itsjacky

PLEASE HELP! It's been almost a year now that my 08 Cherokee shakes! The first time it happened, supoosedly it read "misfire" so, which ever one that was broken, the mechanic changed it... The engine light came right back on after a few drives... The Check Engine light goes on and off.. if I drive far, it tunes off... if I drive close, it comes back on, and it flashes... My mechanic checked again and it's reading MULTIPLE misfire, but he didn't know which one.. so I brought it in to the dealer... and supposdly it's reading a code: P0152... meaning an O2 sensor... but now that is changed... unless they told me the wrong one to change, the car is still shaking!!!

PLEASE HELP!! I must get this problem resulved, I have a newborn and I can't even take her to the dr. appointments because I'm scared that something will happen when she's in the car. PLEASE HELP!!!!

jomps

08 cherokee?

wjnfirearms

He probably meant '98.

The flashing light means a misfire condition. One drawback to the OBD II systems is that misfires itself don't necessarily throw a code that relates to the particular problem if it isn't in a sensor, etc. It's personally frustrating that when I do a code read on someone's car and it only shows a misfire condition that I cannot relate a specific defect to fix. Bad tune up parts, coils, and the like can cause this problem and often do. Bad fuel can also cause it. This is where I'd start looking. Look at your vacuum lines as well. It can be more serious if it's an issue with your cylinder valves not opening and closing properly. The 4.0 has a known issue with worn valve springs at high mileage occasionally happening, but this isn't the most common reason for a misfire condition.

Misfires can be one of the most common reasons for people throwing parts at the problem (and I hate doing it as well as recommending others to do it), but sometimes in this case, unless something really stands out when you start looking at things, there's little else to do to try to correct it.

itsjacky

Yes, it's a 2008 Cherokee Laredo. Sometimes, when it shakes and before the check engine light comes on, i give it some gas, the car won't go..... vut if i floor it, then sometimes the shaking will stop...

ktmracer419

It would be a grand cherokee.

Your mechanic doesn't sound like a very good one...

P0152 indicates that bank 2 sensor 1 voltage is high.

This indicates that bank 2 (one side of the motor on an engine, in your case the right side when sitting in the car) exhaust gases are rich with too much fuel.

Rich means that unburned fuel is making to that o2 sensor.

Judging from the misfire codes it sounds like the cylinders on that side of the motor arent always firing. This can be caused by a few things, but most likely the coils are on their way out.

I can't diagnose much further without actually being there, but i hope this helps.

The coils seem to go out pretty often on newer jeeps expecially when the milage starts getting high, most people replace them one by one as they stop working so it doesnt hurt their wallet all at once, but many car manufacturers reccomend to replace all of them at once because it is only a matter of time before the rest go out.

Im not sure how severe the shaking is, but many people won't even notice a coil misfiring on a v6 or v8 engine and just drive it until the check engine light comes on.

itsjacky

To ktmracer419:
The mechanic at the dealer told my mechanic that it's Bank 1 sensor 2, so that's what he changed... I didn't trust the dealer to fix my car because everytime I come out of there.. something else goes wrong.... It took them 6 hour so change the oil and 4 hours to change my tires from summer to winter... when I asked why it tool so long, they said: "Lady, it takes that long to change tires...."

So your suggestions is that I have the coils changed? How many are there? And I know unless the computer tells my mechanic which one, how will need know which one to change? How much are my looking at??
I don't think my car has alot of milage on it, (61,000). I don't drive it much...

And how about the vaccum lines? (suggested by wjnfirearms) I put the more expensive gas in the car already and I make sure that I turn the cap to the point where i hear click multiple times..

Willys55

Is this a 3.7L?

itsjacky

Yes, it is a 3.7L

Boost Happy

worked on a few that had coolant seepage into cylinder causing misfire

itsjacky

To ktmracer419:
The mechanic at the dealer told my mechanic that it's Bank 1 sensor 2, so that's what he changed... I didn't trust the dealer to fix my car because everytime I come out of there.. something else goes wrong.... It took them 6 hour so change the oil and 4 hours to change my tires from summer to winter... when I asked why it tool so long, they said: "Lady, it takes that long to change tires...."

So your suggestions is that I have the coils changed? How many are there? And I know unless the computer tells my mechanic which one, how will need know which one to change? How much are my looking at??
I don't think my car has alot of milage on it, (61,000). I don't drive it much...

And how about the vaccum lines? (suggested by wjnfirearms) I put the more expensive gas in the car already and I make sure that I turn the cap to the point where i hear click multiple times..

ktmracer419

A good mechanic should be able to tell which cylinder is misfiring byt unplugging the coils one at a time, especially with a 6 cylinder motor. Id hate to tell you to start replacing parts when im not there to diagnose it myself, but it likely could be your issue. And that code is for bank 2 sensor 1. Your mechanic replaced the wrong sensor, and it may not have even needed replacing.

AlaskanJ

Instead of going for the more expensive parts right off the bat, try simply replacing the spark plugs. Factory installed plugs are always the cheap copper center electode type, and copper being as soft as it is, wears out a lot quicker than that of platinum or iridium plugs.

Whenever you have mutiple misfires happening in a very random order with no rhyme or order, its a safe bet to start with the plugs.

Branahyou