SaturnFans.com
what's new (beta) - classifieds - forums - photos


Go Back   SaturnFans.com Forums > Models > Saturn S-Series > S-Series Mods
Register FAQ Members List Groups Calendar Chat Room Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Display Modes
Old 02-16-2019, 04:11 PM   #1
nealt
Member
nealt is on a distinguished road
 
nealt's Avatar
 
Join Date: Mar 2015
Location: Peoria,IL
Posts: 110

1997 SC2
1999 SC2
Default IAT Sensor Fastened to Engine Coolant Hose

Anybody have any thoughts about taking the IAT sensor out of the intake and "afixing" it to the hot coolant hose nearby so as to fool the ECM into a hot air ambient temperature once the engine warms up? (for winter driving of course)

This is a really simple mod that can be easily done and will solve the cold start driveability problems since it will be somewhat dependent on the engine coolant temp.

REWARD EXCELLENCE!

Add to nealt's Reputation
Rate the quality of this post and help nealt reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
nealt is offline   Reply With Quote
SaturnFans.com Sponsored Links
Old 02-16-2019, 05:01 PM   #2
fdryer
Super Member
fdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond repute
 
fdryer's Avatar
 
Join Date: Jan 2006
Location: NYC
Posts: 43,287
 

2003 L-Series 3.0L Sedan
Default Re: IAT Sensor Fastened to Engine Coolant Hose

If you search for cheapybob, you'll read about his experiments to raise fuel economy with adjusting the iat signal as well as moving it to the exhaust manifold. Last reports from him, approaching 50 mpg with several mods. His ideas were to create a hot air intake and use the iat sensor to send high temperature signals to help the pcm lean out fuel mixtures. I don't remember if he wrote about winter running but cold temps will increase fuel use insofar as the pcm sensing intake air temps.

If you are having cold start issues, this mod may mask an inherent problem that may need to be addressed first. Describe symptoms, ambient temps, maintenance done, parts replaced. Was the coolant sensor replaced with the flat nosed brass one? Thermostat replaced? What's operating temps? Temperature needle position after a full warm up? What's cold idle rpm? Warm idle rpm?

REWARD EXCELLENCE!

Add to fdryer's Reputation
Rate the quality of this post and help fdryer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
fdryer is offline   Reply With Quote
Old 02-16-2019, 07:41 PM   #3
nealt
Member
nealt is on a distinguished road
 
nealt's Avatar
 
Join Date: Mar 2015
Location: Peoria,IL
Posts: 110

1997 SC2
1999 SC2
Default Re: IAT Sensor Fastened to Engine Coolant Hose

I am having no problems with cold starts or with running the car. The car just seems to sound quieter with less exhaust noise when the ambient air temp is above 25 deg F. Also I was thinking that the ECM would inject less fuel when the ambient air temp is higher, leading to a slightly leaner mixture for better mileage and perhaps less engine exhaust noise.

I have read elsewhere that a richer mixture tends to make the engine exhaust sound louder. My thought was to simply "clamp" a another brass IAT sensor against the coolant hose to raise the air temp 150+. I didn't want to put any resisters in the circuit, because I didn't want cold start problems nor did I want to introduce any weird signal characteristics. The original circuit essentially remains identical, I'm just moving the sensor to get a warmer reading... and a nice warm coolant hose happens to be conveniently located nearby.

REWARD EXCELLENCE!

Add to nealt's Reputation
Rate the quality of this post and help nealt reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
nealt is offline   Reply With Quote
Old 02-16-2019, 08:14 PM   #4
nealt
Member
nealt is on a distinguished road
 
nealt's Avatar
 
Join Date: Mar 2015
Location: Peoria,IL
Posts: 110

1997 SC2
1999 SC2
Default Re: IAT Sensor Fastened to Engine Coolant Hose

Plus, my car always seems to have more "pep" when it's above freezing outside. I'm not sure if faking out the IAT reading will have any impact or not.

REWARD EXCELLENCE!

