Hey guys

I have next to no technical understanding of cars, so thought I'd ask about this

For a while now i've noticed that every few times I've gone to accelerate, generally harder acceleration, but not necessarily, the car violently joilt a little bit forward then accelerates normally.

I get the feeling its getting worse in terms of how often and that its getting more violent, and its also starting to not just be when im accelerating from stationery, but now just speed increasing.

Has anyone had this before or have any idea what it could be?

Cheers
-Blaine

More than likely, its your spark plug leads.

Easy way to check.

Put car into neutral, rev it. If it doesnt do it, but does it while driving, its your leads.

Mine (3rd gen) came and went......got to the point where I nearly burnt the car down.

Everytime I went to the mechanics, it would stop. Even if I thought about going.

It also seemed to happen the further I was away from my house. I swear the car was/is possessed.

hmm, thing is though, my leads were replaced around 2 months ago because I was having problems and i was running on 3 cylindars
if im not confused with what you mean of course
but pretty sure if you mean the ones that run over the top of the engine, they're brand new so i hope they aren't stuffed

Mine happened when I done a full service on the car.

1 month later this happened, I replaced everything else before going back and re-doing the leads. That solved it.

Change all the leads, sometimes there are just manufacturing defects and they break down really fast. Pain in the back side to replace on a 3rd gen, not sure about 2nd gen.

Other things that can go wrong that have similar symptoms:

Cracked Dizzy cap
Worn Rotor button
Blocked fuel filter
Worn Dizzy

After replacing $250 worth of stuff, I replaced the leads......on the plus side, I dont have to check the dizzy for a while lol

If you have an auto trans, could be the clutch band grabbing through something on the way out. Get an opinion from a auto trans repairer.

yep - had the same problem but it is all fixed now.
The autobox is in second gear when stationary, to avoid creep if in first. It changes into first as you open the throttle.
Initially, I overcame the problem by manually starting off in first and changing up as the car sped up. Try that to see if it helps.
My fix was to reset the TPS and increase hot idle by 100rpm. No hastles now, hot or cold.
Mine's a TS wagon, V6 auto with 233,000 Km on the clock. If yours is similar I would check the TPS adjustment before spending money on anything.

yep - had the same problem but it is all fixed now.
The autobox is in second gear when stationary, to avoid creep if in first. It changes into first as you open the throttle.
Initially, I overcame the problem by manually starting off in first and changing up as the car sped up. Try that to see if it helps.
My fix was to reset the TPS and increase hot idle by 100rpm. No hastles now, hot or cold.
Mine's a TS wagon, V6 auto with 233,000 Km on the clock. If yours is similar I would check the TPS adjustment before spending money on anything.
Very true, mine does it, just don't give it heaps of throttle suddenly so it doesnt shudder heaps when it's changing down gears, or like madmax said use the gearbox from L to 2 to drive.

Could be transmission related.. what RPM does the car idle at while stopped in drive? It could have issues remaining engaged in gear / bands slipping

I wouldnt be surprised if its transmission related, sounds about right, but i'll take a look at the rest too
it doesnt happen always, but enough to annoy the hell out of me

could it be related to a time my brother switched me to neutral at the lights then when i accelerated switched me to drive?
Im assuming this'd probably do bad things for the car considering its an auto
dont think it was happening before then

im just hoping its nothing too expensive, already had enough bad luck and replaced so much stuff

i'll try the upshifting from L, 2, D tomorrow morning and see if it helps

EDIT: and in relation to the idle, its about 900 or something if i remember right, could be a little off possibly though because of when I changed to dials over theres always the possibility the needles slightly off

Don't think of it as a mechanical problem - its an adjustment problem.
When you open the accelerator from a standstill, the TPS sends that information to the gearbox and it changes into first. It should do this before the car starts to move, but if the TPS adjustment is out, the car has already started to move in second gear and the revs are up - you then get an awful thump as it engages first gear. Feels like a major gearbox problem, but it isnt.

Try this - put on the handbrake, in "D", raise the rpm to 1200 and release the handbrake. If the car now takes off smoothly in first it is definitely a TPS adjustment problem.

your rpm sounds about right. Mine goes up to 1,800 on cold start, then drops to 1,100 quickly, and I let it settle to 900 before I take off. Just enough time to put on the seatbelt and tune the radio.

Don't think of it as a mechanical problem - its an adjustment problem.
When you open the accelerator from a standstill, the TPS sends that information to the gearbox and it changes into first. It should do this before the car starts to move, but if the TPS adjustment is out, the car has already started to move in second gear and the revs are up - you then get an awful thump as it engages first gear. Feels like a major gearbox problem, but it isnt.

