bit of increased safety margin for the engine since it will measure the actual air charge temperature coming out of the supercharger discharge.

 

[Blackened302]

there was a thread about this a couple weeks ago... i think the general consensus was to leave it somewhere in between the throttle body and MAF.

 

[HISSIN50]

I'd agree with Paul. The sensor is supposed to see inlet temps in the rubber bellows. If you put the sensor in the lower intake, I have the feeling your puter will think the incoming air is super super hot and it will pull timing.

You can generally do it the reverse way (fox III's put the IAT in the airbox) but you dont wanna do the reverse swap as you propose IMHO.
Good luck.

 

[SVT3183]

I'd agree with Paul. The sensor is supposed to see inlet temps in the rubber bellows. If you put the sensor in the lower intake, I have the feeling your puter will think the incoming air is super super hot and it will pull timing.

You can generally do it the reverse way (fox III's put the IAT in the airbox) but you dont wanna do the reverse swap as you propose IMHO.
Good luck.

based on this theory wouldn't all foxes with this setup pull too much timing (that wouldn't make much sense) or are you saying that their computer is made for it and ours isn't?

 

[zenboy99]

based on this theory wouldn't all foxes with this setup pull too much timing (that wouldn't make much sense) or are you saying that their computer is made for it and ours isn't?

Yep, I've seen this on my Tweecer. Fox computers are tuned different than 94-95's in many different ways.

Our cars start running richer with air intake temps over ~120 degrees. I found this out the hard way. Not sure about timing values, but I can look it up if you'd like.

 

[SVT3183]

Yep, I've seen this on my Tweecer. Fox computers are tuned different than 94-95's in many different ways.

Our cars start running richer with air intake temps over ~120 degrees. I found this out the hard way. Not sure about timing values, but I can look it up if you'd like.

i actually just moved my IAT to the lower last week i hope i'm not going to run into a problem. i didn't see anything weird on the dyno, but then again i don't know how hot the intake temps got. i'm sure on the street i'll be wayyy over 120 degrees with the KB

 

[final5-0]

If you think about

Each application is gonna be very much different as far as temps go
therefore
Each pcm is gonna have to have different values

This is a good example to show how things can get outta whack
when changes are made and the pcm does not know about it.

Don 95Vert has given info on this in other posts so you may want
to look it up. I'm pretty sure the info is in the tuning forum.

While I do not have specific info on moving the act .......
It is a common thing seen on forced combos
and
You would have better success if you ..........
adjusted the pcm values to compensate for the move IMHO

Grady

 

[95Vert]

This is good to know for someone like me that has the PIH conversion. I have it hanging between the fender and the engine bay. Havent' had any problems running rich or anything. I'll find out for sure with Paul's tweecer.

 

[Stanger007]

It's not a bad idea to move the sensor if you are running meth, the tune could then be programmed to pull massive timing in the event that the meth is not working.

I will do this when I make the jump to meth next summer.

I posted in your other thread the general guidelines Mike Glover uses when dropping spark based off of ACT temps, here it is again for everyone else: http://www.mustang-tech.org/wiki/Ca...ark_Retard_via_ACT_.28ACT_AFTER_the_blower.29

Good luck!

Wes

 

[HISSIN50]

SVT, the guys explicitly said what I had implied. Each given computer knows where its sensor is placed. The fox puters don't take action against ACT changes till things get hotter as I recall.

Whether it's the fox's forgiving tune or the move of the sensor from a more heat-saturated spot to one that's less saturated, they can get away with having the ACT moved to the airbox. This is done for GT40 swaps sometimes. To me that indicates that Nacho should be fine either way. Sometimes when you pull a Fox ACT, it has hair and chit growing on it (whereas we have to clean ours constantly to keep the tune in check).

 

[95Vert]

lol at hair growing on the fox act. you can't be more right. You can only imagine how dirty mine gets in that location and after a year, i haven't had any problems. I don't plan on leaving it there, but I still haven't decided on my induction set-up.

 

[ramonspeed]

In the future I do plan on running water/methanol injection to cool the air charge. It would be a good idea to have the sensor in the new location so the transfer function can pull timing in case of water/meth injection failure for added safety just like Stanger007 mentioned.

Should I use the Fox mustang sensor (metal) instead of my plastic one?

What values should I use for the sensor function? Currently the J4J1 cobra uses these values for the stock sensor location:
Temperature.........Timing
254oF...................-60 degrees
160oF...................-40 degrees
120oF...................-20 degrees
60oF.....................-0 degrees
0 oF......................40 degrees

I would think that these values need to be slightly changed if I relocate the sensor to the intake manifold because the air charge temperatures can reach or exceed the upper limit (254Degrees) at the supercharger discharge when not running water/meth injection. Also, 60 degrees of timing retard seems a bit on the aggressive side. Perhaps I should extend the temperature range a little higher and take out a little timing retard since 60 seems a lot. I am assuming the sensor operating range is sufficiently high enough and the EEC simply does a linear interpolation for these values.

What other functions/tables are IAT dependent for the J4J1 tune that I should worry about when relocating the IAT sensor? (Besides Spark timing)

 

[millhouse]

Just a hint of real world experience for you guys. I switched locations on my fox from the lower intake to the intake piping in my fenderwell entirely due to heatsoaking the sensor in the lower intake. While the stock fox computer had no qualms with it, the megasquirt ecu I'm running did. The fueling equation for megasquirt relies on MAT's far greater than the stock computer…and it was causing tuning issues where once heatsoaked, it ran different than cold/cool. Tuning hot/cold starts was a chore because of the differences as well.

As far as numbers go…here is what I found. In the stock lower intake during the middle of summer, my MAT's were showing in the 150*F to 170*F range just cruising down the freeway. Once I got into the boost…the temps actually dropped. Crazy, isn't it?

Now with the relocated sensor (fenderwell) my temps read ambient…or damn close to it. If it's 80*F outside…it's reading 80*F air temps cruising down the freeway. Now, once I get into boost…guess what happens? You got it, the temps go up as they should…and the megasquirt adjusts the tune accordingly. Those 80*F temps go up to 90-95*F by the time I'm done with a long 4th gear run…letting me know that everything is working as it should, and my intercooler is doing it's job.