Contour Enthusiasts Group Archives Forums Modifications Zetec Maintenance Low Idle

When warm the idle is around 600 RPM which is not too bad in the winter but in summer with the A/C on it is too low. Dealer says it should be around 750 RPM. Also says it cannot be adjusted. All that they can do is run diagnostics to determine which component is not working up to par and replace it. Seems like the long way to go when it is running fine. Plus, dealer wants $110 to diagnose the low idle.

Any comments or suggestions on an easier way to get it up to 750 RPM while in gear. Neutral or Park are fine.

Has it always idled at 600 while in gear?
For instance, mine has always idled at 650-675 when in gear and around 800 in park or neutral.
It's been this way from the very beginning... I even feel that 650 is kinda low compared to my mom's 4 cyl camry which idles at 800 whether in gear or not?

Anyone w/ OBD-II scanner should be able to do the diagnosis for you. I found out yesterday my throttle position sensor is slightly off, but I don't have a low idle. See if any CEGers in your area have a scanner.

What would I be looking for in the OBD-II scanner? I have one on loan that I'm about to return, but I can do some more scans before I return it. I did look at it while I was sittin there in idle (no tach in my car).. 650 - 670 in drive, over 800 in neutral.

What values should I track with the scanner?

I'm assuming all scanners will check sensor voltages, fuel trims, etc. Granted, the one the guy used on my car was an extremely nice one, I'd be willing to bet they all have a diagnostics test they run on the car (how to run it, I'm not sure). If this doesn't result in any errors, try looking at things like TPS percentage. For example, if the TPS is supposed to read 1.00% while at idle, but reads 0.88% (like mine did) you may have located the culprit. Even though mine idles fine, in actuality it may need to idle slightly higher (currently idles around 750). Just the 0.12% it's off could keep the idle 83 RPMs lower than it should be.

Not claiming to be an expert here, but any info I pick up I'm more than willing to pass along

TPS percentage you say? What range is it supposed to fall between? Mine is reading at 19% at idle, in and out of gear...

If I remember correctly, it should sit at a solid 1.0% at idle. I may have mis-read the decimal placing...but I don't think so. Are you sure it doesn't read 1.9% at idle? 19% seems way off...

Yea, it says 19 percent (says percent,not a % sign) TPS, Throttle Position Sensor, Right?

I've re-played the last test I saved, and its reading is that high, the lowest it went was 18.8 and the highest was 21.5...

It's nice to be able to read the values of everything, now if I just knew what they were supposed to be at...

Maybe I'm mis-understanding the concept of the TPS. The way I see it, idle should show a very low position (in the neighborhood of 1%). Full throttle should show 100%. If that's the way it works, I don't see how your car can move unless your TPS is wacky. If you were always between 19 and 21% throttle, mashing the gas would get you nothing and letting off the gas would be like cruise control...you'd keep going!

Again, assuming I have the theory of operation correct, your sensor reading should somehow coincide with other factors involving how the car runs. If your TPS is at 20%, your fuel trim probably won't change much which could have you running constantly lean (or rich), thereby robbing you of power simply because the computer is reading an inaccurate sensor and adjusting the engine according to that sensor.

Does this make sense to anyone?

Just wanted to ask...the 18.8% - 21.x% range was only at idle? I wrote the above thinking that was moving, but if at idle, it would apply differently. Maybe the valve in your TB is hanging...?

Full throttle does not read 100%, more along the lines of 91 - 93. 100 tells the computer that something is wrong and it'll throw a CEL. I imagine that the same is true if it gets too low.