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Idle Vibrations

B

Bowzer

NAXJA Forum User
Location
NOR*CAL
I did a search, came up with nothin.. so here goes:

2000 XJ Sport-I6/4.0-AW4-NP231-D30/8.25-87,7xxMI
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Vibrates when idling (or under 1000rpm), when my brakes are applied-I can hear/feel the vibration a little more. Here's what I can tell ya: Not enough to shake the mirrors, all the gauges read ok, pretty sure I need new rear brake shoes and adjustment, I bought the XJ bout 3months ago with 85,670mi-haven't changed spark plugs or wires (still gettin used to havin no distributer) I have replaced the battery, tensior pulley is good, motor/tranny mounts are good- not positive about my u-joints.. I run 87, tried 89.. nothin.. It's been sounding more like a diesel lately.. ?


:repair:
:dunno:
 
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I have the same thing...i had posted a thread about it a week ago. Basically i have a pretty good idea thats its a vacuum leak somewhere, cant find it tho ? For your situation if braking makes it worse then that wouild make sense it also runs on vacuum. You can clean the connectors for your main sensors that deal with idle such as the TPS, MAP and o2 sensor, i replaced them with little results.

good luck
pete
 
semisynth said:
could be dirty injectors.
Click to expand...

I used Techron with a tank of gas yesterday, I noticed smoother throttle today when I took it out...

I'm doin a tune up in portions cuz of low budget.. got some Champion Plugs #4412, and new wires, I'm installing them tomorrow.. see how it runs after that. After that, whatever needs to be replaced/adjusted in the rear...

Somone mentioned it might be the Harmonic Balancer, cuz I told him it vibrates worse when the A/C is on... I also get this weird 'tick/tack' kinda noise-happens once, when idling(in Park, or N,Stopped)-I barely tap the gas pedal-when the RPMs almost come back to "idle" and when I turn it off... kinda 'dieselish'. wish I had a sound clip.. I know the injecters 'tick' and that the 4.0 has valvetrain chatter....


:dunno:
Keep ya'll up 2 date
 
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Didn't put the plugs in yet... lil busy today-they go in tomorrow...

here's somthing new to the vibration:
(I was rollin down the windows at the stop sign by my house, when they dropped all the way, I was still stopped and noticed the vibration got louder): windows are down, if I hold down 1+ window switches the vibrations get's a lil worse/noticable. When stopped in driveway in 'P', more noticable at a light in 'D' with brakes applied...

I dunno.. Alternator? maybe some wire(s)? I'm gonna hunt this sucker down!
 
Installed the Champion #4412 plugs today... all 5 went in accept one lil b!tch broke :doh: , had to put in an old one, drive down to NAPA, comeback and tear it all apart again. By the way, I know one can reveal info about the engine after changing spark plugs, the old plugs gaps were at 55! the engine bay sticker says 35! Overall, the old plugs seemed 'ok'- they also looked like factory ones, dunno what that means.. except that I needed new ones!

Update:
I noticed some performance gains from the new plugs :thumbup: but.. the vibration and all is still there. Here's somthing I noticed after the tune up: maybe I had a lil spark knock too? cuz I can hear the "tick or tack/dieselish" type of noise I described a lil more clearly now: I stuck my head under the XJ, listening... sounds like that noise is coming from bellhousing :mad: My budget and I are not ready for any Torque Converter issues...
 
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Dude i have the same dieselish sound coming from where the engine pan meets the bellhousing. After investigating most of the issues i found out that the 4.0 are nioisy engines that think they are diesels ..lol. I believe the nise you have is normal. One thing you can check is the torque converter to flywheel bolts , sometimes they get loose and cause a weird sound.

As for a vibration i had somthing similar a while back and it turned out to be the bolts that connect the tranny to the engine where loose, causing a noise/vibe at certain speeds/RPMs.

Good luck and keep us updated.
pete
 
I've been following your post too jeepsrock I hear that tick/tack noise by the bellhousing and HarmonicBalancer, HB-visibly, is in good shape. I didn't take off the sheild on the bottom of the bellhousing to check the flexplate yet..


I've been with the XJ all day... :eek: I was under it, penetrating all the bolts I'm takin off for the lift kit- again, and since I have this weird vibration-I'll tighten every damn bolt, with every size in my socket set! So I did.. front to back :) nothing was loose, I literally got every freakin bolt under the XJ...

