My 92 Corolla is a 4-door sedan, engine model 4-AF California, 16-Valve, EFI, DOHC, automatic 3-speed, 198,000 miles. Initial problem was Lack of Power. The only DTC pulled was Code 24 (IAT Sensor). Once cleared it never showed up again. At first start engine starts up but idle speed doesn’t go up. Just like starting it when it was already warmed up. Pulled wire to Cold Start Injector and engine started. Resistance reading is 3.5 ohms, 0V with power On. Is it faulty? Idle speed when stopping goes down and almost stalls. Raised idle speed by turning the adjusting screw. Engine starts & idles fine but when stepping on the gas takes slow to rev up with no pick up. Cleaned throttle and plate with carb cleaner (little dirty). When driving off letting your foot of the gas pedal will start to increase speed. Thought it was transmission shift out of timing. Car has fairly new spark plugs and wires, new distributor cap and rotor. No whirring sound heard from fuel pump when ignition key is turned on but fuel pressure and regulator tested OK when checked with fuel tester – discharge press at 78 psi, after pressure regulator at 28 psi w/ vacuum hose disconnected, 21 psi w/ vacuum hose connected. EGR valve checked with handheld vacuum pump OK. Checked ignition timing - it was late. It fluctuates below the Zero BTDC and 1 degree. Adjusted at best and still fluctuates between 3 to 5 degrees BTDC per VECI on hood. Engine ran good with power. To improve performance I added Seafoam cleaner in ags tank and cleaned the combustion chamber with Seafoam cleaner thru vacuum intake. Noticed leaks at exhaust manifold (smoke and liquid cleaner). Dirty ATF and filter was also changed.
Three days later car died while driving on the freeway and will not re-start after a few attempts. Engine rotates but will not start and no check engine light. Added 5 gallons of fuel in the tank to make sure there is fuel because gage level is defective – close to 1/3 level when full. Attempted to start without success. Towed to home for troubleshooting.
Troubleshooting: Checked for spark and fuel are both OK. I individually checked each spark plug wire with clip-on calibrated tester OK. Then individually removed each spark plug and checked for spark (attached plug to engine block)-all OK. I could not tell if it was a healthy blue spark because it was daylight. But the spark was arcing on the tester and ticking sound was heard. Used another fairly new spark plug to verify old plugs and spark was the same. Removed each spark plug and the tips were all wet with fuel and black. Cleaned and re-gapped to.031 inch. They were.029 inch. Looked down inside cylinder and found raw fuel on top of piston. Cleaned carbon tracks from distributor cap. Reinstalled spark plugs and re-checked for spark with same results. Timing belt was not broken but will need replacement due to cracks.
Checked battery with multi-tester at 12.5V, with Load Tester 12.5V without load, 11.6V with load. Pulled all fuses and are OK especially EFI, IGN and the rest. Power to fuse block OK, 12.54V at IGN. Checked all fuses in engine compartment OK and terminal block has power. Engine Main relay read 81 ohms between outer terminals (nothing on other terminal combination).
Disconnected sensors to check for resistance and wiring for voltage (Ignition key ON) to as many sensors as I can identify as follows. I don’t have the book specifications to compare: IAT 1781 ohms or 1.6 on 20k or 1.5 on 200k scale, with 5V; Cold Start Injector 3.5 ohms, 0.01V; EGR 3.5 ohms, 0V; MAP 13.94 ohms, 5V; MAF 12.5V, 0V. Checked Ignition Coil (inside the cap)for resistance no reading found but found 4.5V , Fuel injectors were all at 14 ohms, ECT (orange color pointing to radiator) at 36 ohms.
Turned ignition key on but heard no whirring sound from fuel pump. Re-checked fuel pressure with tester is OK like previously. EGR valve and Modulator checked OK with handheld vacuum pump. Removed and cleaned EGR valve. Attempted to start engine again but it only rotates and will not start. Pulled spark pugs again and were wet with fuel. Usually this is a blown fuse in ECM, EFI, IGN, PCU which powers the ECU or PCM but all fuses checked OK.
Performed cylinder compression check No.1 to 4 respectively: 117, 106, 111, 111. With oil – starts 120 then drops to 105, 150 dropped to 123, 150 to 81, 150 to 108 respectively. They're low but enough to start the engine. Engine ran fine before with these readings. They're need work in the future.
Dried all oil and raw fuel from top of cylinders and wet spark plugs cylinders and re-started engine. Noticed at the first start it attempts to fire for a second only. Engine cranked good with each start. Adjusting the idle speed adjusting screw while cranking did not help. Battery was checked to make sure it is not run down. Floored the gas pedal while cranking had no results. Checked for spark and is still the same. Pulled out plugs again and sure enough the tips wet with fuel again. Sound s like symptoms of flooding or lack of air or insufficient spark. Explain how. Maybe adjusting the timing while cranking to find the sweet spot is what I need to try. I’ve read that bad Camshaft or Crankshaft sensors will prevent the engine from starting but maybe not for Corolla. I don’t know if the Engine Main relay is bad. But I have spark. Without a check engine light it is hard to find the problem. Changing one emission part at a time is just too expensive. I am very detailed here to show that I was kinda paying attention to details. I’m sure I have missed something here. I’m out of ideas. I very much appreciate your comments. Thanks.
Saturday, May 12th, 2007 AT 3:46 PM