Add to nealt's Reputation
Rate the quality of this post and help nealt reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
nealt is offline   Reply With Quote
Old 02-17-2019, 01:06 AM   #5
fdryer
Super Member
fdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond reputefdryer has a reputation beyond repute
 
fdryer's Avatar
 
Join Date: Jan 2006
Location: NYC
Posts: 43,287
 

2003 L-Series 3.0L Sedan
Default Re: IAT Sensor Fastened to Engine Coolant Hose

By all means, if you already have success running with the iat sensor taped/clamped to the radiator hose with better performance, there isn't any downside for winter operation. You are correct - the iat has some influence on fuel mixtures but less so compared to the engine coolant sensor. Its been said the S-series tends to run on the rich side yet maintain the ideal emissions, slightly rich overall. Since cold starting requires rich mixtures, cold air is denser so its presumed the dense cold air is mixed with the appropriate fuel mixture to maintain emissions as well as ideal fuel/air mixtures. Since the O2 sensor measure exhaust, signals are fed back to the pcm for precise fuel/air mixtures. Tweaking the iat signal by locating it on a warmer surface allows some tweaking of overall fuel mixtures. As long as no ill effects are seen or felt, its your choice.

REWARD EXCELLENCE!

Add to fdryer's Reputation
Rate the quality of this post and help fdryer reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
fdryer is offline   Reply With Quote
Old 02-17-2019, 10:20 AM   #6
Signmaster
Master Member
Signmaster is a splendid one to beholdSignmaster is a splendid one to beholdSignmaster is a splendid one to beholdSignmaster is a splendid one to beholdSignmaster is a splendid one to beholdSignmaster is a splendid one to beholdSignmaster is a splendid one to behold
 
Join Date: Jan 2007
Location: Virginia Beach, VA
Posts: 6,215
 

1995 SL1
Default Re: IAT Sensor Fastened to Engine Coolant Hose

Beyond Cheapybob, there have been a number of people that have tied the IAT to a warmer air source without actual hot air being pulled into the engine. Some had some changes, others reported none.

DIYguy took another approach and fooled the IAT circuit. I don't know the extremes of weather he encountered, but the data showed MPG improvements, and he said the overall performance was better if anything.

DIYguys multiple mods thread with data

...
Alordofchaos is worthy and hides in shadows only to hone his S Series knowledge ninja skills. Swift, silent, trustworthy.

REWARD EXCELLENCE!

Add to Signmaster's Reputation
Rate the quality of this post and help Signmaster reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
Signmaster is offline   Reply With Quote
Old 02-17-2019, 04:39 PM   #7
nealt
Member
nealt is on a distinguished road
 
nealt's Avatar
 
Join Date: Mar 2015
Location: Peoria,IL
Posts: 110

1997 SC2
1999 SC2
Default Re: IAT Sensor Fastened to Engine Coolant Hose

I went ahead and bought another brass tipped IAT sensor from OReilly for $12. I left the pre-existing sensor in place, and just covered the sensor connector to keep it safe from the elements.

I clamped the new sensor onto the coolant hose with a piece of EPDM rubber and a hose clamp. I can already tell a difference in winter driving... engine sounds quieter and smoother. Regardless of any MPG gains, I like how my car is driving with the elevated IAT temp, so I'll keep the mod in place.

I suspect I'll see a slight MPG improvement. I'll provide an update once I get some more mileage on it.

REWARD EXCELLENCE!

Add to nealt's Reputation
Rate the quality of this post and help nealt reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
nealt is offline   Reply With Quote
Old 02-17-2019, 04:52 PM   #8
Saturn Night
Master Member
Saturn Night is just really niceSaturn Night is just really niceSaturn Night is just really niceSaturn Night is just really nice
 
Join Date: Aug 2016
Location: Leavittsburg, OH
Posts: 3,386

1995 SC2
Default Re: IAT Sensor Fastened to Engine Coolant Hose

Running the engine too lean will burn the pistons and valves. The AIT sensor works with the MAP, to calculate the mass of air inside the intake manifold.

GM would later(like many automakers) male both of these sensors into a single, MAF sensor on many of their cars. The MAP signals were often used as a backup, in case of MAF failure.

Any immediate gains to MPGs, would later be offset by a very expensive rebuild of the bottom end or cylinder head(dependent on which part of the engine fails from lean fuel conditions).

To improve the MPGs of a richer fuel mixture, you simply need more spark voltage or side-gapped spark plugs(for greater spark surface area) to burn the fuel more completely.

Increasing the spark advance(if it were possible with the stock PCM), would also help.

Leaning out the fuel mixtures, in addition to the internal damage it does to the pistons and valves, also opens the EGR more(adding more exhaust back into the intake to cool the combustion temperatures), and can cause spark knock under load. From there, the knock sensor will retard ignition timing, which reduces performance and fuel economy.

...
"What does a Saturn owner do, at the gas station?"

"He checks the gas, and fills the oil....."

