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

1997 4.6 dead spot off idle

  • Thread starter Thread starter Jmc6000
  • Start date Start date Sep 25, 2019
J

Jmc6000

New Member
Sep 25, 2019
1
0
1
Lebanon, OR
Sep 25, 2019
#1
  • Sep 25, 2019
  • #1
Just bought a 97 Automatic with 180,000 miles on her and she runs great. Nice and smooth no no CEL on or any other warning lights for that matter. Before I picked it up the car was sitting for about 9 months that was started occasionally throughout that time. So there is at least a 2 second delay by the time I mash the throttle while in park to the the time the engine actually revs up. In drive there is a 3 to 4 second delay when I mash the throttle off idle to where the engine starts to finally catch up to itself. Any help or ideas would be great. Maybe seafoam in the tank might be what it needs?
 

General karthief

wonder how much it would cost to ship you a pair
20+ Year Stangneter
Aug 25, 2016
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polk county florida
Sep 25, 2019
#2
  • Sep 25, 2019
  • #2
Get your fuel pressure checked. Seafoam helps clean it up but will not fix it.
 

wmburns

SN Certified Technician
Aug 14, 2009
5,892
514
204
Houston Texas
Sep 26, 2019
#3
  • Sep 26, 2019
  • #3
+1 on above. Also double check that the fuel pressure regulator intake vacuum reference line is connected and leak free. Verify that the fuel pressure is correctly intake vacuum referenced. That is the fuel pressure as measured via an external gauge jumps to 40 PSI when the intake vacuum reference line is disconnected.

I would be interest in knowing the intake vacuum at idle and under a load.

Have you cleaned the MAF? Have you looked for excessive carbon deposits inside the throttle body?

What have you done to rule out an intake vacuum leak?

What have you done to rule out a clogged exhaust?

What have you done to rule out clogged fuel injectors? Consider an injector cleaning and flow test service such as InjectorRX.com.

Do you have an ODB2 scanner? Do you know what the long term fuel trim (LTFT) is at idle and under load? Being able to view various PID's might make short work of your issue.

ForScan ODB2 scanner w ELM327 USB

ForScan ODB2 scanner w ELM327 USB

While working on your car have you ever wanted: to find an ODB2 operational PID value (say fuel pressure or MAF)? How about graph a PID value over time? Or compare multiple PID's over time? Access a bi-directional PCM control such as test a...
www.stangnet.com
 
Last edited: Sep 26, 2019
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