Funny IAT readings - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


MSPNP MSPNP specific Megasquirt related discussion.

Reply
 
 
 
LinkBack Thread Tools
Old 09-25-2013, 06:18 AM   #1
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Jan 2012
Location: Ireland
Posts: 465
Total Cats: 16
Default Funny IAT readings

Hey Guys

i have an MSPNP2 with the diyautotune IAT sensor wired into the AFM wires as per instructions.

Recently i've noticed the wideband reading very rich seemingly randomly. i plugged into the laptop and saw my IAT reading were all over the place from -20 to +20 Celsius.

I rewired it last night and did a log from cold today.

It seems like the temperature reading are weird all the way up until the CLT is above 82 Celsius.

i've attached two logs. the first one is from cold and the second is when the CLT starts to rise above 80.

Note i work in Celsius not Fahrenheit!

Any thoughts? i have no idea how long this has been happening..
Attached Files
File Type: msl 2013-09-25_07.42.33.msl (466.3 KB, 68 views)
File Type: msl 2013-09-25_07.47.07.msl (1.12 MB, 112 views)
rhysmate is offline   Reply With Quote
Old 09-25-2013, 06:23 AM   #2
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Jan 2012
Location: Ireland
Posts: 465
Total Cats: 16
Default

Also, the outside temp this morning was 15 Celcius
rhysmate is offline   Reply With Quote
Old 09-25-2013, 08:47 AM   #3
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,872
Total Cats: 1,790
Default

did you reboot?


serious: did you check your wiring from AIT back to MS?
Braineack is offline   Reply With Quote
Old 09-25-2013, 08:53 AM   #4
Elite Member
iTrader: (2)
 
Join Date: Jun 2009
Location: Istanbul, Turkey
Posts: 2,050
Total Cats: 433
Default

Seems lke you have a bad connection in the sensor wiring.

An open circuit will show up as extreme cold, for instance.
I'd hook up the laptop and do a wiggle test with the engine running.
Godless Commie is offline   Reply With Quote
Old 09-25-2013, 09:02 AM   #5
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Jan 2012
Location: Ireland
Posts: 465
Total Cats: 16
Default

Quote:
Originally Posted by Braineack View Post
did you reboot?


serious: did you check your wiring from AIT back to MS?
No i didn't. i'll check it after work a report back.

Quote:
Originally Posted by Godless Commie View Post
Seems lke you have a bad connection in the sensor wiring.

An open circuit will show up as extreme cold, for instance.
I'd hook up the laptop and do a wiggle test with the engine running.
I tried this, and couldn't get it to change. i'll try again at the ecu wires and report back
rhysmate is offline   Reply With Quote
Old 09-25-2013, 09:27 AM   #6
Elite Member
iTrader: (2)
 
Join Date: Jun 2009
Location: Istanbul, Turkey
Posts: 2,050
Total Cats: 433
Default

Quote:
Originally Posted by rhysmate View Post
I tried this, and couldn't get it to change. i'll try again at the ecu wires and report back
Checking the connections at the sensor, especially inside the sensor plug will be very useful.

Also, a lot of temp sensors degrade internally.
Godless Commie is offline   Reply With Quote
Old 09-25-2013, 09:33 AM   #7
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Jan 2012
Location: Ireland
Posts: 465
Total Cats: 16
Default

Quote:
Originally Posted by Godless Commie View Post
Checking the connections at the sensor, especially inside the sensor plug will be very useful.

Also, a lot of temp sensors degrade internally.
it only has couple thousand miles done though, if even that!
rhysmate is offline   Reply With Quote
Old 09-25-2013, 09:59 AM   #8
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,872
Total Cats: 1,790
Default

a disconnected sensor should show 70F so 20C...
Braineack is offline   Reply With Quote
Old 09-25-2013, 10:06 AM   #9
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Jan 2012
Location: Ireland
Posts: 465
Total Cats: 16
Default

Quote:
Originally Posted by Braineack View Post
a disconnected sensor should show 70F so 20C...
ok. it was showing 21 Celsius before i rewired the connections, so that's something.

ill do another log tonight if i have no luck checking the wiring to try and find a pattern
rhysmate is offline   Reply With Quote
Old 10-10-2013, 09:40 AM   #10
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Jan 2012
Location: Ireland
Posts: 465
Total Cats: 16
Default

ok, no luck yet...

im wondering about the way its wired

ive wired it as below



But i was looking at the MS pinout guide and it says pin 10 is an IAT sensor input. would it ok to wire it directly to this instead of the way i have it currently wired?



