Jerky at low throttle/cruise - TPS enrichment settings?

Moderator: Tom Notch

Post Reply
User avatar
petew
Posts: 3743
Joined: Sat Oct 07, 2006 6:05 pm
Location: Sydney/Australia
Contact:

Jerky at low throttle/cruise - TPS enrichment settings?

Post by petew » Thu Sep 20, 2018 7:39 pm

Hi all, been driving the car around a bit and I'm sick of this ongoing slight jerkiness. At low throttle. I was initially thinking this was not enough spring on the throttle, but the more I thought about it, the more I thought it was TPS settings. Here's my current table...
Jerky throttle TPS settings.jpg
Here's a log from a while back too...
Jerky throttle TPS settings.jpg
Thoughts?
You do not have the required permissions to view the files attached to this post.

Clonebug
Posts: 3412
Joined: Fri Feb 16, 2007 12:28 am

Re: Jerky at low throttle/cruise - TPS enrichment settings?

Post by Clonebug » Sat Sep 22, 2018 9:37 am

I have that a little bit right now too......

I'm thinking it's a little leanness on accel and also in the lower rpm cruise areas.

Mine does it between 1500-1800 rpm in the first 3 gears especially in third cruising through town really slow.
I never have the computer along with me to fix it though since most of my driving this summer has been to work and back only.

My thoughts are it is a combo of afr and timing......try afr first.

Running an engine at a constant 14.7 or leaner is not what most of them want.

Mine has a slight lean spike at initial throttle when accelerating that I tried to correct with accel enrichment.

According to Andy Whittle you want to use the map bins to get as much accel as possible. All you use accel enrich for is to get that last little bit.
He has a video on it for MS-3 and it makes sense. I just haven't had time to incorporate it into my tune yet since I very seldom get into that situation when driving to work and back..... :roll:

Here is the video....it's for a W/C car but it's something you can play with.....

https://www.youtube.com/watch?v=KSUUVuSqRCY
Stripped66 wrote:The point wasn't to argue air temps with the current world record holder, but to dispel the claim that the K03 is wrapped up at 150 HP. It's not.

User avatar
petew
Posts: 3743
Joined: Sat Oct 07, 2006 6:05 pm
Location: Sydney/Australia
Contact:

Re: Jerky at low throttle/cruise - TPS enrichment settings?

Post by petew » Sun Sep 23, 2018 3:02 am

Clonebug wrote:
Sat Sep 22, 2018 9:37 am
I have that a little bit right now too......

I'm thinking it's a little leanness on accel and also in the lower rpm cruise areas.

Mine does it between 1500-1800 rpm in the first 3 gears especially in third cruising through town really slow.
I never have the computer along with me to fix it though since most of my driving this summer has been to work and back only.

My thoughts are it is a combo of afr and timing......try afr first.

Running an engine at a constant 14.7 or leaner is not what most of them want.

Mine has a slight lean spike at initial throttle when accelerating that I tried to correct with accel enrichment.

According to Andy Whittle you want to use the map bins to get as much accel as possible. All you use accel enrich for is to get that last little bit.
He has a video on it for MS-3 and it makes sense. I just haven't had time to incorporate it into my tune yet since I very seldom get into that situation when driving to work and back..... :roll:

Here is the video....it's for a W/C car but it's something you can play with.....

https://www.youtube.com/watch?v=KSUUVuSqRCY
You nailed it. That's exactly where the issue is. I spoke to another friend (non VW) and he said AFRs straight up. Sent me an AFR table and it helped straight away.

User avatar
panel
Posts: 3718
Joined: Sun Sep 24, 2000 2:01 am
Location: Victoria B.C. Canada
Contact:

Re: Jerky at low throttle/cruise - TPS enrichment settings?

Post by panel » Wed Sep 26, 2018 8:54 pm

This is a great video re setting up your accel. I bet you'll lower your TPSdot threshold % after watching this vid.

https://www.youtube.com/watch?v=HSE3CxaWF-I&t=815s
Subaru JDM EJ20 Turbo bus
Built by Germans powered by Japanese and brought together by Canadians

Post Reply