Hi all,

Have been having a persistent (and very frustrating) problem with my manual TJ Magna Sports (2001). Its a problem that was noticeable only slightly initially as a slight shudder when accelerating hard in 5th at low revs (1400rpm).

Now there is a rough idle where it hunts around a bit and vibrates. And the shuddering has become a lot worse - it can usually be replicated by acceleration at low revs - in most gears.

Would appreciate any ideas from experienced people from AMC - my mechanic is tearing his hair out about it as he has done the following with no luck - hes an honest sort so not charging labour for following only parts - but still :( lots of $$

major service
* spark plugs
* timing belt + tensioner
* fuel filter
* air filter

recently
* leads
* diz cap
* oxygen sensor
* fuel injector clean
* crank angle sensor
* ignition coil

He has also had engine hooked up to oscilloscope - but didnt help him diagnose problem.

I think it might be a dodgy spark plug - but not hugely confident and they are all new ones.

Thanks in advance to any bright sparks out there :bowrofl:

Hi all,

Have been having a persistent (and very frustrating) problem with my manual TJ Magna Sports (2001). Its a problem that was noticeable only slightly initially as a slight shudder when accelerating hard in 5th at low revs (1400rpm).

Now there is a rough idle where it hunts around a bit and vibrates. And the shuddering has become a lot worse - it can usually be replicated by acceleration at low revs - in most gears.

Would appreciate any ideas from experienced people from AMC - my mechanic is tearing his hair out about it as he has done the following with no luck - hes an honest sort so not charging labour for following only parts - but still :( lots of $$

major service
* spark plugs
* timing belt + tensioner
* fuel filter
* air filter

recently
* leads
* diz cap
* oxygen sensor
* fuel injector clean
* crank angle sensor
* ignition coil

He has also had engine hooked up to oscilloscope - but didnt help him diagnose problem.

I think it might be a dodgy spark plug - but not hugely confident and they are all new ones.

Thanks in advance to any bright sparks out there :bowrofl:

I presume you have a manual from your profile otherwise I would have suggested to get
an auto box service. Otherwise, take it to a front-end specialist and also have a look at
the diff, engine mounts etc.

Hi all,

Have been having a persistent (and very frustrating) problem with my manual TJ Magna Sports (2001). Its a problem that was noticeable only slightly initially as a slight shudder when accelerating hard in 5th at low revs (1400rpm).

Now there is a rough idle where it hunts around a bit and vibrates. And the shuddering has become a lot worse - it can usually be replicated by acceleration at low revs - in most gears.

Would appreciate any ideas from experienced people from AMC - my mechanic is tearing his hair out about it as he has done the following with no luck - hes an honest sort so not charging labour for following only parts - but still :( lots of $$

major service
* spark plugs
* timing belt + tensioner
* fuel filter
* air filter

recently
* leads
* diz cap
* oxygen sensor
* fuel injector clean
* crank angle sensor
* ignition coil

He has also had engine hooked up to oscilloscope - but didnt help him diagnose problem.

I think it might be a dodgy spark plug - but not hugely confident and they are all new ones.

Thanks in advance to any bright sparks out there :bowrofl:

Maybe:
Is it lowered?
You can get some slight shudder when accelerating if lowered and camber not quite right.
Even factory standard VT-VX S, and SS models had this to a certain extent due to that models lowered sports suspension, that highlighted its old world rear suspension, and the troubles it had with camber.

More likely:
You mention rough idle though, so it is more likely engine mounts.
All 3.5 TH to TJ, and I now hear some TJ2-TW models (and verada models), though less widespread have a problem with engine mounts. Some were replaced under warranty (like mine) with a revised model, but it did not solve the problem completely with it usually returning to a lesser degree with time. The revised model was fitted from about tJ2 onwards, so the dreaded rough idle and shudder does not usually appear as early on in the ownership experience:) First noticed mine on my August 2000 TJ after about 30,000km's!!!
There is NO know complete fix for this!!!! I have been over this with Mitsubishi many many times.
If yours has this you could replace engine mounts with the revised model (not cheap) for a quick short to mid term fix, otherwise welcome to the 3.5 rough idle-slight shudder club;) Most of us just put up with it now:)
Does the idle improve heaps when you go from drive to neutral when idling???? Usually a pointer that its the engine mounts.

