rpm idle low problem, but only at complete stop !!???

Wingman21

Member
I have the "low rpm at idle" problem since about 3 weeks. It drops at 500 and sometime the car want to die and suddently the rmp goes up again !!! Dealer changed my EGM valve last weekend but it didnt do s*** so Im going again this week. I realized though today that my RPM is low (around 500) only at complete stop !!! When Im at neutral or with the cluth pressed and Im still moving (like when you approach a red light or a stop sign) the idle is perfectly as it use to be, i.e. around 800-900 !!! What can cause this (dunno) !!???

any idea !??

thanks
 
possibly the Idle Air Control Valve getting stuck or acting up. Maybe when you drive and hit boost it unsticks it like when you hit a clogged EGR valve with the end of a screwdriver. I'm guessing on this, any one of a ton of things could be causing your low idle
 
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jersey_emt said:
Is it consistently low? Or does it just dip every so often?

When Im not moving (complete stop) it is always low (around 500), and like I previously said it sometime almost die, but goes up again and settle again around 500 !!!
But I cant find the reason why the idle would be higher when Im moving than when Im stop (dunno) !? The load is the same on the motor, no !? What sensor could the CPU be reading when Im still moving that would change the idle rpm !? Because at the second I stop completly, the RMP drop... its like the CPU is reading the speed or something and when I hit 0mph it drops the idle (screwy) !!!

Any idea ?
 
The load is the same on the motor, no !? What sensor could the CPU be reading when Im still moving that would change the idle rpm !? Because at the second I stop completly, the RMP drop... its like the CPU is reading the speed or something and when I hit 0mph it drops the idle (screwy) !!!

Any idea ?[/QUOTE]

The PCM changes the IACV, it opens and closes off a vaccum leak to control idle. were you talking about the dealer changing you egr valve in the 1st post?
 
maybe it's a vacuum leak? did you change any hoses or install a boost guage or a boost controller...
 
ZenProtege said:
The load is the same on the motor, no !? What sensor could the CPU be reading when Im still moving that would change the idle rpm !? Because at the second I stop completly, the RMP drop... its like the CPU is reading the speed or something and when I hit 0mph it drops the idle (screwy) !!!

Any idea ?

The PCM changes the IACV, it opens and closes off a vaccum leak to control idle. were you talking about the dealer changing you egr valve in the 1st post?[/QUOTE]

But wouldnt the IACV act the same wheiter Im moving or not (dunno) !? And yes my dealer changer my EGR valve last week, but I wasnt the problem.
 
apocman said:
maybe it's a vacuum leak? did you change any hoses or install a boost guage or a boost controller...

I have a boost gauge for a year now and I didnt have any problem till about 3 weeks ago! Anyway, if I had a leak, wouldnt my boost be acting crazy or not be stady while driving !?
 
My idle does the same thing. It will hover around 8-900 until just before I come to a stop. And when stopped it idles at 7-750.

If your tach needle is in the middle of 0 and 1 then you are at the correct idle (7-750). If you take a look at the 0-500 increment and the 500-1k increment the latter is actually a smaller increment. That is the car is not idling at 500 if the needle is in the middle of 0 and 1k.
 
Wingman21 said:
I have a boost gauge for a year now and I didnt have any problem till about 3 weeks ago! Anyway, if I had a leak, wouldnt my boost be acting crazy or not be stady while driving !?

That doesn't mean nothing has happened since then. I justed installed a boost guage and an eletronic boost controller.

I have the exact same problem now, but I know there are a few things I need to do to most liely resolve the issue. Also my boost is fine it just wants to die every now and then when at idle, so I have to do a lot of downshifting to make sure i have enough RPM's while slowing down or at a stop. Then I can slowly let off andf it will stay at normal idle...

1. I need to replace the large hose going to the boost guage and use the proper hose that was meant for the guage which is this little hard black hose, almost looks like hard shiny plastic and is very hard to bend.
2. I need to redo all of my connections and make sure they are on there as tight as possible and make sure I use hose clamps as well.

My friend who has a large amount of knowledge using turbos for many years told me just becuase it's not leaking while at idle or when your revving it doesn't mean that it's not leaking under heavy loads and such...

Agian, remember things can break so something may have happened since you install of the products...

Best of luck...
 
Stormtrooper77 said:
My idle does the same thing. It will hover around 8-900 until just before I come to a stop. And when stopped it idles at 7-750.

If your tach needle is in the middle of 0 and 1 then you are at the correct idle (7-750). If you take a look at the 0-500 increment and the 500-1k increment the latter is actually a smaller increment. That is the car is not idling at 500 if the needle is in the middle of 0 and 1k.

Yeah I noticed that this morning... Im idling at 700-750, but I used to be around 900 when I got my speed. Anyway, if I would idling at that RPM and not stalling I would be OK with that... just need tp find the reason. I think Ill try changing my boost gauge hose this weekend to see if it isnt cracked or something !!!

apocman said:
That doesn't mean nothing has happened since then. I justed installed a boost guage and an eletronic boost controller.

I have the exact same problem now, but I know there are a few things I need to do to most liely resolve the issue. Also my boost is fine it just wants to die every now and then when at idle, so I have to do a lot of downshifting to make sure i have enough RPM's while slowing down or at a stop. Then I can slowly let off andf it will stay at normal idle...

1. I need to replace the large hose going to the boost guage and use the proper hose that was meant for the guage which is this little hard black hose, almost looks like hard shiny plastic and is very hard to bend.
2. I need to redo all of my connections and make sure they are on there as tight as possible and make sure I use hose clamps as well.

My friend who has a large amount of knowledge using turbos for many years told me just becuase it's not leaking while at idle or when your revving it doesn't mean that it's not leaking under heavy loads and such...

Agian, remember things can break so something may have happened since you install of the products...

Best of luck...
Yeah I know things can break, that is the way of life (friday) !!!
Question though, if my boost gauge hose would be cracked or leaking, would my boost be unsteady, or the turbo would compensate for the leaking ?Because, now that Im thinking about it, I think (maybe Im paranoid or something) my turbo is louder after 3000RPM since a couple of weeks, like if it were spinning faster (dunno) !?
Anyway, I think Im gonna replace it just in case, because Im still using the white plastic hose that came with the autometer gauge !!!
 
I have this problem. I'm going to try replace the gasket that connects the intake manifold to the head. I did some work on the manifold a while back and have had idle problems since then, so I think I just didn't get a good seal. I remember reading there was another board member that replaced this gasket and it fixed his problems.
 
peepsalot said:
I have this problem. I'm going to try replace the gasket that connects the intake manifold to the head. I did some work on the manifold a while back and have had idle problems since then, so I think I just didn't get a good seal. I remember reading there was another board member that replaced this gasket and it fixed his problems.

You and I both. I think I'm leaking boost under WOT from that location. Man I dont' feel like taking it off again lol.
 
CustomMSP said:
You and I both. I think I'm leaking boost under WOT from that location. Man I dont' feel like taking it off again lol.
It is quite a b**** to remove. I'm hoping all the experience I've gained from working in my engine bay since the first time I removed my manifold will make it easier. I'm shooting for doing it in just one day this time. (headshake
 
ZenProtege said:
it doesn't sound like you have a vaccum leak then, it should pull 21-22 inches

true, but it could create a leak under pressure and when you let off the gas you suffer the leak at that moment, but at other times it maintains proper vaccum...

just a thought...
 
How many miles do you have? Have you changed the spark plugs recently? Spark plugs at the end of their life will cause the idling problems, particularly on four cylinder engines.
 
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