How do you adjust the idle speed on a 1992 paseo it idles at like 2200rpm after its warm and if you switch it into neutral at a light?

Answer 1

Check for a vacuum leak.

Is the air conditioning turned on when this is happening? If so there is an air bleed screw/knob that needs to be adjusted (turned in or out) with the A/C turned on to decrease (turn clockwise) the amount of air that is bled into the intake manifold when the A/C is on.

It may also be a bad coolant temp sensor or as mentioned above you may have an air leak.

Is the "service engine soon" light on when the engine is running? If it is then you need to get someone (or yourself) to retrieve the code(s) from the ECU (computer in the car) as that may/will tell you what is not working properly. A Repair manual like Haynes or Chiltons will tell you how to jumper the diagnostic box under the hood so that with the ignition key turned on, will then allow you to retrieve the Diagnostic Codes.

--

I have a '92 Paseo, M/T, it has well over 200K miles... and predictably, some issues with idle.

My troubleshooting here is for a M/T model. If yours is an auto, you may need to troubleshoot the throttle opener module for those cars. You'll need to consult a Toyota or Chilton's service manual for how-to.

On a M/T '92, low or rough idle is much more common than high idle. Unless you've been messing with the idle screw atop the intake manifold, it doesn't just creep up on its own. However, there's one cause of high idle that IS very common: the infamous IACV (Idle Air Control Valve). Even so, it usually prevents the car from starting, rather than causes high idle. But since it's easiest, let's fix and rule this out.

The IACV is a thermally-operated valve that opens and raises idle when the engine is cold, to speed warming of the engine and catalyst. Set correctly, it should top out at 1500 rpm, and as coolant via hoses warms the bimetallic spring inside the IACV, it'll close, slowly bringing idle down to a normal 750 rpm, fully warm.

When they fail, they usually fail fully-open, or fully-closed; yours may have failed fully-open. Here's how to fix it...

-- engine cold and off

-- remove the intake air hose clamps (for the big black hose connecting air filter box and throttle body). Remove the side hose going to the valve cover, and set aside.

-- On the floor of the TB, outside the brass throttle plate, is a big hole about 7 o'clock. This is the air bypass port for the IACV. Spray carb cleaner all around in it, for a few seconds (don't go too crazy, though). Let set for a few minutes, repeat once.

-- while you're in here, get an old toothbrush, and spray the throttle plate with cleaner, and scrub off the dirt and crap on it (open the bellcrank to clean the inside of the plate, too). This can improve response, power and mileage, if the buildup is bad enough. Wipe off any excess cleaner.

-- Reinstall the air hose. There are two arrows on the hose that line up with arrows and marks on the TB and air filter box -- make sure they line up, or when the engine rocks, it can damage a poorly-installed hose.

-- Get in the car, and start the engine WOT. This is to allow air to get in and cut the fumes from the cleaner; otherwise it won't start. You may need to crank for a few seconds to get it to catch. Several cranks at a few seconds each, are better than one long one; save your battery.

-- Is idle still high? If not, your IACV was stuck open; should be better now. If so, shut off engine and go on to the next adjustment... you'll need an inductive tachometer for this one -- can't use the car's tach unless you have no other choice.

-- Get a big paper clip. This is your jumper wire. Look next to the fuse box in the engine compartment (next to the air filter box) for a small brown box; this is your diagnostic port. On the inside of the cover, look for the location of TE1 and E1 connectors.

-- Start engine cold, and rev to 2500 rpm for two mins. You need the engine warm enough to completely close the IACV, but not hot enough to kick on the cooling fan.

-- When the engine it warmed, go to the diag port and jump TE1 and E1. The idle should change and a clicking sound should be distinctly audible. This is normal.

-- Take a blade screwdriver and twirl the idle screw atop the intake manifold, above the TB under the rubber plug, until the tach shows 750 rpm.

-- Remove the paper clip when done, close the diag port cover and remove the tach. Go for a test drive. If it's still too high, consult a service manual.