Contour Enthusiasts Group Archives Forums General Troubleshooting Stumble/hesitation after start-up...

Just wondering if anyone has light to shed on my subject. I have a '97 Contour V6 auto. On some days, mostly cold or damp days, immediately after I start my car, the rpm's drop like it's gonna stall but then "it catches itself". The rpm's rise, then the process repeats itself usually 2 or 3 times. If I put the car in drive right away, it does the same thing. The only hint that I have is this: It seems to do it more if I play with the HVAC controls right away. Vacuum problem maybe? On hot days or if the engine is warm (after driving) it doesn't exhibit this problem. Any ideas? Thanks in advance,

Chad

Most likely cause is a sticking IAC (idle air control) valve. Try cleaning it. Clean the throttle body at the same time.

Mine does that too. I'm wondering if theses symptoms are the cause of the IAC.

1. Start Up - Car Idle's at a high rpm 1500.
2. A Brief Moment after Start Up - rpms drop down to almost = dead.
3. Put Car into reverse - rpms drop and then goes up really high
4. same thing for putting the car into drive.

Just yesterday, I came to an almost complete stop and the car apparently lost power. It seems sometimes my powersteering does not work either.

Where is the idle control valve located?

the idle control valve or IAC (correct me if I'm wrong) sits on the UIM (upper intake manifold) right behind the EGR valve. It bolts right onto the UIM and has an one electrical connection.

I have heard a few things with regards to the IAC.

1. clean it with carb cleaner
2. don't clean it at all
3. only give it light taps..?? What with, I dunno
4. clean it with brake cleaner
5. clean it with electrical circuit cleaner..

...I think I would stay away from carb cleaner...main because when you (ie)clean the TB with carb cleaner it liquifies the carbon but if you don't remove it right away, it solidifies again.

I may try the light tapping method and move up the scale from there.

If you remove this, you'll see that its not easy to get at the internals if you spray cleaner in there.

Well, I took off my IAC as indicated in the common problems section of the FAQ by the picture. The news was it was clean! Bad news - I went ahead and cleaned it out anyway by spraying GumOut carb cleaner into the two holes it had. Then I let it sit for a while to dry and put it back on. Now my car starts up at 1000rpms and drops right down to exactly 500. I would let it idle and it would go down to almost 0 rpms... yes 0 zero no typos. Just as it is about to die it kicks back in to 1000 rpms and repeats. I drove it 10 miles hoping it would disappear but everytime I braked or hit 20mph it almost dies. Although it will not or has not died. Then I came to almost a complete stop and the O/D overdrive green light blinked a couple of times for the duration of the red stop light. When I revved the engine it goes back to normal.

Does this mean that I need a new IAC now? Are there any other problems that could cause this?


Here's my car history:
Bad Water pump(broken impeller)... replaced
Bad Speed Sensor(ABS)....replaced
Bad Oxgen Sensors...replaced
2 Precats replaced... 1 main cat replaced(Main cat is not stock...universal).
Clean Throttle Body and EGR Passages.

Any Ideas? Please help...

When mine did that the "Check Engine" light also came on. I found it was the Oxygen Sensor.

If you car is between 45,000-65,000, or 90,000-110,000 or keeping adding 45,000 to one side and 65,000 to the other, then it is most likely the 02 sensor, they fail about every 45,000-65,000 miles.
They arent cheap mine was $180, plus $48.00 to scan the computer, then some $8 shop supply fee, but the guy did the labor for free, it only takes about 15 minutes.

If you dont get it fixed and it is that expect your gas mileage to decrease SHARPLY, I mean badly, they say you can lose to $150-$200 a year in gas, if you have a faulty O2sensor.

Before any of you go messing with the IAC, try the obvious search for a vac leak. Most likely problem for those with these symptoms only when the car is cold.

Next thing to look at is your AIR FILTER. Check it, change it if needed - or even if you haven't in a while. Its a cheap fix.

Anybody getting a CEL?

My car also had the same problem recently,I also focusing on the IAC but that didn't help much so I try cleaning the MAF sensor (using brake cleaner)this morning,just one spread the stalling and hesitation was gone,car was running smoothly for the whole day.

95se mtx