Check Engine Light - Toyota Nation Forum : Toyota Car and Truck Forums

mud runner · 08-18-2004, 08:23 PM

Okay so here is my problem, I just finished rebuilding my 3.0L V6 in my 4 runner. It has been bored out .50 and now my Knock Sensor is going crazy. Everytime I drive it just around the corner the light comes on the book I have says it has an open circuit. The only problem is the book is a haynes. I have taken 2 yrs of college to work on cars but this is boggling my mind. I have checked my spark plugs, timing, and fixed my one exguast leak. If you have any ideas please let me know.

thespud · 08-18-2004, 11:23 PM

If it's the knock sensor, try going up a few octane points on the fuel first... see if that stops the knocking. that is the cheapest and easiest way.

mud runner · 08-19-2004, 01:27 AM

Well i already use plus, I think it's rated at 89, so i think this should be right, maybe ur right. The weird part is i have been noticing that the light only comes on when i hit 1500rpm's in any gear but first. The engine and trans have just been rebuilt I hope i can solve this before to long. thanks.

chronoti · 08-19-2004, 01:55 AM

well open circut would mean the sensor is bad right? so either the sensor is bad or the wire are bad. check too make sure the sensor is good agianst your haynes manual

mud runner · 08-19-2004, 02:04 AM

Well it all depends on how the sensor works. Some sensors will go open to make the light go on. So i don't know if the light is because the sensor is bad or if that is just the way it works. Thanks for your suggestion and besides the haynes sucks has no info on the knock sensor.

thespud · 08-19-2004, 04:36 AM

The knock Sensor in Toyotas works like a backwards relay... it is closed until it is 'knocked' open, hence the circuit open CEL. like Chronoti said, it could just be a bad sensor, or it could be actually knocking.

alltrac165 · 08-19-2004, 12:32 PM

It may be that the thinner cylinder walls from the rebuild have made the noise higher around the sensor, causing it to trigger. At .050 over, and possibly having the head and deck resurfaced will raise your compression a smidge as well. So maybe higher octane will help.
I think I have heard of people using GM knock sensors in place of the toyota ones, but I don't know if that would actually work.

mud runner · 08-19-2004, 08:21 PM

In testing the sensor i found that after blowing out the code i then tested with my dmm and found on open on the ground and power side of the sensor. Thus leading me to belive the sensor is bad. However alltrac you may be right, about the sensor needing to be changed. thanks for all your help guys i will worry about it later so right now i'm just trying to get 500 mi on my engine, by tomorrow 5 pm west coast time.