360 Anti-Evap leak diagnosis

As a diagnostic test, would it be acceptable to plug the intake manifold where the evap hoses connect? If so, should the disconnected vacuum lines be plugged also?

 

Are you looking for intake leaks or do you have a fault code for the evap system?

If you’re running the engine up to temperature, I don’t think I’d want fuel vapour drifting into the engine bay, but if you’re just doing intake smoke checks on a cold engine, that sounds relatively safe.

 

The goal would be to run the engine.

As far as “…vapor drifting…,” seems that plugging both ends would take care of that, no?

 

In theory, the only thing you would need to disconnect would be the purge solenoid valve electrical connectors and that would stop the vapours going into the intake. I assume there is some system which would vent the vapours to atmosphere if the pressure got too high in the tank.

Or do you think you have a leak in the evap system?

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Sorry.... just re-read the title...

 

How does plugging those hoses lead to a diagnosis?

 

Are you getting codes for an evap system leak... or are you more worried about the engine getting unmetered air from somewhere (affecting fuel ratios)?

I see there are some variations in the USA evap system (basically 1999 vs 2000 onwards). The later models have a pressure sensor on one of the tanks, allowing better fault detection. I assume the sensor is used when the vent/purge valves are in certain configurations.

 

This video answered most of my questions on the evap system:



The 360 doesn't have the diagnostic pump (the 430 does).

If you're not getting evap codes, then it's unlikely you have a leak.

 

Will provide my thoughts on diagnosis, but first do we agree that a leak in the anti-evap lines could lead to a change in lambda?

if that’s an incorrect assumption, no sense in going further.

 

Not likely. Motronic detects leaks far smaller than the engine will ever notice.

There is one reliable test for eveap leaks. A smoke machine.
9 times out of ten it is the seals at the roll over valves. Sometimes it is the electro vent valve at the cannister.

 

Your feedback is much appreciated.

Thanks.

 

Ian,

Thanks for the video; will take a look.

 

I’m writing up notes while trying to solve a fuel trim problem with my 360; I’m guessing at a number of things.

Any chance you would have a look? It’s written in outline form.

Feedback or direction to other documents would be appreciated.

Thanks for your consideration.