Tuning Up the Older Car and CEL

Joined
Sep 2, 2007
Messages
950
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Brooklyn, NY
So, in my quest to get rid of a P1300 Check Engine Light on my 97 Toy Avalon, I had replaced the Cam Position Sensor, which was out of spec- this solved the problem for about a month, then the CEL came on again last night. Thinking that possibly there was a bad spark plug (even though I had checked 4-6 plugs and found that they looked good), I ran to the auto parts store and got new NGK plugs. I started removing the old plugs one by one and when I got to cylinder 6, lo and behold, one of the plugs was almost shorted on one of the electrodes (they were double electrode platinums). However, it wasnt shorted by carbon, but it looked like the electrode possibly bent or warped somehow so that it was more or less touching the middle core. I am hoping changing the plugs fixed the problem. Anyway, I was wondering how it is possible for an electrode to "bend" like that. Could it have been a careless mechanic putting it in when they did the timing belt? I wonder... Thanks for any replies.
 
Joined
Sep 5, 2006
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19,479
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Chicago Area
Check that same plug again -it is your best shot. It is very rare for this to happen in an engine. It may have been that way originally, but more likely was hit by a piece of carbon .
 

parimento1

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Sep 2, 2007
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Brooklyn, NY
New plug looks good...I just changed the wires and light went on, I reset it using the scan tool. I will check it tonight once it cools down. By the way, the holder/router thing for the spark plug wires is way overengineered and extremely tedious to take apart and put back together!
 
Joined
Aug 21, 2008
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ON, Canada eh?
How about a bad wire to that cylinder? Also the coil pack might be bad as it could be arcing inside under load or when hot/cold. Have seen this many times on other vehicles. Edit: I did some research just now and aparently low compression from either worn piston rings or bad valve seal can cause this error too. Check the compression in this cylinder and make sure it is within 10% +/- from the other cylinders. Also check to see if the ignitor is good as this can cause this error as well.
 

parimento1

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Joined
Sep 2, 2007
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Yea, the ignitor was replaced when it threw this stupid code a 3 years ago...Last time the alternator happened to go bad, so I replaced it and the code disappeared immediately. I wonder if the battery is going bad a little bit and not giving enough amps at startup for the ignition system to fire correctly (this problem only occurs at startup- never had it illuminate while driving)...just a thought. I don't know how feasible it is to check compression...I dont have a gauge, but the engine does not really feel down on power on my "butt dyno." So far I have replaced: within the past month I have replaced: cam pos. sensor, plugs, and wires. Also I think I should add that the battery is leaking I guess...the tray was full of acid, so I washed it out today. It actually leaked down onto the subframe and started to corrode that, but just superficially...so a new battery may be in my future. Even with the "leak" of whatever is going on, it still holds a charge and cranks fine (about 12 volts even while cranking).
 

parimento1

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Joined
Sep 2, 2007
Messages
950
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Brooklyn, NY
I can tell you one thing, that the light coming on is temperature dependent, it usually comes on first thing in the morn when the car is "cold."
 
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