Car bucking under decelleration/coasting
- Thread starter Brando 91LX
- Start date
ninety15.0
New Member
- Mar 10, 2004
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What is the timing set at? Did you install a cam or anything when you put the motor back together? Does the bucking happen at lower rpms...say below 1500? Be a little more specific.
Dump the codes and see what the computer says is wrong…Codes may be present in the computer even if the Check Engine light isn’t on.
Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.
See http://www.troublecodes.net/Ford/
IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.
89 through 95 cars have a working Check Engine light. Watch it instead of a test lamp.
Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.
Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.
For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.
Or for a nicer scanner see http://www.midwayautosupply.com/pc-7208-90-equus-digital-ford-code-reader-3145.aspx – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.
Look for codes 27 or 29. Post whatever codes you get & I will try to help.
Here's the link to dump the computer codes with only a jumper wire or paper clip and the check engine light, or test light or voltmeter. I’ve used it for years, and it works great. You watch the flashing test lamp or Check Engine Light and count the flashes.
See http://www.troublecodes.net/Ford/
IF your car is an 86-88 stang, you'll have to use the test lamp or voltmeter method. There is no functional check engine light on the 86-88's except possibly the Cali Mass Air cars.
89 through 95 cars have a working Check Engine light. Watch it instead of a test lamp.
Codes have different answers if the engine is running from the answers that it has when the engine isn't running. It helps a lot to know if you had the engine running when you ran the test.
Trouble codes are either 2 digit or 3 digit, there are no cars that use both 2 digit codes and 3 digit codes.
For those who are intimidated by all the wires & connections, see http://www.actron.com/product_detail.php?pid=16153 for what a typical hand scanner looks like. Normal retail price is about $30 or so at AutoZone or Wal-Mart.
Or for a nicer scanner see http://www.midwayautosupply.com/pc-7208-90-equus-digital-ford-code-reader-3145.aspx – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $30.
Look for codes 27 or 29. Post whatever codes you get & I will try to help.
My money's on it being an EGR-related issue.
Check all vacuum lines for leaks/breaks/dry-rotting. Spend a buck or two on a new EGR valve gasket, pull that puppy off, and start reaming all the built-up carbon gunk out of there. Make sure the valve will hold vacuum (push in the plunger, put your thumb over the vacuum nipple, let go, see if you can feel the vacuum on your thumb - it'll make a "ttthhhuck!" noise when you pull your thumb off) to verify that the diaphragm is still good in it.
Oh yeah ... and pull the codes, too.
Check all vacuum lines for leaks/breaks/dry-rotting. Spend a buck or two on a new EGR valve gasket, pull that puppy off, and start reaming all the built-up carbon gunk out of there. Make sure the valve will hold vacuum (push in the plunger, put your thumb over the vacuum nipple, let go, see if you can feel the vacuum on your thumb - it'll make a "ttthhhuck!" noise when you pull your thumb off) to verify that the diaphragm is still good in it.
Oh yeah ... and pull the codes, too.
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