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-   -   Tried everything to stop the misfire...Help! (http://www.wranglerforum.com/f218/tried-everything-to-stop-the-misfire-help-90897.html)

Jmnem21 04-25-2011 11:00 AM

Tried everything to stop the misfire...Help!
 
Okay, I'm working on my brother's 95 4 cylinder YJ and it has been acting like it is misfiring. As you push on the gas, it intermittently will miss. It is not every time I push on the gas though. It will be fine for 5 seconds and then do it ocassionally. Usually under a load it is worse.

We have lived with the problem until this past weekend it just started the miss almost all the time while you push the pedal down. When it is idling it misses occasionally but not constantly. We changed the coil last night and now it randomly does it again.

Here is what we have changed so far:
Spark plugs
Spark wires
Ignition coil
Distributor cap/rotor
Crankshaft position sensor
Throttle position sensor
Cam sensor or pickup
Oxygen sensor
Fuel filter

:banghead:

Any help would be appreciated!

JonsBlue90 04-25-2011 11:23 AM

I'm by no means an expert, but have you checked your grounds? I had a 4Runner that was missing like crazy and it ended up being a grounding issue.

Jmnem21 04-25-2011 11:48 AM

Do you happen to know where the ground/grounds are located on the YJ's? But I will also add that to the list, thanks!

JonsBlue90 04-25-2011 12:08 PM

I honestly wouldn't even know where to begin bro, sorry.

MellowYellow89YJ 04-25-2011 05:03 PM

Have you thought about the tming chain? Easy and cheap to do.

94impactyj 04-25-2011 05:55 PM

Check all of the injector plugs to make sure they are tight and in good shape

Jmnem21 04-25-2011 09:46 PM

-We just cleaned out the grounds. No Change.
-We just unplugged all the injectors to make sure they are clean and also checked the electric on them and they seemed good.

Still nothing yet.

JonsBlue90 04-25-2011 10:08 PM

Have you done a compression test?

Jmnem21 04-26-2011 10:54 AM

Quote:

Originally Posted by JonsBlue90 (Post 1201940)
Have you done a compression test?

Yes we did and still nothing has changed. Now we can check that off the list too. :facepalm:

Driller 04-26-2011 11:31 AM

had a problem like that once with a mustang and it was bad gas. put in a gas tank drying additive and put in new high test BP and it seemed to stop. What else is there that you haven't checked.........Driller

Jmnem21 04-26-2011 12:16 PM

Quote:

Originally Posted by Driller (Post 1202748)
had a problem like that once with a mustang and it was bad gas. put in a gas tank drying additive and put in new high test BP and it seemed to stop. What else is there that you haven't checked.........Driller

What is the "high test BP"?

As for what we have not checked; I really can't tell you what is left...

Here is everything we have done as of now:
Spark plugs
Spark wires
Ignition coil
Distributor cap/rotor
Crankshaft position sensor
Throttle position sensor
Cam sensor or pickup
Oxygen sensor
Fuel filter
Grounds
Injectors cleaned and checked the ohms going through
Compression in cylinders

Therunner 04-26-2011 12:40 PM

Double check the voltage going to the coil, pull the plugs to try and determine which cylinder is misfiring or if you have a lean condition, pull the main connector off of the CPU and make sure all the terminals are clean and making good contact. Had an F150 misfiring under load and went through all of the same steps, turned out to be a bad contact at the CPU. Worth a shot, it's free.

jeepers92 04-26-2011 12:50 PM

Have you checked it to see if any codes have popped up?

Jmnem21 04-26-2011 02:52 PM

Quote:

Originally Posted by jeepers92 (Post 1202906)
Have you checked it to see if any codes have popped up?

No codes have come up. That is what we have been hoping for though. We checked the light on the check engine and it is working fine too.

@Therunner, thanks for the info we will try those steps next.

jeepers92 04-26-2011 02:57 PM

Im not sure if there is a way to test or not but could be just a bad injector.
my dads f 150 had one go bad and when it was idling you could barley tell.
but when you accelerated it was really sluggish and would sputter and fall on its face. and since it sounds like youve tested for fire with no red flags im guessing its a fuel problem.

Wantstojeep 04-28-2011 12:29 PM

i would like to know what the compression was of all the cylinders, also you are going to want to check you vacuum let me know what that is it should be steady at idle about 18-21, i don't think that a timing chain is going to be the problem if you are not hearing a lot of noise or a problem all the time. random misfire can be a carbon build up as well you might want to get some SeaFoam and run that as it tells you.

Nick

Jmnem21 04-28-2011 02:27 PM

Quote:

Originally Posted by Wantstojeep (Post 1207529)
i would like to know what the compression was of all the cylinders, also you are going to want to check you vacuum let me know what that is it should be steady at idle about 18-21, i don't think that a timing chain is going to be the problem if you are not hearing a lot of noise or a problem all the time. random misfire can be a carbon build up as well you might want to get some SeaFoam and run that as it tells you.

Nick

The compression came in at a little over 115 psi per cylinder.
I'll look into the vacuum pressure and let you know.

Thanks for the help!

Buster.D 04-29-2011 05:28 AM

i just had the same problem. i would b driving and the check engine light would come on and it would miss and then correct and only often then some days would do it bad. I replaced all that u did then come to find out it was a fuel injector connector on my last fuel injector. check those, they cause what u are talkin about. specially if you have got a few miles on it


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