1991 Ford Ranger 1991 Ford Ranger won't idle after cold sta

Tiny
CWIGGS
  • MEMBER
  • 1991 FORD RANGER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 152,000 MILES
Problem started over a year ago. 3.0 L Engine idles extremely rough, or not at all, when started cold. The problem disappears after approx 60 secs. Then starts fine the rest of the day. I've found I can shorten the duration of the problem if I start and immediately force the rpms to 1500 or greater for about 15 secs. Last time I checked (6 mos ago), there were no computer codes. I've replaced the IAC, fuel pump and filter, cleaned the MAF sensor. Symptoms are very much like the Ford 4.0 L problem which requires a timing belt tensioner and new lower intake manifold O-rings/gaskets. I put in a short block in 2004, around 125,000 miles; this problem did not begin until late 2007.

Thanks

Chip Wiggs
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Thursday, September 10th, 2009 AT 11:51 AM

7 Replies

Tiny
MERLIN2021
  • EXPERT
Check for carbon under the EGR, clean all the way to the throttl, check ECT(engine coolant temp)sensor.
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Thursday, September 10th, 2009 AT 1:55 PM
Tiny
DOCFIXIT
  • EXPERT
Hi
Ohm check the ACT rear of IAC then check ECT top right front near throttle body. AT 86 Deg. Both should ohm at 24,200 ohms.
Let me know
Thanks for donate
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Thursday, September 10th, 2009 AT 1:58 PM
Tiny
CWIGGS
  • MEMBER
I checked the resistance on the ECT (7.6k ohms) and ACT (10.9k ohms). Truck had been at operating temp for a hour and then turned off for an hour. Ambient temp was around 84 deg during check. One of the latches on the ECT connector was broken off. My plan is to replace the ACT, ECT and ECT connector, and then clean the carbon from the intake as far as possible past the throttle plate as reasonable. It will not be until the tomorrow morning until I know if the problem is corrected.

Thanks to both Docfixit and merlin2021 for your replies. I will update when I know more.

Chip Wiggs
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Friday, September 11th, 2009 AT 10:17 AM
Tiny
MERLIN2021
  • EXPERT
I'll check back.
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Friday, September 11th, 2009 AT 2:31 PM
Tiny
CWIGGS
  • MEMBER
Replacing the ECT corrected my problem, the ECT connector was slightly damaged and may have contributed to the problem by not having a reliable electrical connection. I replaced the ECT connector also. I replaced the ACT sensor this morning simply because it has 155k plus miles on it.

Thanks for the help!

Chip Wiggs
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Monday, September 14th, 2009 AT 8:37 AM
Tiny
DOCFIXIT
  • EXPERT
Great news Thanks for letting me know you got it running. Use us again, tell a friend
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Monday, September 14th, 2009 AT 9:33 AM
Tiny
MERLIN2021
  • EXPERT
Good work, thanks for the assist Doc!
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Monday, September 14th, 2009 AT 12:52 PM

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