Higher RPM's Due to Electrical Load? - Mustang Evolution

Go Back   Mustang Evolution > 4 Cylinder | V6 | Classic Mustangs || Tech and Talk > Pre-2005 V6 Mustang



Reply
 
Thread Tools Search this Thread
Please support our sponsors and let them know you heard about them here!
Old 03-29-2005, 05:56 PM   #1
Legacy Member
Legacy
 
Join Date: May 2003
Posts: 1,895
Send a message via AIM to Rellik Send a message via Yahoo to Rellik
Higher RPM's Due to Electrical Load?

Ok, put your thinking caps on.

I usually dont pop into electronics, but since a question arose, I've been wondering myself as the possible cause and or solution.

The electrical load on a car is never constant, it varies with lights being on, fans, your RPM's in relation to your spark plug firing speeds, your stereo system, ect.

My question to you all, will a higher amount of load cause your computer to increase the RPM's at idle to keep an adaquate charge output?

A few times, a question about Cold Air Induction mods would come up stating that the RPM's are higher at times. The only thing that I've found that were in common with most of them, was that they had either their heater on full blast, or their A/C on.

Would the heater core and the fan create enough of a load on an engine to make the RPM's raise higher than normal? I know the AC usually will increase the RPMs only because of the extra load it puts on the belt (the comptuer is attempting to keep the idle up with the extra load). Since electric motors are considered to be one of the highest electrical hogs in the electronics world, I would assume that COULD be a possibility.

Any ideas? Am I even in the right ballpark?

Thanks guys!
Rellik is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 03-29-2005, 06:16 PM   #2
Legacy Member
Legacy
 
Fishers Stang's Avatar
 
Join Date: May 2003
Region: Indiana
Posts: 1,507
Send a message via AIM to Fishers Stang
idk, but on my Vic it has a high idle setting due to the power load it has. but on the stangs, i have no idea
__________________
Charles
2006 F150 4x4 with the 5.4L V8
Fishers Stang is offline   Reply With Quote
Old 03-29-2005, 06:18 PM   #3
Registered User
 
01mineralgrey6's Avatar
 
Join Date: Jun 2003
Region: Florida
Posts: 1,715
Send a message via AIM to 01mineralgrey6
i don't know either
__________________
-Tony
'99 cobra 'vert
01mineralgrey6 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 03-29-2005, 06:41 PM   #4
Legacy Member
Legacy
 
lowflyn's Avatar
 
Join Date: Aug 2003
Region: Mississippi
Posts: 19,890
Send a message via AIM to lowflyn
I know when I run my subs full blast...my car idles higher. I'm also pulling about 1000 watts of constant power then...so that may have something to do with it. I'm gonna kill my alt, but that's ok, won't be my first to kill lol
__________________
"I'm not driving too fast...just flying too low"
Mine:
-03 SB Cobra vert- 2552 of 5082 Born 02/25/03
Our's:
90 7up vert - new project-07 DSG Focus -DD
335
lowflyn is offline   Reply With Quote
Old 03-29-2005, 07:15 PM   #5
Legacy Member
Legacy
 
Join Date: May 2003
Posts: 1,895
Send a message via AIM to Rellik Send a message via Yahoo to Rellik
Hmm... I seemto have asked aquestion that NO ONE knows the real answer to.

I guess it was a good question then

Still waiting on logical answers.

Brad, your statement only strengthens my intreptation of the electrical load vs. RPM's.
Rellik is offline   Reply With Quote
Old 03-29-2005, 07:45 PM   #6
Legacy Member
Legacy
 
Fishers Stang's Avatar
 
Join Date: May 2003
Region: Indiana
Posts: 1,507
Send a message via AIM to Fishers Stang
"Engine, gasoline, 4.6L overhead cam, SEFI V8, unique with Police Pursuit calibration including increased idle speed for improved charging system output and cooling"

"Alternator, heavy duty 135-amp maximum output, 82-amp at idle w/unique drive pulley for improved charging system" (https://www.fleet.ford.com/downloads...ice/police.pdf) so i still dont know. EDIT* thats on my 02 P71 Vic
__________________
Charles
2006 F150 4x4 with the 5.4L V8
Fishers Stang is offline   Reply With Quote
Old 03-29-2005, 08:25 PM   #7
Road Trip!
 
