Mazda 2000 Protege LX Detonation Problems...

[Marik123]

Hello:

I bought this car in 1999 around December and I drove it for 4 years for now. It got ~47000 miles on it. Recently, when I was driving uphill or attempt to accelerate in the freeway, I hear this knocking noise from the engine. At first I thought it's just normal noise, but as time goes by, the noise got louder... I tried to ask my friend's for help, they said try to fill it up with Plus or Premium grade gas, and I did. I tried Plus and Premium gas, no luck, the engine still knocking at heavy load. Then I did a basic tune-up, hoping it wil fix the problem, but it still exist... I'm out of ideas right now. I dont have that much $$$ to go to Mazda dealer and have them check it out for $80/hr (rip off). So I'm here for suggestions....

Things I tuned up or replaced
1. All 4 Spark Plugs, using the NGK model
2. I flush out the transimmission fluid and replace it with new
3. I flush out the coolant system and replace it with new
4. I also add this special addicitive to my fuel that can help reduce knocking, improve acceleration and reduce fuel consumption.
5. I add this special additive to my engine oil so it can restore the compression of my engine... (It did quiet down the engine quite a bit, but thats all).
6. I replaced the air filter and replace the break pads.
7. Current Tire PSI is at ~33.

Also... This problem occurs when...
1. The knocking sound is more signficant when the temperature is > 60F
2. When I first start the engine and give some load, it does not have knocking sound, but after driving it for 5 minutes, knocking sound kicks in when there is a heavy load. When I turn on A/C, its more signficant.
3. When 2000 < RPM < 3000, the noise is most signficant here...

Any suggestion or compliments are appreciated.

Sincerely
MarK

[GNO]

With the premium, did it knock less? If not, it might be an exhaust leak.

Did you replace the thermostat when you changed the coolant? Where does your temp guage sit when the vehicle is warm?

47k sounds a bit low to have severe carbon build up in the combustion chambers, but you can try to clean that out. Pull the spark plugs out and pour some transmission fluid into the cylinders. Rotate the engine slowly a few times by spinning the crank. Let it sit for several hours. Afterwards, with the plugs still out, cover the holes with rags and turn the engine over a few times using the starter. This will allow the fluid to come out without hydrolocking your motor, so don't plug the holes with the rags. Replace the plugs and start the vehicle. Lots of white smoke will come out the exhaust. After the smoke clears, check your plugs and change if necessary. Then change the oil and filter.

[Marik123]

When I fill it up with Premium gas, it's the samething as if I was filling up regular. It still make the knock sound under heavy load. I did not replace the thermalstat, but when my vehicle is warm, the thermalstat indicator always stay inbetween Cold and Hot, so I'm not sure if that is the problem there... Also the fan turns on and off regularly.... What you said is to clean up the combustion chamber, I went into Juffy Lube and did a complete fuel injection cleaning service. They connect this oxygen tank into some pipe in my engine, then they pour this special additive into the gas tank and also pour this special additive into my transmmission... When they start the car, alot of smoke coming out from the back of the tail pipe (last for like 2-3 minutes and so)... Is that the one you are talking about? I spent $69.95 on that one. I did that service when my car was at 40k mile... I also ask a friend about this issue, he said it could be a timing problem. If so, how can I adjust the timing of my vehicle. I heard alot of people said retard the timing will reduce the knock while advance the timing will improve performance, yet required octane rating of 100+... something like that... What do you mean by exhaust leak? How can I check for exhaust leak?

Sincerely
Mark

[dominoy2k1]

get someone to help. get a rag to cover exhaust tip. look under the hood for any smoke. covering the tip will enhance exhaust leaks.

[GNO]

What you said is to clean up the combustion chamber, I went into Juffy Lube and did a complete fuel injection cleaning service. They connect this oxygen tank into some pipe in my engine, then they pour this special additive into the gas tank and also pour this special additive into my transmmission... When they start the car, alot of smoke coming out from the back of the tail pipe (last for like 2-3 minutes and so)... Is that the one you are talking about? I spent $69.95 on that one.
Yep, that's one way of doing it. What I suggested just cleans the combustion chamber. The induction cleaning does a bit more.

Sounds like t-stat is working fine, too. I just wanted to ensure the engine wasn't running too hot. . . another cause of knock.

Since niether the cleaning nor the increased octane helped. . . I don't think it's detonation.

Exhaust leaks can make all sorts of different noises. A small leak will make ticking noises under load that sounds very similar to knock. The exhaust system goes through a number of heat cycles causing stress on the welds and flanges. Somethimes this stress causes leaks. Doing what dominoy2k1 suggested may help you isolate where the failure occurred. However, the additional pressure may make the noise worse. You'd just be comfortable knowing what the problem was as you wait to get it fixed. In order to fix it you'd have to re-weld or replace a gasket depending on where the problem occurred. A good exhaust shop would be able to sniff it out and fix it fairly easily. That way you'd have a little less anxiety.

Timing is computer controlled. In order to take control over it, you'd need an engine management system.

[Shane5425]

another thing the dealer told me.. if u dont use the factory oilfilters.. have something different in there factory ones... at start up u will have a small knock.. but once it warms up its ok...