Update on the noise:
"...cuz I can hear the "tick or tack/dieselish" type of noise I described a lil more clearly now: I stuck my head under the XJ, listening... sounds like that noise is coming from bellhousing ..." -Bowzer

In the driveway, XJ parked & idling: "tick/tack/diesel" noise, I notice it with my head by the Harmonic Blancer, and the Bellhousing less noticable under oil pan (more dense area?) Are my valves tap dancing? Maybe the flex plate? cam? :wierd:

I don't wanna bring more confusion to this but, the vibration is more noticable in cold weather (only mornings in Cali :sunshine: ) could this simply be my IAC goin bad? (hopefully, cheap fix)

:gonnablow
 
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forgot to mention: I double checked the engine/trans mounts.. got at every angle I could, I also used a Mechanics Mirror (extendable pen, with round mirror on it) didn't find any wear that would cause problems.


:smsoap:
:looney:
 
This was a lil odd.. went to loosen the belt, put the wrench on the Idler Pulley nut (15mm), figuring I'm gonna hafta use some elbow grease to loosen this sucker (heard of others using breaker bars), start to loosen and just gives.. there was hardly any resistance. Is there a torque # on the Idler Pulley and/or tensioner bolt?

So, having the Idler Pulley nut on 'hand tight' made my mind slip the whole idea of loosening the belt to see if somthing is loose. Tightened that sucker and the tensioner bolt.. Vibes are less but, still more noticable when XJ is stopped, with brakes applied in R or D.

...my 4.0 still thinks it's a Diesel.. Oil Change is comin up, I'll probably put somthin thru it before I put fresh oil in.

Is there any actual 'Tests' I can perform on the MAP or IAC :confused: I'm almost ready to purchase new sensors, motor/trans mounts- that's the thing! It's not throwin codes! No CHK ENG LHT, I've done the "key trick" a few times, no codes.. is a sensor/signal cut or blocked off or somthin?

:mad:
 
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Bowzer said:
No CHK ENG LHT, I've done the "key trick" a few times, no codes.. is a sensor/signal cut or blocked off or somthin?

:mad:
Click to expand...

The 2000 no longer has the "old key trick" to check codes... you need the new trick... and it may or may not check anything other than the instrument cluster. An OBDII reader is needed. (I'd buy one... but I know that the feds will invent an incompatible OBDIII as soon as I do!).

My 2000 also has a mild knock when idling cold -- I attribute it to the piston slap that 4.0's are famous for.

If I wanted a quiet engine, I woulda bought a Honda...

Den
 
I've been thread-surfin:
casm said:
This is one of my pet peeves (and it's not your fault - it keeps getting reiterated by a *lot* of people) with how people perceive the OBD-II system on an XJ as reporting its codes. The method outlined above will work on some Chrysler models that were built concurrently with the XJ, but to the best of my knowledge no-one has yet provably made it work on an XJ.

Holding in the trip meter button while turning the key to the 'Run' position has - on every digital-odometer XJ I've seen - simply done the gauge/light test for the instument cluster. No OBD-II codes or the vehicle's serial number have ever come up for me using this method. Similarly, I don't know anyone who has ever provably made the ON-OFF-ON-OFF key trick work on a digital-odometer XJ.

To summarise: if it's an OBD-II XJ, you'll need an OBD-II scan tool to get the codes. I'm willing to admit that there are always exceptions to the rule, but until someone can honestly show either of these methods working in an OBD-II XJ with a stock instrument cluster and computer, I'm calling SPOBI on it.

(And no, I'm not attacking you by any means - just getting tired of seeing the myth perpetuate itself. Until proven otherwise, that's exactly what it is: a myth, not fact.)
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Somone mentioned gettin my XJ scanned.. thought the Key Trick would tell me somthin, NOPE, ON/OFF trick didn't work, Trip button does only a gauge test... I guess I'll go get it scanned somewhere.
 
Woo Hoo! :woohoo:

found a piece of the puzzle! :roll:

thought I'd check my vaccum lines again.. inspected every single one as well as I could.

