• Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang Tech

RPM fluctuates

  • Thread starter Thread starter 97GTSTANG
  • Start date Start date Jul 24, 2005

97GTSTANG

Founding Member
May 25, 2000
852
0
17
Virginia
www.geocities.com
Jul 24, 2005
#1
  • Jul 24, 2005
  • #1
Whenever i start the car in the morning, the car idles fine around 1100rpm, then after it warms up, it drops down to 850rpm. but after its in the driving temp the RPM drops around 650-700RPM and i also notice the battery meter drops down to R on NORMAL, but when its started in the morning its on M. What do you all think is causing it? Is there a way to raise the RPM up on idle back to 850. What is the factory set at? The TPS sensor wire coating is peeling off, can that be the problem? I have cleaned the MAF and IAC and not much help. any suggestions??
 

triggz

Founding Member
May 15, 2002
1,218
0
37
Gadsden, AL
www.triggz.org
Jul 25, 2005
#2
  • Jul 25, 2005
  • #2
Thats normal idle RPM... Your alternator may be going out, or the battery starting to die. Take her to autozone or some place and they'll do a free check on it with their test equipment.
 

Jones331

Banned
Oct 2, 2004
142
0
0
Oakland CA
Jul 25, 2005
#3
  • Jul 25, 2005
  • #3
Yea the minor "surging" between 1100rpm and in some cases as low as 500 rpm is normal.As far as the coating coming off I don't see that being a problem either.......jj
 
F

four.six

New Member
Nov 27, 2004
443
0
0
43
Corpus Christi, TX
Jul 25, 2005
#4
  • Jul 25, 2005
  • #4
97GTSTANG said:
Whenever i start the car in the morning, the car idles fine around 1100rpm, then after it warms up, it drops down to 850rpm. but after its in the driving temp the RPM drops around 650-700RPM and i also notice the battery meter drops down to R on NORMAL, but when its started in the morning its on M. What do you all think is causing it? Is there a way to raise the RPM up on idle back to 850. What is the factory set at? The TPS sensor wire coating is peeling off, can that be the problem? I have cleaned the MAF and IAC and not much help. any suggestions??
Click to expand...

my car does that with the RPMs too and also when i am down shifting to a stop, sometimes my car dies (i look really cool when that happens)..... i have cleaned the IAC. still does it. guess i should buy a new IAC????
 
You must log in or register to reply here.

Similar threads

7
Engine Random hanging idle
  • 706 Saleen
  • Feb 11, 2026
  • Fox 5.0 Mustang Tech
Replies
9
Views
674
Fox 5.0 Mustang Tech Feb 19, 2026
86HO5.0
8
A
Rough idle - cylinder 1 and 6 misfire HELP
  • austindavies935
  • Jul 24, 2025
  • SN95 4.6L Mustang Tech
Replies
12
Views
748
SN95 4.6L Mustang Tech Jul 24, 2025
gkomo
K
Engine 2000 Mustang GT - Fuel issue post-blown spark plug repair
  • kenster1092
  • Feb 26, 2026
  • SN95 4.6L Mustang Tech
Replies
4
Views
384
SN95 4.6L Mustang Tech Mar 10, 2026
kenster1092
K
SURGING IDLE / NO IDLE CHECKLIST FOR 1996–1998 MUSTANG GT (4.6L 2V) - Work In Progress
  • Noobz347
  • Aug 30, 2025
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
765
1996 - 2004 SN95 Mustang -General/Talk- Aug 30, 2025
Noobz347
SURGING IDLE / NO IDLE CHECKLIST FOR 1999–2004 MUSTANG GT (4.6L 2V) - Work In Progress
  • Noobz347
  • Aug 30, 2025
  • 1996 - 2004 SN95 Mustang -General/Talk-
Replies
0
Views
950
1996 - 2004 SN95 Mustang -General/Talk- Aug 30, 2025
Noobz347
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1996 - 2004 SN95 Mustang -General/Talk-
  • SN95 4.6L Mustang Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?