P0301/p0302 - JeepForum.com
 
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post #1 of 7 Old 11-17-2019, 08:40 AM Thread Starter
ottoman89
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P0301/p0302

I get these codes randomly. One will pop up and then go away for weeks, the other will then pop up and then go away weeks later too. I know they're "misfires" on cylinders 1 and 2?

I don't notice my Jeep running or starting rough. The gas mileage seems to be inconsistent. Is it as easy as bad spark plugs?

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post #2 of 7 Old 11-17-2019, 09:31 AM
LuthWJ77
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Garage
Year and engine?
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post #3 of 7 Old 11-17-2019, 09:46 AM
Shouden
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Could be:
Faulty spark plug or wire
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector
Burned exhaust valve
Faulty catalytic converter(s)
Running out of fuel
Poor compression
Defective computer

If it were my Jeep, I'd work it from cheapest to most expensive:
* put 1/2 a can of Seafoam in the gas tank
* Replace Oxygen Sensors (although usually this throws a separate code)
* Replace Spark plug/Coil
* Replace Fuel Injector
* EGR Valve
* Test for Compression

2003 Jeep Grand Cherokee Limited 4.7L HO
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post #4 of 7 Old 11-17-2019, 09:48 AM
Shouden
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Oh.. you could also try reseating the coil pack.

2003 Jeep Grand Cherokee Limited 4.7L HO
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post #5 of 7 Old 11-17-2019, 09:59 AM Thread Starter
ottoman89
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It's a 2002 with 4.7m.


Is seafoam similar to HEET or completely different?
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post #6 of 7 Old 11-17-2019, 10:30 AM
jtec
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Did you use a scanner to get those codes?
The p0301 and p0302 are the only codes? Post ALL codes.

Start simple -
Seafoam not heat.
Spark plugs - 'read' the old plugs Wet Dry Black Tan damaged - Brand and type matter !

Cyl 1 and 2 are on different banks - might want to check connectors on injectors and coils.
I would also look at fuel pressure post PSI.

Ideally with a scanner we would look at live data - ECT, TPS, MAP, O2 sensor voltages,
Fuel Trim,

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #7 of 7 Old 11-17-2019, 11:17 AM Thread Starter
ottoman89
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Quote:
Originally Posted by jtec View Post
Did you use a scanner to get those codes?
The p0301 and p0302 are the only codes? Post ALL codes.

Start simple -
Seafoam not heat.
Spark plugs - 'read' the old plugs Wet Dry Black Tan damaged - Brand and type matter !

Cyl 1 and 2 are on different banks - might want to check connectors on injectors and coils.
I would also look at fuel pressure post PSI.

Ideally with a scanner we would look at live data - ECT, TPS, MAP, O2 sensor voltages,
Fuel Trim,
was not with a scanner. Just the old code reading trick. I should be able to get a scanner reading today. I'll keep you posted!

Thanks!
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