I was following one of em that starts at the intake manifold, to the firewall, to the passenger fender, to the "bubble" in the front bumper (right corner) ... I forgot what the "bubble" is and it's function :spin1: anyway, that vaccum line runs right next to the battery, there was about 4"-5" of line missing! so, I used my redneck instincts- used some of the tube off of my fuel-siphoner, taped the ends on the vaccum line, used some of the 'splash shield' (piece of rubber material under front end) material on the corner of the battery for 'hose protection'. Hopefully the plastic tubing won't melt..

anyway- my idle is a lil better, the "shake" on engine shutdown is less.. my lazy :moon: hasn't performed the "driving test" ... so, I'll let ya'll know how that goes. :wave:
 
every now & again I can 'reenact' that "shifter rattle", which actually isn't the shifter itself. It will happen when it wants to, tends to be after start-ups, so.. when I catch it - I try this:
parked, engine running, put in Reverse, begin to hear the rattle (comes from under the shifter console) holding my foot on the brakes while backing SLOWLY it'll get 'worse'. Knock/tap under the shifter, jiggles the front end and steering wheel a lil...

that's the best I can describe for now... I dunno guys ...I checked the flexplate's bolts-they're tight- is it possible I didn't see the crack? Front driveshaft maybe? Timing Chain? ...just tossin ideas out...
 
I mentioned I can "reenact" that 'rattle' ... hasn't happened since I posted it.

I got some pics of the mounts, they seem OK to me.

Driver's Side Engine Mount (couldn't position the digi-cam for Passenger side but, both mounts look similar):
82806.jpg


Trans Mount:
82807.jpg

82803.jpg


When the XJ was on the rack the other day, I noticed my exhaust touches my oil pan, is this a problem? I took a big flat-blade screwdriver to pry it away from the oil pan, didn't help much...
82805.jpg

82804.jpg




I really appreciate all ideas or advice guys...

I just can't add these symptoms up...
 
My xj rattles at idling and it happen to be the transfer case shifter that has a loose bushing under the floor. It shakes when the transmisson is on D or anyelse speed but on P. I just pull the shifter a little and it stops...
 
I think you're likely feeling normal engine vibration transmitted back through some component grounding out on the body. The exhaust shouldn't be touching the oil pan, for starters. That in and of itself will not cause a vibration, but since the system is out of whack at the front of the exhaust pipe, it's very possible you have a hanger at max misalignment toward the rear of the vehicle transmitting the noise/ vibration.

It looks like there's plenty of room between the exhaust pipe and crossmember so that area's OK. Grab the tailpipe and move it around in all directions, it should be able to move around freely on the flexible hangers.
 
Mine has made some awful diesel engine noises since I've owned it.It has 175,ooo miles and the valve train is loose....noticed that I have the infamous cracked exhaust manifold(made it sound like a helicopter!!)....so I think my rough idle problems are related to the crack which is right above the oxygen sensor and probably tricking it into thinking the engine is running too lean,in turn causing the ecm to richen up the mixture.
On a side note:Whenever I turn my 4 100w offroad lights on it puts a strain on the alternator that makes my engine idle really rough and shake the whole jeep.Does it get worse when you turn all the electrical accessories on(i.e. heat,stereo,brakes,high beams)?That might just be a poke in the dark,though.

Sorry for the long winded post.....
 
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Haven't checked on this thread in awhile....

jeepdeepfreak said:
On a side note:Whenever I turn my 4 100w offroad lights on it puts a strain on the alternator that makes my engine idle really rough and shake the whole jeep.Does it get worse when you turn all the electrical accessories on(i.e. heat,stereo,brakes,high beams)?That might just be a poke in the dark,though.
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Not neccesarily Accesories.. I don't have lights, or woofs, or any extra electrical. But, it get's worse when dropping the windows? So, I suppose it would IF I had extras...

(before leaving for work) I was in the driveway, parked, idling. I rolled the 2 front windows down, I held the switchs down a couple secs after they dropped all the way, I busy changing radio stations :laugh3: and I heard/felt worse idiling. I held all 4 window switches down after the windows drop all the way and it gets even worse. It makes a rattling heatshield noise.

So I checked the cat, hit with my hand, shaked it.. doesn't make noise.

Checked exhaust hangars, etc. Negative...

I pryed the manifold pipe away from the oilpan. Not the source..
 
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