Runs rough and shakes when car is warm

Tiny
PERTPAT
  • MEMBER
  • 1990 MERCURY MARQUIS
  • 130,000 MILES
1990 mercury grand marquis. Runs rough and shakes when car is warm especially going up hills. Put on new distributor car was worse. Only 6000 miles on spark plugs and wires.
when car is cold car runs much better
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Monday, September 9th, 2013 AT 5:22 AM

16 Replies

Tiny
WRENCHTECH
  • EXPERT
The age of the wires doesn't guarantee anything. The wire could be damaged or burnt and the plug could have been cracked during installation. The first thing that needs to be done is to isolate which cylinder is causing the problem.
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Monday, September 9th, 2013 AT 5:59 AM
Tiny
PERTPAT
  • MEMBER
How do you isolate which cylinder is causing the problem?
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Monday, September 9th, 2013 AT 6:07 AM
Tiny
WRENCHTECH
  • EXPERT
That will require equipment and experience which I suspect you don't have either of. You're probably going to need a shop to help you with that.
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Monday, September 9th, 2013 AT 6:53 AM
Tiny
PERTPAT
  • MEMBER
Is it bad to use Bosch Platinum +4 in a 1990 mercury grand marquis?
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Monday, September 9th, 2013 AT 7:31 AM
Tiny
WRENCHTECH
  • EXPERT
Yes, very bad. Use Motorcraft only
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Monday, September 9th, 2013 AT 7:48 AM
Tiny
PERTPAT
  • MEMBER
Could you tell me why they are bad
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Monday, September 9th, 2013 AT 8:16 AM
Tiny
WRENCHTECH
  • EXPERT
They are nothing but gimmick that the car was not designed for and they do not work in a Ford engine. NEVER put ANY Bosch plugs in a Ford.
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Tuesday, September 10th, 2013 AT 7:08 AM
Tiny
PERTPAT
  • MEMBER
Ok, replaced plugs with autolites, wires, distributor, map sensor, coil.
Idle is rough almost missing. Car bucks wildly when plugging in spout connector for electronic timing advance
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Friday, September 13th, 2013 AT 5:43 AM
Tiny
WRENCHTECH
  • EXPERT
So, it only runs bad when the spout connector is in place?
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Friday, September 13th, 2013 AT 5:47 AM
Tiny
PERTPAT
  • MEMBER
Yes the problem only occurs with the spout connector in place.
New distributor timing advances about 20 degrees, old distributor timing advanced 4 degrees when plugging in spout connector.
New distributor much worse than old due to incease in advance timing I assume. What computer sensors could be feeding the wrong signal to the computer.
Throttle position sensor?
Coolant temp sensor?
Problem amplified when engine is hot after driving at least 7 miles
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Friday, September 13th, 2013 AT 6:02 AM
Tiny
WRENCHTECH
  • EXPERT
Did the new distributor include an ignition module?
Was the problem the same before and after the distributor?
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Friday, September 13th, 2013 AT 6:12 AM
Tiny
PERTPAT
  • MEMBER
Yes, worse after the new, not remanufactured distributor
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Friday, September 13th, 2013 AT 6:43 AM
Tiny
WRENCHTECH
  • EXPERT
It seems obvious that there is some kind of issue with the new distributor. If you still have the old one, try swapping the ignition modules.
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Friday, September 13th, 2013 AT 6:52 AM
Tiny
PERTPAT
  • MEMBER
We already tried that
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Friday, September 13th, 2013 AT 7:01 AM
Tiny
PERTPAT
  • MEMBER
Its doing the same with the old one too
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Friday, September 13th, 2013 AT 7:02 AM
Tiny
WRENCHTECH
  • EXPERT
Then I suggest you let a professional look at it. There is only so much that can be done without seeing the car.
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Friday, September 13th, 2013 AT 7:16 AM

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