Finding Vacuum leaks - Toyota Nation Forum : Toyota Car and Truck Forums

toyotadriftr · 08-17-2009, 11:24 AM

Hey guys I think my car has a vacuum leak but I don't have an Evap Smoke machine. Is there an easy way to find the leaks that I could do at home?

Pineapple · 08-17-2009, 02:08 PM

Why do you think it got vaccum leak?

Get a can or 2 of throttle body cleaner. With engine idling, spray around intake manifold and vaccum hose. Engine will try to stall when you get to the leak.

toyotadriftr · 08-17-2009, 03:02 PM

I thought it was a vacuum leak just because every time I research into the behaviors it's having i get either vacuum leak or EGR problems. While I'm driving the car cuts out and drops about 300-500 RPMs then goes right back to normal for a little while. You can feel a good jolt in the car when it does it.

Any ideas? It used to only do it once I was doing 70 MPH+ but it's been doing it lately when I'm doing any one speed for more than 3 or 4 minutes

Pineapple · 08-17-2009, 03:23 PM

Vaccum leak will not cause drop in RPM. It'll cause high idle.
Does it cut out when you step on the gas to accelerate? Or cut out when maintaining speed?

toyotadriftr · 08-17-2009, 03:28 PM

K well it does have a high idle so I will have to figure that out but for now back to the subject.. >_<

It only cuts out while trying to maintain speed. When I hit the accelerator it goes away if it is doing it

Pineapple · 08-17-2009, 03:53 PM

First try to clean the ICV - idle control valve. Remove intake so you can look into throttle body. You'll see the butterfly valve inside. Right below it is a few rectangular holes. Spray throttle cleaner in there. Let it seat for a minute. Spray some more, wait. Repeat until it doesn't come out brown. Clean the throttle body while you're at it.
Get a timing light and check ignition timing.

toyotadriftr · 08-17-2009, 06:16 PM

Ok.. Sounds like a plan. I will try it and be back with results.

Thanks for the information

Pineapple · 08-18-2009, 10:00 AM

Oh you might have a idle adjust screw on the throttle body. Its on top covered by a round black rubber plug. Only 90-91 has it.

toyotadriftr · 08-18-2009, 11:55 AM

I wish it was the idle screw. That was the first thing I looked at but the screw is as low as it will go and it still idles at 12-1400. So my bet is the vacuum leak. And I've been thinking about the cutting out and I'm leaning closer to the timing being off on it