Bought a new Prelude.. RPM up and down.. help

hello, I just bought a prelude not long time ago. Recently, whenever I start the car, the rpm will go up and down from 1500-2000rpm, and it never stable. Help please..

I think many people have posted about this. please use the search option

That is an easy fix. There is a sping in your throttle body that just needs some tinkering. I'm not sure how, but my buddy had this problem with his car. Find someone that knows a little bit about hondas. It is a 2 minute fix bud. No biggie.

It might have to do with your distributor cap, i had the same problem in my prelude, the rpm would go up and down, I had the dis cap changed, and the problem was fixed

Dount this is what is wrong with it, but my H23A1 powered 4WS SI Lude had the leaping tach. It slowly got worse until the distributor and coil needed replacing. Just a thought.

That is an easy fix. There is a sping in your throttle body that just needs some tinkering. I'm not sure how, but my buddy had this problem with his car. Find someone that knows a little bit about hondas. It is a 2 minute fix bud. No biggie.

This does work, but only in carbuerated Preludes. In the case of any +92 Prelude (and some from earlier years), Preludes are fuel injected, and this trick does not work.

The surging idle seems to be a common problem in Honda Preludes.

In any case, just type in 'idle' in the search. It's been discussed several times before. Good luck man.

have your idle air controller tested (IAC) this is a common problem in hondas. does it only happen when the engine is warming up?

I am having to replace my "Bypass Control Solenoid valve" on my 88 Lude... Does anyone know where to get one... dealer wants $83.00

I had this problem in my 93 prelude with the engine light was also on. The light came because of a O2 sensor but the revving was fixed by our Honda tech by cleaning out the throttle body and intake. He explained that it extremely dirty in there screwing up a sensor hence the annoying revving. Hope this helps.

I trouble shot the system down to the Bypass control solenoid valve, reset the codes and they haven't come back, solenoid coil is open thus, not energizing the valve, Bypass control diaphram is not getting vacule control from the ECU. I am trying a work around for less than the 80 bucks for the dealer part.

while you could go ahead and start pulling parts off, or mess with the idle control screw, I'd take the first step, and trace all of the vacuum lines that run out of the air distribution chamber (between the throttle plate and the intake runners. Chances are, you have a small crack in one.

With the car running, you can try to squeeze each vacuum line, to see if the idle changes, that might help you narrow down the problem.

You can also get a spray can of carb cleaner, and spray around intake gaskets, or basically anything post-TB right up to the head.

Slowly spray small amt's around the seating areas, with the car running. If the idle changes, and the cleaner is sucked in, you know a leak is present.

If you go thru all of that, and still have no luck, the IAC is cleanable. I'm sure there's info on it somewhere if you do a search for it. preludeonline.com has plenty of info about it. It's probably in the 4th gen faq.

I'd recommend getting yourself a helms manual. They have flow charts for problems, and you could probably help yourself out in less time than it takes for you to type a post or ten. If I had mine in front of me I'd look it up.

-erik

look at the thread below this with a similar problem i decribed how to fix the problem or at least how i fixed mine