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1992 Toyota Celica ST w/1.6L engine

Hello.

I could really use some help. I lost power and the car wouldn't start. I checked the computer and the only error code was the vacuum sensor. If I unplug the vacuum sensor on the firewall, the engine will at least start but not rev past 1,200 RPM. I now have a new $360 dollar Toyota sensor and the car still will not run.

During my testing with the sensor unplugged, I then noticed the exhaust down pipe was glowing red and there was air blowing out of the vacuum lines vs. sucking air in.

I then thought that maybe I had blockage in my exhaust. I removed the exhaust at the Catalytic converter and it seems to run easier but I still have air coming out of the vacuum lines (the line going to the pressure sensor & at the valve cover). Before taking the exhaust off, I could only get the RPM up to 1,000 without the sensor. With the exhaust off, I can get the RPM up to 1,200.

At this point, if I plug in the vacuum sensor wire harness then the car stalls very quickly. I have the exhaust off the car right now and the brand new sensor installed.

What should I be looking at? I am confused. Do I have a sticking or bent valve? I don't hear any funny noises and the car seems to turn over easily. I put a wrench on the crank and can readily turn it.

I have not pulled the valve cover off yet.

I could really use some help right now as I don't know what to make of these symptoms.

Reply to
George Spafford
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It is never a good idea to replace a part without first checking the part to see if it is functioning properly or not.

Also, when a computer identifies a particular component, the correct procedure is to check to see if the component is functioning properly, and if it is, check the circuit for that component and other systems and components that are related to the identified component.

It is very unlikely that a bad vacuum sensor will prevent a car from starting.

I think you still have a blockage in the exhaust. When you say that you removed the exhaust at the catalytic converter, is that before or after the converter? In other words, is the catalytic converter still on the car?

What happens if you remove the converter?

Reply to
Ray O

With the converter off, it runs a little better - RPM increased from

1,000 to 1,200. I'm getting ready to put a replacement exhaust on right now to see if lack of backpressure is causing any issues. I figured that eliminates the entire issue.

Why do you think I have air pressure coming out the vacuum lines vs. a vacuum? Air is literally blowing out the lines.

Reply to
George Spafford

Reply to
Ray O

I doubt if the lack of backpressure is causing the problem. A crack or leak in the exhaust manifold can make it get hot and glow cherry red, and an obstruction in the exhaust can also cause problems. ]

I've never run across that problem, but I would imagine that an obstruction in the exhaust could cause it, along with a valve train problem like a stuck valve or incorrect valve timing.

Reply to
Ray O

I sorted it out finally - I thought I was going nuts.

A clogged catalytic converter kicked matters off causing all the backpressure. Little did I know that the distributor cap was loose and had shifted all the way to one end of the bracket last night causing all the poor running today. You were right - lack of backpressure wasn't the problem.

Thank you for your help Ray. I th>

Reply to
George Spafford

You're welcome and thanks for sharing your results!

Reply to
Ray O

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