1998 Mazda Millenia S (car stops when idle) - Mazda Forum
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post #1 of 20 (permalink) Old 03-14-2008, 11:43 AM Thread Starter
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I have a 1998 Mazda Millenia S. The car stops when idle and sometime makes a whistle sound. I am suspecting a vacum leak or ckp sensor. The troubleshooting code is p0725 ( Engine speed input circuit malfunction) from the oem. Can you help me?
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post #2 of 20 (permalink) Old 03-14-2008, 06:34 PM
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A slipped timing belt has been shown to cause P0725 for a couple of other members here, usually caused by a bad timing belt tensioner or improper timing belt installation. The ECM is seeing conficting results when comparing the input of a speed sensor in the transmission against the angle of the crankshaft position sensor, which flags P0725. The whistle sound is residual pressure from the supercharger bleeding off right after shutdown. Mine does that a bit too.
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post #3 of 20 (permalink) Old 03-14-2008, 09:33 PM Thread Starter
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A slipped timing belt has been shown to cause P0725 for a couple of other members here, usually caused by a bad timing belt tensioner or improper timing belt installation. The ECM is seeing conficting results when comparing the input of a speed sensor in the transmission against the angle of the crankshaft position sensor, which flags P0725. The whistle sound is residual pressure from the supercharger bleeding off right after shutdown. Mine does that a bit too.[/b]

So what do you think I should do or replace?
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post #4 of 20 (permalink) Old 03-15-2008, 01:57 AM
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So what do you think I should do or replace?[/b]
If the car hasn't had a recent timing belt job then that rules out an improper installation. If your car has more than 100,000 miles it's conceivable that the original timing belt has slipped due to deterioration or from failure of the belt tensioner. If my hunch is right, a timing belt job is all the car needs. Otherwise, the problem is electrical, which Mazda's aren't known for.
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post #5 of 20 (permalink) Old 03-15-2008, 10:48 AM Thread Starter
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If the car hasn't had a recent timing belt job then that rules out an improper installation. If your car has more than 100,000 miles it's conceivable that the original timing belt has slipped due to deterioration or from failure of the belt tensioner. If my hunch is right, a timing belt job is all the car needs. Otherwise, the problem is electrical, which Mazda's aren't known for.[/b]
I understand but the whistle or hiss is coming from the right of the engine and the time belt and stuff is on the left. Why wouldn't you think is a Engine Vacuum Leak?
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post #6 of 20 (permalink) Old 03-15-2008, 02:24 PM
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Have you checked the codes? If it was a vacuum leak you would usually have a coded stored in the cars computer. Go to AutoZone and they lend you their OBDII scanner.
-Steven



<span style="font-family:Verdana">2001 Mazda Millenia L R.I.P
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post #7 of 20 (permalink) Old 03-15-2008, 05:20 PM Thread Starter
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Have you checked the codes? If it was a vacuum leak you would usually have a coded stored in the cars computer. Go to AutoZone and they lend you their OBDII scanner.
-Steven[/b]
OBDII scanner gives me: P1794, p0300, and p0725.

I asked someone to do a tune up and when it came back it start shut off on idle and i start hearing a hissing sound real loud. What's going on?
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post #8 of 20 (permalink) Old 03-15-2008, 08:46 PM
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Ok well then MillyOwner was right, if it just had the timing belt changed then it was installed incorrectly. Take it back to them and explain to them what has been said here and tell them to readjust it properly and while they are they tell them to check the TB tensioner.

The P1794 is "Battery voltage circuit malfunction". I just read online that it could be cause by a loose fuse so I would check to make sure all of your fuses are in snugly.

"A P0300 OBD code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why."
http://www.obd-codes.com/p0300 Check this page for the full p0300 code symptoms and causes.
-Steven



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post #9 of 20 (permalink) Old 03-15-2008, 10:21 PM Thread Starter
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Ok well then MillyOwner was right, if it just had the timing belt changed then it was installed incorrectly. Take it back to them and explain to them what has been said here and tell them to readjust it properly and while they are they tell them to check the TB tensioner.

The P1794 is "Battery voltage circuit malfunction". I just read online that it could be cause by a loose fuse so I would check to make sure all of your fuses are in snugly.

"A P0300 OBD code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why."
http://www.obd-codes.com/p0300 Check this page for the full p0300 code symptoms and causes.
-Steven[/b]

But the person never touch the timing belt. I was there watching it get tune up. Do you think it is still the time belt even though it was not touch. Also standing in front of the car where will the timing belt be located at? Right,Middle or left?
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post #10 of 20 (permalink) Old 03-15-2008, 10:40 PM
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Looking at the engine, the timing belt is on the left side behind the engine cover. I'm not so sure now that P1794 has shown up. It can't be related to P0725 unless it's causing it. If the timing belt has slipped, a simple compression test would reveal abnormal or uneven cylinder pressure.
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