Tbird232ci's Avatar
 
Join Date: Jun 2003
Region: Maryland
Posts: 1,170
Send a message via AIM to Tbird232ci
with the a/c example, the idle speed is increased, and a few other things change, such as in some cases, the timing will get retarded (in dodges, not sure about ford), and the electric fan will be kicked on if so equipped

with my cars, the more stuff i turn on, the car bogs, ive had cases where my 3.8 car actually stalled when i had the heat, my lights, and my sub on, but if i increased the idle myself, no problem

as we know, with electric motors, they have an effeciency range, an alternator is an electric motor, but that produces power, and even at idle, its out of its effeciency range, i believe even 120amp alts only put out 60amps at idle

as for the idle increase, i personally think its because when the idle drops because of the extra load, the EEC see's that, and increases the idle, only because it see's the dropping idle as something it needs to adjust, not sensing the electrical load, the car will strive to keep a certain idle, and any variation (within reason), it will try to compensate for, and thats just one of the cases
Tbird232ci is offline   Reply With Quote
Old 03-29-2005, 08:45 PM   #8
Legacy Member
Legacy
 
wiarumas's Avatar
 
Join Date: Aug 2003
Region: Maryland
Posts: 1,738
Send a message via AIM to wiarumas Send a message via MSN to wiarumas
hmm ya learn something everyday.
__________________

Please visit: TheEchoBoom: Gen Y Blog and Forum
wiarumas is offline   Reply With Quote
Old 03-29-2005, 08:54 PM   #9
Legacy Member
Legacy
 
MonteCitan's Avatar
 
Join Date: Aug 2004
Region: California
Posts: 2,506
Send a message via AIM to MonteCitan
yes, it does.. your car is smarter than you think.. if it's reading an amount but its not within range, it'll do whatever it can to get back in that range.. that's why when you first flip your headlights on, your idle dips then readjusts... with much heavier loads it can definitely ramp the idle up..
__________________
2012 IS F Blue IS F Sport
2006 Mustang V6 wannabe
MonteCitan is offline   Reply With Quote
Old 03-29-2005, 09:20 PM   #10
Legacy Member
Legacy
 
lowflyn's Avatar
 
Join Date: Aug 2003
Region: Mississippi
Posts: 19,890
Send a message via AIM to lowflyn
I think my alt is going out..my headlights have been dimming while stopping here lately...like noticably
__________________
"I'm not driving too fast...just flying too low"
Mine:
-03 SB Cobra vert- 2552 of 5082 Born 02/25/03
Our's:
90 7up vert - new project-07 DSG Focus -DD
335
lowflyn is offline   Reply With Quote
Old 03-30-2005, 09:41 AM   #11
Registered Member
Regular
 
Join Date: Jul 2003
Posts: 246
On most Fords here's how it works.

Often there is an idle speed adder when you flip the AC on, the computer will raise idle speed 50-75rpms. This is to get a little bit more power out of the alt (to run the engine fan for the condenser and to run the blower fan for the interior), the ac compressor works a little better at higher RPMs, and in some cases to make the engine run smoother with the increased load of the AC compressor.

Increasing load on the alternator does put more drag on the engine, but there is no seperate logic to account for this other than the computers built in ability to control idle speed. It uses a PID type algorithem to learn and adjust the amount of air (through the IAC valve) to keep the engine at a given idle speed. If your idle speed gets higher with a lot of electrical load then its just the computer overcompensating and adding too much air, over time it will learn back down to the normal idle speed.

The computer does try and compensate when the engine fan kicks on. The fan draws so much power (over 30 amps) that it will cause a noticeable dip in idle. There is an air adder (through the IAC valve) that adds in air whenever the computer commands the fan on, this is to keep the idle speed constant and prevent a large dip. You'll probably still feel it anyways to a small extent.
__________________
Justin Starkey
2007 Shelby GT500 705RWHP/708RWTQ
2000 Mustang 3.8 A4 TT 450RWHP/475RWTQ 10.996@127 17psi stock 3.8
2006 F250 CC 4x4 6.0L 14.3 @ 93
2006 Mustang 4.0 M5 Vortech 13psi 395RWHP/374RWTQ wife's car
justin00stang is offline   Reply With Quote
Old 03-30-2005, 10:45 AM   #12
Legacy Member
Legacy
 
Join Date: May 2003
Posts: 1,895
Send a message via AIM to Rellik Send a message via Yahoo to Rellik
Thank you gentlemen, you adaquately answered my question to a satisfactory degree
Rellik is offline   Reply With Quote
Reply

Lower Navigation
Go Back   Mustang Evolution > 4 Cylinder | V6 | Classic Mustangs || Tech and Talk > Pre-2005 V6 Mustang

Thread Tools Search this Thread
Search this Thread:

Advanced Search

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 On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
rpm's for gear ratios chart Herbstang The Bar 10 06-21-2007 04:23 PM
Cop Blows Load on Stripper bluemustang The Bar 6 02-27-2007 01:58 PM
Feedback on site load times Brent The Bar 20 04-12-2006 09:27 PM
RPM's top out at 3,000 stangracer 1979-1995 Mustang GT 11 06-02-2005 02:20 PM

» Like Us On Facebook



04:09 PM


Powered by vBulletin® Version 3.8.8
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0

MustangEvolution.com is in no way associated with or endorsed by Ford Motor Company.