Feels like a misfire under load 🤷****♂️

[ike84]

Wait, everyone hold up a minute...

Over the last few days, a clear understanding of the vacuum system components has been bestowed upon me...

That check valve lads to the half of the vac system that controls the SAI function and the resonance flapper.

This means two things -

1 - you have a MASSIVE vac leak if that is not hooked up properly

2 - you resonance flapper is not functional

Both of these things will cause problems while running. Especially the vac leak - stomp on the gas, get a huge amount of unmetered air, run super lean, detonation...which is your problem right?

That is, unless I've totally missed something

Sent from my SM-G970U1 using Tapatalk

[blue62]

Originally Posted by ike84

Wait, everyone hold up a minute...

Over the last few days, a clear understanding of the vacuum system components has been bestowed upon me...

That check valve lads to the half of the vac system that controls the SAI function and the resonance flapper.

This means two things -

1 - you have a MASSIVE vac leak if that is not hooked up properly

2 - you resonance flapper is not functional

Both of these things will cause problems while running. Especially the vac leak - stomp on the gas, get a huge amount of unmetered air, run super lean, detonation...which is your problem right?

That is, unless I've totally missed something

Sent from my SM-G970U1 using Tapatalk

You are correct with some caveat's.
This is not a North American version. it is a European version boxster
So no SAI system
What he is hooking into is the EVAP system.
At least that is what it appears to be.
The proper way to test engine intake vacuum is to disconnect the EVAP and SAI systems.
Then you test out the EVAP and SAI systems seperately.

So I am trying to have him run two tests one with EVAP system connected via the "TEE Fitting" and a second test with the EVAP system disconnected.
So depending on what the readings are and what the action of the gauge needle is (if any) and any differences from one test to the other(if any).
I will know what to have him test next.
If he has vacuum issues maybe I can point him in the right direction.
We should be able to isolate them to a system. SAI EVAP or Intake

If his vacuum tests are good then there are a few very simple tests he can do with the Duarametric that will tell me if his MAF sensor, potentometer, (gas pedal) and throttle position sensors are working correctly.

If all the above test out good then I would have him move to the fuel system.
Starting with a fuel pressure test at the fuel rail.

Simplest things first:
Go step by step from simplest to most complex
one system at a time.
The simplest system to start with considering his issue is the intake system.

The greatest amount of unmetered air from a vacuum leak is entering the system "at idle".
When you stomp on the gas as you say, the unmetered portion of the air entering the system becomes less and less a part of the whole.
So typically when you have an intake vacuum leak your idle is a little higher because it makes the fuel/air mixture lean and or the idle is lumpy or hunting.
When you give it gas the engine smooths out because the unmeterd air is becoming less and less a part of the entire amout of air entering the system.
If he was running super lean and creating detonation (as you suspect) he should be getting a flashing CEL and some DTC codes. misfire codes something He has none.
So I am trying to go with "my diagnostic procedure" to help him find the problem.
So

[colacharlie]

Originally Posted by blue62

You are correct with some caveat's.
This is not a North American version. it is a European version boxster
So no SAI system
What he is hooking into is the EVAP system.
At least that is what it appears to be.
The proper way to test engine intake vacuum is to disconnect the EVAP and SAI systems.
Then you test out the EVAP and SAI systems seperately.

So I am trying to have him run two tests one with EVAP system connected via the "TEE Fitting" and a second test with the EVAP system disconnected.
So depending on what the readings are and what the action of the gauge needle is (if any) and any differences from one test to the other(if any).
I will know what to have him test next.
If he has vacuum issues maybe I can point him in the right direction.
We should be able to isolate them to a system. SAI EVAP or Intake

If his vacuum tests are good then there are a few very simple tests he can do with the Duarametric that will tell me if his MAF sensor, potentometer, (gas pedal) and throttle position sensors are working correctly.

If all the above test out good then I would have him move to the fuel system.
Starting with a fuel pressure test at the fuel rail.

Simplest things first:
Go step by step from simplest to most complex
one system at a time.
The simplest system to start with considering his issue is the intake system.

The greatest amount of unmetered air from a vacuum leak is entering the system "at idle".
When you stomp on the gas as you say, the unmetered portion of the air entering the system becomes less and less a part of the whole.
So typically when you have an intake vacuum leak your idle is a little higher because it makes the fuel/air mixture lean and or the idle is lumpy or hunting.
When you give it gas the engine smooths out because the unmeterd air is becoming less and less a part of the entire amout of air entering the system.
If he was running super lean and creating detonation (as you suspect) he should be getting a flashing CEL and some DTC codes. misfire codes something He has none.
So I am trying to go with "my diagnostic procedure" to help him find the problem.
So

Hi again one and all.

I’ll redo the test In the way You’ve suggested but here’s what I found yesterday …

https://youtu.be/LBDL8U04HRE

https://youtu.be/ra3oX95adVM

[blue62]

The first thing you need is a proper vacuum gauge.
A mighty vac like your using is not ideal for for the type of tests we are trying to do.
Google automotive vacuum test gauges or look up some you tube videos on automotive vacuum testing. Then you will see the type of gauge I am talking about.

Then do the vacuum test with it hooked up the way you had it in your pictures.
Then run the test again but disconnect the check valve from the TEE fitting and run the test again.

I need readings and needle action from both tests..

The P1128 code is for a lean condition on bank 1
So did the Check engine light come on???

Lean conditions can be caused from many things.
Bad sensor like the MAF
Bad O2 sensors
Exhaust leaks
Vacuum leaks
valve train issues.
Fuel delivery issues.

The reason I had you recalibrate the E-gas
The reason I am having you do the vacuum tests
also the reason I had you unplug the MAF
all the things I am having you do is how I would go about trying to finding the cause of the problem.

Simplest to most complex step by step one system at a time.