Constant Jerking

Tiny
BAMMI
  • MEMBER
  • 2009 SUZUKI SX4
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 120,000 MILES
The issue is that the car kept jerking when I started the ignition yesterday morning. The jerking was so much that a neighbor advised that this might not be good enough for my outing. I drove out all the same, but it stabilized on the way. On getting to my destination and dropping off kids within 6 minutes, it started fine when I went back to it. However, at my next destination, after stopping for about 30 minutes, it started jerking again and would later normalize. This is happening after plugs, valves, and gasket have all been changed a month ago. There seems to be nothing else to troubleshoot as the pump has also been confirmed okay.
Do you
have the same problem?
Yes
No
Friday, August 13th, 2021 AT 9:52 AM

11 Replies

Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

Has the CAN-bus system been scanned? CAN stands for controller area network. Basically, all the computers/modules are tied together via a few wires. If you scan the entire system, it will identify codes regardless of the module they are stored in.

Here is a video showing how it's done:

https://youtu.be/InIlnsjOVFA

Let me know if that was done and if codes were found.

Next, when you feel the jerking, is it when you are sitting at idle or when you try to accelerate and the engine is under a load? Also, at this point, has it only happened when the engine is cold? What is the temperature of your location?

Let me know as much as you can.

Take care,

Joe

Was this
answer
helpful?
Yes
No
Friday, August 13th, 2021 AT 8:39 PM
Tiny
BAMMI
  • MEMBER
Thanks for your reply. About 3 weeks ago, a technician did a scan which resulted into changing of valves and gasket.
I feel the jerking when about to accelerate. It has so far happened when the engine is cold. The first time was in the morning after leaving it overnight. I also observed that it does not jerk after like 5 minutes of putting off the ignition. But it'll jerk a little (not as much as in the morning) if it's more than 25/30 minutes of parking. The temperature around me lately is between 18 c - 25 c.
Was this
answer
helpful?
Yes
No
Friday, August 13th, 2021 AT 10:54 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
When you say valves, are you referring to the intake and exhaust valves? Basically, was the cylinder head overhauled?

By any chance, can you get your hands on a live data scan tool? If you can, the short-term fuel trims are important for me to know. Also, I would like to know if the engine coolant temperature sensor is sending a signal similar to ambient temperatures when the engine sits overnight.

One other question. Is the check engine light staying on when the engine is running? If so, you really need to have it scanned again to see if there are diagnostic trouble codes stored.

Let me know. The idea that it seems to do it when it's cold or nearly cold is making me think it is either a fuel pressure-related issue or something with the temp sensor. The fuel trims will help me determine if it is a low fuel pressure issue. Otherwise, you could check the fuel pressure after the vehicle sits overnight and hasn't been started.

Here is a link that shows how it is done:

https://www.2carpros.com/articles/how-to-replace-an-electric-fuel-pump

You will need a fuel pressure gauge, but most parts stores will lend one to you.

Let me know.

Joe

Was this
answer
helpful?
Yes
No
Saturday, August 14th, 2021 AT 8:59 PM
Tiny
BAMMI
  • MEMBER
Thanks Joe.
Yes, it is the intake and exhaust valves. And basically the cylinder head was overhauled. Your mention of fuel-pressure related issue reminds of what the mechanic claimed he noted in his last efforts on the engine: that the nozzle is pumping excess fuel into the engine. I can't get my hands on a live data scan tool for now. And yes, the check engine light has been staying on with engine running since not too long ago. Thanks.
Was this
answer
helpful?
Yes
No
Sunday, August 15th, 2021 AT 4:45 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

If the engine is getting too much fuel, that is the problem. Since the light is on, I do suggest having the computer scanned. I'm not sure where you are located, but most parts stores will do it free of charge.

Next, we need to check fuel pressure. Here is a link that shows in general how it's done:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

Pic 1 below shows the manufacturer's specifications for fuel pressure. The remaining pics show how to test pressure specific to your vehicle. You will need a fuel pressure gauge, but most parts stores will lend one to you.

If the pressure is too high, the fuel pressure regulator is likely bad. It is located in the fuel tank. The very last pic below shows its location.

I do suggest having the computer scanned so we know exactly what diagnostic trouble codes are stored. If you do, let me know what codes are found.

Let me know if I can help or if you have other questions.

Take care,

Joe

See pics below.
Was this
answer
helpful?
Yes
No
Sunday, August 15th, 2021 AT 8:31 PM
Tiny
BAMMI
  • MEMBER
Hello Joe,

Been able to get a technician to do a computer scanning. Below are the results. Also attached here is the snapshot of the result from the computer screen of the technician.

HO2S Heater Control Circuit (Bank1 Sensor1) P0030

Evaporative Emission System Purge Control valve Circuit P0443

Mass or Volume Airflow 'A' Circuit High P0103

Engine Coolant Temperature Sensor1 Circuit High P0118
Was this
answer
helpful?
Yes
No
Monday, August 16th, 2021 AT 2:52 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

There are a couple of things there that can cause the issue. The mass airflow sensor (MAF) is higher than 4.5v which is beyond where it should be. That can certainly cause an issue. Also, the coolant temp sensor is exactly the same. The voltage is higher than 4.5v. And also can cause the problem.

Here is what needs to be done: Since they are both showing high voltage (MAF and ECT), I don't think the sensors are bad. Instead, I have a feeling there is a short to power.

The first thing I would check is the reference voltage to both. Each should have a 5v reference from the PCM. I suspect they will be a good bit higher. If they are, then the tech needs to determine where the short is located.

Do you know if that has been checked?

Let me know.

Joe
Was this
answer
helpful?
Yes
No
Monday, August 16th, 2021 AT 8:40 PM
Tiny
BAMMI
  • MEMBER
Thanks.
Tech said short is from the ECU.
Was this
answer
helpful?
Yes
No
Tuesday, August 17th, 2021 AT 6:19 PM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

That will do it. Something internal must have shorted. If you have a chance, let me know if that takes care of your problem.

Take care,

Joe
Was this
answer
helpful?
Yes
No
Tuesday, August 17th, 2021 AT 8:12 PM
Tiny
BAMMI
  • MEMBER
Kudos, Joe, you've been quite helpful. But can whatever the thing internal be fixed? Besides the fact that it's not easy to come by, I'm afraid I may not be able to afford a new ECU now. By the way, is this ECU same as brainbox?
Please recommend steps to take if this internal shorting can be repaired. Thanks.
Was this
answer
helpful?
Yes
No
Wednesday, August 18th, 2021 AT 1:11 AM
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

The ECU, if bad, usually would need to be sent out to be repaired. However, there are sites you can purchase a rebuilt one online. I purchased one from a place called car computer exchange for my own vehicle. It was already programmed based on the info I sent. It was under $200.00 and basically, all I did was remove my old one and install what they sent and it worked perfectly. They already had it programmed so there was no need for me to update or change anything. You may consider checking if one is available for your vehicle. I can help you replace it yourself if you would like.

Also, please understand that the site I mentioned is not affiliated in any way with the site or myself. I just had a good experience with them. I'm not trying to sell anything. LOL

And yes, the ECU is sometimes referred to as the main computer. An ECU is a small electronic control unit. Basically, it controls different functions in the vehicle. There are different control units on today's vehicles. When the mechanic mentioned ECU, I suspect is referring to the PCM or powertrain control module which could be responsible for the problems you are experiencing.

You take care of yourself and let me know if there is anything I can do to help you.

Joe
Was this
answer
helpful?
Yes
No
Wednesday, August 18th, 2021 AT 1:23 PM

Please login or register to post a reply.

Sponsored links