2007 Grand Cherokee engine light - JeepForum.com

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post #1 of 20 Old 09-13-2013, 03:53 PM Thread Starter
schabot
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2007 Grand Cherokee engine light

Hello. I am brand new here, so I apologize in advance if this is in the wrong place. I recently purchased a 2007 Grand Cherokee Limited with the 5.7l Hemi. It has 76,000 miles. It is in immaculate condition! Just "trying" things out, I wanted to see what the motor had so I got into the gas. As the RPMs built up, 5,000 or so, the check engine light flashed a few times. I immediately slowed down and it stopped. It hasn't happened again under normal driving conditions. Is this something to be concerned with? Is there are problem I should look into? Any help is appreciated.

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post #2 of 20 Old 09-13-2013, 04:09 PM
Zlartibartfast
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the CEL is very generic so it's difficult to diagnose anything from that. I'm not a Hemi guy, so I had to look up some info from wkjeeps.com. 5K RPM is right at max HP, and beyond max torque output which is @ 3.5K RPM - Max RPM is specified @ 5.8K so there's nothing to be gained by running it that high. The CEL could have been triggered by just about any parameter getting out of normal range (oil press low, fuel rail press high, O2 sens out of range, etc), but if it doesn't persist then probably nothing broke.

I don't recommend taking the engine to those limits without getting some gauges and an OBD scanner. If your Jeep hasn't had it's 60K mile service, then NOW is the time!

(and welcome to the forum ;-})
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post #3 of 20 Old 09-13-2013, 05:14 PM Thread Starter
schabot
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It's not my intention to "race" it like that. I was just seeing what it was capable of. Thank you for the info!
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post #4 of 20 Old 09-13-2013, 07:31 PM
Drudgery1971
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I would seriously check the oil quality and level since it only takes a second. I had a beater Neon that did that when oil wasn't prefectly at the high range and i redlined it (it was a beater and I liked beating it).

2007 WK Limited 3.0 CRD - Stock (Mine)
2010 XK Sport 5.7 Hemi - Stock (Wife)
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post #5 of 20 Old 09-13-2013, 10:51 PM
Shafer57
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I'd recommend draining the oil and putting in new 5w20. MDS is dependent on using this specific oil, and if you use others, the hemi may act weird.

Try that and don't forget the hemi takes ~7 quarts.

What type of fuel are you using?

Dodge Dakota R/T 360ci Small-block _sold_
Jeep GC 5.7L Hemi- Magnaflow Cat-Back, BT Catch Can, 20" Gloss black SRT Reps
275/45R20 Nexen Roadian, Blacked out, 180 Stat _SOLD_
2008 335i Twin-Turbo
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post #6 of 20 Old 09-14-2013, 08:47 AM
WieSeL
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Flashing cel is usually a class a misfire or a gross misfire bad enough to cause cat failure
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post #7 of 20 Old 09-17-2013, 01:39 PM Thread Starter
schabot
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Oil level looks fine. As for the viscosity, not sure. I intend to use synthetic oil forward going. My '99 Explorer 5.0L runs like a top still and up until this Jeep was my daily driver for 12+ years. Fuel, I have been using standard 87 octane.

On the note of the misfire, what is involved with that?
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post #8 of 20 Old 09-17-2013, 08:40 PM
HurriJeff
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schabot,

Check engine light is an indication that something needs to be checked. If the light goes out its probably nothing. Mine comes on all the time and it just wants me to tighten the gas cap. My point is this..so long as the check engine light goes out your probably fine...but if you abuse it, it will break. If your really concerned about it take it to a dealer and have the codes read, will cost you around $100.00 but it could save you thousands, ya never know.

FYI, 07' 5.7 Hemi WK is equipped with rev limiter because the engineers at jeep know better than your foot how fast the engine should spin and the rev limiter should be used by accident and never by choice.

