so i thought it was only happening when my ac was on, but now that it's hot out, it happens with the ac off too.. my car idles fine..sometimes 600 rpm but not always.. when i'm slowing down to stop, i'll push the clutch in and the idle will drop literally to 100 rpms, almost die, and then bounce back to regular idle. this only seems to happen when it's REALLY HOT out, and the car is warmed up and been driven for a little while.. what the heck?
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an alternative browser.
You should upgrade or use an alternative browser.
Idle Drop
- Thread starter Birdman_7
- Start date
so i thought it was only happening when my ac was on, but now that it's hot out, it happens with the ac off too.. my car idles fine..sometimes 600 rpm but not always.. when i'm slowing down to stop, i'll push the clutch in and the idle will drop literally to 100 rpms, almost die, and then bounce back to regular idle. this only seems to happen when it's REALLY HOT out, and the car is warmed up and been driven for a little while.. what the heck?
I'm also having the same problem, except for that my car runs better with the A/C on. And it also runs much better when the engine is cold. Not exactly sure what would cause this problem. Help anyone?
Having a similar problem myself...
It makes me think it's more than a vacuum leak since the A/C effects my idle, but I'm not completely sure what it could be.
I'm going with vac leak.
Have you recently changed your coolant?
No I haven't changed it. How would the coolant effect idle?
If recently changed and it wasn't completely bled, bubbles could affect the idle.No I haven't changed it. How would the coolant effect idle?
If you have low coolant or bubbles it can throw off the coolant temperature sensor. Whenever air passes over this sensor, it throws the ECU off and changes the Air/Fuel mixture to try and stabilize itself, causing the bouncy idle
If recently changed and it wasn't completely bled, bubbles could affect the idle.
If you have low coolant or bubbles it can throw off the coolant temperature sensor. Whenever air passes over this sensor, it throws the ECU off and changes the Air/Fuel mixture to try and stabilize itself, causing the bouncy idle
Hmm well I'll have to check that out! It's just weird to me that it idles much better when the A/C is on.
When you turn on the A/C it uses extra power so the engine speeds up (raises idle) to compensate for the pull. So if you're idle is low with the A/C off then you turn the A/C on ECU says hey I've got to raise the engine X amount to compensate, so it makes sense for it to raise to a higher (normal) RPM.
I had the same problem with my Civic, when the idle started acting screwy I would just hit the A/C and it would sort itself out for about 10 min.
If you haven't changed coolant recently then it's not likely to be the cause (unless it's low)
I'd check for vac leaks and maybe cleaning out the IACV.
It's also worth checking the PCV valve (or just replacing since it's only about $3)
When was the last time you changed your plugs?
I had the same problem with my Civic, when the idle started acting screwy I would just hit the A/C and it would sort itself out for about 10 min.
If you haven't changed coolant recently then it's not likely to be the cause (unless it's low)
I'd check for vac leaks and maybe cleaning out the IACV.
It's also worth checking the PCV valve (or just replacing since it's only about $3)
When was the last time you changed your plugs?
When you turn on the A/C it uses extra power so the engine speeds up (raises idle) to compensate for the pull. So if you're idle is low with the A/C off then you turn the A/C on ECU says hey I've got to raise the engine X amount to compensate, so it makes sense for it to raise to a higher (normal) RPM.
I had the same problem with my Civic, when the idle started acting screwy I would just hit the A/C and it would sort itself out for about 10 min.
If you haven't changed coolant recently then it's not likely to be the cause (unless it's low)
I'd check for vac leaks and maybe cleaning out the IACV.
It's also worth checking the PCV valve (or just replacing since it's only about $3)
When was the last time you changed your plugs?
The guy who owned it before me recently had it "tuned" (new plugs, etc.) before I bought it, which was about 3 months ago. But since then I've cleaned the EGR as well as the MAF which didn't help. I've only noticed recently that it ran better with the A/C on since it's been so freakin hot here in st. louis. And my car definitely runs much better cold, but after it reaches normal running temperature the idle is horrible, unless A/C is on.
IllaNoizeTV
Member
- :
- 2003 Mazdaspeed Protege
Try doing a fuel injector, intake manifold and valves, and throttle body cleaning. I should be around $75.00. Sometimes dirt and grime buildup in there and cause the idle to be rough.
hornsfan10609
Certified Mazda Tech
- :
- 2003.5 Mazdaspeed Protege x2
This is usually caused by a vac leak
IllaNoizeTV
Member
- :
- 2003 Mazdaspeed Protege
How do you find where the vacuum leaks are and where are the vacuum lines?
hornsfan10609
Certified Mazda Tech
- :
- 2003.5 Mazdaspeed Protege x2
Vacuum lines run all over the motor to different things, once the rubber gets old they split in random places and cause a leak that must be repaired. Replace with silicone lines, you can find the leaks visually by going over all the lines or you can spray soapy water and look for bubbles while it is idling.
- :
- Mazdaspeed Protege 2003.5
Or light a cig and slowly let the smoke come out of your mouth or the cig itself where the vac lines connect to things and see if any of the smoke gets sucked into a line, that would be where your leak is.. sometimes it works if your lucky and its a big enough leak but its probably decent leak if its causing idle problems.
I took starting fluid and while the engine was cold I started the car and let it idle. sprayed all over the lines and engine. If you spray in one spot and the engine starts to rev up a lot, thats where the leak is. I just did this myself and came up with no leaks. Other than the usual Mazda clunk. THis is the one issue thats driving me insane.
