Vibration - Power Lacking

Hi All,

I have had the new engine installed, but a few problems seem to remain. In idle/park there is a vibration when at around 1500+ rpm. It's probably there driving but really can't feel it as much when driving. There also seems to be somewhat of a lack of power/acceleration. These seemed to be there before the engine replacement that was needed and yet they remain. The engine/transmission mounts looked good with no deterioration and tomorrow will check the exhaust back pressure but did not know if anyone had other ideas.

All typical parts with new engine including new NGK plugs, belt, hoses, thermostat, water pump etc. Even has new tensioner and balancer and the wobble at the crank is gone after that. Vibration remains and is there even with serpentine belt removed. It's not earth-shaking but definitely vibrates more than it should. Misfire monitor shows nothing there and relearn performed.

It seems to drive well other than what seems to be also some lack of throttle response from what I would expect based on driving other vehicles.

Thanks!

Cheyne said:

Hi All,



I have had the new engine installed, but a few problems seem to remain. In idle/park there is a vibration when at around 1500+ rpm. It's probably there driving but really can't feel it as much when driving. There also seems to be somewhat of a lack of power/acceleration. These seemed to be there before the engine replacement that was needed and yet they remain. The engine/transmission mounts looked good with no deterioration and tomorrow will check the exhaust back pressure but did not know if anyone had other ideas.



All typical parts with new engine including new NGK plugs, belt, hoses, thermostat, water pump etc. Even has new tensioner and balancer and the wobble at the crank is gone after that. Vibration remains and is there even with serpentine belt removed. It's not earth-shaking but definitely vibrates more than it should. Misfire monitor shows nothing there and relearn performed.



It seems to drive well other than what seems to be also some lack of throttle response from what I would expect based on driving other vehicles.



Thanks!

Click to expand...

Was the throttle body cleaned? What about the IAC Valve?


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What about new injectors? A licking injector can make one vibrate. Also if it's dumping to much fuel the o2 will do what it can to bring the mix back in line. This means cutting back fuel from the other injectors. This will create a power issue.

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Ngk plugs maybe the problem. I thought these engine management systems were extremely sensitive to the right plug.
Injector are a real possibility.
I'm thinking more of a igniters/coils, giving weak sparks.
My f150 got a new motor shaky idle remained with the new motor, only thing not replaced so far is the throttle body and injectors. F150 people tell my the tbody is more likely. I think it's electronic instead of cable controlled.

What's the set up in this Liberty?
I can't think of a good reason for lacking power but the throttle response is wrong or the cats are clogged.


Edit BTW if the cats are clogged enough to do this change them quick they can kill the new motor real fast!

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Thanks for the replies.

I'm not sure about the throttle body, but I did point it out for cleaning near the end of the install. While it would explain an idle problem especially an
IAC, I don't believe it would explain the issue when revving. The throttle response definitely seems to be more than a sticky throttle. More like lack of power while accelerating.

Injectors could be the problem and did occur to me as a possibility. I don't remember the acceleration being an issue when we first got it, but I do recall it right before the engine swap. Fuel may have been getting a little stale also as I waited for the title. I did stop to fill up on high octane while test driving it hoping that it may help to clear it up. I would like to have an idea before throwing new injectors at it, as I'm already in pretty deep on this.

I thought the NGK plugs that I installed were the OE plug which is why I used them. The 2006 Liberty 3.7 2WD has just over 141K on the chassis. The engine that came out did not look like it had been neglected badly. I imagine it just overheated to cause the problem/bottom engine noise. So I'm not sure if the oil usage/cat is an issue since I have a very limited history. It was just a possibility that occurred to me with the vibration and slow response. The back pressure test should help to confirm or rule out.

Thanks again for the ideas. Trying to think if I missed anything.

I may be wrong about NGK plugs . I just remember something about them being sensitive to the right plug.

I think the 2006 is cable controlled throttle body, at least it was on my 06 commander
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NGK copper plugs are the OEM plug.

Just a thought, but I've had engine/****** mounts that looked fine but were in fact toast.

I'm not sure about the shaking but my KJ was lacking power also
I changed TPS and it's amazing how much better it accelerates
Before, I'd have to press the gas to the floor to speed up
Now I can lightly tap the pedal and it'll speed up just how I want it to
Cleaning the throttle body would make it even better probably, but if you haven't changed the TPS I would look into that as a start
I got mine at O'Reillys for about $40 I believe and you can literally feel the difference as soon as you drive it

IIRC 07s have an integral TPS in the TB. You'd have to change the whole thing.

I'll pick up the vehicle to look at and start going over it myself if the back pressure test doesn't reveal anything. I'll look at the TB and at the TPS for replacement. It appears to be available separately on the 2006. I don't see the TBI base gasket unless it's one of those odd ones unlike I would expect and the local places don't list it?? I may need to just take it off to see which one it is.

May have to check with the local CDJ dealerships for the gasket. I drive an older vehicle than this one as my DD which makes the lack of parts on the local shelves kind of odd with the 2006. Then again my parts shelf is normally stocked with maintenance items for my DD.

I may have to take the belt off and drive it down the driveway (very short) when cold to make sure the lack of power isn't in the belt drive also. Belt off did not solve the vibration at 1500 rpm. Regular cooling so no fan clutch.

On another note, the shop said the desired idle was low for this one per manual. I asked about it since the tach showed just over 500. Of course, the idle speed is somewhat of another issue from above.

Thanks for the suggestions.

