1997 Aerostar 4.0L Miss Fire
#16
10-22-2018, 04:58 PM
That's happened to me too. The most common cause is when I let off the key from the start position too soon, and the engine was on the verge of catching and starting but did not. The resultant combustion ends up as a backfire through the intake, and blows off the vacuum caps on the tree in the back of the intake manifold on the driver's side. I ended up removing two of the caps and replacing them with a short section of hose looped from one to the other. It turned out the two nipples on the tree were of slightly different size, so the hose fits tightly on one and loosely on the other. So when engine backfired again, it blew to hose off from the looser fitting nipple. And the engine running like crap was the clue that something went wrong, and I will pull the doghouse cover to put the hose back onto the nipple, instead of looking into the dark engine compartment to try to find a cap that had blown off to who knows where.
#17
10-22-2018, 09:32 PM
Posting Guru
When I started having Similar Problems, I discovered that a Vacuum Cap, on the Back of the air horn was Blown out...From the Front, you can reach in on the Right Side and reach right around the back and feel the little vac. nipple...The High Heat seems to Cook the Rubber Pretty Quick ....
2nd.... Touching the Throttle at Start Up, will cause a Back fire in the Intake and blow the cap off.... so Missing after an engine warms up.... Points to a Vac. Leak.... the Cap, Was Blown off... I keep an assortment of Vac. caps, under the seat...
If you pull the Dog House.... from inside, you can see the vac port on the Left side... from the Drivers side....
2nd.... Touching the Throttle at Start Up, will cause a Back fire in the Intake and blow the cap off.... so Missing after an engine warms up.... Points to a Vac. Leak.... the Cap, Was Blown off... I keep an assortment of Vac. caps, under the seat...
If you pull the Dog House.... from inside, you can see the vac port on the Left side... from the Drivers side....
Here is a pic of the plastic side.
#19
11-02-2018, 06:29 AM
in my 4.0 liter 1997, the missing turned out to be the intake Gasket. A revised gasket superceeds the original gasket.
disassembly is a pita. Fortunately my nephew took the job, found the revised gasket kit, and fixed it.
removing the EGR tube from the intake is another pita. Scraping the old burnt gasket is another pita. But it must be done. Reassembly wasn't so bad. Getting to the coil bolts is not easy.
disassembly is a pita. Fortunately my nephew took the job, found the revised gasket kit, and fixed it.
removing the EGR tube from the intake is another pita. Scraping the old burnt gasket is another pita. But it must be done. Reassembly wasn't so bad. Getting to the coil bolts is not easy.
#20
07-09-2023, 04:20 PM
The double platinum plugs can be used on either side. The waste spark EDIS of the 4.9L engine uses a single coil to power two plugs, one on each end of the coil. So it sends current in one direction to the plugs on one side and the other direction to the plugs on the other. If you use the single platinum plugs long enough, you can see the wear on the ground electrode on one side. You MAY be able to get the plugs with the platinum tip on the ground electrode from your Ford parts dealer, but it may cost a lot. It's cheaper to get the double platinum plugs, and you may eventually see the different wear patterns on each side, but they should be a lot less than on non-platinum plugs.
#21
07-09-2023, 05:16 PM
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