Shudder When Accelerating Hard / Idle Issues

crazynick505

Doing mad Helis
Lifetime Member
Location
Brisbane, QLD
First Name
Nick
Drive
'96 Galant VR4 - 300kW
'19 Kia Stinger GT
'95 R33 Skyline
Hey guys,

Got a couple of problems I thought I'd chuck into 1 post here.

1st is an issue I am having is a pretty noticeable shudder as I accelerate hard in mainly 3rd gear (That's when it is most noticeable). I have had a look around and there seems to be a fair few causes for this.
I don't think it can be my engine mounts as they are all poly mounts (and one is solid) and have never caused issues previously. I don't think it'd be transmission fluid as I changed that not long after I got the car, less than a year ago.I have recently lowered the car but I have had the coil overs for ages without a problem.

This started happening after Lakeside happy laps last weekend. I noticed when I went to accelerate down the straight once that it felt like I got a bit of clutch slip which I have never gotten before. I have also been doing ALOT of city driving lately, so I was thinking this might be a clutch issue? Not sure on the CV shafts as I have 0 wheel play whatsoever and have just had a wheel alignment and balance done. Any ideas would be appreciated.


The 2nd issue is my idle randomly dropping from 700~ to about 300~ while sitting in traffic on the way home from work. Almost happens 100% without fail on the hour drive home. I usually have the aircon on and it tends to help keep the idle up to the 300 mark. If i turn the aircon off the idle will drop to right on that thick line on the tacho and vibrate all over the place. Weird thing is, this can all be fixed by turning the car off and on again. o_O I was starting to look for a manual throttle body to replace my auto one which I still have after the manual conversion, thinking maybe replacing that will rule out my idle screw being loose or any ISC/IACV issues. Let me know what you think there too.

Alright that'll do me for now haha.

tl;dr: My car is being retarded.
 

crazynick505

Doing mad Helis
Lifetime Member
Location
Brisbane, QLD
First Name
Nick
Drive
'96 Galant VR4 - 300kW
'19 Kia Stinger GT
'95 R33 Skyline
how old are you plugs? and what brand / model are they?

I've got a set of vk22 plugs, probably about 5 months old. They were changed at the same time I had my timing kit done etc.

It feels like my power is fine, it's just like a vibration more than anything, seems driveline related?
 

TME_Steve

3 AYC Bars
Lifetime Member
Location
NSW
First Name
Steve
Drive
2010 nt did pajero tow car / 2000 6spd gc8 wrx tarmac rally car / 2000 Manual Subaru Outback 2.5 just a car
Firstly poly mounts are crap and usually designed wrong. So I'm guessing the engine is hanging low. If your car is lowed this makes it worse. 9/10 times vibration during acceleration is cv joints protesting about the angle they're trying to deal with.

Idle sounds like iscv playing up. Give it a clean ;)
 

crazynick505

Doing mad Helis
Lifetime Member
Location
Brisbane, QLD
First Name
Nick
Drive
'96 Galant VR4 - 300kW
'19 Kia Stinger GT
'95 R33 Skyline
Firstly poly mounts are crap and usually designed wrong. So I'm guessing the engine is hanging low. If your car is lowed this makes it worse. 9/10 times vibration during acceleration is cv joints protesting about the angle they're trying to deal with.

Idle sounds like iscv playing up. Give it a clean ;)

Ahh righto, that makes sense.
Am I gonna have to look at some oem engine mounts? Or is there another way to sort that out?

I'll give that a clean and see how she goes (y)

Thanks Steve!
 

crazynick505

Doing mad Helis
Lifetime Member
Location
Brisbane, QLD
First Name
Nick
Drive
'96 Galant VR4 - 300kW
'19 Kia Stinger GT
'95 R33 Skyline
Wouldn't the poly and solid mounts make the engine sit higher and out less stress on the CVs?

Not sure how I go about stopping that shudder :confused:
 

TME_Steve

3 AYC Bars
Lifetime Member
Location
NSW
First Name
Steve
Drive
2010 nt did pajero tow car / 2000 6spd gc8 wrx tarmac rally car / 2000 Manual Subaru Outback 2.5 just a car
Poly mounts usually don't offset the mounting hole. the stiffer rubber ones we use are offset so when the weight of the engine is applied they sit centre of mount. Poly will hang lower
 

crazynick505

Doing mad Helis
Lifetime Member
Location
Brisbane, QLD
First Name
Nick
Drive
'96 Galant VR4 - 300kW
'19 Kia Stinger GT
'95 R33 Skyline
Poly mounts usually don't offset the mounting hole. the stiffer rubber ones we use are offset so when the weight of the engine is applied they sit centre of mount. Poly will hang lower

Ahh makes sense. I'll send you a message in that case ;)
 

Gt_Galant

EC5A
Location
New South Wales
First Name
Fred
Drive
Galant
Just curious (im sure other will be too)
I know you had 2 problems, one is the shuttering problem and other is the rev drop/idle issue.
Did you fix the rev drop/idle issue ? Was it just a simply cleaning the ISC valve ? Or you haven't looked into that yet ?
Thanks.
 

crazynick505

Doing mad Helis
Lifetime Member
Location
Brisbane, QLD
First Name
Nick
Drive
'96 Galant VR4 - 300kW
'19 Kia Stinger GT
'95 R33 Skyline
Just curious (im sure other will be too)
I know you had 2 problems, one is the shuttering problem and other is the rev drop/idle issue.
Did you fix the rev drop/idle issue ? Was it just a simply cleaning the ISC valve ? Or you haven't looked into that yet ?
Thanks.

Nah not yet, I'll be looking into that this weekend. It has been fairly good this week, maybe because I haven't had to use the aircon? Not sure.

But I'll update anyway once I have done that (y)
 

crazynick505

Doing mad Helis
Lifetime Member
Location
Brisbane, QLD
First Name
Nick
Drive
'96 Galant VR4 - 300kW
'19 Kia Stinger GT
'95 R33 Skyline
So I removed the throttle body today and gave it a good clean out. Was a bit of stuff around the plate but nothing crazy.
Got that all nice and shiny and took the IACV out, below is a pic of how it looked. Didn't look like much to me although the plastic end on the valve looks a little gross (Not sure if that really matters)

Gave it a good clean also, making sure to get everything out of where it sits.
Chucked it all back in and started her up. Ran a little weird for a couple of seconds but once it smoothed out it was idling up around 1k revs which is what I was hoping would happen as I've turned my idle screw loose a bit in the past to get idle to come up from 400~. So I was able to close the crew back to where it was originally and achieve my correct idle which seems like a good thing :p

We'll see how she goes with the air con on when I take it for a proper drive again but seems promising so far :)

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B1FnuzE.jpg
 
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