REWARD EXCELLENCE!

Add to Saturn Night's Reputation
Rate the quality of this post and help Saturn Night reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
Saturn Night is offline   Reply With Quote
Old 02-17-2019, 05:13 PM   #9
nealt
Member
nealt is on a distinguished road
 
nealt's Avatar
 
Join Date: Mar 2015
Location: Peoria,IL
Posts: 110

1997 SC2
1999 SC2
Default Re: IAT Sensor Fastened to Engine Coolant Hose

Has anyone reported serious engine problems with an IAT mod?

I would guess that the outside of the coolant hose at the top of the radiator is probably around 150-170 deg F.

REWARD EXCELLENCE!

Add to nealt's Reputation
Rate the quality of this post and help nealt reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
nealt is offline   Reply With Quote
Old 02-17-2019, 06:59 PM   #10
nealt
Member
nealt is on a distinguished road
 
nealt's Avatar
 
Join Date: Mar 2015
Location: Peoria,IL
Posts: 110

1997 SC2
1999 SC2
Default Re: IAT Sensor Fastened to Engine Coolant Hose

I hooked up a scan tool, and the IAT reading was about 115 deg F when connected on top of the coolant hose. When idling stationary for a few minutes, it would creep up to 120 but would then drop to 110-115 deg as soon as I started driving again.

I think that's a pretty safe temperature without any ill effects. I really like how it drives now that I am in "summer mode" in the dead of winter.

REWARD EXCELLENCE!

Add to nealt's Reputation
Rate the quality of this post and help nealt reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
nealt is offline   Reply With Quote
Old 02-19-2019, 09:03 AM   #11
fetchitfido
Super Member
fetchitfido has a brilliant futurefetchitfido has a brilliant futurefetchitfido has a brilliant futurefetchitfido has a brilliant futurefetchitfido has a brilliant futurefetchitfido has a brilliant futurefetchitfido has a brilliant futurefetchitfido has a brilliant futurefetchitfido has a brilliant futurefetchitfido has a brilliant futurefetchitfido has a brilliant future
 
fetchitfido's Avatar
 
Join Date: May 2006
Posts: 14,364
 

2001 SC2
Default Re: IAT Sensor Fastened to Engine Coolant Hose

Sounds odd, but at least you're not swapping the TB for one with coolant passage's in it to get the same effect.

REWARD EXCELLENCE!

Add to fetchitfido's Reputation
Rate the quality of this post and help fetchitfido reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
fetchitfido is offline   Reply With Quote
Old 02-19-2019, 09:59 AM   #12
OldNuc
Super Member
OldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond reputeOldNuc has a reputation beyond repute
 
Join Date: Apr 2008
Location: Far Southwestern Iowa
Posts: 66,693
 

1998 SC2
Default Re: IAT Sensor Fastened to Engine Coolant Hose

Quote:
Originally Posted by nealt View Post
Has anyone reported serious engine problems with an IAT mod?

I would guess that the outside of the coolant hose at the top of the radiator is probably around 150-170 deg F.
No significant bad effects created as it all cools off as it should when the engine is off. If you look at the LTFT you will see the shift is rather minor.

REWARD EXCELLENCE!

Add to OldNuc's Reputation
Rate the quality of this post and help OldNuc reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
OldNuc is offline   Reply With Quote
Old 02-21-2019, 11:46 PM   #13
cbizzme
Member
cbizzme is on a distinguished road
 
Join Date: Dec 2017
Location: SoCal...and not happy about it in many cases
Posts: 63

1994 SL2
Default Re: IAT Sensor Fastened to Engine Coolant Hose

What are the highest IAT temps youíve seen from the standard sensor location? Not on a Saturn because mine isnít OBD2 but iirc highest temp Iíve seen is 145 or so during 90-100 temps in prolonged stop and go traffic. Has anyone seen how much the fuel is trimmed going from say 50 IAT to 125 or so?

REWARD EXCELLENCE!

Add to cbizzme's Reputation
Rate the quality of this post and help cbizzme reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
cbizzme is offline   Reply With Quote
Old 02-23-2019, 01:57 PM   #14
Signmaster
Master Member
Signmaster is a splendid one to beholdSignmaster is a splendid one to beholdSignmaster is a splendid one to beholdSignmaster is a splendid one to beholdSignmaster is a splendid one to beholdSignmaster is a splendid one to beholdSignmaster is a splendid one to behold
 
Join Date: Jan 2007
Location: Virginia Beach, VA
Posts: 6,215
 

1995 SL1
Default Re: IAT Sensor Fastened to Engine Coolant Hose

Quote:
Originally Posted by nealt View Post
I hooked up a scan tool, and the IAT reading was about 115 deg F when connected on top of the coolant hose. When idling stationary for a few minutes, it would creep up to 120 but would then drop to 110-115 deg as soon as I started driving again.