This is a widespread problem, and there are plenty of other threads on here about this.....it effects many magna/verada's of this model, though some are luckier then others!!!
Most mechanics do the same thing replacing various other components, before even thinking about the mounts. Its a design fault with the original mounts, so it will not show up as a damaged mount, so most mechanics would never find it!!

Mine were replaced with the new version after I hassled Mitsubishi for a fix, and they finally admitted this was a know fault, and the revised engine mounts existed. Pity they were only a temporary fix though, as the problem returned after about another 20,000km's though not as bad as it was on the original mounts!!!
If you speak to you local Mitsubishi service centre they will be aware of the revised engine mounts, and will quote you a price.
Goodluck.

still to be checked is the air flow meter and tps

I too am going to say it's probably your engine mounts. If this is the case, aftermarket versions are available which will last longer than you will probably own the car, and can come in different degrees of firmness. PM Megatron for more info if required.

Don't Spend any more money on it. I went down the same path a while back and as already mentioned, there is no known cure for the rough idle/hunting. You've already spent a fair bit of $$ replacing various parts. The revised engine mount people are talking about is expensive and it's just a softer compound that attempts to mask the problem. Some of the early 3rd Gens had a tuned mass damper fitted on one of the engine mounts. Don't know if it did much for the rough idle though.

Thanks for the replies

Car is manual and not lowered

I understand what you are saying about engine mounts - however the rough idle is just as rough when in neutral or 1st gear - wilsact mentioned this could be a factor for engine mount problems. Also the problem is getting gradually much worse and is not something I am happy to live with on a daily basis.

My mechanic called me today and spoke to mitsubishi who said that the connectors on 3rd gen magnas were a weak spot and could be causing this problem. So he is going to check all connectors i.e those into crank angle sensor etc. Also going to replace ECU and MAS with spares and see if that helps.

Is there a way I can check to some degree of certainty that the problem definitely is engine mounts?

Thanks all

I have a rough idle, I was told it was an issue with one of my injectors, and aside from the rumble there would be no ill-effects.

this is more than just a rough idle though - it shudders like hell at low revs when accelerating at any more than snail pace :(

If the mechanic has had the vehicle hooked up to a scope, and can't fault it, then we must assume it is not an ignition fault.
The rough idle people are talking about affected the auto trans models at idle, not the manuals.
It's not a clutch shudder is it?? Surely the mechanic would know that????!?!?!

thanks for post mitumad - dont think anything like clutch shudder - definitely seems engine related :) im no mechanic tho

Is there a way I can check to some degree of certainty that the problem definitely is engine mounts?



You can inspect them yourself on the car, but depending on the degree of damage, it can be hard to identify if they are broken without removing them.

If any of them are damaged, the top drivers side one will be showing some wear - and it is the easiest one to inspect. To me - the fact that it is shuddering so much under accelleration, and getting worse makes the mounts the main suspect in my mind. Dust off a torch and have a good look to see if you can see any tears in the rubber of the mounts. Jacking the car up at the front and getting underneath should give you a good view of the front lower mount.

G/luck.

I dont think engine mounts would cause the idle to hunt around though - would it? It is lumpy and vibrates a lot while at stop. How do engine mounts affect idle- dont they just hold engine in place.

i've always been one to believe accelerating in 5th gear wasnt something you really wanted to do.

not sure if what i say is fact or fiction but by accelerating in 5th gear your putting stress on the driveline. always try to accelerate when im above 2000rpm and never in 5th gear.

but yeah vibration seems like engine mounts. either that or maybe my belief is true about effects of accelerating in 5th gear... btu there are lots of other people that would know more than me, just giving you my 2c

i've always been one to believe accelerating in 5th gear wasnt something you really wanted to do.

not sure if what i say is fact or fiction but by accelerating in 5th gear your putting stress on the driveline. always try to accelerate when im above 2000rpm and never in 5th gear.