I just replaced IAC and TPS, easy job almost nothing in the way.

I think idle should be 550, I wish I could bump it up 50 because every so often it fluctuates to 500 then to 400 almost stalling, jumps to 800 then back to normal. Been trying to figure it out why, electrical load seems to be the only factor I can prove.

Some say it's torqconvert drag on the motor. Not sure how that works unless the circulation pump is tired. Fluid levels are correct. Just a mystery a lot of 3.7 owners have




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Conundrum2006 said:

I just replaced IAC and TPS, easy job almost nothing in the way.

I think idle should be 550, I wish I could bump it up 50 because every so often it fluctuates to 500 then to 400 almost stalling, jumps to 800 then back to normal. Been trying to figure it out why, electrical load seems to be the only factor I can prove.

Some say it's torqconvert drag on the motor. Not sure how that works unless the circulation pump is tired. Fluid levels are correct. Just a mystery a lot of 3.7 owners have




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Click to expand...

Did the same, mine has a bit of a surge at 1500 as well. But swapping these parts out made a significant difference in overall drivability. I used Mopar parts, spent about 100 bucks and about 25 minutes cruising time. Very easy swap.

There also seems to be a fuel mapping issue if several have the same symptoms. This type of stuff is pretty common on motorcycles. Flat spots in throttle response. I have figured out the ******/rpm sweet spots are about 45 mph and 18-1900 rpms and 65 mph at 2000-2100. This thing is dialed for very specific driving, which is why I drive around town/hills with overdrive turned off. IMO a motor should never be dropping down to 1200 rpm driving 35-40 mph. That's like driving a 5 speed in 5th noodling around. I wish now I had bought a stick. I hate the shift characteristics of this ******. It needs a sport mode.

Geof3 said:

Did the same, mine has a bit of a surge at 1500 as well. But swapping these parts out made a significant difference in overall drivability. I used Mopar parts, spent about 100 bucks and about 25 minutes cruising time. Very easy swap.



There also seems to be a fuel mapping issue if several have the same symptoms. This type of stuff is pretty common on motorcycles. Flat spots in throttle response. I have figured out the ******/rpm sweet spots are about 45 mph and 18-1900 rpms and 65 mph at 2000-2100. This thing is dialed for very specific driving, which is why I drive around town/hills with overdrive turned off. IMO a motor should never be dropping down to 1200 rpm driving 35-40 mph. That's like driving a 5 speed in 5th noodling around. I wish now I had bought a stick. I hate the shift characteristics of this ******. It needs a sport mode.

Click to expand...

Oh, the other part dealer technicians recommended replacing is the Crank sensor and cam. Supposedly if the signal is wrong at idle it can do exactly what described. I've read of plenty who did replace it with no results.

The commander transmission is that Mercedes NAG1, it is ok far as shifting up or down. Generally it down shifts about right to fourth when you need a bit more power.
I haven't figured out where it's sweet spots are yet, 65 mph is one for sure. Only weird thing is on hills in traffic if likes to keep it in a lower gear longer, but it's a heavy jeep with a v6, so that shifting probably makes sense going up hill try to keep them off your bumper at 60 mph.

Generally I hate automatics, our Sienna is the worst. But I hear that it's all in the programming, they set it up for economy and if you ask Toyota can reflash it. Supposedly with the update it will drive like a new car.




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I'm still working on this. The acceleration seems to be picking up, but the vibration is still there. I hope to get some miles on it this week to see if anything pops up. Transmission shifts odd, but it may just be the 42RLE. There is some lag around 40 mph.

As for lack of power with both engines, have you lifted each corner of the Jeep and checked that you did not have any brakes dragging? I've seen it a half-dozen times... get a sticky caliper or wheel cylinder, parking brake, etc.... one stuck or sticking wheel can bring the entire vehicle to a crawl.

The acceleration is improving. I've been trying to run out the fuel while treating the injectors with Techron. I hope to know more definitively within the next week or so. The vehicle seems to coast too well for it to be the brakes, but it's definitely worth a look the next time I can get the corners up in the air.

On another note, there does seem to be something going on when accelerating and letting off of it. Feels like the u-joints need inspected. I think Tom mentioned to check these on my initial posts of what to look out for :gr_grin:

I don't really care for how this transmission shifts ...

Almost there. Vibration is pretty much gone except for a slight bump on moderate throttle that I believe is injectors. It also has the new tires and universal joints and now drives better than most of the others in the driveway. It's also looking pretty good under the hood except for the split loom tubing that fell apart during the engine swap. That will hopefully be replaced next weekend when the new rolls of nylon tubing arrive. I think perhaps the OCD is setting in ...

if youve got a battery charger put it on a battery charger on trickle for a few hours and see if it still does it

I assume you're wanting to diagnose a properly shifting transmission? Battery is new and the alternator in addition to the power steering pump are the only two belt drive accessories not replaced. Alternator was putting out 14+ V when checked. I do have a charger and can still put in on 2a trickle charge if you think it is worth eliminating.

When I got it and it originally overheated, I pulled a cooling system malfunction code and P0700, but I couldn't pull specific trans code. No codes have reappeared since engine swap, clearing codes and now have over 1K miles. I had forgotten to mention the codes since they were early on.

I decided to get a Lube Locker gasket for trans and differential for ease of changing fluids down the road. When they arrive next week, I do plan on changing the fluids again even though the vehicle history shows them having been done fairly recently. It said transmission flush, so I want to drop the pan to change the filter.

Where were you stationed? (flag)