Welcome to the DoItYourself Forums!

To post questions, help other DIYers and reduce advertising (like the one on your left), join our DIY community. It's free!

89 Mercury won't idle and misses after shifting to next gear

rozebek's Avatar
Visiting Guest

Posts: n/a

06-02-02, 05:47 PM   #1  
89 Mercury won't idle and misses after shifting to next gear

1989 Mercury Grand Marquis 5.0L

About a year ago I started having problems with my car starting to miss and then die. It would happen after about an hour into my highway drive. I would let it cool down for about 30 minutes and then it would drive again with some hesitation at acceleration. Once I got back up to highway speed and set the cruise it would run fine at that constant speed.
Then, after a couple of months it would hesitate everytime the car shifted gears and the rpm's dropped.
Now, the car will not make it down the road even a mile without dying. It will restart after letting it cool for 15-30 minutes. It also will not Idle at all now. When I start the car in park, I can rev the engine and it runs perfectly smooth, but when I shift to park it has problems right away.
The car has 187,000 miles.
In the last 2 months I have changed the fuel pump, fuel filter, distributor cap and rotor, coil, spark plugs and wires.
I do not have a clue what it could be.
Please help me through this, I would appreciate any and all information.

Sponsored Links
Joe_F's Avatar
Visiting Guest

Posts: n/a

06-03-02, 06:11 AM   #2  
Change the TFI module mounted on the distributor with the updated Ford/Motorcraft part.

These have been known to be problematic. In fact, Ford mailed some letters to customers about reimbursement through a class action settlement.

I'd start there first. The parts have been updated many times.

fordtech's Avatar

Join Date: Jun 2001
Posts: 247

06-03-02, 06:13 AM   #3  
A couple things to check would be the idle air control valve( for the idle concern) and for any vacuum leaks such as hoses,or egr valve sticking open.

Search this Thread