Hi all, hope everyone's well. I'm trying to find what the standard max boost pressure should be on my AMF. I've logged via OBD and finding around 12.7 psi in 1st gear and 10 psi in the rest. This seems pretty low to me. I'm wondering what it should be but also if it reads the pressure directly from a boost sensor? 

 

Thanks 

 

Ben

The pressure information comes from the MAP sensor.

Given that your car makes so little power then one bar of boost sounds about right.

3 hours ago, sepulchrave said:

The pressure information comes from the MAP sensor.

Given that your car makes so little power then one bar of boost sounds about right.

Thank you, its only 0.87 bar in 1st gear dropping to 0.68 thereafter. Even given its limited power output this just seems low to me. There must be somewhere I can find what it should be just not sure where. 

10 minutes ago, Bengunn007 said:

Thank you, its only 0.87 bar in 1st gear dropping to 0.68 thereafter. Even given its limited power output this just seems low to me. There must be somewhere I can find what it should be just not sure where. 

 

The ECU would throw a fault code if actual boost did not match requested.

 

Get it remapped if you want more but please bear in mind that it's a tiny turbo.

It is a small turbo however it still seems capable of pushing 1.2-1.3 bar if my research is correct. 

I'll not look to getting a remap until I can confirm its boosting correctly as it stands. I'm going to check the boost control solenoid operation I think.

As I said, the ECU has full control of boost so if anything were amiss there would be a fault code, the MAP sensor is very accurate.

4 hours ago, Bengunn007 said:

It is a small turbo however it still seems capable of pushing 1.2-1.3 bar if my research is correct. 

I'll not look to getting a remap until I can confirm its boosting correctly as it stands. I'm going to check the boost control solenoid operation I think.

Are you using torque? Is it set to read from the map sensor? I know it can be set to read for maf or map signal for boost. Torque works well to read boost in my Monte Carlo but with my mk1 fabia (which is an sdi mind) it reads 36 psi at idle!

A 1.4 tdi would not have a big turbo in anycase and a manufacturer wouldnt set it to run max boost from the factory. Odds are if its running good then its probably fine.

I did some testing with my 1.6tdi fabia. From 50 to 80 mph in 4th it peaked at 14.6 psi and trailed off to around 13.3 psi during this run. My car is a 105 hp model for reference. Again this was using torque and I have it set to calculate boost from the MAF ( as thats what my car has). More than likely your cars fine. You could run some premium diesel through it and see if it makes a difference.

On 24/02/2021 at 18:26, DieselMonte said:

Are you using torque? Is it set to read from the map sensor? I know it can be set to read for maf or map signal for boost. Torque works well to read boost in my Monte Carlo but with my mk1 fabia (which is an sdi mind) it reads 36 psi at idle!

A 1.4 tdi would not have a big turbo in anycase and a manufacturer wouldnt set it to run max boost from the factory. Odds are if its running good then its probably fine.

I guess it would struggle to read boost on your sdi given its non-turbo? 

1 hour ago, Bengunn007 said:

I guess it would struggle to read boost on your sdi given its non-turbo? 

Yep! thats why I felt I should mention it. It goes back to 0 psi when I'm actually driving so I can only guess its reading vacuum but thats a stretch. It seems to read accurate for my mk2 though so ymmv. I usually just have it open for water temp, intake temp and voltage anyway. I just have the boost gauge there to fill up the screen and only use it as a guide and as a heads up for any trouble codes. What miles are on your car? If it has high miles and wasnt driven very hard it could either be a worn turbo or it could just need some dipetane and some very hard driving. Diesels do tend to like being driven hard every now and then. If your car is driving fine and isnt smoking much then you're most likely fine.

Yeah every now and then it will just seem a little more sluggish than usual, no codes but a noticeable lack of power. It still boosts just not as strong. I've just cleaned the egr and blocked off the vacuum and took it for a 20 minute thrashing and it boosted fine the whole time. It seems to hold torque at a little over 10psi but can initially peak at just over 13psi. I'll drive it for a week or so and see if I get the lack of power at any point, if I don't I'll put it down to the egr and book my remap in.

Edited 28 February, 20215 yr by Bengunn007

Diesel engines don't make a vacuum, that's why there's a special pump to make it instead.

Torque isn't reliable enough for diagnosis purposes so it's safe to ignore it, it's a solution in search of a problem.

Just now, sepulchrave said:

Diesel engines don't make a vacuum, that's why there's a special pump to make it instead.

Torque isn't reliable enough for diagnosis purposes so it's safe to ignore it, it's a solution in search of a problem.

I figured it was a stretch, don't know what the sensor its scanning from is doing then. Should probably make a second set of gauges for it then.