Erratic jerking

[Manie Booyjens]

Hi all, well I had my 2016 Sonic 14 RS at the dealers for about 4 months for this problem. They replaced the ECU and cleaned all the sensors and the problem is still there. It only happen in 1,2,3 gear ( manual 6 speed)
I managed to buy HP tuners pro and it seems i can not add the recording I did. At the moment I will appreciate all the help I can get.

 

[ScarabEpic22]

What kind of jerking? Under hard acceleration, normal cruising? I have a 13 RS 6MT and the gearing in 1st means it's almost impossible to not have the car jerk a bit when decelerating.

Check your spark plug gap and check the coil pack (and boots). These are known to have issues.

 

[Manie Booyjens]

Hi Erik,
Here is what it does.
Normal drive is perfect for some odd ( miles) or days but only jerkes when I Accelerate hard with no fault codes or engine light on.
This morning I drove it and at some stage under normal driving the engine light came on and went away with jerking and back fire.

With the HP tuners i did a recording over the weekend and when the jerking starts everything on the dash and recording goes crazy.

I will check the coil pack this afternoon if I can see any problems.
Thanks for your reply.

I checked the following:
Coil pack was replaced with a new one by the agency but i checked it any way. The two outside suppressor springs were not straight when I removed it and I carefully removed the rubber boots and refitted the springs straight.
I removed all the plugs and this were replaced by the agency with new ones and they did the gaps, well they were all 0.23" and I adjusted it the same as what was discussed on the forum to 0.28"
I am now going to test drive it an will reply later.

 

[Manie Booyjens]

Hi Erik,
Here is what it does.
Normal drive is perfect for some odd ( miles) or days but only jerkes when I Accelerate hard with no fault codes or engine light on.
This morning I drove it and at some stage under normal driving the engine light came on and went away with jerking and back fire.

With the HP tuners i did a recording over the weekend and when the jerking starts everything on the dash and recording goes crazy.

I will check the coil pack this afternoon if I can see any problems.
Thanks for your reply.

I checked the following:
Coil pack was replaced with a new one by the agency but i checked it any way. The two outside suppressor springs were not straight when I removed it and I carefully removed the rubber boots and refitted the springs straight.
I removed all the plugs and this were replaced by the agency with new ones and they did the gaps, well they were all 0.23" and I adjusted it the same as what was discussed on the forum to 0.28"
I am now going to test drive it an will reply later.

Back from a drive in town and what I see is that just before the jerk starts the RPM needle drops down and sometimes the odo meter goes to zero.
then it is all normal for a few stops and it all starts again. With the plug gap sorted i can feel the difference.
My feeling is that maybe i have a bad connection somewhere but it is a needle in a haystack.

 

[ScarabEpic22]

Can you zip the recording and post it here? If not, PM me and I'll send you my email so I can take a look at it.

Bummer, was hoping it was a coil pack or spark plug issue!

 

[Manie Booyjens]

Can you zip the recording and post it here? If not, PM me and I'll send you my email so I can take a look at it.

Bummer, was hoping it was a coil pack or spark plug issue!

Hi Erik, I was hoping for that too.
I checker the ignition and fuse box but no luck. attach is the zip file from this mornings recording. it is a short one and you will see that the speedo is crazy.
I will do a few more recordings this morning
It seems the ZIP file is too big for the forum allowed size. I will wait for your e mail address.

 

[Manie Booyjens]

Hi Erik, I was hoping for that too.
I checker the ignition and fuse box but no luck. attach is the zip file from this mornings recording. it is a short one and you will see that the speedo is crazy.
I will do a few more recordings this morning
It seems the ZIP file is too big for the forum allowed size. I will wait for your e mail address.

Hi Erik,
I have some good news. I fount the problem this morning. In 2017 my local dealer at the time replaced the starter motor under warranty for me. well the technician some how broke the earth cable terminal and did a poor repair.
I replaced the terminal with a heavy duty one and seems like the problem has gone. I drove it the whole morning and no jerking and no gauges jumping.

Once again thank you for your time and willing to lend a hand.
Attach is the pictures

 

[ScarabEpic22]

Oh man, that was definitely hacked together! Glad you found and fixed it, ground issues cause lots of problems!