bad idle on cold engine, improves at operating temp. stock 1990 240sx

[Rag]

1990 240sx. stock engine and trans.

i run the engine while cold and it will idle low, bounce, juggle, in other words it will idle quite horribly. it is not uncommon it will stall during this time.

the vehicle warms up and the idle improves, not perfect but an improvement nonetheless. it improves enough so that i can drive it around.

a sensor range chart or a spec sheet would be perfect. i've been told its the coolant temp sensor, that and/or the idle air control motor.

any input would be appreciated.

[vancouverbc]

it is the air regulator or coolant temperature sensor. look up coolant temp sensor in tutorial link in my signature.

re. air regulator. it has to be open to supply extra air when cold. if squeezing it does not cause the idle to be worse when cold it is shut closed. replace


Modified by vancouverbc at 7:24 PM 12/7/2007

[Rag]

it is now sitting in my driveway.

i want to reword my issue. i start the engine and the vehicle will surge from what looks to be 300rpm to about 6-700rpm, most of the time it will stall out.

keep in mind this in on a warm engine.

if i apply light throttle while it surges up and down the idle will improve. from there on in it will idle steadily at 6-800rpm (sort of low for my tastes, normal?)

-also, applying the clutch pedal down to the floor will give me a chatter/grind sort of noise. if i cycle the pedal up then back down it will either change in sound or go away. this happens out of gear.

-driver side wiper arm in-op, it is obviously somehow making contact to moving parts because it moves in rhythm with passenger side

-dome light in-op

-exhaust smells quite rich to me, too rich. smells like "1970 351 Ford being started up in the morning, poof of blue smoke momentarily, knocking", hard to explain.

-engine misfire, could be attributed to idle

if the rain lets up i will tinker with it.

any help appreciated. thankyou

[navysnail]

*the engine improving with light throttle means the problem is likely with the cts (coolant temp sensor) or your idle air controle valve. I think i posted the specs on the CTS up here a while ago, a search might bring that up

*the chatter from your clutch may be your throwout bearing, how many miles are on the clutch and car?

*does the exhaust smell rich when warming up or all the time? our cars are designed to run a little rich at cold start to help warm the engine up to temp

[Rag]

-found the range chart, going to ohm out later tonight.

-roughly 130,000 on vehicle, unknown clutch miles, previous owner apparently recently replaced it, found clutch tool under passenger side seat, clutch engages strong.

-smells extremely rich at all times. no smoke, no coolant smell/taste.

i also found:-tons of play in shifter when in gear (told it was a bushing). b&m apparently makes by far the "best" shifter, but for a price ofcourse.-trouble shifting trans into first. i want to say fiddling with the clutch pedal in the same manner to change the growling/scratching noise made it easier to shift into first.-rear driver side tire has high negative camber.-previous owner changes all 4 hub/bearings in wheel assemblies trying to solve his growling/scratching problem-stock muffler has a rust hole, exhaust leaking at rust hole.

now... the fun begins. point me in the right direction of a full clutch kit and muffler/piping. this is to be my daily driver, i come from the 4x4 hobby and i cannot stand loud exhaust noise, nor do i want to bother my quiet neighborhood.

any issues i should know about before i pull off the trans and inspect the clutch parts?

[Rag]

quick update.

-ohmed out the coolant temp sensor, turned out close to specs. i installed a new unit anyways, no change.

-cleaned the hotwires in the MAF, no change

-cleaned engine grounds, added a ground to the intake. no change.

im going back outside, i might get some ideas. also going to check timing, set it to 15degrees BTDC. see what that does

but a point in the right direction would be awesome.

many thanks
Modified by Rag at 3:36 PM 12/15/2007