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MAF sensor voltages?

Tiny
GéZA KOVáCS
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New glow plugs were installed a year ago. Even after that it started with difficulty. They were replaced due to difficult starting. I removed them a few months ago. They glowed within 10 seconds. I don't remember any resistance. I'll check again tomorrow. The glow indicator lights up for several seconds even in such good weather, the glow is so important.

Thanks,

Cheers, Géza
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Wednesday, September 6th, 2023 AT 7:46 AM
Tiny
BORIS K
  • MECHANIC
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Hello,

With high ambient temperatures glow plugs become less important.
Depending on engine condition, compression, glow plug activation is still important.
The other thing you could try is to spray some Quick or Easy start into the intake and see if the starting behavior changes.
Also, as the engine fuel supply relies purely on vacuum suction to get the fuel from the tank to the high-pressure pump, you could try and bypass the fuel supply system.
Install a small, 2-5L, container filled with clean diesel at the high-pressure pump and run a clean rubber tube directly to the pump inlet. The pump will then suck directly from this container. If the starting improves then this would prove that we are having a possible vacuum leak from the supply side.
Have you carried out an injector leak off test?

How to:
https://youtu.be/U2ek-FwoT5w?si=QOPQIllW9q1vMcwY

Cheers, Boris
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Wednesday, September 6th, 2023 AT 8:58 AM
Tiny
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One of the injectors is new, the other 3 have been tested for a few thousand km, with a report, and the high-pressure pump has been refurbished. The fuel pipes in the engine compartment are new, as are the connectors and seals.
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Wednesday, September 6th, 2023 AT 9:17 AM
Tiny
BORIS K
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Hello,

I am just giving possible causes of hard starting for a diesel engine.
Suggestions to check certain components, if you are certain that these are in good condition then do not follow my suggestions.

A leak off test for the injectors will show if any require replacing, it is something you could do yourself, the equipment is inexpensive.

Cheers, Boris
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Wednesday, September 6th, 2023 AT 9:27 AM
Tiny
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Is it possible that there is not enough compression in the cylinders? Due to carbon deposits, compression is lost at the valve. Can it start hard because of this? Thanks

Cheers Géza
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Thursday, September 7th, 2023 AT 12:37 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 47,513 POSTS
Yes, this is possible especially if you have an intake valve leaking is can mess with the MAF readings.

Here is a guide to help you:

https://www.2carpros.com/articles/how-to-test-engine-compression

Please go over this guide and get back to us.
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Saturday, September 9th, 2023 AT 9:29 AM
Tiny
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Hi,

Now I had time to measure the compression. And it seems quite little.12-13( 180 PSI) bar in each cylinder. How can it be determined that the rings are worn or that the valves are not closing properly? Does the cylinder head always have to be ground flat when disassembling?
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Sunday, September 17th, 2023 AT 10:00 AM
Tiny
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It sounds like this when the engine is warm. I hear a little chirping in the background.
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Monday, September 18th, 2023 AT 3:31 AM
Tiny
BORIS K
  • MECHANIC
  • 795 POSTS
Hello,

12-13 bar compression is very low for a diesel, expect to see around 20bar normally.
That blowing/chirping noise could be caused by an injector not seating properly.
To check if compression loss is caused by rings or valves there is a quick test you can perform.
With either injector or glow plugs removed squirt some engine oil into each cylinder, crank the engine a few times to spread the oil in the combustion chambers. Next carry out another compression test. This is called a "wet" compression test
If piston rings are leaking the oil will seal off the rings and improve the compression, if valves are leaking then the compression will remain the same or slightly higher

If the compression is equally low on all 4 cylinders, I would suspect a possible valve timing issue rather than a mechanical failure in a combustion chamber.

A good video:
https://youtu.be/8peTMD1RMF0?si=MqB-o-yYHdkC8W7_

Cheers, Boris
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Monday, September 18th, 2023 AT 5:36 AM
Tiny
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I injected 12 ml of oil into each cylinder and measured the compression with the engine at operating temperature.
1. Cylinder: 15 bar, 220 PSI.
2nd cylinder: 17 bar, 245 PSI.
3rd cylinder: 17 bar, 250 PSI.
4th cylinder: 17bar, 250 PSI.

Here, at 30-degree water, I can't hear the small chirping in the background, only when the engine is at operating temperature.
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Monday, September 18th, 2023 AT 10:16 AM
Tiny
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A question. When I unscrew the coolant temperature sensor, shouldn't liquid flow from its place? Is this normal? In my other car (Focus mk2.5 2.0 petrol) it was leaking when I took out this sensor.
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Tuesday, September 19th, 2023 AT 5:59 AM

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