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Normal timing advance at idle

Tiny
CLASSIC1968
  • MEMBER
  • 2009 MERCEDES BENZ E350
  • 3.5L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 78,000 MILES
Hi!

My car has the M272 engine (3.5L V6), and at idle (around 650RPMs) the Timing Advance is between 12.50 and 18.50 in a 30 sec. Lapse. MAF air flow rate is 3.20 and 3.41 grs/sec. Throttle position is 13.73%, MAP is 32 kPa.

Is this normal?

The scan doesn't show any DTC codes.

The car hesitates/jerks a little after changing from 2nd to 3rd gear.

Thank you!
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Thursday, February 24th, 2022 AT 6:29 PM

7 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

Based on the manual, what you listed seems to be within the manufacturer's specifications. When you feel hesitation, is there any notice of a power loss prior? Also, when you scanned the computer, did you use a scanner capable of reading all codes (can-bus)?

CAN stands for controller area network. If there is a code stored in any of the modules, this will identify the code. If you are using a basic scan tool, most only read engine codes.

Here is a link explaining how it's done:

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

Also, the idea you don't feel it until the 2/3 shift, there could be a low fuel pressure issue. Let me know if you have checked fuel pressure.

I will watch for your reply.

Take care,

Joe
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Thursday, February 24th, 2022 AT 8:32 PM
Tiny
CLASSIC1968
  • MEMBER
  • 4 POSTS
Hi Joe!

I'm using iOS app inCarDoc Pro with an ELM327 v1.5 ODB II Wi-Fi interface. The connection protocol says 6-ISO-15765-4 CAN.

The jerking is 1-2 seconds after I feel the transmission made the change from 2nd to 3rd. Between 1600 - 1900 RPM.

On idle, Fuel System bank 1 shows -0.75%, bank 2 shows -0.43%.

On a short test (where the problem also appeared), I got:
Short term fuel % trim Bank 1: Min. -16.41 Max. 7.03 Avg: 4.41
Short term fuel % trim Bank 2: Min. -14.06 Max. 5.47 Avg: -4.19
RPM: Min. 524 Max. 1,806 Avg. 1,151.04
Fuel Level Input: Min. 40 Max. 41.18 Avg: 40.97
Engine Load: Min: 16.08 Max. 49.02 Avg: 30.58

I cannot find a Fuel Pressure parameter on the scanner.

Besides changing the MAF for a new one, I also replaced the spark plugs with new ones (bought from the MB dealer).

Thank you again!
Guillermo
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Friday, February 25th, 2022 AT 11:50 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

During the "Short Test", was the engine at operating temps? The fuel trims are indicating a rich mixture. The two different readings above tell me when they were done. For example, one was at operating temperature and the other wasn't.

Also, can you drive the vehicle with the scanner connected to see if there is anything that jumps out when it happens? For example, do the oxygen sensors drop to 0v, or does the MAF signal jump?

Since there are 0 codes and it sounds like an electrical connection issue, I have a feeling we will need to identify it when it happens. Maybe you could have someone drive while you watch the scanner.

Let me know.

Joe
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Friday, February 25th, 2022 AT 6:50 PM
Tiny
CLASSIC1968
  • MEMBER
  • 4 POSTS
Hi Joe. The cooling temperature at the moment of those readings was around 90C (194F).

They were taken in a 30 seconds period drive, from still start to complete stop.

I will find someone who can drive the car while I watch the scanner as you suggested.

Keep you posted.

Thank You!
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Saturday, February 26th, 2022 AT 8:17 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

Thanks for the update. When you are watching the scanner, stay focused on it because the issue could be difficult to catch.

Take care of yourself,

Joe
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Saturday, February 26th, 2022 AT 7:01 PM
Tiny
CLASSIC1968
  • MEMBER
  • 4 POSTS
Hi Joe,

I'm sending you the scans, indicating the moment of the hesitation/jerking.

Temp: 81C
Green line: RPM
Orange line: Fuel level Input (%)
Blue line: Short term fuel % trim - Bank 1
Yellow line: Short term fuel % trim - Bank 2
Red line: Engine load (%)

The jerking is more notorious when the AC is on.

I drove the car around the neighborhood for around 7-10 minutes.

Still no DTCs. On the scanner.

I hope this can help a little.

Thank you again!
Guillermo
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Wednesday, March 2nd, 2022 AT 4:55 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

Is the circled section where you noticed the issue? I ask because I'm not seeing anything standing out.

Let me know. Also, sorry for the delay in responding.

Joe
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Thursday, March 3rd, 2022 AT 5:48 PM

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