Engine knocks/shakes and car turns off?

Tiny
DILER
  • MEMBER
  • 2018 VOLKSWAGEN TIGUAN
  • 2.0L
  • 4 CYL
  • TURBO
  • 4WD
  • AUTOMATIC
  • 60,000 MILES
Hello, I have the vehicle listed above TSI 2.0t, recently I ran out of gas and on my way to get gas the car ran out and shook and turned off, I put some gas in it and then the car started and it started shaking and the RPMs would come down and up and suddenly the car would turn off. I called a towing truck and I took the car to a mechanic were he said the problem was a cracked piston due to the dirty debris from no gas and it broke the piston (i wasn’t there when he got the pistons out, he just showed me a “cracked piston”), we opened the engine and got it out and replaced the piston, after just two days the same thing happened again, I will start the car after 10 seconds the car engine will shake and make knocking noises and the rpm will go down and up and the car will turn off, I heard somewhere it might be a MAF sensor issue, the mechanic didn’t mention it, but whenever I unplug the sensor the car works fine it doesn’t shake o knock or turn off, Can you please help me?
Tuesday, August 20th, 2024 AT 4:38 PM

10 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

The knocking has me concerned. Is it possible for you to record it and upload it for me to hear?

As far as the MAF is concerned, when it is disconnected, the PCM performs in a predetermined setting from the factory, so the engine keeps running. The sensor could certainly be faulty.

Have you checked to see if there are any diagnostic trouble codes stored? If not, have the vehicle scanned at a local parts store. Most do it free of charge. Also, here is a link that shows how the entire system can be scanned:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Also, MAF sensors can be serviced. You could try that as well. Make sure you get a cleaner specifically designed for cleaning a MAF sensor.

Here is a link that explains in general how it is done:

https://www.2carpros.com/articles/mass-air-flow-service

Let me know.

Joe
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Tuesday, August 20th, 2024 AT 7:10 PM
Tiny
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It’s not certainly knocking, I don’t know how to explain it, the RPM just goes down and up and the engine makes that noise as if it’s shaking, last time it was at the mechanic this code showed up after the car was done but I don’t know what it means.
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Tuesday, August 20th, 2024 AT 7:15 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
The code is a generic code. The OBD2 standard identifies it as a Databus error value received. This error can appear from any of the several control modules, and it can be an initiating fault. In other words, something other may have inadvertently set this code.

If the engine isn't truly knocking, we need to try having the entire CAN bus scanned. CAN stands for controller area network.

Basically, all the different modules are tied together via a few wires. This type of scan (attached above) will retrieve codes regardless of the module storing them.

Let me know your thoughts.

Joe
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Tuesday, August 20th, 2024 AT 7:24 PM
Tiny
DILER
  • MEMBER
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I’m concerned if it’s related to the engine because I already had it opened apart and changed the piston I don’t know what else needs to be done, I hope it’s a MAF issue or another wiring/sensor issue and not the actual engine, I will have it checked at the original mechanic and see what he says, I’ll give an update.
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Tuesday, August 20th, 2024 AT 7:28 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

Sounds like a plan. Let me know. I'm interested in knowing. However, if it runs well with the MAF disconnected, it sounds like that could be the issue. Make sure the connector is good and none of the connector pins are bent or damaged.

Let me know.

Take care.

Joe
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Tuesday, August 20th, 2024 AT 7:35 PM
Tiny
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Update:
I went to four different mechanics no one saw any problems all scanners were clean, they said the problem isn’t the MAF there was absolutely nothing, we even put smoke in the pipe to see if there’s any leaks there were none, at the end the original mechanic disconnected the oxygen sensor and told me to drive for a couple of days without it to see if the issue reoccurs, if it doesn’t then that’s probably what’s causing it, if it occurs again then it’s probably something else he didn’t mention anything in particular.
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Wednesday, August 21st, 2024 AT 3:29 AM
Tiny
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Update 2:
I drove for 2 hours and it happened again, when I disconnect the MAF sensor and it works I’m still concerned that it’s the MAF sensor it might be a little dirty.
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Wednesday, August 21st, 2024 AT 7:58 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

Have you tried cleaning the MAF sensor? If not, that is an inexpensive test. It could help.

Here is a link that explains how it's done:

https://www.2carpros.com/articles/mass-air-flow-service

Let me know.

Joe
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Wednesday, August 21st, 2024 AT 7:21 PM
Tiny
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Update 3:
Unfortunately it wasn’t the MAF sensor, we replaced it with another and at first it was well, then after 5 hours of the car being parked and cooled down, I turned the engine ON and the same thing happened, here is a video on what’s happening to it, look closely at the RPM, I’m not pressing on anything, and if I switch the gear from P to D the car turns off.
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Thursday, August 22nd, 2024 AT 3:39 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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Hi,

That isn't good. I watched the video and saw the tachometer. It reminds me of an idle air control issue, but that should have set a code.

Have you checked to make sure the fuel pressure is consistent?

Joe
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Friday, August 23rd, 2024 AT 9:10 PM

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