1990 cressida over revving. where is idle screw on carby?

thee should be 4 sets of mixture screws on the carby
turn them all in till stop and then screw each one out 2 full turns
you may have use a bit of throttle to keep it idling but it is idles the screw one mixture screw in until the engine prms goes down turn it back out slowly until the engine again starts to die
count the screw turns and turn it back in 1/2 that number of turns
do that for all the mixture screws
have you set the float level correctly
iare there any vacuum leaks

Unless your engine has a carburetor, you can't adjust your fuel mixture. That is done by your cars computer. It analyzes your exhaust emissions and adjusts your fuel/air ratio.
Your oxygen sensor(s) may need to be replaced, or there may be a computer glitch causing the problem.

If this is a carby engine then there is a solenoid at the base of the carby that shuts off the idle circuit when the ignition is turned of. Check for gunk of faulty needle on that solenoid as run on means that there is still fuel /air mixture getting past the carby throttle plate.
and being ignited by hot spots in the combustion chamber.

run fault codes if you can -- if you have a carby then adjust the idle mixture screw and accelerator screw . Check that the idle stop solenoid is operational; and connected.

check that the idle solenoid shut off needle is connected . It is used to stop engine run when the ignition is turned off. If it is not connected the idle circuit of the carby will not function and the engine stops.

The mixture screw is located in a resessed hole just above the therma start plate at the rear of the carby. The rear of the carby faces away from the inlet manifold and you require a special tool to access this adjustment. The other screw adjustments on the carby and linkages are for idle, fast idle, and choke limits including those models with automatic (thermal type) choke mechanisms.
I would advise that if you make any adjustments to the mixture that you have the mixture checked using an exhaust gas analyser.However, as a general rule of thumb, screw the mixture adjustment all the way in until you feel it tighten but DO NOT FORCE IT !! the screw has a delicate needle valve on the end which will be damaged if the screw is forced beyond it's normal length of travel.
Unscrew the mixture screw a total of one and a quarter turns back out and then have the setting checked with a exhaust gas analyser. Too rich and not only is this expensive but will cause damage to spark plugs etc. Too lean a setting will cause a misfire which will damage valves and pistons.

check map senser if thats good check your fuel filter

hi sounds like your engine is surging due to incorrect mixture now your idle screw is on the thottle cable were it connects to the carb and the mixture screw is on the carb body as an approx guide turn the mixture screw fully in then out two and a half turns that should help but y may need to fine ajust later

adjust the fuel mixture to the position where you get the highest rpm at idle...You can ues a tach for this , but if you don't have one, you can do it by ear
please rate this.

If we are talking the three cylinder CB23 engine the mixture screw is hard to get to and has an anti tamper shroud to stop prying fingers.

The Aisan carby is pretty reliable and problems with them on these engines is usually due to improper vacuum hose connections, or improperly adjusted idle, fast idle and deceleration screws.

A/F ratio is around the standard 14.7, but being a carby you will not get consistent mixtures because the jets sizes are fixed . On an EFI engine you can control the fuel flow, but not so with jets.

If you do decide to give your carby a birthday make sure you only buy the Daihatsu genuine, because the after market units have issues with quality. The minor rebuild kit part No 0421287704000 and the major overhaul kit with plunger, needles, gaskets, clips, etc is part No 0421187729000.

If it was me I'd be concentrating on the hoses, the PCV valve, contact points in the dizzy and better spark plugs first. If you want much better idling and a bit better pull get an electronic dizzy and coil from a G200 series Charade.