Huge Vacuum Leak and MPG Loss – Need Help

[Meridivs]

One of the ’92 Pontiac Trans Sports (3.1L V6 engine) had developed a huge thirst – the fuel consumption had doubled along with a serious loss of power. All ignition components – distributor cap, rotor, spark plug wires and oxygen sensor are new ACDelco’s.

ECM is not throwing-up any fault codes but we suspect a vacuum leak since this engine runs better with the air intake covered-up almost completely.

Is there any way to trace and fix this kind of issue? Does anyone have a vacuum diagram for this car – I couldn’t seem to find it in the GM Service Manual… How would you suggest we proceed?

Topic

[Coty Miller]

All vacuum hoses are connected to a single spot that is the intake manifold, you can trace them from there…

Eric and scotty kilmer both have videos on finding a vacuum leak.

One from Eric:

[URL]http://www.youtube.com/watch?v=9CPqbaSgcok[/URL]

And scotty Kilmer:

[URL]http://www.youtube.com/watch?v=zMok2y05jNE[/URL]

[college man]

Does the car have a MAF? if so try and clean it.

[Meridivs]

We have just a basic MAP sensor on this type of engine, I will try and disconnect that/put the engine back in the Open Loop mode to see if that changes anything.

Tried spraying carb cleaner over the engine at a local repair shop – that didn’t take us anywhere. Giving the fire hazard I would rule-out that method completely.

The Scotty-Smoke method seems more effective but we don’t like smoking cigars that much so we need to improvise a machine like this Basic Smoke Machine Video

[Bill]

It’s possible the catalytic converter is partially plugged.

[spelunkerd]

That smoke machine vid is worth a look — great idea.

[Author]

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