My prelude stated idleing at about 500-600 rpm's. It used to idle at 900 rpm or so. My mechanic said it was the TPS sensor, so we replaced it and it didn't work. I also just replaced the PVC valve and I thought that was the problem but the car started idleing low again.
Any suggestions???

 

well first of all i think in that 900 is kinda high, my cars idle at about 500, i think thats actually what they should be at, if my prelude or accord started to idle tha high i would get worried, but maybe im wrong.

 

mine idles around 800-900

 

Any ideas? I also played with the adjustment screw on the throttle body and I thought it helped, but after driving it a bit it went back to idleing low.

 

did u adjust the idle the right way? your supposed to unplug the iacv to adjust the idle

 

Any vac probs?

 

Preludes are supposed to idle at 700.

 

Are you sure? I didn't know you were supposed to unplug the IACV when turning the idle screw on the throttle body.
Also, when I come to a stop, the rpms drop to about 200rpm and go back up to 500rpm where it will sit. It shakes a bit when it drops down to 200rpm.
There are no vacuum leaks what so ever.

 

probably some **** with the IACV. m having the same prob now. try cleaning it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbo Si &raquo;</TD></TR><TR><TD CLASS="quote">Are you sure? I didn't know you were supposed to unplug the IACV when turning the idle screw on the throttle body.
Also, when I come to a stop, the rpms drop to about 200rpm and go back up to 500rpm where it will sit. It shakes a bit when it drops down to 200rpm.
There are no vacuum leaks what so ever. </TD></TR></TABLE>

yes im sure

 

So should I just unplug the IACV and begin adjusting the idle from where it is now, or should I turn the adjustment screw back to where it was and and unplug the IACV and begin adjusting it? Or does it even matter?

 

Mine idles at 500-600 rpm.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bigblockvtec &raquo;</TD></TR><TR><TD CLASS="quote">probably some **** with the IACV. m having the same prob now. try cleaning it.</TD></TR></TABLE>

 

Yes try cleaning the iacv thats what I did and I had the same issues you have and now I idle at 700 constantly.Honda charges about $220. for a new iacv valve.....ouch!

 

yeah im around 7-800 at idle.. cold days.. goes up!

 

Mine does the same. I have tried everything.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Evil Nick M &raquo;</TD></TR><TR><TD CLASS="quote">Any vac probs?</TD></TR></TABLE>

repeat..

 

you prolly just need to clean or replace your IACV. I dont even have mine connected, i just raised my idle a lil bit. Everynow and then it will idle down around 500-600. Usually around 900-1000.

normal idle is ~750.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 98vtec &raquo;</TD></TR><TR><TD CLASS="quote">normal idle is ~750.</TD></TR></TABLE>
, and remember that your stock tach isn't perfectly accurate. If you are above 500 and below 900 at operating temp, I wouldn't worry about it. Farther off than that, clean the IACV.

 

My car idles at 700 during the day and at 900 at night with the head and foglights on. Do you ever get a CEL at all when this happens? Does the car feel like its choking during idle, also does the car seem to bog when you take off. If so it could be a misfire in a cylinder, this could be due to your sparkplugs, wires, fuel delivery, or compression (ouch!). If your symptoms are as discribed above first change your plugs and wires. Test each wire and the distributor and coil that there is sufficient spark. Even though the platinums and iridiums don't require gapping I cant stress enough not to trust it. Measure each plug in the store to make sure the gap is correct if not replace the plug, as much as plat and irid plugs cost you'll do urself and favor by making sure the plugs are to spec. If the problem still persists you will want to change your fuel filter and check the pressure to make sure the fuel pump is delivering sufficient fuel. If this continues you make have a clogged and gummed fuel filter, some recommend taking it into the shop to have it cleaned but I recommend first changing your oil. Then go and fill up the gas tank 1/2 way (Use good gas although some gases are bargins they are crap and are the things that clog your injectors in the first place) and add STP super concentrated fuel injector cleaner (will clean your injectors and intake and exhaust valves). Find a open road or highway and rip on it. Once this tank is empty refuel (full tank) and add one more bottle of STP SCFIC. Drive as you do normally. If it continues after the full tank you may either have a damaged injector or insufficient compression. Before chugging out the $150 for a new injector (more considering you may have aftermarket ones for your turbo setup) do a compression and leakdown test, that will tell you if you have compression lost and where its coming from. If everything checks out then I would buy a new injector (cheaper than if you had compression problems).

 

I agree, no accessories, idles between 690-700 on the VAFC, with the headlights on, or the cooling fan, it jumps up to 780-790 on the VAFC.