I tend to agree tho I dont have a manual magna. I had a 5 spd manual EA Falcon and very rarely did I accelerate in 5th. Got up to the speed I wanted in 4th then went to 5th for ecconomy(only as low as 70km/h). When giving it sh!t occasionly would wind up to 180km/h in 4th then go to 5th and wind up to 215km/h, but engine was reving at around 5500rpm on gear change, not alot of stress on driveline at that rpm.
As for your problem, I'm no mechanic but I say bearing in gear box, used to drive a small truck which developed a vibration/shuddering in low revs which went away with higher revs. Mechanics had a look and couldnt fine it, few weeks later gearbox blew up due to r00ted bearing.

Had this issue with a friends 97 Verada
Once the driveshafts were changed + new gearbox oil/filter the problem went away

So the list so far:

driveshafts??
engine mounts??
wiring connectors (mechanic)??

looking good :cry:

1400 rpm sounds a bit low for ANY acceleration in 5th gear, the engine would be labouring.. maybe try using 4th or 3rd at those speeds.. at 1400rpm i'm guessing the car would be doing about 55km/h, bit slow for 5th unless u're on flat or downhill with little acceleration in my opinion. As QMD///801 said above, 5th isn't a gear that you'd accelerate with, at least under 2000rpm anyway.

Ps, this will also create a high fuel consumption, and probably stress the driveline. A mechanic also mentioned it can cause more heat to generate in the engine bay.

1400 rpm sounds a bit low for ANY acceleration in 5th gear, the engine would be labouring.. maybe try using 4th or 3rd at those speeds.. at 1400rpm i'm guessing the car would be doing about 55km/h, bit slow for 5th unless u're on flat or downhill with little acceleration in my opinion. As QMD///801 said above, 5th isn't a gear that you'd accelerate with, at least under 2000rpm anyway.

Ps, this will also create a high fuel consumption, and probably stress the driveline. A mechanic also mentioned it can cause more heat to generate in the engine bay.

finally i give correct advice:bowrofl:

just been a life long rule I have lived by, only use 5th gear over 80km or if your holding constant speed along a flat road that isnt going to need acceleration.

back on topic.. does it do it in all gears or is it just when your in 5th and trying to take off?

Guys thanks for input on not accelerating in 5th gear - I usually drive to conserve fuel as well. However it was while accelerating in 5th one day when I first started noticing the problem.

However, the problem exists in all gears - the shuddering can be felt in 1st all the way through the box - and let me clarify I am not driving hard in any way - under normal fuel efficient driving the problem is very noticeable. Shuddering etc.

More interested in posts by people who can diagnose the mechanical problem rather than driving tips :) Any ideas on what is causing the misfiring apart from those already mentioned?

1400 rpm sounds a bit low for ANY acceleration in 5th gear, the engine would be labouring.. maybe try using 4th or 3rd at those speeds.. at 1400rpm i'm guessing the car would be doing about 55km/h, bit slow for 5th unless u're on flat or downhill with little acceleration in my opinion. As QMD///801 said above, 5th isn't a gear that you'd accelerate with, at least under 2000rpm anyway.

Ps, this will also create a high fuel consumption, and probably stress the driveline. A mechanic also mentioned it can cause more heat to generate in the engine bay.

Mine cruises at just over 60km/hr at 1400 rpm and will happily accelerate from there on at
half throttle. I tend to chuck it down a gear or two if I need to accelerate faster.

GOOD NEWS EVERYONE!!!

