Quote:
Originally Posted by john walker's workshop
Carreras often suck in one of the intake gaskets and cause that cylinder to drop at idle and low rpm, due to too much air in the mix. Pull off one plug wire at a time and see if the idle drops off or not. A compression and leakdown test would be good. Look under the distributor cap for carbon tracking.
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To add to this:
When mine became a "
great sucking vacuum leak™" I figured out which three cylinders (
yup 3 of them!!!) had a problem by putting the car up on jack stands and starting it cold. I then took an IR thermometer and measured the temp of each of the exhaust ports as it started to warm. Three of them were quickly more then 100° warmer then the others. Checked the cold ones for other easy to check issues like injector flow and spark then I chased after the intake gaskets.
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If it is the intake gaskets:
You will need 12 gaskets because each port has 2 gaskets. One above an insulating plastic spacer and one below.
ALSO! With the age of the car the plastic spacers will almost certainly be crumbling when you try to clean them (
just like mine were). So before diving too far into the job make sure you order the 12 gaskets and 6 plastic spacers.
If this is your issue, it is a major "while you are in there" opportunity. Check the fuel hoses very carefully and go through all the rubber hoses looking for cracks and vacuum leaks. I had Mese Hose here in the OC replace the rubber fuel lines with a more permanent line. I also found a couple cracked vacuum lines and the main breather hose cracked when I tried to reconnect it. Turns out the main breather line isn't supposed to be a hard, almost plastic like hose! A new one is VERY flexible rubber.
I also did a major cleaning while I was in there. I used the gaskets as a stencil to cut some masonite port block-offs so I could go to town and not worry about junk going down the intakes.