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Thread: 02 Dodge Dakota 3.7L V6

  1. #1
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    02 Dodge Dakota 3.7L V6

    Ok So put this under dodge tuning because they both have the same motor and I didn't know where else to put it, but here is my situation.
    I have a 2007 Jeep Liberty with 303,000 miles on it. I got it for a $1,000 buck because it didn't run but everything else was in great shape. The seller told me they had swapped out the motor from a 2002 Dodge Dakota but couldn't get it to run, and told the issue was timing. So I pulled the engine, replace a bent valve from bad timing, set the timing correctly, and It fired up on first crank. One issue I ran into was the liberty had EGR and the Dakota didn't so I used my HP tuner to disable the EGR and that issue was resolved. The only error u get now is P0507 Air Idle Control Higher Idle than Expected, I've looked everywhere for vacuum leaks and the only thing I found was the psi dropped a little with the hose the driver side valve cover was connected to the back of the manifold, i'm assuming there is a crack or just not a tight fitting, so I blocked that hole on the manifold and now I have a steady high vacuum and no more error. The only issue I can't resolve is that it falls on it's face when you try to leave from a dead stop and only from a dead stop. I did a compression check and all 6 cylinders are right around 150psi 144-155 the book says it should be 175-225, but the engine runs great at high speeds and 3+seconds after a take off but that 0-3 seconds after take off it just stumbles. I'm wondering it the timing might be off by like one link on timing chain, or still something to do with vacuum, or even if the transmission could be causing it. I noticed there is like 0 vacuum and like 0 timing right when it give it throttle from dead stop and I'm wondering if that is the issue, and if I can fix that in the tune or now. Any suggestions would be greatly appreciated. I'm also attaching the Tune file and Log file. Thanks.

    Can someone tell me what is happening at 7:58:50.277, 00:04:35.275 to about 07:58:51.963, 00:04:36.961 I feel like this is when it happened.

    jeep log vacuum from head blocked.hpl
    my 07 Jeep Liberty 3.7l with 04 dodge ram tune.hpt
    Last edited by ccuccia; 06-24-2019 at 10:58 AM.

  2. #2
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    Check the injector o-rings for leaks. The injectors go directly into the head on the 3.7 & 4.7. The o-rings cook and get hard as rocks over time, causing vacuum leaks.

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    Spoolboy, Thanks for the tip. I didn't think about injector O-rings, and that's a really good idea too, I remember the extra set of injectors that came with the truck had cracked O-rings so I will definitely check and let you know. Thanks again.

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    FYI - I have a 2002 3.7 (liberty) that stumbles like you describe as well but only when engine is warm and it seems to happen after taking sharp turns which has me suspecting the fuel pump...not uncommon problem on the 2002 3.7. Also hot starts seem to require particularly long crank time...now you have me wondering about the orings as well...although they are only 2 years old. Swapped out the fuel rail and injectors from a dakota because the rail is stainless...unlike the steel one on the stock liberties.

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    I wasn't able to check yesterday because it poured down rain the entire day and night. I'm hoping to check when I get off work today.

    Homer-your issue sounds different than mine. Mine doesn't matter if engine is cold or warm it does it for both, and turns don't matter either, mine mostly happens right after pulling up to a stop sign and then going. Also when I first got the jeep it had no fuel pressure at all so the very first part I replaced was the fuel pump & assembly and it resolved the no pressure issue. Oh and mine cranks up instantly every time.

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    Quote Originally Posted by ccuccia View Post
    I wasn't able to check yesterday because it poured down rain the entire day and night. I'm hoping to check when I get off work today.

    Homer-your issue sounds different than mine. Mine doesn't matter if engine is cold or warm it does it for both, and turns don't matter either, mine mostly happens right after pulling up to a stop sign and then going. Also when I first got the jeep it had no fuel pressure at all so the very first part I replaced was the fuel pump & assembly and it resolved the no pressure issue. Oh and mine cranks up instantly every time.
    Yeah, my issue happens usually when the engine is hot and I swear it gets worse after turns and the stumble is more of a shudder. I am having a heck of a time figuring out what it is? I've read some posts on jeep forums and I now wonder if it could be trans related as the engine runs fine out of gear?

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    Homer, is it when actually turning, or just when turning the steering wheel but sitting still?

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    No, it's happens when I just get out of a turn and accelerate moderately to hard. Almost feels like TC shudder but at low speeds. Funny thing is if I going into 4 wheel drive it seems to be no as bad. Rear u-joints were replace a couple of years ago and I ditched the lunch box locker I had....boy that was a b!tch to take the C clip out...never again!

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    Dude you got it. This has been bothering me for 3 months ever since I got the engine put back together. It wasn't cracked o-ring but it was the O-rings. It's looks like the dumbass before me pulled some of the O-rings off and put them half way back on. Some of the O-rings were on the bottoms of the injectors and some were where they were supposed to be, and my dumbass didn't even look at them before I put them in to check the placement. The jeep runs like new now. THANK YOU THANK YOU THANK YOU! I really appreciate your help.

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    Glad you got it sorted.
    Only took me 2 years to figure it out on my truck, lol

  11. #11
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    I wanted to update you and anyone else having similar issues. The problem came back the next day, I even swapped out the entire fuel rails, and all 6 injectors with the extra set that came with the jeep, and i tried blocking off all vacuum lines to the manifold to see if that would fix it and it would still bog down right after coming to a stop then accelerating. I found a pcv valve laying amongst part left over from the swap they did, so I went and looked at both heads and niether of them had a pcv valve on them, so I checked the book.and it said for 07 up its supposed to be on the left head at the back. There was only a vent line their just like on the right head, so I took that one off and replaced it with the pcv valve and I cant believe how differently it drives now, now when i hit the pedal the Damn thing just goes. Thanks again for helping me stay in the vacuum troubleshooting area, thats what it was, crankcase pressure, unbelievable.