I think that's a pretty safe temperature without any ill effects. I really like how it drives now that I am in "summer mode" in the dead of winter.
I did similar after seeing DIYguys thread, and noticed the off idle throttle tip in seemed to change. I didn't do it long term since with my '95 there is no cheap or easy way to watch trims and such.

In the thread by DIYguy he went into detail about his changes and the reported fuel use from his Scangauge (or similar) device. Idle fuel consumption went down a decent amount. But IIRC he was using the resistance to simulate IAT temps up in the 220+ range.

...
Alordofchaos is worthy and hides in shadows only to hone his S Series knowledge ninja skills. Swift, silent, trustworthy.

REWARD EXCELLENCE!

Add to Signmaster's Reputation
Rate the quality of this post and help Signmaster reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
Signmaster is offline   Reply With Quote
Old 03-10-2019, 07:45 PM   #15
NWSaturn247
Senior Member
NWSaturn247 will become famous soon enoughNWSaturn247 will become famous soon enough
 
NWSaturn247's Avatar
 
Join Date: Feb 2012
Location: PNW
Posts: 1,113
 

1999 SL2
Default Re: IAT Sensor Fastened to Engine Coolant Hose

I finally performed the mod with a used brass IAT just collecting dust. First 20 mile excursion seemed to run pretty good and maybe little less of the usual Ratlurn LOL

I will update in the future.





.

...
1999 SL2 A4 -86k miles
Currently sipping Mobil 1 & LiquiMoly mos2

TCW3 dosed fuel

https://www.ls1.com/forums/f48/been-testing-oil-91206/

.....
1993 SL2 SOLD @189k

REWARD EXCELLENCE!

Add to NWSaturn247's Reputation
Rate the quality of this post and help NWSaturn247 reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
NWSaturn247 is offline   Reply With Quote
Old 03-13-2019, 05:44 PM   #16
Mr. magnificent
New Member
Mr. magnificent is on a distinguished road
 
Join Date: Mar 2019
Posts: 3
Default Re: IAT Sensor Fastened to Engine Coolant Hose

The Coolant Temperature Sensor, Transmission Oil Sensor and Air Charge Temperature Sensor, should all be "Brass Tip".
I found this out last week, when I had transmission fluid everywhere.
It's, also best to change the wiring harness too!

REWARD EXCELLENCE!

Add to Mr. magnificent's Reputation
Rate the quality of this post and help Mr. magnificent reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
Mr. magnificent is offline   Reply With Quote
Old 03-13-2019, 05:50 PM   #17
Mr. magnificent
New Member
Mr. magnificent is on a distinguished road
 
Join Date: Mar 2019
Posts: 3
Default Re: IAT Sensor Fastened to Engine Coolant Hose

If anyone has surging or idle problems, after changing the "IACV", it's the Air Charge Temperature Sensor, that should be replaced.
This is a sure answer, to anyone who thinks it's a "vacuum leak" causing the rpms to idle up and down.
Also, change your "Air Filter" with "ACTS"!

REWARD EXCELLENCE!

Add to Mr. magnificent's Reputation
Rate the quality of this post and help Mr. magnificent reputation points. Click the reputation button near the bottom left corner of this message box. Thank you!
Mr. magnificent is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
2000 Saturn SL2, Self Revving Engine, Coolant Sensor or Throttle Position Sensor? aygc271 S-Series Tech 5 08-06-2018 08:39 PM
Engine coolant sensor DWHITTED S-Series Tech 3 09-20-2013 03:27 PM
engine coolant sensor adhhaahok S-Series Tech 11 02-14-2006 10:43 AM
Ignition Module / Engine Coolant Sensor Prob? Service Engine Light, Rough Performins Brendo613 S-Series Tech 14 10-19-2005 07:12 AM
1997 SL1 Did they redesign Engine to Coolant Res. Hose? Chris0381 S-Series General 1 05-28-2005 02:03 PM


All times are GMT -4. The time now is 12:16 PM.

Advanced Forum Search | Advanced Photo Search


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
SaturnFans.com. The Saturn Enthusiasts Site.