It says input 10 is the IAT input
Attached Thumbnails
Funny IAT readings-mafconnector_zps571e838c.jpg  
rhysmate is offline   Reply With Quote
Old 10-10-2013, 09:51 AM   #11
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,872
Total Cats: 1,790
Default

no.
Braineack is offline   Reply With Quote
Old 10-10-2013, 09:55 AM   #12
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Jan 2012
Location: Ireland
Posts: 465
Total Cats: 16
Default

What is that input for?
rhysmate is offline   Reply With Quote
Old 10-10-2013, 10:02 AM   #13
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,872
Total Cats: 1,790
Default

an AIT.
Braineack is offline   Reply With Quote
Old 10-10-2013, 10:06 AM   #14
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Jan 2012
Location: Ireland
Posts: 465
Total Cats: 16
Default

Can you or someone else elaborate? An AIT or IAT?
rhysmate is offline   Reply With Quote
Old 10-10-2013, 10:08 AM   #15
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,872
Total Cats: 1,790
Default

same thing different acronyms.


I'm assuming you had diy build your MS. They would have wired the AIT correctly to match your model year and have the AIT/AIT/MAT sensor come in on stock wiring. Apparently they also wire it so you could bring it in on the db15.
Braineack is offline   Reply With Quote
Old 10-10-2013, 10:13 AM   #16
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Jan 2012
Location: Ireland
Posts: 465
Total Cats: 16
Default

Ill keep looking for a reason behind the funmy readings then. The sensor reads 70f which you said means disconnected? But every so often it reads - figures and rarely it reads seemingly correct figures.

I found an ecu pinout diagram, so ill check and see what voltages it reads and the temp its reading and report back.
rhysmate is offline   Reply With Quote
Old 10-10-2013, 10:14 AM   #17
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,872
Total Cats: 1,790
Default

not voltage, resistance.

this screams loose vagina connections.
Braineack is offline   Reply With Quote
Old 10-10-2013, 10:19 AM   #18
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Jan 2012
Location: Ireland
Posts: 465
Total Cats: 16
Default

Ive cut and spliced the wires from the sensor into the loom so its definitely not that. Ill investigate at the ecu after work in a few hours.

Could the sensor just be a bad one? I have a feeling it never worked correctly
rhysmate is offline   Reply With Quote
Old 10-10-2013, 11:16 AM   #19
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,872
Total Cats: 1,790
Default

it's possible. I've seen a dud once, the element was just dangling.
Braineack is offline   Reply With Quote
Old 10-10-2013, 11:23 AM   #20
Junior Member
Thread Starter
iTrader: (1)
 
Join Date: Jan 2012
Location: Ireland
Posts: 465
Total Cats: 16
Default

So first things first

Ill check the resistance between the two sensor wires, and note what the outside temp is.

Then ill check the resistance between the two wires that are for the afm at the ecu pins?

Then visually check the sensor
rhysmate is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Project Gemini - Turbo Civic on the Cheap Full_Tilt_Boogie Build Threads 58 12-13-2017 10:04 PM
OTS Bilstein to motorsports ASN conversion stoves Suspension, Brakes, Drivetrain 5 04-21-2016 04:00 PM
Expected intake temps on the track? tazswing Race Prep 20 10-03-2015 12:04 PM
Low oil pressure after 1.8 swap and new turbo setup JesseTheNoob DIY Turbo Discussion 15 09-30-2015 03:44 PM
Missing/knock at idle, can someone point me in the right direction? Mikel MEGAsquirt 4 09-28-2015 05:46 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 02:49 AM.