Is this normal (weird idle)?

[barich]

I've been driving a company car a lot for the past year. Now, I no longer have it and am driving my P5 a lot more than I used to. I've noticed that it's doing some strange things that I don't recall happening before.

First, when I start it when it's already warm, it starts right up, but then the RPMs fall to 450-500 RPM and it shakes for a second or two and then bounces back to about 750 (where it's supposed to be). I've hit the gas more than once when it does this because I think it's going to stall. It hasn't yet, but I'm not sure if it wouldn't have if I hadn't helped it along.

Second, when the A/C is on in Park and it cycles off, it does the same thing (drops from about 800 RPM to about 500, bounces back to 800, then levels off at 750). When the compressor kicks back on it bumps up to 800 again, then repeats itself.

I've also noticed when idling that there is a slight whistling sort of noise which I assumed to be air moving through the rather complicated looking factory airbox. I suppose that it could also be an intake or vacuum leak of some kind that might be causing these issues? It runs perfectly fine otherwise.

Do everyone's cars do these things, or is there something wrong and what might it be?

 

[Action Jackson]

It happens once in awhile to my car. Now and when totally stock.

As for the A/C changing your idle it's normal for some cars to drop slightly in revs.

To be honest, I find that my idle is much better when I drive the snot out of it. If I drive conservatively my car doesn't idle well.

If this happens all the time and you get a CEL then get it looked at. I guess it wouldn't hurt to check your intake system if you suspect a leak.

 

[JCell]

the idle thing has started happening to me too, i'm far from stock so i can't take it for warranty work, it only happens when already warmed up, and lasts about 10 seconds, she has dies on me twice

i've cleaned the intake mani but no effect

 

[nate0123]

sounds normal to me

 

[JCell]

sounds normal to me

even the idle?

 

[nate0123]

yea it will occasionally bog while the fans are kicking in, it's nothing to be alarmed about

 

[JCell]

cool, annoying, but cool

 

[digitalricepape]

happens to me as well .. never stalled though so i guess its a normal thing

 

[JCell]

i've stalled....

 

[nate0123]

my car has never stalled

 

[JCell]

weird thing is that she has never done this until 2 weeks ago, now she does it non stop

 

[nate0123]

failing cat?

 

[JCell]

true, the cel fix is probably ******* with the ecu, and the ecu doesn't like it

 

[ebmp5]

me too

but never stalled so far now wit the awr mounts it does it alot more

 

[Mazda P5 driver]

First, when I start it when it's already warm, it starts right up, but then the RPMs fall to 450-500 RPM and it shakes for a second or two and then bounces back to about 750 (where it's supposed to be). I've hit the gas more than once when it does this because I think it's going to stall. It hasn't yet, but I'm not sure if it wouldn't have if I hadn't helped it along.

It's normal for our cars but shouldn't be. Mine hasn't done it in a while but was constantly. I think it's related to the pathetic EGR problem.

 

[Mazda P5 driver]

i've stalled....

me too. about 3 times or so now. Even while parked it almost shut off. One day it tried to shut off about 3 times as well in less than 5 minutes.

 

[Action Jackson]

I thought it was the EGR valve too. Cleaning that may help.

I also had a leak in the intake manifold gasket. They were the crappy paper ones that come with my Outlaw Engineering Spacer. I had the dealer remove those "gaskets" and put in OEM's on the spacer. No problems since.

I've read that if the gas cap isn't on tight, rough idling could happen [at least on late model Civics and the B15 Sentra series].

I was told that our car really shouldn't stall b/c the ECU would try to prevent that. I did get a CEL b/c of the spacer gasket problem, but it never stalled.

 

[GGKAuten]

Oh man this post is right up my alley. Althought I think my cases have been a little more dramatic.

I bought my car brand new with 12 miles on it. Two months after having it my RPMs starting dropping for no reason in idle. I thought it a bit odd but just figured it was the engine breaking in. 2 days later it stalled on me right as i took my foot off the break and was getting ready to accelerate.

Took it to the dealership and they tried to accuse me of taking out my spark plug in coil 4 and messing with it then putting it back in. As you can imagine that didnt go over well with me after having dropped 17g's cash for this car and not even having opened the hood since I bought it. So they claimed to fix it and I went on my way.

Everything seemed fine for about a month then it started doing it again. This time I thought maybe it was because I was using the "Sport Mode" on my automatic transmission and it didnt like me. Stalled out twice while on the way to the dealership. Again the spark plug in coil 4 was destroyed and again they tried to accuse me of messing with it, or someone "playing a prank on me". I wouldnt know how to take a spark plug out if my life depended on it, let alone one of my friends. So again I bitched them out for making such accusations, they "fixed" it again and I went on my way.

Again everything seemed fine...for about another month. Stalls out on me again after RPMs bucking all over the place, just dropping and chopping all over the place. This time it even happened when I was driving at like 3500 rpms i could watch the needle jump everywhere. Took it back again, this time I thought maybe the Cold Air Intake I had just put on was causing the problem. I get there and again they tell me it's fixed, they avoided accusing me of anything but this time asked if I had washed my car lately, and that water might have gotten down in the spark plug housing and wore out the spark plug. Coil 4 AGAIN!

So I go on my way quite pissed with my car and everything seemed fine for about 2 months this time. Then in the middle of the highway my RPMs drop from like 3600 to 1000 and then back up to 2700 then back down to 800 then back up and so forth so I had to immeditately dive between two semi's to get off the highway because my car would no longer accelerate and the fastest it could get to was about 10 mph. Then it just wouldnt go at all so I had to call Mazda Roadside and get towed to a dealership. Again they couldnt give me a real reason for why the car was doing that but told me it was fixed. If you cant explain what the problem is how can you claim you fixed it? Anyways I again went on my way.

THE NEXT MORNING on the highway trying to drive home, exact same thing happened. No power to accelerate engine bucking all over the place like a rabid bull just going friggin hay wire all over the place. Again I get towed to a different dealership about 150 miles from home and this time they tell me a brass screw fell out of one of the butterfly valves and ripped up everything in coil 4 AGAIN.

Now my question is, if this screw caused the problem, how could it fall out twice and do the same thing twice when they didnt find that there was a problem with the screw the day before when it was at the other dealership? Again the problem was found in coil 4. The dealership cannot tell me why it is happening, nor what could possibly cause it, but they told me time and time again it was fixed and wouldnt happen again. Now I am sitting here and it is happening again going back to doing what it was doing the first 3 times, now I have to worry that it is going to break down like it did the last two times. Fortunately for me there is this beautiful little thing called the LEMON LAW. So I told them they have one last chance to solve this problem and if it isnt for sure fixed this time then they had better have the paper work ready to go cause I would not be getting back in that car again.

So I warn you, if your engine is bucking or your RPMs are dropping drastically without explanation, you better get your ass to the dealership before the damn thing breaks down. Tell them to check out the Coil Packs, that seems to be the recurring trend with mine, specifically the Coil pack on cylinder 4.

Food for thought.

 

[Action Jackson]

Ouch. That's a pretty messed up car.

Which one is coil 4? closer to the driver or passenger side?