Rouhg and low idle?
01_Celica_GT
05-21-2006, 12:20 AM
My '93 MX-3 has really low and rough idle and I was just wondering what could be wrong. It's a 4 cylinder but i'm not sure if its 1.6 or a 1.8 so any information would be helpful.
corning_d3
05-21-2006, 12:31 AM
The most common culprits are plugs, wires, distributor cap and rotor. It could be a hung open EGR valve (if your engine has one). Burnt valves, low compression and clogged injectors could also cause it.
01_Celica_GT
05-21-2006, 12:59 AM
how can i tell if i have an EGR valve? I have the 93 1.6 4 cylinder.
How can I tell if i have burnt valves without taking off the head? that would require to much work and how can i tell if i have low coompression?
How can I tell if i have burnt valves without taking off the head? that would require to much work and how can i tell if i have low coompression?
corning_d3
05-21-2006, 01:43 AM
You do have one, and a complex one at that. http://autozone.com/servlet/UiBroker? (http://autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/14/46/b7/0900823d801446b7.jsp)ForwardPage=/az/cds/en_us/0900823d/ (http://autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/14/46/b7/0900823d801446b7.jsp)80/14/46/b7/0900823d801446b7.jsp (http://autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/14/46/b7/0900823d801446b7.jsp)
This page has a diagram, and describes how to test, remove and install components. The best way to check for bent valves and low compression is to get your hands on a vacuum guage and hook it up to a vacuum port (full vacuum, not ported)on the intake. A good chiltons or an underhood sticker should give the locations. After installing the guage, start the vehicle and let the idle settle out. You should be getting at least 15 inches of vacuum at idle. I'd like to see at least 18(higher vacuum indicates good sealing valves and piston rings). If the vacuum needle wiggles back and forth quickly, you have a valve not sealing properly. Another way to check is to screw an air fitting into the spark plug hole, bring that cylinder to TDC, and put shop air into the cylinder. Make sure the shop is quiet and start listening for leaks. Pop the radiator cap and make sure you see no bubbles, as this indicates a leaking head gasket. Pull the dipstick and listen for air. this or listening at the pcv hole in the valve cover indicates leaking rings. Remove the air cleaner and open the throttle and listen for rushing air. This means there's a leaking intake valve. Last, put you ear up to the exhaust pipe and listen for air, this means there's a leaking exhaust valve. If you use a compression tester, you can isolate the low compression cylinders and test them with shop air. Make sure the cylinder being tested is at TDC(both valves closed). My fingers hurt..... This needs to be a "how-to"...
This page has a diagram, and describes how to test, remove and install components. The best way to check for bent valves and low compression is to get your hands on a vacuum guage and hook it up to a vacuum port (full vacuum, not ported)on the intake. A good chiltons or an underhood sticker should give the locations. After installing the guage, start the vehicle and let the idle settle out. You should be getting at least 15 inches of vacuum at idle. I'd like to see at least 18(higher vacuum indicates good sealing valves and piston rings). If the vacuum needle wiggles back and forth quickly, you have a valve not sealing properly. Another way to check is to screw an air fitting into the spark plug hole, bring that cylinder to TDC, and put shop air into the cylinder. Make sure the shop is quiet and start listening for leaks. Pop the radiator cap and make sure you see no bubbles, as this indicates a leaking head gasket. Pull the dipstick and listen for air. this or listening at the pcv hole in the valve cover indicates leaking rings. Remove the air cleaner and open the throttle and listen for rushing air. This means there's a leaking intake valve. Last, put you ear up to the exhaust pipe and listen for air, this means there's a leaking exhaust valve. If you use a compression tester, you can isolate the low compression cylinders and test them with shop air. Make sure the cylinder being tested is at TDC(both valves closed). My fingers hurt..... This needs to be a "how-to"...
01_Celica_GT
05-21-2006, 11:59 AM
wow thats crazy. alright i'll look into that fo sure because its getting really rough to the point of it dying. alright thanks alot dude.
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