2005 Wrangler X Hesitation

[Zinyekim]

My 2005 Wrangler X is hesitating in high gear, generally between 1000 and 2000 rpm. It is intermittent, but getting worse. It generally only happens under load, but feels as though the whole Jeep is bucking.

There is a clicking noise coming from the engine bay, around the spark plugs, as well as a harsh puffing coming from the exhaust. This led me to believe that one of the spark plugs was fouled. After removing and inspecting them all, one had a blue end. I replaced this plug, but the problem persists.

I still believe the cause may be on the electrical side, but am planning on checking fuel pressure next. Does any one have any other suggestions on what the problem could be?

 

[JeepZilla380]

Could try looking for vacuum leaks as well. On my 05 the o rings on the back 5th and 6th injector were toast and I had a bad vacuum leak there.


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[Chris]

Have you scanned it for codes yet?

 

[Zinyekim]

Could try looking for vacuum leaks as well. On my 05 the o rings on the back 5th and 6th injector were toast and I had a bad vacuum leak there.


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I will certainly check that out, there potential for a leak, as I can hear a slight hissing as I get closer.

 

[Zinyekim]

Have you scanned it for codes yet?

No CEL, but no actually, I haven't checked OBD II. With no light on I never thought to, but I will now.

 

[Chris]

I would check just to be sure. Sometimes there are codes stored even though there isn't a light on.

 

[Daryl]

What did your spark plug boot look like on the cylinder you replaced the plug in?

 

[billiebob]

you should never be under load in high gear at 1000 to 2000 rpm.

 

[JeepZilla380]

I will certainly check that out, there potential for a leak, as I can hear a slight hissing as I get closer.

I used a spray bottle of water and just lightly misted and listened. Some folks use propane but I’m not a fan of using something flammable.


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[Zinyekim]

I would check just to be sure. Sometimes there are codes stored even though there isn't a light on.

I checked this morning, no codes are being thrown. I was hoping if it was misfiring a code would let me pinpoint the cylinder, but oh well.

 

[Zinyekim]

What did your spark plug boot look like on the cylinder you replaced the plug in?

Here are all of my spark plug boots and the whole coil pack assembly. Also, the boots don't "pop" onto the spark plugs like I'm used to for other cars. Should there be more of a pop when the boot goes on?

 

[Zinyekim]

I used a spray bottle of water and just lightly misted and listened. Some folks use propane but I’m not a fan of using something flammable.


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Will do, the hissing noise may be from the injectors just doing their job but I will check none the less!

 

[Chris]

I checked this morning, no codes are being thrown. I was hoping if it was misfiring a code would let me pinpoint the cylinder, but oh well.

I was afraid of that. The best thing to do may be to just keep driving it until it throws a check engine light (which it will eventually). I say that because there's nothing I hate more than blindly throwing money at a problem without having any idea of what it is for sure. This could be so many different things. The vacuum leak is definitely a good place to start though.

 

[Daryl]

Here are all of my spark plug boots and the whole coil pack assembly. Also, the boots don't "pop" onto the spark plugs like I'm used to for other cars. Should there be more of a pop when the boot goes on?

View attachment 43834 View attachment 43835 View attachment 43836 View attachment 43837 View attachment 43838 View attachment 43839 View attachment 43840

As a rule of thumb you normally replace the boots when the plugs are replaced. Are the boots still soft and flexible? A very small amount of dielectric should be put on the boots if not already present. The spark on modern ignition systems are very “hot” to ignite the comparatively lean mixture of today’s automobiles so the boots do need to fit snugly. One last comment, several of the boots have an “oxidized” look to them that could be an indication of the spark jumping to ground occasionally.

 

[Zinyekim]

Just to close this thread out (a year later, my apologies) one of the spark plugs was likely dropped pre-installation. I purchased one extra new one and compared it to all 6 in the motor to find the dud, and then replaced that one. For reference, the plugs had around ~200 miles on them or so, so one plug isn't significantly newer than the others.

Just wanted to close this out, in-case anyone else was having this issue!