datz

ok i am sick of the idle issue im having. its a 1990 gxl completly stock, it starts cold and warm fine, when on the throttle it drives fine, but wont idle below 1100-1600 (occasionally it will idle at 300-800 at red lights, ect.)
i took the intake plenums/manifolds off. i think its a combo of sensors and vacum leaks that are causing my high idle (1500 cold or warm). the bac, aws, tps were bad so i replaced them, the water temp sensor is fine the afm is fine, ive cleaned and adjusted the tb acording to the fsm. so im replacing the three gaskets and oring on intake manifolds/plenums, gasket for bac, vdi, ive replaced all vacum lines and fuel lines(it has fine fuel pressure acording to the fsm)secondary fuel injector lower gromets and upper orings. due to the car not running cause all this i cant get in the pass. door to check the ecu wiring, connectors, grounds, ect.

is there anything else anyone can think of that i overlooked to combat this problem. if i cant fix this problem i will probably continue replacing all kinds of things and crossing my fingers.
please help.

RotaryRocket88

iTrader: (7)

Is the thermowax separating from the cam when warm? That can keep the idle from settling down. 300 RPM is about to die, so I think I'd suspect electrical or mechanical load causing that. The ECU is supposed to compensate with BAC air in these situations, but poor grounding throughout the car can be too much for it.

datz

ya the thermowax does push the cam so the roller seperates

i previously replaced all fluids, sparkplugs, tb(adjusted propperly), and tps.

jjwalker

Check your leading plugs. One of the leading plugs on my front rotor lost the anode insulator piece (it broke off and I assume went out the exhaust). It idled just as you described. I replaced the plugs and it idled high until i readjusted the idle screw again afterward. In my case, I had adjusted the idle screw to correct the funny idle and when i actually fixed the root problem, it made my old adjustment now incorrect and I had to change it.

HAILERS

With the cam and roller seperated, the primary clearance should be what is seen in the attached jpg.

If that is so, then you might have a vacuum leak or vacuum hose put on the wrong place.

Or disconnect the BAC and see if the rpms go down. OR jumper the initial set coupler and see if the rpms go down.

Or try this. With a fully HOT engine, hold the brakes on. Then with engine idling, put the car in first gear and slowly let the clutch out enough to drop the rpms well below 900 rpm. Then let off the clutch and see if the rpms remain below ??? 1000 rpm or not. I'd do this suggestion first.

datz

thanks i will try, just curious what will this procedure do( i want to know how and why everything works on my car so i dont pay people a buttload of cash to fix somthing.)
bac disconnected or not it makes no difference, the primary valve clearence is about .6mm, the idle screw on top of the tb does not change rpms either.