1996 Ford Escort Cold start surging, when coming down from

Tiny
BACKYARDFORDGUY
  • MEMBER
  • 1996 FORD ESCORT
  • 4 CYL
  • FWD
  • AUTOMATIC
  • 206,000 MILES
When coming down from fast idle the rpm surges.I have check fuel pressure 31psi at idle 34psi at 2000rpm.I also checked the egr seals fine, mass air flow sensor voltage readings fall within spec, vacuum gauge reads 18 inches steady check for plugged cat seems fine on the vacuum gauge, I also notice at -20 cel the car is hard to start I have to hold my foot to the floor but it does start and run ok sometimes it does stall. This problem is only when it is cold when hot no surging. Any ideas?
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Sunday, September 5th, 2010 AT 12:00 AM

10 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
It sounds like a throttle position sensor or idle air control valve. Has the check engine light come on?
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Monday, September 6th, 2010 AT 12:21 AM
Tiny
BACKYARDFORDGUY
  • MEMBER
I have replaced the Idle Air Control Valve and no response, it only does it when cold. I am going to check for a plugged converter again, also when hot the rpm doesn't come down right away it slowly comes down to idle with no surge. I cleaned the intake with spray in cleaner and it seems to throttle better but still same problem. No engine check light yet.
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Tuesday, September 7th, 2010 AT 1:56 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Let me know what you find with the converter.
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Wednesday, September 8th, 2010 AT 7:03 AM
Tiny
BACKYARDFORDGUY
  • MEMBER
Hi, Bob, Ken
I checked the vacuum again, I got, at a somewhat rough idle 18.5 in Hg to 19 in Hg. Then at 2500RPM was 20 in Hg it dropped under acceleration down to about 15 in Hg then recovered to 20 in Hg and held that reading without going up or down. So I think by this reading my converter is fine. I am trying to get a code reader to check if the check engine light came on then went out and stored a code. Because no check light yet. I am leaning towards the throttle position or MAF but MAF resistance checks out within the normal range and resistance changes with no lag time.
Jeff
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Thursday, September 9th, 2010 AT 8:37 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
If the maf reading are good, try cleaning it. They make a special cleaner that you can get at a parts store.

Let me know if that takes care of the problem.

Joe
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Thursday, September 9th, 2010 AT 9:37 PM
Tiny
BACKYARDFORDGUY
  • MEMBER
I cleaned the maf sensor no change. I managed to get another code reader. Still no codes, but, I cannot get the o2 sensor heated o2 sensor monitors and cat monitor to run. I managed to get all the rest to say done on the code reader. Why is the monitors not running I am using the drive mode set by ford.
Jeff
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Monday, September 13th, 2010 AT 5:41 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
The only thing I can think of is a wiring problem or the PCM may need reflashed or is damaged.
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Tuesday, September 14th, 2010 AT 7:18 AM
Tiny
BACKYARDFORDGUY
  • MEMBER
I was able to have all the monitors check in and run and done. No codes at all, but I did notice the car runs very smooth now. I think when I had the o2 sensors, idle air control valve changed awhile ago the PCM was not cleared properly. So I do not know if that will make any difference or not, maybe it will not allow the PCM to return to it's original fuel tables. Any ideas?
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Tuesday, September 14th, 2010 AT 4:35 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
That could be the case. Let me know if things change.
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Tuesday, September 14th, 2010 AT 8:18 PM
Tiny
BACKYARDFORDGUY
  • MEMBER
Thanks I will let you know if things change. I have to drive the car again. Thanks alot for your help. It s not easy some times working with this obdII computer cars.
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Thursday, September 16th, 2010 AT 11:25 AM

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