Ok Im tryin to describe this, when the Jeep is runnin I hear a intermintant baffle or slight pop coming out the tail pipe. When Im in front with the hood open I dont hear it in the engine. Its a 87 with 175K. It idles o.k. but that sparratic miss or baffle out the exhuast drives me nuts, any help>?
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What would cause my 4.0 to have a miss?
- Thread starter Heep
- Start date
- Location
- Indiana-Missouri
dude, that could be anything...
you gotta throw us a bone....
what can you eliminate?
what parts are new?
what parts are old?
what have you checked?
what are the patterns?
you gotta throw us a bone....
what can you eliminate?
what parts are new?
what parts are old?
what have you checked?
what are the patterns?
8Mud
NAXJA Forum User
- Location
- Central Germany
When chasing down little misses, pops and stutters. I often use a timing light, pointed at any handy dark spot, on the motor. You can see the missed pulse pretty easy. Narrows down which cylinder is acting up.
That little pop out the exhaust, can be a slight leak somewhere in the exhaust system or even the exhaust manifold. Pretty easy to see (a little cloud of water vapor), on a very cold morning, right after starting up.
Misses in my 4.0´s, most often turned out to be, the distributor cap. Second place was a sticky injector.
That little pop out the exhaust, can be a slight leak somewhere in the exhaust system or even the exhaust manifold. Pretty easy to see (a little cloud of water vapor), on a very cold morning, right after starting up.
Misses in my 4.0´s, most often turned out to be, the distributor cap. Second place was a sticky injector.
Ok, when I first got it it idles like crap so I tuned it up a bit and ran some sea foam through it and put new oil pump in and the stuff aboveBeezil said:
-Im new to gettin into the 4.0 but it seems pretty easy, what other things should I check that would cause this?
- Location
- Indiana-Missouri
how is the ignition coil?
wires?
plugs?
dist. cap?
injectors?
does it miss through out the rpm band?
wires?
plugs?
dist. cap?
injectors?
does it miss through out the rpm band?
- Location
- Indiana-Missouri
oh, I didn't see you replied to my questions in the quote!
sorry!
it doesn't look like you mentioned the ignition coil....
you may wanna check that thang.
sorry!
it doesn't look like you mentioned the ignition coil....
you may wanna check that thang.
8Mud
NAXJA Forum User
- Location
- Central Germany
If you hook a timing light up to each cylinder 1-6, you can usually pick out a missed pulse, on a single plug. If they all/most randomly miss fire, it´s usually coil wire, plug wires (cross fire), plugs or distributor cap
Champion or Delco are the only plugs, I´ve used that worked reliably.
An occasional load of injector cleaner, in with the gas seemed to help.
Cleaning the ground connections at the dip stick and the drivers side firewall also helped (really smoothed out my idle).
An ohm test on the plug wires has also helped in the past. Too short, of a coil to distributor cap, high voltage cable, also seemed to hurt idle (OEM or equal ohm, seemed to work better/ large diameter, low resistance cables seemed to make things worse, at least for the coil wire).
I don´t spray cleaner down the throttle body. Always affraid of dislodging something that will catch in a intake valve seat. Or using a solvent that isn´t sensor friendly.
Low idle will cause a miss, usually caused by a gummed up idle motor.
Champion or Delco are the only plugs, I´ve used that worked reliably.
An occasional load of injector cleaner, in with the gas seemed to help.
Cleaning the ground connections at the dip stick and the drivers side firewall also helped (really smoothed out my idle).
An ohm test on the plug wires has also helped in the past. Too short, of a coil to distributor cap, high voltage cable, also seemed to hurt idle (OEM or equal ohm, seemed to work better/ large diameter, low resistance cables seemed to make things worse, at least for the coil wire).
I don´t spray cleaner down the throttle body. Always affraid of dislodging something that will catch in a intake valve seat. Or using a solvent that isn´t sensor friendly.
Low idle will cause a miss, usually caused by a gummed up idle motor.
