i've had this problem for a while now and no one can give me a straight answer/solution. In every gear at about idle-1500 rpm's i have a learn misfire (or so my mechanic says) popping sound. i have cleaned MAF, ran fuel inject cleaner, replaced all the spark plugs. The timing is at 14 degrees. There is no popping above 1500, and it pulls hard, can anyone give me a suggestion? thanks
lean misfire popping solution?
- Thread starter custom89stang
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Gotcha. Is there any chance the EGR valve is leaking? It will cause idle and low RPM degredation. EGR functions at cruise (steady speed, like cruisin at 65 mph on the highway). The valves can leak though, so EGR is introduced at idle and non-cruise situations.
In the course of troubleshooting, just as an FYI, O2's, EGR and smog are not used at WOT.
How is fuel pressure at idle? Are plug wires old (if you do the rain test, you do see leakage? Bad wires can cause funky intermittant issues in my experience). Is the TPS set correctly?
Just my random ideas. I am sure others will have better stuff for ya.
Good luck.
In the course of troubleshooting, just as an FYI, O2's, EGR and smog are not used at WOT.
How is fuel pressure at idle? Are plug wires old (if you do the rain test, you do see leakage? Bad wires can cause funky intermittant issues in my experience). Is the TPS set correctly?
Just my random ideas. I am sure others will have better stuff for ya.
Good luck.
ok, thank you thats EXACTLY what i was looking for HISSIN, is just anything i can replace, and i will keep replacing the small things till it gets fixed. Thanks a bunch dude! ANYONE else have this problem? i'm just looking for anything that could cause this kind of behavior and you gave me some good ideas!
bgjohnson
Founding Member
i second the EGR or possible a dead point in the TPS sensor which is less likely but still valid. also if the MAF is weak it won't read incoming air at low rpms due to less air coming because of the sensative wires in the MAF might have higher resistence due to a loose connection in those tiny wires, and it might take more air(velocity) to make them respond. an easy way to tell is use a voltometer and while the car is idling, check the power wires or reference voltage, should be around 4.7v. then read the voltage coming back to the computer which at idle should be around 1 volt i believe and it should go up with rpm.
Black1987Stang
Active Member
EGR-Exhaust Gas Recirculation TPS-Throttle Position Sensor, the egr helps reduce NOX in the exhaust
Don't throw parts at a problem, do some troubleshooting. Dump the codes and see what the computer says is wrong.
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.
See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html
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.
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 Walmart.
Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $35.
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.
See http://www.troublecodes.net/Ford/
OR
See http://www.mustangworks.com/articles/electronics/eec-iv_codes.html
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.
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 Walmart.
Or for a nicer scanner see http://www.midwayautosupply.com/detailedproductdescription.asp?3829 – It has a 3 digit LCD display so that you don’t have to count flashes or beeps.. Cost is $35.
gcwh02
New Member
i have the same problem and I am intrested in ideas, my car does this from 1500-1900 and more so when it is cold, it does not do it when in WOT at all, i get the popping in that 1500-1900 range, but if i go WOT it goes away
gcwh02
New Member
gcwh02
New Member
gcwh02
New Member
gcwh02
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RyanSG
Founding Member
whats your fuel pressure set at. mine used to do that once and a while and i had to increase my fuel pressure a little then it went away. since it sounds like it may be hapening when it's under vac it would make sence, may just be taking out a little to much fuel when in vac... FPR may be bad as well... won't hurt to check it though, see what it's at i'm not sure if you have an adjustable FPR either...
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