Try this - put on the handbrake, in "D", raise the rpm to 1200 and release the handbrake. If the car now takes off smoothly in first it is definitely a TPS adjustment problem.
ah this sounds really likely actually
it often feels like similar to when you switch down from d to 2 or L

I'll go out to the car and try this quickly

Yeah its normal to me, doesnt worry me, my friend knocks my car into neutral when im driving just to piss me off, doesnt hurt it to much as long as you dont build up revs and knock it back into drive.

Took off fine from 1200rpm, but then again, it wasnt taking off badly just then normally either, probably cos the engines still pretty warm

All i know is that i think my breaks are on their way out, it seemed struggling to hold it back climbing to 1200

oh and my bad on the idle, its more about 200 i think, dont know if thats a normal idle


oh cool about the neutral deal, although this time it happened my revs went pretty high (probably 3000ish+) because the dick decided to do it when i was needing to accelerate into a spot quickly

200 rpm is not a normal idle!
750 to 850 by the manual. This is needed to keep the engine turning over smoothly as well as keeping the auto box oil pump working as a suitable pressure to drive off smoothly - if you really meant 200 rpm this would be part of the problem.

mm it is saying 100-200ish the needles on
its at about 850 in park

unless its just because iv stuffed up my needle alignment
is there a way of checking your needle alignments?

Ferox, could you describe as accurately as possible what the car does? even if you think you sound stupid, describe it to me because I THINK i may be having the same problem...

Is this only from standstill to move forward or is it when already moving?

mm it is saying 100-200ish the needles on
its at about 850 in park

unless its just because iv stuffed up my needle alignment
is there a way of checking your needle alignments?

EXTERNAL TACHO????

Get the Mitsu dealer to check rpm with his instruments - will tell you how much your tacho is fibbing.
By the way, rpm should be the same in park, drive, reverse and neutral - it has an ISC motor, you know!

EXTERNAL TACHO????

Get the Mitsu dealer to check rpm with his instruments - will tell you how much your tacho is fibbing.
By the way, rpm should be the same in park, drive, reverse and neutral - it has an ISC motor, you know!
aha okay no worries
i'll take it there asap

yeah well theres definately a big difference between drive park and neutral.
reverse, 2 and L are the same as D

Oh and I have no idea what an ISC is, im pretty nooby with just about everything technical


Yann, i'll try describe as best i can

When I'm stopped in drive, then accelerate at any level of hardness, the car seems to give a real hard jerk forward, along with a feeling very much like if you were travelling at good speed then put the auto into 2 or L, then you can hear the revs cut for a split second and pick up again and the car accelerates normally
I have also found this a couple of times when i'm cruising at say 50-60, then put the foot decently heavy down to bring the speed up, it gives the same sort of feeling as though you've been put to 2 then accelerates as normal
Its like the engine just stops doing anything for a split second and gives a real draggy feeling for that little bit of time
Wether or not this happens more when the car is colder im not really sure but im pretty certain it is, although not necessarily only when its cold - its been known to happen at any time

Not sure if that helps or makes any more sense, let me know if its the same as yours

Regarding TPS issues.

If you have access to a multimeter and a service handbook, the tps is easy to check, takes about 30seconds.

The TPS works as a resistor, as you open the throttle the voltage should gradualy change from X value to Y value. With no sudden jumps. A worn TPS can present symptoms like yours. Though, what generally happens is the TPS is worn in the section thats most used (idle-3000rpm) which causes the contact inside to wear/corrode. This then leads to issues like this, as the computer doesnt know the throttle position and then suddenly gets the data.

If you cant get a multimeter/manual - try the wreckers, a TPS is maybe $15, takes 2 seconds to change - and will let you know if its stuffed. If it is, buy a brand new one. If that doesnt fix it, there's 2 options:

A) you bought a stuffed 2nd hand TPS
B) thats not the issue,

I think I may ahve a similar problem since ive had the car. Except, it only ever does it when starting from cold, on the very first acceleration only. I can reverse out the drive, then put it in D, the car moves forward slightly, then you accelerate and it jolts and goes. After that, it NEVER does it again, ever, which is weird.

To stop it doing that, the first time I ususally put it into L instead of D, and then as soon as I take off i put it back to D. This makes it start off in 1st, and hence doesnt jolt.

Anyone know why it does this only the 1st time? As it doesnt do it after that it doesnt seem liek the TPS is broken or anything..

Ollie

Possibly the gearbox oil pressure is low with a cold engine that has been just started, or some band/plates that hold it in second gear are sticky when cold? - just a guess. Mine does it too, occasionally, and only when cold. I put my foot on the brake, build up revs to 1100 then release brake - results in a smooth takeoff. When warm, and stopped at a traffic light, I pull the handbrake up 3 notches to stop the car from creeping forward. When the light changes I take off, and once the car is moving release the handbrake. Takeoffs are smooth this way. I have adjusted the TPS, chacked idle speed and ISC, but it still does it - a tired gearbox I guess - 233,000 on original box is not bad.