Exhaust smell & misfire like popcorn

[greg91366@gmail.com]

I have a 94 YJ 4cyl and it's been running really rich lots of fumes, and when you de-excelerate it pops like a pop corn popper. I have replaced the MAP, upper and lower exhaust/oxygen sensors, idle control sensor, all plugs, wires, distributor cap and rotor and little or no difference. Any thoughts?
I think it's timing but I'm told you can't change the timing on these?


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[98Chero]

Greg the exhaust leak might be affecting your 02 sensor causing your computer to enrich the fuel flow. you might have to fix the exhaust leak then see if it changes anything..

I hope this helps.

 

[k-2]

I am unsure if there is an exhaust leak? clear that up.

Start simple try to get codes - its easy fast & FREE.

Next check for vacuum leaks -
Check FPR - good vac & no fuel in VAC line.
In center of fuel rail there may be a Schrader valve for checking pressure

 

[JPNinPA]

Exhaust smell & misfire like popcorn

There are a few things that could lead to this.
Timing
Fuel loading from a leaky or stuck injector.

You should be getting a misfire code from the poping. The code will point to the items to check at the cylinder.
To check an injector you could use a engine stethoscope or a long screwdriver. Place the tip on the back of the injector and the handle on your ear. Be carefully not to get caught in any belts or moving parts. You should hear the ticking of the injector firing. No noise is either open or closed. But by your description of gas smell it's likely leaking.

JPNinPA
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[greg91366@gmail.com]

Greg the exhaust leak might be affecting your 02 sensor causing your computer to enrich the fuel flow. you might have to fix the exhaust leak then see if it changes anything..

I hope this helps.

Thanks I started looking for the exhaust leak, haven't found it yet, but I did discover the oil leak that I thought was the rear seal is actually coming from the distributor, go figure. I'll work on both this weekend, thanks!


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[greg91366@gmail.com]

I am unsure if there is an exhaust leak? clear that up.

Start simple try to get codes - its easy fast & FREE.

Next check for vacuum leaks -
Check FPR - good vac & no fuel in VAC line.
In center of fuel rail there may be a Schrader valve for checking pressure

I did do the turn key three times and just got the normal codes that the battery has been disconnected and that I don't have AC. Should I invest in a $100 reader from the auto parts store? They keep telling me it will be more accurate??


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[greg91366@gmail.com]

Re: Exhaust smell & misfire like popcorn

There are a few things that could lead to this.
Timing
Fuel loading from a leaky or stuck injector.

You should be getting a misfire code from the poping. The code will point to the items to check at the cylinder.
To check an injector you could use a engine stethoscope or a long screwdriver. Place the tip on the back of the injector and the handle on your ear. Be carefully not to get caught in any belts or moving parts. You should hear the ticking of the injector firing. No noise is either open or closed. But by your description of gas smell it's likely leaking.

JPNinPA
Using Jeepz.com app

Good points I'll try that after the other ideas


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[JPNinPA]

Exhaust smell & misfire like popcorn

I did do the turn key three times and just got the normal codes that the battery has been disconnected and that I don't have AC. Should I invest in a $100 reader from the auto parts store? They keep telling me it will be more accurate??


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No
The key trick should give codes. You could borrow a reader from AZ, O'reilly's or advanced.


Also a poor battery connection or ground will cause piping and poor idle.

JPNinPA
Using Jeepz.com app

 

[Dragon5126]

Re: Exhaust smell & misfire like popcorn

Your 94 wont give you codes with a reader, that came post 95.
Popping on deceleration is almost always fuel delivery on injected engines. (on a carburated engine, it would most likely be timing) you are hearing fuel igniting in the exhaust manifold. On a wierd it could happen, make sure your sparkplug cables are not running parallel and cross firing...

 

[Dragon5126]

your exhaust leak will be at the cat or exhaust manifold

 

[greg91366@gmail.com]

Update; oil leaking from my distributor so I replaced it set the timing Jeep running much better. Still small kine popcorn noise so I've ordered a new exhaust system since the cad is missing as I think that may clean it up a bit. Thanks for all the advise


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