A couple of questions...
 

1. When ever I start my car, I hear something rattling within my motor, but it goes away after a while. I know my description might not help that much, but what could it be?

2. When I start my car when it's cold, my tach fluctuates from about 1800 to 2200 rpm, and it sounds like someone is giving it gas, then letting go. What could that be?

Thanks in advance for your help

Tom

When your car is cold, the thermostat senses that and regulte the air fuel mixture. On a standard thermostat, it operates at about 13lbs of pressure, this in turn allows for a greater aount f fuel to etner the combustion chamber. I believe that it is about 14.7:1 whereby for every 1 part of fuel there is 14.7 parts of air. Therefore, on cold starts you often hear knocking, then when the engine heats up and is at normal operating temperature, the air fuel mixture decreases and less is needed because the heat produced within the engine, is enough to generate proper combustion in the power stroke. Like all car engines, it operates on a 4 stroke cycle. For the intake stroke, the air and fuel is let in, then you have the compression stroke then the power stroke then the exhaust stage. I wont get into the intricate details, of how the engine works and to optimize power with variousengne components and so on. But the information I stated previously, should answer both of your questions. But one more thing that you could be hearing is the tensioner or the various bolts that are used to adjust the tension in the belts. The worst case scenari would be that the pulley is seizing and the belt is just spinning around it, but I highly doubt this as, the symptoms you provided do not correlate to such a problem. Like I said, what I said first is most likely the problem, and its not a really big deal, it could even be something loose within the engine bay that maybe knockin against something.

Hope I could help, if you have anymore problems or concerns let me know and I will try my best to assist you with it.

MAZDA KID

1. Better get that rattling checked out.. any rattling can't be good.

2. What motor you have in your car? Is it a swap? Perhaps the ecu and the idle air control valve arent' compatible. It may have something to do with the IACV, but not necessarily. The flucuating may be caused by improper timing or even vacuum leak.

HTH:thumbup:

Would it be my valves?

I have a b16 in a 5th gen hatch which was put in about 2 and a half years ago. How do I check for a vacumm leak?
Here's more info if it may help. I have a DC CC header, Ractive intake (for now), and an ecu that was chipped about 8 months ago by a guy named Adrian that lives in Sauga. He has a website, but I don't have it on hand. Its ducktuning.com or something like that.

The rattling sound could be your valves, but valves make more of a ticking sound.

I guess it is kinda like a ticking sound, but this ticking sound is kind of off tone if you know what I mean

This would be a great exuse to come to a meet on wed. night. Come on out, so we can hear it, and give you our opinion.:working:

I know Adrian.. He does great work.. I've had him program ecu for me MANY times and never any problems. So the problem might not be from the chip.. What kind of ecu was it? Was it originally auto?

To check for vacuum leak.. you'll need a vacuum pressure gauge. You can get them from Canadian Tire, or Walmart for that matter.

I don't think it was originally auto. He supplied the ecu for me as well. Though it does run rich all the time, and now I've lost about 100 kms on a tank of gas.

Damn, I just got back from Canadian Tire.

The ticking sound could be a bearing in your tranny...

I just rebuilt mine and put new bearings in because it was doing that.

18$ each bearing.

Regards,
OK

When you had that problem, did the ticking sound go away after you drove it for a while, or was it continuous regardless how long you were driving for?

It was intermitent.. Sometimes it would happen and sometimes it wouldn't.. (shrugs).

Regardless I had it opened and looked into and yep, a bearing was cooked.

Regards,
OK

what year is the car?
if its a couple of years old it could be something as simple as the heat shield for your headers....they rust pretty fast

I don't have a head sheild

Looks like you might need a "head shield " from the looks of you avatar