Idle Problems

Apr 2nd, 2003, 01:30 PM

Hi. I've tried getting information about this from other sources and have had no luck so i thought i'd try here.
I have a 1987 Sentra with 1.6L and a hitachi Carb. The problem is this. When i first start it in the morning it revs high until it warms up. then while i'm driving if i take my foot off the gas to slow down it tries to die. I have to continually flutter the gas pedal while sitting at a light to keep it alive. I have power. It LOVES the highway. But trying to slow down and continually having to give it gas is becoming a nuisance to say the least. I just purchased this car and the guy who i got it from about 6000 miles ago repalced the engine that was in it with an identical engine..This was an old guy (72) who was pretty exacting. He used color coded speaker wire to mark where the hoses go and i would presume that he did a good job. I'm thinking vaccum leak or something like that? Have tried to adjust idle, sprayed cleaner to look for hoses that made a difference in the idle. Have run out of ideas and can't afford to get a different car. Any help appreciated.
Thanks

OZMAN · Apr 2nd, 2003, 07:16 PM

Usually the most common problem that i get with these motors suffering from an idle problem like that is the V.C.M vacuum control module its located by the passenger side fender well, good luck 9 out of ten times its that valve, like you explained with your idle problem.

Myetball · Apr 6th, 2003, 04:01 PM

The first thing you should do is go out and buy a bunch of vacuum hose and replace every damn hose on the car...one at a time. You'll need a couple different sizes but most of it is 3/16.

From what you described it may very well be a primary vacuum leak. A leak in a hose that comes off the intake manifold.

When I bought my '85 it had a similar problem. Turned out to be a hose running from the carbon canister to a nipple on the lower rear of the intake, small nipple coming off brake booster nipple. Couldn't see it, had to jam my arm down there and fiddle around till I found it. Once I replaced it, it ran like a million bucks...and still does.

Apr 16th, 2003, 06:00 PM

VCM VCM VCM!!!! I hate that thing, mine is unhooked right now, I capped off the lines, of course you will have no "high idle" or cold compensation, but I adjusted the idle manually. Its a bit cold natured now, but all of the indy car idle starts and dying at stop signs went away. Took me a while to get the idle adjusted good. Finnally figured out that the gas pedal inside was sticking too, so I cut the rubber bump stop off and the pedal goes back further, idles great now, and still has same power. Good luck!