05 Grand Cherokee Limited 5.7 Hemi 265/65/17 Revos, K&N
HEMI CLUB MEMBER #10
Previous Jeeps:
1998 ZJ Special Edition 2wd- Traded
1991 XJ 2.8 2wd Sold
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post #9 of 20 Old 09-18-2013, 07:16 AM Thread Starter
schabot
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Thank you for all the info. Like I said, it's not my intention to use it as a racer at all. Never had a Hemi before and just wanted to "try it out". The light went off immediately and purrs like a kitten otherwise. Thanks again!!
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post #10 of 20 Old 09-18-2013, 07:46 AM
yzjwk
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Quote:
Originally Posted by schabot View Post
Hello. I am brand new here, so I apologize in advance if this is in the wrong place. I recently purchased a 2007 Grand Cherokee Limited with the 5.7l Hemi. It has 76,000 miles. It is in immaculate condition! Just "trying" things out, I wanted to see what the motor had so I got into the gas. As the RPMs built up, 5,000 or so, the check engine light flashed a few times. I immediately slowed down and it stopped. It hasn't happened again under normal driving conditions. Is this something to be concerned with? Is there are problem I should look into? Any help is appreciated.
I regularly have my HEMI at 5000 +RPM , they are rated MUCH higher then that. Even in manual shift mode you should never hit the rev limiter because the trans will up shift automatically if you come close . If you want to spend $100 , buy yourself a code reader or put it towards a superchips tuner (which is a tuner and reader/eraser) .You can also use the key dance to check for codes , you just can't erase them . As suggested , At 76K mi the 60 K service was probably not done . That's the big one that includes the plugs and ALL the fluids .I suggest getting that done , or do it yourself if your so inclined , then you know where your starting from and a little research on here will better your knowledge about your engine and drive system .
Just my .02
welcome and good luck .

5 and counting :05 WK 5.7 HEMI
90 YJ Islander 4.2L
94 ZJ Ltd 5.2 ,00 WJ 4.0
2010 MK Patriot
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post #11 of 20 Old 09-18-2013, 09:00 AM Thread Starter
schabot
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Key Dance? Sorry for the questions. This is my first Jeep.
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post #12 of 20 Old 09-18-2013, 09:04 AM
yzjwk
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You can search on here for a more acurate description of how , but basically you need to insert the key in the ignition and cycle it from off to on - 3 times within 5 sec ending in the on position (and without starting). Any stored codes will display on your evic.Mind you this only works for PCM codes and this won't work for ABS or TCM codes , but the majority of codes are PCM anyway .

5 and counting :05 WK 5.7 HEMI
90 YJ Islander 4.2L
94 ZJ Ltd 5.2 ,00 WJ 4.0
2010 MK Patriot
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post #13 of 20 Old 10-12-2013, 02:36 PM Thread Starter
schabot
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~ UPDATE ~ Shortly after looking at all of this, the engine light came on. I brought it to my brother who owns a mechanic shop and he read the code. Came up as a P0475 vacuum leak. Likely caused from over filling the fuel tank or loose gas cap. Out of the blue, it went away. Now I notice when driving on the highway or any road at a steady speed, if I lightly try to step on the gas to maintain speed without "getting on it" it seems to "buck". Almost like it is starving for fuel or possibly misfiring. If I continue to step on the gas, it levels out and runs great.

I know that this motor has the system where it shuts cylinders off at cruising speeds in an effort to save fuel. It seems to me (not a mechanic at all) that when running in this mode that it is struggling to keep up.

Thoughts? Any help is appreciated!
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post #14 of 20 Old 10-12-2013, 04:51 PM
yzjwk
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Are you sure the p0475 code is for a vacuum leak ? All the data i could find on that code says P0475 = Exhaust Pressure Control Valve Malfunction
From how you explain the "bucking" , i think that may be the MDS disengaging excessively harsh . which could mean your mds lifters or the part of the system that allows the exhaust pressure to be realeased during mds mode is failing . You should probably get that looked at by someone familiar with MDS operation .

5 and counting :05 WK 5.7 HEMI
90 YJ Islander 4.2L
94 ZJ Ltd 5.2 ,00 WJ 4.0
2010 MK Patriot
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post #15 of 20 Old 10-12-2013, 05:37 PM
WieSeL
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It's the egr (exhaust gas recirculation valve). Sounds like the egr is partially stuck open. Chrysler has issues with their egr valves. If it's stuck open it can kill the motor at idle, or if partially open can cause lack of power bucking at cruise. Replace the egr valve.
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