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jerky On/Off throttle, fix?


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#21 El_Freddo

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Posted 25 April 2015 - 01:03 PM

Mate with the h6 conversion found out his rear diff had some serious backlash issues.

I believe he's swapped that out to another known good diff. I'll have to touch base again when I know more about his problem and if this is the fix.

Cheers

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#22 Adictions

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Posted 03 May 2015 - 02:52 PM

I cleaned out the IACV, it didn't fix it but it needed a clean anyway, it was really dirty anyway so was still a good idea to do it. I'm still thinking its the engine mounts (they had small cracks in them and i can move them with a bit of leverage on a bar) so I thinking of upgrading them to group n mounts while i'm at it. whats the best place to buy them from, how much would i be looking at for a full set? (both engine mounts, trans and pitch stop mounts)

 

let me know how he goes ben  ;)


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#23 El_Freddo

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Posted 03 May 2015 - 07:39 PM

So with the H6 lib the rad diff has been swapped and the old one seems to be within spec but is being checked anyway.

He found two drive shafts with an issue so replaced these. Issue seems to have gone so it seems to point at drive shafts. How old are yours Addictions? Drive shafts can continue to operated without noise even when they're super loose! I had mine create an oscillation effect when cruising on the freeway. A new set of shafts sorted that! This was when I was still front wheel drive and rocking the 23 inch tyres.

I'll update when I know more.

Cheers

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#24 Adictions

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Posted 03 May 2015 - 07:51 PM

All of my uni joints seem fine and have no movement. I can turn the driveshafts a bit. So there is some play in the gearbox/diff (under 1/4 turn from FL and FR wheels when of the ground) but thats normal slack isn't it?

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#25 crjohnson

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Posted 03 May 2015 - 08:52 PM

Must have been the day for it cause I tried something today too, but a bit different to you guys.

 

After reading El Freddo's link I tried the restrictor plug for the iacv idea.           Results:                           Awesome!

 

I machined an alloy plug to go on the manifold side of the iacv and pressed/tapped it into the machined port (Have a looked at the back of a throttle body and you'll see it, sorry I didn't get a photo!). The plug measured 18.05'ish mm x 17mm long with a 4mm hole through the centre.

 

It hasn't 100% completely fixed it (maybe due to driveline play) but it is the best thing I have done so far! I even drove over a speed bump (slowly) in 1st gear and didn't jerk back and forth looking like a retard! (well it did but only a tiny bit!). The engine is heaps smoother on/off the throttle when driving and it doesn't seem to have effected the idle at all. Small bonus too is that it cant fall into the intake manifold because its too big. It if comes out i'll feel or hear it..

 

A good test will be on the freeway with the cruise on, down a slight hill. I know a spot inbound on the monash where it used to buck around every time.

 

Also I took a photo of how much the tail shaft rotates and marked it with a sharpy. Had the handbrake on and front wheels on the ground (think it was in neutral), and just rotated it by hand as far as I could. It bounced back a tiny amount so that's where I marked it.

 

Also I still haven't changed the engine mounts to the WRX ones I got ages ago, or the trans mount..



#26 crjohnson

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Posted 03 May 2015 - 08:55 PM

Cant seem to get the photo to work so heres the link:

 

http://carphotos.car...70/19105207.jpg



#27 crjohnson

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Posted 05 May 2015 - 01:26 PM

One affect I've noticed is cold starts.

 

The engine does not rev up anywhere near the 1500-2000rpm range, almost struggles to idle unless you hold the peddle down for a sec to get it to around 1000-1500rpm. 

 

Otherwise it still drives awesome! 

 

Anyone think it will slightly mess with a/f ratios? I read somewhere that the oacv is almost always slightly open even when on the throttle.. 



#28 Adictions

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Posted 05 May 2015 - 06:47 PM

I would think its OK the ECU should be able to adjust

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#29 crjohnson

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Posted 27 September 2017 - 08:05 AM

Well I'm reviving this old thread as I stumbled across something interesting the other day, found a bunch of people in the USA with the same jerky throttle issues and 1 guy found out the neutral safety switch on the gearbox can be a big cause. 

 

I bought a new switch for my manual outback ej25, car was a dream to drive today! Easy to install with a 19mm spanner. 

 

I tried to test the old and new switches with a multimeter. When changing into gears the old switch would jump all over the place and sometimes settle on a really high resistance value. The new switch was much better, generally settling on a clean 0 ohm resistance. I tested the old switch by hand after i removed it and it was still all over the place.. 

 

The switch cost me about $32 shipped from partsouq, 32008AA074 is the part number. 

 

 

I think it first gets suggested by about the 5th page, just search for 'neutral' until you find it.. 

 

http://legacygt.com/...ual-189786.html



#30 Adictions

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Posted 27 September 2017 - 09:02 PM

That's surprising, I would not have thought of that, good find. Would try it but sold the car a year ago. The spec B does it a little but not enough to worry about.


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#31 Barbbachello

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Posted 28 September 2017 - 09:37 AM

Not sure if its been mentioned but the factory ECU turns the injectors off at low rpm to save fuel, then obviously turns them back on when you accelerate but takes a split second to get them going again. To my knowledge thats the main course of this issue. 

So v1/2 STi/RA ecu or aftermarket ecu will fix it :)


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#32 El_Freddo

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Posted 02 October 2017 - 11:49 AM

Well I'm reviving this old thread as I stumbled across something interesting the other day, found a bunch of people in the USA with the same jerky throttle issues and 1 guy found out the neutral safety switch on the gearbox can be a big cause. 
 
I bought a new switch for my manual outback ej25, car was a dream to drive today! Easy to install with a 19mm spanner. 
 
I tried to test the old and new switches with a multimeter. When changing into gears the old switch would jump all over the place and sometimes settle on a really high resistance value. The new switch was much better, generally settling on a clean 0 ohm resistance. I tested the old switch by hand after i removed it and it was still all over the place.. 


Hmmm... I still question this, while it might work with gear changes etc, how does it effect the light throttle response in the one gear - eg: first or second in the car park at low speed/just off idle?

This is where I've experienced the issue before.

Cheers

Bennie
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#33 crjohnson

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Posted 02 October 2017 - 03:19 PM

On/off throttle changes are what has improved heaps for me. I even used to get real bad jerks with the cruise control on going down slight hills, now that does not happen. 

 

I can literally drive around a carpark in 1st or 2nd gear and go on/off throttle without looking like a learner driver..

 

There is still some driveline slop thats for sure which is why i still need to be careful but overall it made a decent improvement. 






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