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1998 Cadillac Deville

Tiny
MYSOPHTIA
  • MEMBER
  • 1998 CADILLAC DEVILLE
  • V8
  • FWD
  • AUTOMATIC
  • 11,400 MILES
Car runs rough for first 15 -35 seconds or so when started cold. Serice engine soon light was on and brought to dealer. Told that the car needed spark plugs, which they changed. Didn't seem to change the situation, although the Service light was out. After the initial running rough period, the engine smooths out and runs beautifully, with no roughness or loss of power. What do you think the problem could be?
Thanks for any info you can give me!
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Monday, March 31st, 2008 AT 10:34 AM

3 Replies

Tiny
BLACKOP555
  • MECHANIC
  • 10,371 POSTS
Is either a bad IAC module or your coolant temperature sensor is missreading.
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Monday, March 31st, 2008 AT 8:21 PM
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
I would start by installing a manual fuel pressure gauge to se if it it bleeding down from an injector. This would explain the rough then smooth running in the morning. Do you have to crank it a little longer in the morning to get it started? Or it may be coolant in the cylinder, does it use coolant with no leaks on the ground?
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Tuesday, April 1st, 2008 AT 5:39 PM
Tiny
BUZZSAW
  • MECHANIC
  • 1,198 POSTS
Actually if it was still running rough it would set a ck engine light still, I would do a top engine clean to it, or just go out and blow out the carbon, punch it, start out slow and then gun it

guys it would set a light right away if it still was missing on this model and year
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Friday, April 4th, 2008 AT 2:03 AM

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