idle question

[siberiankiss]

i did a search and couldn't find anything, but the past couple days, when i've been sitting at a light, the car feels like it is idling funny. the tach shows the rpms as being steady and normal. i dont know what it is that's making it feel like that...it feels like the car has a faint "shake" to it when im at a dead stop. it's only happened a couple times...any ideas? thanks guys.

[t3ase]

when this happens, do the rpms drop down a bit?

[siberiankiss]

when this happens, do the rpms drop down a bit?

not that i've noticed...i havent actually been able to watch the tach when if first happens, but as soon as i feel it and check, the rpms are normal...so unless it drops down really quick at first, no.

[t3ase]

Proteges do have a touchy idle control that will cause the rpms to drop for a second and then kick back up. However, you can normally catch it in time even if you're not paying attention.

Check for that first. Is your car modded at all?

[JDM Sam]

Sounds like boost leak. check the bpv hose plastic fitting from the turbo outlet pipe into intercooler. That part that is glued and if the glue comes loose it will have leak.

[siberiankiss]

Proteges do have a touchy idle control that will cause the rpms to drop for a second and then kick back up. However, you can normally catch it in time even if you're not paying attention.

Check for that first. Is your car modded at all?

car is completely stock...flashed...but that's it...

[siberiankiss]

Sounds like boost leak. check the bpv hose plastic fitting from the turbo outlet pipe into intercooler. That part that is glued and if the glue comes loose it will have leak.

i'll check that...thanks.

[Leigh]

How many miles do you have on it?
Mine had a funny idle from about 1200 until I topped 2500.

Also - occasionally when the fans kick on it will cause the front end to shudder. Try to listen for when they come on (they're pretty loud - shouldn't be too hard) and see if it parallels the rough idle.

[BremertonMSP]

i did a search and couldn't find anything, but the past couple days, when i've been sitting at a light, the car feels like it is idling funny. the tach shows the rpms as being steady and normal. i dont know what it is that's making it feel like that...it feels like the car has a faint "shake" to it when im at a dead stop. it's only happened a couple times...any ideas? thanks guys.

Mine does the same thing. I'm pretty sure it's the fans kicking on. It puts a load on the alternator, which in turns puts more of a load on the engine. It takes a split second for the PCM to kick the idle up a bit to make up for it. Feels like it's rattling, but it's idling fine.

I wouldn't worry too much about it.

[siberiankiss]

How many miles do you have on it?
Mine had a funny idle from about 1200 until I topped 2500.

Also - occasionally when the fans kick on it will cause the front end to shudder. Try to listen for when they come on (they're pretty loud - shouldn't be too hard) and see if it parallels the rough idle.

i have a little over 5000 on mine...i've been able to notice when my fans kicked on since i've got the car, they make it jump a bit when they turn on and feel like the rpm's drop a little, but this has been different. i'll try to see if it does it while the fans are on if it happens again...

[YellowMSP4KP]

It could be your ac compressor cycling on and off. If you have it set to heater or defroster the compressor will cycle on and off and cause the idle to jump around.

[blu_msp]

My car does the same thing. When I'm sitting at a light the idle drops from 750 to about 400 like its gonna die out. It then surges a couple of times a settles at 750 rpm. It doesn't do it consistently and has nothing to do with the fans, the dealer couldn't verify the problem (ofcourse). I also have a CEL every couple of days and is also inconsistent, no codes on computer when at the dealer. Any ideas?

Thanks in Advance

[JDM Sam]

Lots of possible things. Stuff I would check are: boost leak, vacuum leak, spark plug condition and gap and wires, EGR valve, fuel pump voltage readings, timing, and there are some others (leaking head gasket and camshaft lobes worn). I highly doubt those 2 since it's a new car. I bet it has something to do with the shitty ass fuel map.

[pip7441622]

A leak on the bypass valve hose seems to cause most rough idle issues. Thats been the case on all the times I have had that problem. But this is with a custom intake. However, its just something to check out. Oh and also this 4cyl engine idles pretty rough compared to Honda's 4 cyl (my old 01 Civic), so if the car is new to you, that could be it. Oh and I'm in Houston tooooo!

[blu_msp]

Thanks JDMSam I'm gonna check for boost and vacuum leaks today as well as change out the spark plugs. The car is completely stock save for the "flash". It has 7600 miles on it.