Surging and low power when cold

Tiny
BOB ADONIZIO
  • MEMBER
  • 1989 MERCEDES BENZ 190D
  • 250,000 MILES
When I start out in the morning, it surges when driving up a hill. It also seems to have a loss of power. The air cleaner is clean. It goes wa, wa, wa up a hill.
Wednesday, April 6th, 2022 AT 7:53 AM

8 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Surging is normally an air intake issue or vacuum leak, but this is not limited to this. So, let's start with this guide which covers surging, and we can start working our way through this:

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

What I would also suggest we do is monitor the fuel pressure when this is happening. Here is a guide that will help with this as well:

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

I assume that running through these two things, we will either find the issue or get on the right path. So please let me know what questions you have with this and we can figure out next steps.

Thanks
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Wednesday, April 6th, 2022 AT 4:00 PM
Tiny
BOB ADONIZIO
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Thank you. The car is in PA. I am in S.C. Now. I will check your suggestions when I get back to PA.
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Thursday, April 7th, 2022 AT 4:24 AM
Tiny
KASEKENNY
  • MECHANIC
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Not a problem. Thanks for letting us know. This link will remain active for however long it takes to get back to us.

Thanks for the update.
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Thursday, April 7th, 2022 AT 10:16 AM
Tiny
BOB ADONIZIO
  • MEMBER
  • 4 POSTS
My car is a 1989 Mercedes 190d. I do not think it has an output for a code reader. I'm not sure if it has a mass air flow sensor or a manifold pressure sensor.
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Thursday, April 7th, 2022 AT 11:16 AM
Tiny
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Correct. Your vehicle is what is known as OBD I and does not have the port under the dash. That started about 1995.

Also, you have an air flow sensor with the intake temperature sensor so this is traditionally called a mass air flow sensor.

Take a look at the info attached for more detail.

Thanks
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Thursday, April 7th, 2022 AT 7:17 PM
Tiny
BOB ADONIZIO
  • MEMBER
  • 4 POSTS
Thank you for getting back. What should I have my mechanic check when I get back to PA?
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Friday, April 8th, 2022 AT 4:33 AM
Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
I would focus on two things to see if that points us in a clear direction. First, fuel pressure and then check for vacuum leaks using this technique.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Based on this we should be able to find something.
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Friday, April 8th, 2022 AT 12:42 PM
Tiny
BOB ADONIZIO
  • MEMBER
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Thank you.
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Friday, April 8th, 2022 AT 12:46 PM

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