Surging, bucking, lungin, taking off/low speed, mostly when A/C is on

Tiny
GENESIS88
  • MEMBER
  • 2003 MERCEDES BENZ E320
  • 3.2L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 125,440 MILES
Hello, lately my car has been acting up. It will buck and surge when going very slow or taking off. Plus acceleration is poor when it happens. Also car will start shaking but only in drive. It doesn't happen all the time. The other issues I listed happens mostly with A/C on. Best comparison is to a new person driving stick when you don't give enough gas. I haven't checked plugs wires, coils or fuel pump. There aren't any codes except for a pending o2 sensor. The car went into limp mode 2 times in one month but only last few seconds. I replaced my 13 pin adapter and did new fluid. I pulled a p0715 code so I felt I'll try that first. I have a feeling my conductor plate is bad and will be doing that too. But I doubt that would cause this issue especially since it really only happens with A/C on. With A/C off it happens on occasion but it's not bad. Over all car seems to drive fine.
Friday, August 6th, 2021 AT 12:17 PM

3 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
The only difference between the A/C on and off is the engagement of the clutch which adds additional load to the engine.

So this means with this additional load either there is an engine system that is weak and cannot handle the load like the fuel pressure or ignition.

Or the compressor is adding too much load for the engine to handle.

So what I would do is check the fuel pressure as that is the likely other cause of this as it is unlikely to be weak spark. If that were the case, it would be more common.

Here is a guide that will help with this:

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

Also, here is a guide that will get us started on this issue:

https://www.2carpros.com/articles/engine-surges

I don't think the code is related as that is a speed sensor issue but did you clear it and it come back after this happened again?

If it did then it is related and we need to chase it down.

I attached some info on this code below if that is the case.

Let's start with this info and let us know what the fuel pressure is when this happens and we can go from there. If this is transmission related then that code should come back.

Thanks
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Sunday, August 8th, 2021 AT 9:55 AM
Tiny
GENESIS88
  • MEMBER
  • 140 POSTS
Sorry I didn't respond. Very busy but fix it back in August. It was the conductor plate. Replaced it and runs great, not a single issue since.
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Friday, October 29th, 2021 AT 4:30 PM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Oh wow. So, the added torque of the AC must have been just enough. I didn't expect that, but it makes perfect sense now.

Thanks for coming back and updating us as this will surely help someone in the future.

Thanks, and please come back in the future.
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Saturday, October 30th, 2021 AT 7:57 AM

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