I Recently Purcahsed A Used 2001 Double Cab Toyota Tacoma. 3 Weeks After Purchase I Began To Hear A Knocking Noise or thump like noise Coming From The Engine Bay or so i think. The Truck Has Approx. 36000 Miles. it has racerunners coilover lifted about 3 inches on the front and a leaf and bilstein on the rear. It Always Occurrs When I Come To A Complete Stop At A traffic Light And Sit There fOr About 15 Seconds or longer and during regular idle. It Will Usually Knock About 2x's And Then Go Away. Sometimes Its Loud And Sometimes Its Very Low. I Took It To The Dealer, Who Said That They Tightened Everything Up , And Lubed All Parts, But After Driving Off The Lot I Began To Hear The Noise once again. If You heard anything about this type of noise or Problem And Or Know Of A Solution Pls Help Me Out.l the noise is starting to drive me Crazy because i can hear it even when my radio is on. Thx For Your Replys

I have a 99 Tacoma 4x4 with a 2-1/2" fabtech coilover lift. I have the exact same problem. I have taken it back to the shop and they say there is no problem. I have not been able to tackle the problem yet. If you find out what it is, I sure would like to know.

please let me know as well, I have the same problem..I cant seem to pin point it..Im going to check if its the something rattling in the catalytic converters. If you find anything, please post as I will do the same

I can't remember what the title for the thread is but other people are having the same trouble and from they said that Toyota claims it's normal and that a couple of technicians drove one off of the lot with about 9 mi on the OD and it did the same thing, it's a long thread and may be worth looking at.

I have the 2.7 and mine did it for a while, right after I got the truck i put exh on it and heard it on my truck it was the cover on the cat converters so i bent the daylights out of the w/ a screw driver and it stoped, but don't do that if you want to keep the truck in mint cond.

My 2001 Tacoma 2.7 developed a severe similar noise. Several visits to the dealer including having a Toyota Rep drive the car resulted in no solution (They couldn't replicate the situation) Finally the noise got quite loud and the dealer diagnosed a scuffed piston. Since the vehicle is still under warranty, I am in dispute over uncontrolled repairs to the engine which I believe should be replaced.

Not sure what it is just yet,,,

I'm not quite positive what you are experiencing, but I had a knock under acceleration and found that all I had to do was use a higher octane gas. I have the 2.7 L and it just doesn't like low grade fuel. It could be a stretch, but maybe that is what you are hearing coming from the engine.

Finally found the problem - a cracked flex plate in the tranny. Now I have a $1650 wall decoration in the form of a flex plate. By the 3rd shop I figured at least this one figured out the problem.

Might be the rocker arm too. Atleast that is what it sounds like.

I've got a '98 4x4 reg. cab; I had the same problem (surprise surprise, the 2.7L I4). The problem comes from the timing with the undersized engine. A 4cyl in a 5000lb truck isn't very effective, so Toyota maxed out the timing to boost the power. Because of the timing, the fuel predetonates and "knocks," sounding like a diesel engine. If you really torque the engine at low speeds (like climbing offroad), you can really hear it. I solved the problem by running 2 bottles of Techron to clean up any carbon and going up to 93 octane (higher octane is more stable and won't detonate through compression as easily if at all). Some people will tell you it's a faulty knock sensor or some BS, but try going to higher octane first; even if you don't want to pay the extra 20 cents because it will cost a lot over the long run, it's easier and ultimately cheaper than costly repairs that won't work.

spoon691's problem is definitely not preignition. More likely to be the cracked flex plate

Just expanding and contraction from heating and cooling. Some cars do the tick for years and others it stops ticking as the exhaust get's old and rusty.