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Jeep Misfire problem
- Thread starter SMLEshooter
- Start date
ok after owning jeeps and working on alot of wranglers and cherokees with the same motor here is my report on your issue. First I would check the timing on the jeep and make sure it is dead on. Then I would check with a vacuum gauge for a steady vacuum and not flutuating at idle and that will also check for a bad or leaking exhaust valve. Next I would look for a cracked exhaust manifold which will give you a pop on deceleration only.. Also you can get a temperature gun and start the vehicle and check the manifolds on the vehicle at warmup and see for a hotter cylinder on cylinder one that the other cylinders. This will indicate a bad head gasket only if coolant leaking in cylinder. Also if plug and piston is super clean because of steam.. Check compression again and see if there is a major diff in compression from num 1 versus other 5 cylinders.. Could also be a lean idle circuit as u decel with clutch in it has no load and goes to idle no pop. But decel in gear it has load on engine and is going lean because of a low vacuum condition .. I would rule out a bad coil and a bad distributer advance if it has one... Also rules out injectors and fuel pressure and pump as it would affect all cylinders not one.. Need to focus on numb 1 cylinder.. Also have heard of build up of carbon on back of valves not allowing the valves to rotate. You can pull valve cover and take rockers arms loose from number one cylinder and see if they both have circles on top of pushrod or lines back and forth showing the valve has buildup and is stuck and not spinning freeling in valve face of the seat of the head.. Causes it to stick open slightly.. Causes erratic vacuum and lower compression.. I know this is alot just giving u some direction .. Good luck and let us know what u find..
This is what a true technician would do to diag the problem!! It take tools, and knowledge ! Not just reading a code and following tips you find on the internet!!!!!!! Most technicians have over $40,000 in tools and years of training some of it OJT!! Diagnostic time is underpaid and undercharged!
You guys are killing me!!
Even the ones telling me I'm an idiot with too much money...
Thanks for all the advice.
I'll keep at it and try the more deductive approach.
Even the ones telling me I'm an idiot with too much money...
Thanks for all the advice.
I'll keep at it and try the more deductive approach.
If its only on decell. It might indicate a vacuum leak. Or maybe the EGR valve not closing or not closing quickly enough
Try unplugging the EGR and take a test drive
A lot of the codes are misleading
My 4runner kept throwing a code for the O2 sensor not reaching operating temp within time frame
Turns out t was a sticky thermostat and the entire engine not heating up fast enough to suit the computer
Also there are software programs you can use to see in real time everything that the engine is doing
Sounds like you need someone with one of those to take it for a test drive
Most regular mechanics don't have that program
Usually it's tuners and people who modify engines
You tried to find a tuner that has a dyno?
Also you may want to try unplugging all the o2 sensors and take it for a test run
That will throw several codes. But it will also cause the computer to use its default program and not base the timing and fuel on the real time input
Try unplugging the EGR and take a test drive
A lot of the codes are misleading
My 4runner kept throwing a code for the O2 sensor not reaching operating temp within time frame
Turns out t was a sticky thermostat and the entire engine not heating up fast enough to suit the computer
Also there are software programs you can use to see in real time everything that the engine is doing
Sounds like you need someone with one of those to take it for a test drive
Most regular mechanics don't have that program
Usually it's tuners and people who modify engines
You tried to find a tuner that has a dyno?
Also you may want to try unplugging all the o2 sensors and take it for a test run
That will throw several codes. But it will also cause the computer to use its default program and not base the timing and fuel on the real time input
I dont drink myself but it sounds like you could use a beer or 3.
Thanks for the advice! A non drinker telling someone to have a beer!!! The usual internet advice!!! I'm just in the automotive repair industry, and see this a bunch ! The person who is trying to fix it masks the problem with inferior parts and bad advice!! I got the part at autozone, Is a sentence that makes me cringe.
But, my vehicles run fine!!!!!
Have a nice day!!!
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Okay, an update.
The Jeep began running badly all the time, so I rechecked the compression and discovered that cylinder 1 has no compression. The other five range from 160 to 170 pounds.
So I'm taking it to a local Jeep shop tomorrow morning and they're going to do a leak down test and a couple other things I think to determine if it's the valves or lifters.
After telling the local shop guy about the prior intermittent nature of the problem, he said it sounded more like a lifter problem than a valve problem, but we'll see.
I've started thinking about putting a used engine in until I can rebuild my engine. That was until I discovered that the best price I could find on a used engine was around $1,100 while a remanufactured one is between $1,600 and $2,000.
Without selling a few things, I've only got about $2,000 available to put toward a solution.
What are your folks thoughts? Anybody have a spare 4.0 liter, straight six cylinder with good compression laying around I could buy and install?
The Jeep began running badly all the time, so I rechecked the compression and discovered that cylinder 1 has no compression. The other five range from 160 to 170 pounds.
So I'm taking it to a local Jeep shop tomorrow morning and they're going to do a leak down test and a couple other things I think to determine if it's the valves or lifters.
After telling the local shop guy about the prior intermittent nature of the problem, he said it sounded more like a lifter problem than a valve problem, but we'll see.
I've started thinking about putting a used engine in until I can rebuild my engine. That was until I discovered that the best price I could find on a used engine was around $1,100 while a remanufactured one is between $1,600 and $2,000.
Without selling a few things, I've only got about $2,000 available to put toward a solution.
What are your folks thoughts? Anybody have a spare 4.0 liter, straight six cylinder with good compression laying around I could buy and install?
Faulty lifters won't cause compression loss. You've either got a burnt exhaust valve, blown gasket or cracked head. Glad you're making some progress.
I probably got what the local guy said wrong then. He seemed pretty knowledgeable about Jeeps. He had three willy's in his shop when I stopped by today. They were really neat looking.
Thx.