The problem is fixed. For anyone reading this thread with a similiar problem here is what happened:

Turned out to be a cracked spark plug :( All that work and it turned out to be a dodgy plug. Thought is it cracked at factory and my mechanic didnt notice when he put it in - two cracks down side of ceramic :( And dont ask me how they didnt pick this up on oscilloscope.

All fixed - im happy :bowrofl:

For future ref to anyone who picks up a slight to ridiculous shudder (under load) that can get worse with acceleration and more to one side (driver/passenger) have your respective CV replaced.
You'll know the difference between mechanical and fuel/spark.

Just noticed this thread, I'm suffering from this too. I have noticed applying some revs stops it, so I though raising the idle would fix it.

Now I am unsure, as Madmik mentioned the CV. I'm not sure of the exact name, I'm not a mechanic, but something like the CV boot, is split in the drivers side wheel arch. How much am I looking at to replace it, and is it known to cause shuddering?

Checked your profile......Kings Lows huh. Well i had them also aswell as plenty of other mods and it is just a matter of time. The cv's work overtime when your car is lowered. The CV boots should be kept in good order also. Could be as simple as a wheel tyre alignment, but could be a CV joint or shaft. Best is to replace the whole shaft too, not just the Lower or Upper.

Checked your profile......Kings Lows huh. Well i had them also aswell as plenty of other mods and it is just a matter of time. The cv's work overtime when your car is lowered. The CV boots should be kept in good order also. Could be as simple as a wheel tyre alignment, but could be a CV joint or shaft. Best is to replace the whole shaft too, not just the Lower or Upper.

I only had them fitted 2 days ago!!

I too have just had my GTV lowered and now it is shuddering under acceleration. I had a mechanic look at it and he said straight away that it was the cv joints but he didn't do driveline repairs. He couldn't tell me how much it would be likely to cost.

Can anyone tell me how much roughly to get both cv joints replaced before I take it to the next mechanic. I just want to know so i know if he's charging about right or not.

Thanks!

When you lower a vehicle, extra stress is placed upon the suspension and structural
components. So if your cv joints were getting old and you lower the car, chances are, the
cv joints will go. Have you performed an alignment after lowering the car? Especially
correcting the camber of the front and rear wheels?

lowered and now shuddering under acceleration. I had a mechanic look at it and he said straight away that it was the cv joints but he didn't do driveline repairs. He couldn't tell me how much it would be likely to cost.

Can anyone tell me how much roughly to get both cv joints replaced before I take it to the next mechanic. I just want to know so i know if he's charging about right or not.

Thanks!

Well for starters is the shuddering from one side or both?? and how has the vehicle been drivin, I.E have you owned it the whole time so you know how much thrashing it has had.
Also You can get the inner or outer C.V done, and the cost varies. I had my whole left C.V done up near Coffs Harbour with fully Re-conditioned C.V & Labour for $220 i think. You can get new but then you'll pay for new, i've been told re-conditioned ones are just as good. 'f your mechanic can't give you a rough price i'd give him the flick and get someone who knows what their doing.


P.s My car was lowered from brand new (15km on the clock) and the tach read 178K when i had the C.V replaced. So for that long and low with me driving it has done bloody well. Mind you i have only spun the wheels once..........Ego you did it again!!

When you lower a vehicle, extra stress is placed upon the suspension and structural
components. So if your cv joints were getting old and you lower the car, chances are, the
cv joints will go. Have you performed an alignment after lowering the car? Especially
correcting the camber of the front and rear wheels?

I lowered my TJ at 80,000kms,

1 week after, ball joint went, 2 weeks later Drivers CV joint went. :cry:

Pretty minor repairs though.

Best to place in a Shim Kit in the rear and if you change your shocks (if not already) place in a Camber Bolt Kit. These alone will give you better response and allow for proper full adjustment of alignment etc.
Or if you really want you can throw in the Anti-Lift kit. Better off the line and better turning circle.