Contour Enthusiasts Group Archives Forums General Troubleshooting Intermittent funky idle

Hi all,

Someimes (every couple of weeks) when I am at a stop light, my idle will drop, then rise, then drop, and sometimes stall. This is easily stopped by tapping the gas pedal and raising the rpm, but I would like to know the root cause. If anyone has any experience with this little idiosyncracy, please pass along some info. Thanks!

try injector cleaner through gas tank or complete fuel sytem cleaner/ and try changing gas fuel filter

I have the exact same problem. My dealership has installed a little "black box" recorder into the car which I press whenever this idle pulse occurs. I will reply here once I get some answers.

We find that our SVT will typically do this when the tank is less than half full. When does it occur for you?

Yeah, It shows up on mine occasionally as a 550 rpm idle speed or a stall usually on a hot (85 dg) day after a fast Interstate run or stop and go traffic for 20-30 minutes. A/C has been off every time it happens.
I still have the underhood liner on the car and all the rest under the hood stock except for running the Orange colored coolant. Oh yeah, the car is black in color and has 49,800 miles on it.

I ran some Techron fuel injector cleaner in it and cured it for awhile...but comes back every so often during the summer.

My diagnosis, a guess really, is that the fuel may be boiling slightly causing a drop in fuel pressure. This is with 92+ octane, but not sure it makes a difference in this case. Bottom line is that these SVT motors run HOT and I believe it to be heat related. Live with it. HTH.

ZZZ.

I own a 98 black SVT with 52000 miles on it.
I have the same problem, rpm drops to below 500 at stop light, then shoot up to 1000 then down to normal ~600.
(I know my idle is usually lower than 750 +/- 50 spec)

Since someone here said it is related to the heat, I think it's somewhat. However, I recall that mine has been doing this regardless how hot the weather is.

I'm thinking it's more related to IAC valve. I cleaned it with TB cleaner once, but it seems to be gotten worse after claeaning. So i'm planning on replacing IAC valve soon. I'll let you guys know after replacing the IAC

Just got my SVT back from my Ford Dealer. After interpreting the data from the "black box", the Technicians determined it to be a slow response idle problem. With that they replaced the IAC valve assembly (FP# CX-1707). I am told this is different from the IAC Valve which they previously replaced. That replacement did not cure the idle pulse/stall. I will post again in a couple of weeks letting you all know whether this was a fix for me.