I'm idling at about .3-.4.. theres also a vibration coming from behind my pedals as well. The vibration disappears once you rev a little bit higher. Is this normal on a prelude?

 

mine idles at 600-700, slightly higher when AC is running.

300-400 doesn't sound normal at all. i also have a 1997 lude. too add to the frustration, there's no real sure way of adjusting your idle without reprogramming the ecm either.

 

idle screw? I know there is one.

 

there is an idle screw on the throttle body, I just swapped my throttle body off my 97 h22a4 on to my buddies jdmb16 sirII motor, and I brought the idle up with it

 

check for vacuum leaks

 

check for vacuum leaks, that could have cause your idle to drop some, but if everything seems fine, then adjust the idle screw on top of the throttle body... The reason you are getting vibrations behind the pedals when it idles that low is because the engine isn't getting enough air and it is bogging...

 

You have 3 items to examine first:

The guy who mentioned vaccum hoses made a good and educated comment...just remember that an improperly connected vaccum hose can be just as much of a problem as an unplugged one. One hint is to double check areas where multiple hoses connect to a metal junction area....getting connections wrong there is easy (check near driver's side shock tower...)

Next is ignition timing...if vaccum hoses are OK, check ignition timing and rotate distributor as needed.

If hoses and ignition timing were OK, did you recently have your timing belt changed or removed? If yes, there is a very good possibility the belt was re-installed with 1 or 2 teeth off the mark.

If the timing belt was removed at some point, chances are the balancer belt was too. If the guy who replaced it was not explicitly aware of the balancer belt installation procedure, I can guarantee you it was not installed correctly and this could (partially) explain the rough idle...part of the reason it would idle rough is simply a due to the low idle speed.....let us know what the final solution was.

 

I have the exact problem too.... and i noticed it after my timing belt is replaced........

how do you check for vacuum leak??

 

Dan, on a '99 lude I would doubt very much that there is a vaccum leak caused by deteriorated hoses so in your case, do a visual inspection of all hoses making sure they are "pushed in all the way" and not pinched or cut at any point.

With good lighting, use your hands to squeese and bend the hoses looking for damage.

Most importantly, get a vaccum diagrahm and ensure that the routing is correct.

Whoever worked on your car last could have easily make a mistake.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Silver Bullet &raquo;</TD></TR><TR><TD CLASS="quote">You have 3 items to examine first:

The guy who mentioned vaccum hoses made a good and educated comment...just remember that an improperly connected vaccum hose can be just as much of a problem as an unplugged one. One hint is to double check areas where multiple hoses connect to a metal junction area....getting connections wrong there is easy (check near driver's side shock tower...)

Next is ignition timing...if vaccum hoses are OK, check ignition timing and rotate distributor as needed.

If hoses and ignition timing were OK, did you recently have your timing belt changed or removed? If yes, there is a very good possibility the belt was re-installed with 1 or 2 teeth off the mark.

If the timing belt was removed at some point, chances are the balancer belt was too. If the guy who replaced it was not explicitly aware of the balancer belt installation procedure, I can guarantee you it was not installed correctly and this could (partially) explain the rough idle...part of the reason it would idle rough is simply a due to the low idle speed.....let us know what the final solution was.

</TD></TR></TABLE>
I'll check the first two out tomorrow.. I havent changed my timing belt since my car is is only a 99 with 50k miles.

 

a vacuum gauge.

 

sometimes it can even be a large current draw that you only notice when stoped, like a big amp and a older battery... just a idea

 

all these suggestions, very very good....especially the balancer shaft belt...I researched it and found out there was a way completely different to what I thought was right, or at least close