Weird idle.... - Honda Prelude Forum

GoneLudey · 04-05-2002, 04:57 PM

Well, my car has been parked for a few weeks due to a ticket (d@mn cops!), and I've been getting some stuff done while I wasn't driving. I have my timing advanced and a crankcase filter, and I've done the coolant bypass mod since it's been parked. When I got it out in the neighborhood a few days ago, I noticed that at idle, it kept hopping from 1k -1.5k rpm's and back down over and over. So I was outside today and cranked it to see what makes it do it. For 5 minutes, it idled fine; then it started doing it. I put the gas to 4k rpm's for a minute to get it warm, and it quit. What's up? Other than the coolant bypass mod, I've only changed the spark plugs recently. What might cause the idle to fluctuate? It has done it before well after the engine was warm and drivin on the interstate.

'92 Si

ghettoride · 04-05-2002, 07:26 PM

did u use a timing gun? if not thast ur problem if ya did just adjust it back to normal

brendon2k · 04-05-2002, 11:54 PM

There is a reason why coolant flows through the tb. I think that is the cause of the idle problems. Erratic idle is a listed side affect of the coolent bypass mod.

GoneLudey · 04-06-2002, 10:18 AM

It's not the timing, i've had it advanced for a long time and it didn't affect anything. I'm thinking a sensor in there is reading the cooler temp and is trying to warm up. Thx, i'll try putting it back and see if that's all it is

BoostedH24 · 04-07-2002, 09:12 PM

yea that is more then most likely your problem. However the reason why it will idle like that is because there is a vaccum leak. What you do is pull off your intake where it connects to the TB, start the car wait til it gets up to normal opperating temp. Then, in your TB there is like a hole toward the bottem put your finger over it. If the funny idleing stops then its the coolent bypass mod if it still does it then you have a vaccum leak somewhere.
any questions?