Jerk when hitting boost? Anyone? I dunno...

[dimi_108]

Morning fellas.
Got a question to ask, hope you can help. When driving the car to work this morning, leaving it in 5th on the freeway, if i tried to accelerate slightly for the turbos to spool, from 2300rpm towards 3500rpm on a few occasions i would get this weird "jerk" or "kick". Almost like a mini boost cut, but not as violent or hard. It felt like a "miss".
I also noticed it when i also planted my foot from 5th and when it would drop down to take off it happened once as well.
None of this happened yesterday at all and i drove the car for nearly 400kms on twisties and giving it a boot etc.
Is this the torque converter or transmission about to die? Or turbo spike? Or a bit of boost cut from cold weather?
I wound down my MBC a tiny notch after i parked the car just then.
I don't like mini unexplainable problems things like this! Makes me paranoid

 

[matchtheclown]

Sounds like auto gremlins to me dimi.

I need to turn my boost down a little though because when i plant it in 3rd i just touch boost cut at the top of boost which sounds similar to what your describing.

 

[dimi_108]

Shit man auto gremlins?!
My gearbox is going to die??

 

[matchtheclown]

I am highly experienced in having nothing to do with VR4's with auto's dimi so don't heed my suppositions.

One of the guru's will have much better idea's soon enough i'm sure.

 

[pu-11-me]

Check for Throttle Position Sensor errors bro... You'll need to get Mitsi to do it but

Also, an ECU reset might just fix the issue too. Might just be getting a bit glitchy with the change in weather (its cold here today)

Don't have gearbox fears just yet, i'm sure it'll be fine

 

[dimi_108]

Don't have gearbox fears just yet, i'm sure it'll be fine

Reckon?
I'm hoping it was like a mini boost cut sort of thing caused by the drop in temperature this morning. Perhaps the boost was rising from the cold weather on the freeway?
The jerk was just weird though. It was like a slight jolt only as the turbos spooled. Nothing "violent" like when boost cut hits, just a miss. And it only happened a few times then it went back to norms and there were no more jolts or misses.

 

[matchtheclown]

Also on a lighter note:
Jerk when hitting boost? Anyone? I dunno..

Who doesn't?

 

[pu-11-me]

Reckon?
I'm hoping it was like a mini boost cut sort of thing caused by the drop in temperature this morning. Perhaps the boost was rising from the cold weather on the freeway?
The jerk was just weird though. It was like a slight jolt only as the turbos spooled. Nothing "violent" like when boost cut hits, just a miss. And it only happened a few times then it went back to norms and there were no more jolts or misses.

Perhaps your AFR's have gone spastic because of the weather....

*does something to hint an ECU reset

 

[dimi_108]

Hahaha boost jerk offs
Aye man. Can you hit max boost even in low RPM's? Say if it's in 5th and you press the pedal down and the turbos start to spool up towards 3000rpm plus, can full boost be hit at this rate? Or is it too low to hit full boost/boost cut?

 

[matchtheclown]

I think you can Dimi, I get my peak boost around 3-4000K I think.

Wide Open Throttle creates the boost as far as I know not the RPM.

 

[pu-11-me]

Hahaha boost jerk offs
Aye man. Can you hit max boost even in low RPM's? Say if it's in 5th and you press the pedal down and the turbos start to spool up towards 3000rpm plus, can full boost be hit at this rate? Or is it too low to hit full boost/boost cut?

REBOOT spikes when in Tip mode and i punch it at 100 (Don't get cut though because i have an EBC).... It makes 13PSI at about 3000 - 3500RPM

And what he said ^^^ about the throttle position

You can get to redline without making any boost as long you go light on the accelerator

 

[dimi_108]

13PSI at 3000rpm! Ahhh i see. So it could have been a mini boost cut happening?
Hoping it was.
I wound down my MBC a tiny bit after i parked the car at work. And i'll do an ECU reset at lunch. Hopefully everything will be back to norms after this.

ECU reset is like a mini detox for our cars

 

[pu-11-me]

ECU reset is like a mini detox for our cars

And if you "de-coke" the motor it will be a full detox

If it warms up at lunch take it for a drive and if it doesn't do it, don't worry about it... AFR's take time to remap, and theres no point remapping it for cold weather if its only going to be hot again tomorrow!

 

[dimi_108]

Haha sweet.
I'll disconnect the battery and turn interior light switch on at around 12:00pm then reconnect it all at 1:15pm for ultimate detox.

Then i'll connect it up and go for a drive and give it a few hits on the freeway. Hopefully it won't happen again aye. Please god.

 

[TTVR4]

hi mate you might find your leads or plugs need changing.
mine was doing the same thing so i changed the both and all is fine now

 

[pu-11-me]

Haha sweet.
I'll disconnect the battery and turn interior light switch on at around 12:00pm then reconnect it all at 1:15pm. ECU would have reset for sure aye?
Then i'll connect it up and go for a drive and give it a few hits on the freeway.

After that long it'll wake up with amnesia lol....

 

[dimi_108]

hi mate you might find your leads or plugs need changing.
mine was doing the same thing so i changed the both and all is fine now

Really? Were you getting the same thing happening on and off?

Honestly, i've only changed the front three spark plugs. The other three at the back have not been changed *hides*

 

[Hotwire]

Change the rear three plugs, new set of leads and try again.

 

[Guest]

It sounds similar to what im experiencing. Im trying new leads, fuel filter and plugs and that shouls fix it up! I would try that.

 

[naughtika]

mine's a manual, but had similar issues at around 3500rpm to the red line..

found it was the plugs getting too old.. this happened about 2-3 weeks after turning up the boost.. so i guess if you've just had the car, decided to turn up the boost a little.. expect to replace the plugs alot sooner.. worst case the leads as well..