How to test the ignition coils on 98 camry I4? - Toyota Nation Forum : Toyota Car and Truck Forums

stanleyeye · 02-05-2009, 03:30 PM

Could any one tell me how to test the ignition coils? My car check engine light is on, and I had it checked at advance auto parts and was told that #2 and #3 cylinders misfire. I replaced the spark plugs immediately, but the problem is still there. Then I checked the resistances of the four spark plug wires, which are 8.5K, 8K, 6K, 5K. Are they too high? Should I replace the wire set as well? I also tried to measure the resistances of both ignition coils. From the manual, I know the resistance of the 2nd coil should be from 9.7-16.7K. Mine looks good. But I don't know what's the right value for the 1st coil. Could any one tell me?

Also I was wondering how to check the resistance of the fuel injector?

Thanks a lot for help!

Tom 2000 · 02-05-2009, 09:19 PM

Did you clear the code after you replaced the plugs?

***96paseo*** · 02-06-2009, 12:29 AM

Don't worry about clearing the codes until the engine runs right. You'll know when its fixed if you've got an ignition or injector problem. You can test the ignition coils with a multimeter. The best way is to check the injectors and coils. Pull your plugs a to confirm which cylinder(s) has the misfire, then check your injector with an ohm meter. Pull the harness connector off(squeeze the tab first) and put the 2 probes on the terminals. If your injector reads a short, high resistance or open, the injector is bad. A good reading should be 13-14 ohms. If your injectors check out fine, then the coil is most likely the problem since injectors don't usually go bad in pairs. The resistance on the plug wires is good. 1st coil should be the same or close to the second. Good luck

***new echo owner*** · 02-06-2009, 12:53 AM

The ignition coils should be the same; one for cylinders #1 and #4 and the other for #2 and #3. Sounds like you have a bad coils or connection problem, since both cylinders are on the same coil.

N.E.O.

Hajoca · 02-06-2009, 02:33 PM

You also need to check spark plug wire #2 and #3, both required to complete circuit.

stanleyeye · 02-06-2009, 09:46 PM

guys, thanks a lot for your help.

paseo, I will do what you said step by step. May I just disconnect the spark plug wire to confirm which cylinder misfires?

If I have to replace the fuel injectors, do I need to release the fuel pressure first?

Also, I have a very stupid question, how can I know which coil is no.1 coil, which is no.2?

Thanks again

***new echo owner*** · 02-06-2009, 09:52 PM

The cylinder numbers are right on the coil if they are the original coils. Switch the plug wires from one coil to the other, if #1 and #4 cylinders are misfiring, then the coil is the problem.

N.E.O.

stanleyeye · 02-06-2009, 10:36 PM

Quote:

Originally Posted by new echo owner

The cylinder numbers are right on the coil if they are the original coils. Switch the plug wires from one coil to the other, if #1 and #4 cylinders are misfiring, then the coil is the problem.

N.E.O.

Hi N.E.O.

Actually, I found the coil connected to #2 and #3 is wet. If I switch the plug wires from one coil to the other, will this cause any trouble? I though the order of each cylinder firing can not be changed. Could you tell me about this? Sorry, I don't know much about car.

Thanks

***new echo owner*** · 02-06-2009, 10:42 PM

If the coil is wet, that may have some bearing on why it is misfiring.

Anyway, the coil fire both plugs at the same time; it is a waste spark ignition system, one plug fire from positive to ground and the other from ground to positive. When you switch the plug wires you will need to switch the small connector from the ECM too; the ECM will know which coil to trigger as long as you switch all the wires and connectors.

N.E.O.

stanleyeye · 02-07-2009, 02:57 PM

Hi guys, I read the code again, this time shows only #3 cylinder misfiring. I guess maybe the fuel injector is the problem, but some guy at Auto store checked my car and told me the problem should be the coil. He told me that if the fuel injector bad, the smoke should be really bad but mine is fine. So I was wondering if the coil is bad, is it possible that one cylinder connected to this coil works fine, the other misfires?

Thanks

stanleyeye · 02-08-2009, 06:08 PM

replaced the ignition coil today, but no luck, the problem is still there. furthermore, I got one more code, P0300, multiple/random cylinder misfire, I think maybe because I didn't change the throttle body gasket since I haven't got it. Next. I am gonna replace the fuel injector though the resistance seems ok. Before I do that, I have several questions. Do I need to release the fuel pressure to replace fuel injector? The spark plug in cylinder #3 replaced a few days ago is completely black now, do I need to replace it again?

Does any one can help me? appreciate

***96paseo*** · 02-08-2009, 10:47 PM

Which cylinders did the new coil get attached to? Did you try putting the old coil back in and replacing the other one? Isolating the bad coil should be your priority. If you still have the old coil, try putting it back on and replacing the other one. If you switched the coils like NEO said, you may have replaced the good one. You said the coil is wet. Wet with oil or water? Also, don't change your injector if it reads good. Take readings on all your injectors and compare them. If one measures significantly higher than the others, it may be bad. If your plug is black and dirty, just wire brush it and wipe it clean. It should still work. Throwing parts at it will only help you spend more money. Pin-pointing your diagnostic approach will help you get it fixed. Just be patient and thorough. If you're able to post pics, put em up. It will help us help you.

stanleyeye · 02-08-2009, 11:39 PM

Quote:

Originally Posted by 96paseo

Which cylinders did the new coil get attached to? Did you try putting the old coil back in and replacing the other one? Isolating the bad coil should be your priority. If you still have the old coil, try putting it back on and replacing the other one. If you switched the coils like NEO said, you may have replaced the good one. You said the coil is wet. Wet with oil or water? Also, don't change your injector if it reads good. Take readings on all your injectors and compare them. If one measures significantly higher than the others, it may be bad. If your plug is black and dirty, just wire brush it and wipe it clean. It should still work. Throwing parts at it will only help you spend more money. Pin-pointing your diagnostic approach will help you get it fixed. Just be patient and thorough. If you're able to post pics, put em up. It will help us help you.

Hi paseo, The new coil is for cylinder #2 and #3. I didn't change the other coil. Actually the coil is wet with oil coz I found some oil leaking through the valve cover gasket, and of course I replaced the gasket already today. I measured all the resistances of four fuel injectors, and they are quite close, all around 15 OHM. I will try to switch the plug wires and coil connectors to double check the coils. Does the right resistance of fuel injector gaurantee the fuel injector is fine? Thanks

stanleyeye · 02-09-2009, 11:18 AM

I am gonna switch fuel injectors too to see the misfiring cylinder is gonna change or not...

***new echo owner*** · 02-09-2009, 09:58 PM

Did you switch the coil and plug wires?

BTW, did you do a compression test on the engine?

N.E.O.