Why does your 92 corolla stutter when you give it gas and your subs wont work car starts fine?

Answer 1

As with engines before the days of Electronic Fuel Injection (EFI), stumble had two basic causes- incorrect ignition and incorrect fuel/ air mixture for the required operating condition. With computer controlled EFI, the computer or any of its sensors or actuators can go faulty, and when this happens you can get, you guessed it- incorrect ignition and incorrect fuel/ air mixture for the required operating condition, thus engine stumble. Here is the list of items on the 90+ that can be sources of this problem , in no particular order

Worn or defective spark plugs

PCV hose air leak

Air flow meter

Intake valve deposit

Exhaust gas sensor

carbon canister

fuel pressure

fuel pressure regulator

Injector

injector circuits

ignition coil and circuits

Transistor ignition unit

ECU harness connector

ECU power supply & ground

ECU

AAC valve

Air regulator

clogged idle screw

Battery

alternator

EGR

Temp sensor

Temp sensor connector

Throttle position sensor

Idle switch

Cone Air filter

Crank angle sensor

Fuel temp sensor

Speed sensor

Incorrect timing belt installation

Crank Angle sensor and circuits

Ignition Timing What I observed was that an engine can have quite a few things not functioning properly and still run- The fuel pressure regulator can be inoperative or the EGR can be non functional and you may not notice it, the exhaust gas sensor may not work , so the engine runs a bit rougher etc. Do you get the idea now that if you're having problems that it could be anything? So where do you start? If the problem is intermittent, you may never find it. As another example, I still have a 1987 Mitsubishi Starion, which ran perfectly for 35,000 miles. Then it developed an intermittent hesitation problem- you would be cruising at 60mph, on a 400 mile trip, ease off the gas pedal, and suddenly for 1/4 second, it was as though someone had switched off the engine and then turned it back on again. The car would then run faultlessly for the rest of the trip. This happened 4 times in a period of 1 year, then never happened again. The car has now done 70,000 miles and run perfectly ever since.