Spark Knock ????

[SpeshalK_82]

Here's my situation. When i'm driving my truck and it gets under a load, going up hill or something, I can here a rattling noise from under the hood. I asked the local Toyota man and he told me that it is Spark Knock. The only thing that I can seem to do to get it to quiet down is to run Premium Unleaded gasoline in it, but it never quits, just gets a little quieter. Soooo, first of all, what is Spark Knock exactly and does anyone have any suggestions or possible solutions to this problem? Any help will be appreciated.

Speshal K

[socky3850]

You will normally get a spark knock (preignition) when you use gas that has too low an octane number. My4R is a 2004 and has a knock sensor that advances or retards the timing depending on the octane of the gas that I use. Most newer vehicles use this same system.

[SpeshalK_82]

So if I continually run gas with a minimum octane of 92, what can I do? Is the spark knock bad for my engine? Is there any thing else I can do besides pay like $2.10 a gallon for premium unleaded gas?

[reb]

Severe knocking is not good for an engine. I would check the timing. Excess carbon in the combustion chamber can cause it, too.

[AzToyota]

My 92' r22e does the same thing. My mech. friend and I have tried various things over the past three months. It only knocks when the eng. has been at or above 2500 rpm for about 4 mins. Then only during a slight climb or accel. So far I have lab. scoped the o2 sensor... checked the egr valve. Put in a known good Air Flow sensor... put in a known good computer... replaced the radiator cap and thermostat! Then only thing that really helped was retarding the timing ... unfortunately this caused other running problems, so I returned the timing back to it's normal state. I just made sure the valve timing was correct. Now I am considering changing out the whole distributor with a known good one. (Possibly the spark sensor) for the computer advance is not working correctly.

BTW at the high temps out here in PHX, adding high octane gas does help a little but does not eliminate the problem.

I was looking at this forum to find others with similar problems.

Regards,