Sporadic RPM's at Idle in gear with AC on...

Hey guys, been having this problem for a while now. When im sitting at idle, in gear, with the AC on (and sometimes even with it off) the RPM's will jump between 800 and 450 rpm's and my car will shake and feel like its about to die. I just got it back from the dealer for this problem, and a CEL. They replaced my Idle Air Control Valve, and installed a new Charcoal Canister (to clear the CEL) Well, no more CEL as of yet, but the idle problem has not been fixed. I have even tried to turn the idle screw up, and it then idles higher, but when it does drop...it still drops to about 450.



I have read alot about Idle Control Solenoids and things like this, or solenoids on the AC that tell the Ecu when the clutch is engaged so it can tell the IACV to idle up. Is there anything like this on our car?



This is driving me crazy, and I had a pretty crappy time at the dealer, it took about 3 weeks before they even took any time to help me, then they just guessed what the problem might be.



Any help guys?

Reply 1 : Sporadic RPM's at Idle in gear with AC on...

How are the basic maint needs looking like plugs, air filter, and such. those can cause your engine to surge also.



I would have thought, much like the dealer you delt with, that maybe the IAC valve was getting a little sticky. Did they clean the rest of the throttle body?

Reply 2 : Sporadic RPM's at Idle in gear with AC on...

Quote:

Originally Posted by HATEnFATE How are the basic maint needs looking like plugs, air filter, and such. those can cause your engine to surge also. I would have thought, much like the dealer you delt with, that maybe the IAC valve was getting a little sticky. Did they clean the rest of the throttle body?

HATEnFATE, I was hoping you'd respond, you helped me alot with some problems I had on this car about 3 years ago. I changed the belt, replaced the spark plugs, air filter, engine oil and filter, cleaned the TB with TB cleaner, and cleaned the MAF sensor with MAF cleaner. all within the past month. It still is doing this surge. Sometimes it even sounds like its camming or something, but most of the time the pattern I notice is this:



Stop at the light, Idle's normal

AC Clutch kicks on, Idles a bit higher

AC Clutch kicks off, Idle falls to normal...but keeps falling until it bogs, then it jumps back up.



Rinse and repeat.

Reply 3 : Sporadic RPM's at Idle in gear with AC on...

This is killing me. $800 worth of repairs and back to square 1. CEL came on again this morning, in the same place it has the past 4 times. A long right uphill curve merging from I-285 to I-20. Only when I'm about 100 miles into the tank.



Took it to Autozone for a CEL check. Getting the exact same three codes that I was getting at the very beginning of this mess (441,442,446)



Hey...what is that little black vertical cylinder that has a small hose coming from either end of it thats right next to the air box? One hose goes to the TB, the other one comes from up under the car. When I got the car back from the dealer I noticed the wire that goes to the little electrical plug that plugs into that cylinder had been cut re-inserted into the plug, there are also a few electrical tape wraps around it as if it had been cut. If you're wondering how I noticed something so small...I have spent the past month looking under my hood with a magnifying glass because of this problem. Also I took note of that plug and cylinder because I remember reading on a forum that a guy had the same 3 codes I had and his problem was that the wires on that plug had pulled off.



Anyone know what that thing is?

Reply 4 : Sporadic RPM's at Idle in gear with AC on...

I'm talkin to some techs about it, one of whom has an xA. I'll get back to you......

Reply 5 : Sporadic RPM's at Idle in gear with AC on...

Quote:

Originally Posted by HATEnFATE I'm talkin to some techs about it, one of whom has an xA. I'll get back to you......

I found that the cylinder is a Vacuum Control Valve or something like that, from the evap line into the TB. I am wondering if this valve has gone bad. Upon unraveling the haphazardly wrapped electrical tape I found this:



[IMG][/IMG]



Do you see the little crimp on the red wire? Its really lose right there, I can bend the wire at a 90 degree bend on that crimp...wondering if its shorted or what.



Do you know if there is a DIY way to test if the valve is working properly or not?



Thanks so much man.

Reply 6 : Sporadic RPM's at Idle in gear with AC on...

Who did that to your wiring on your xA?

Reply 7 : Sporadic RPM's at Idle in gear with AC on...

Quote:

Originally Posted by HATEnFATE Who did that to your wiring on your xA?

This is how it was when I got it back from the dealer. Also, where that hose is connected to the hard hose on the firewall it was pulled ouut of the bracket and making a terrible rattle when I got the car back, I clipped it back in though.



I just did a test on the valve, its giving 30.9 ohms, I think I read it should be between 30 and 39? When I check for continuity of the 2 wires on the harness, I get nothing. I followed the wire down to where 2 new wires have been soldered onto the old ones and checked the continuity there and got it.

Reply 8 : Sporadic RPM's at Idle in gear with AC on...

So are you thinking the valve is bad or the rewire is bad?

Reply 9 : Sporadic RPM's at Idle in gear with AC on...

Quote:

Originally Posted by HATEnFATE So are you thinking the valve is bad or the rewire is bad?

Well, the valve seems to be giving enough ohms and I just went out and tested continuity between the splice points from old to new wires, and the corresponding side of the plug. Between black splice point and black plug side it beeps. Between red splice point and red plug side it doesn't beep.

Reply 10 : Sporadic RPM's at Idle in gear with AC on...

Last night I cut the red wire at the pinch and saw that the wire itself was recessed into each side of the cut wire covering. I stripped back both sides and put a good solid solder on it, then I taped everything up and plugged it back into the VSV. I pulled my battery wires off and cleaned the terminals for good measure. This morning I noticed an immediate improvement in the idle. I had the window defog on so the AC clutch was engaging. I now get a very smooth, still idle. No crazy movements or knocking airbox at all. I also noticed an improvement in my mileage so far (50 mile drive to work). I will have to wait to see tomorrow morning if the CEL returns, as it usually trips at about 120 miles.



So far though, 2 of 3 symptoms cured!

Reply 11 : Sporadic RPM's at Idle in gear with AC on...

Sounds good....please keep me informed.



One of my techs suggested that you might also test the charge from your alternator. That could potentially cause some of the idle issues if it wasn't working right.

Reply 12 : Sporadic RPM's at Idle in gear with AC on...

Quote:

Originally Posted by HATEnFATE Sounds good....please keep me informed. One of my techs suggested that you might also test the charge from your alternator. That could potentially cause some of the idle issues if it wasn't working right.

Tested the charge on my alt and battery today, both in top condition. The idle has been perfect since I repaired that wire, and I'm 200 miles into a tank and the CEL has not come back.



I THINK I GOT IT :-D

Reply 13 : Sporadic RPM's at Idle in gear with AC on...

Sounds like a winner. That repair job looked pretty shoddy.