Contour Enthusiasts Group Archives Forums General Troubleshooting stalling, rough idle, low idle (?)...

Lately, I've been having trouble with the wife's 96 Mystique w/zetec/atx.

First, when I go out for a cold start, the engine will idle at about 1500rpm on startup then work its way down to about 800 in about 1 minute. If I just nudge the gas pedal or turn on the headlights during this time, the engine goes to about 200rpm for about 3 seconds and then dies. Even when the engine is warmed up, if I tap the gas, it almost seems to want to stall out.

Secondly, the engine idles real smoothly at just a tad under 800 rpm when in park. Putting it in any gear causes it to drop to about 500 rpm. I don't think this is a real problem. But sometimes the steering wheel vibrates so badly, it feels like I'm holding a gas-powered weed-eater. If I put my foot on the brake and give the engine a little gas, the vibration goes away.

Now that you have my main compaints, hopefully someone can help me cure (or at least lessen) my problems. My main questions:

Can the IAC valve cause all these problems?

What is the typical idle for these engines?

Will changing to a computer from a newer model Contique help/hurt any (I can get them for about $10 apiece)?

I've replaced the timing belt, engine mounts, oil, filters, checked all vacuum lines. Vacuum is a steady 20". TPS has been changed. Computer was reset after every part was changed.

I'm thinking of doing the IAT mod, but I'd rather not do mods yet (like I said, it's my wife's car ). I've also just spent about $500 in parts to do the belts and related parts. So, I don't want to spent an awful lot more in this car.

Could be the IAC, but more liekly the load sensor. Thats supposed to detect the extra electic load and up the revs

The fact that it follows the cold idle 1500 to 800 warm says to me the IAC is working

Take a look at ly web site below I have a huge section on idle problems in the information pages

I've done just about everything listed on your page, and then some. *sigh*

Where is this load sensor at? Looking through my manuals, I've found that the power steering switch doesn't work like it's supposed to. I'm thinking either a bad ground or the switch has gone south.

The wife found my receipt from the Ford dealer for almost $200 in parts. I'm going to have to be extra careful from now on. hehe

I have exactly the same car your wife has, a '96 with just 64k on it. My car acts the same way. When the car is in drive RPMs are at 500 and if feels as if the car is going to stall.

I had the fuel filter replaced and a MAF sensor replaced. They didn't seem to help. I've been told to replace the spark plugs b/c that may help. I also only use 89 Octane and above.

BTW, what is the IAC valve? Should I be looking into this as well??

Kenneth Clark

This is from a workorder I put in a while back:

Interm when cold, engine stalls after start up...idle drops and fluctuates, then stalls.

What is was doing:

When I started the car, it would start normally, then the RPMs on the tach would fluctuate, then the car would stall out.

What it was(I am not familiar with engines, so I have no idea what all this means) according to the work order:

CAUSE: 2783 42 WDS TEST KOEO PASS DATA LOGGER TEST IAC OUT OF SPECS ORDER NEW IAC

MTDIAG DIAGNOSIS WDS OR CHASSIS EARS 3526 WD94

1 XS2Z*9F715-BA VALVE ASY-THROTTLE AIR BY-
12650D3 VALVE ASSEMBLY (IDLE AIR CONTROL)- IAC (9F715/9F670)- REPLACE

Again, I have no idea what this means, but I know it fixed the problem I was having.

It's the Idle Air Control valve. Basically, it's supposed to let just enough air in to keep the engine idling. It seems like the engine uses more air than the valve is calibrated for, like maybe the idle curve is off. I'm going to try a junker and see if I can't find one that I can try to clean up and possibly dissect to get a feel for how exactly they are supposed to work. I can get the valve off a junker with the entire itake for about $10.

I've got new plugs and wires (plugs gapped a tiny bit smaller than book specs) with no difference. Fuel filter has been replaced, as well as running 2 bottles of Techron through 1 tank of 93 octane.

Do you have the clunking sounds in the rear? If so, the rear sway (stabilizer) bar links have bad bushings. I'm figuring up a way to fix that one on the cheap.

I don't have rear clunking sounds, but I do have something wrong with my front suspension. It feels like the front passenger side is lower than the driver's side while driving it. Outside the car looks normal and my rims and tires are fine. The steering also doesn't feel right. But I don't know what's the cause, and I am learning to live with it.

It sounds like maybe the IAC (thanks for the info) is worth looking into, for now I can live with all the "weird" things my Mystique is doing right now as long as it doesn't get worse (when I got my new MAF, my car kept stalling at Idle all weekend, but its better now) I just hope nothing gets worse

Kenneth Clark