TCR11 Tarago Cold Start/Idle Issue

[Michelin Man]

Hey guys,

Just a brief history, car ran fine previous to replacing pipe and 'cleaning' intake. Spark plugs, leads, cap, rotor, fuel filter, oil filter, air filter have been changed within the last 6 months.

I recently replaced the intake pipe on my 92 Tarago, and at the same time I sprayed some Nulon foaming intake cleaner into the intake to try and clean the throttle plate as well as into the intake itself.

After changing the pipe and putting everything back together it was a bit difficult to start. Which I assumed was just the intake cleaner.

However, the next morning it would not start on its own even after 10 seconds of cranking. If you gave it a bit of throttle it will start but die immediately after you release the throttle. If you hold the revs up a bit till it warms up it will idle but at a very low RPM about 550rpm. After it is warm or even slightly warm it will start up right up and idle where it should be about 800rpm but if it's just barely warm it will idle at 550-600rpm. Normally on a cold start it will idle at about 1100rpm for a bit until it warms up.

Driveability when warm is same as before smooth and strong. Only issue when warm is engine won't idle up for power loads (ie headlights), or A/C.

Long story short I took off the IAC cleaned it and checked functionality, gasket could be replaced but still 3 weeks away so used silicone for the time being. TPS tested within spec. During this time I believe I found maybe the only/one of the first issues. The IDL wire had gone open between the TPS and ECU so the ECU didn't know when to open to close the IAC. Ran a new wire and tested all TPS values on the ECU connector side and all was within spec. Now I can hear the IAC activate when the A/C is switched on but the revs drop way too low when the actual compressor kicks in. Somewhere in between there I fiddled with the big idle adjustment screw on the TB.

TL;DR
*Replaced cracked Intake pipe/sprayed nulon foaming intake cleaner into intake with TB wide open.
*Car no longer starts when cold unless given throttle to warm up.
*Car no longer fast idles (1100rpm)when cold.
*Car no longer idles up for A/C or power draw.
*Warm driveability is unaffected. 
*Found open in TPS wiring on IDL line. Wire has been replaced.
*TPS wiring checks out fine on ECU connector side.
*Replaced IAC with wrecker IAC from a 93.
*Replaced TB gasket.
*IAC now activates (audible click when A/C switched on) but does not idle up, and revs still drop too low.
*Issue still present. 

Let me know what you guys think.

[trentmeyer23]

I would be checking the small IAC passages in the throttle body, just to make sure they haven't been blocked by some dislodged debris; if you have not done so already. Spray some carb/throttle body cleaner through them as well.

[Michelin Man]

hey mate, thanks for the reply!

Where abouts would these IAC passages be? I could only see the small holes for the little outlets ontop of the TB when I was cleaning it before. I did spray carby cleaner in those holes.

Another thing I forgot to mention is I can hear a 'hissing' sound from somewhere with the little cover off. I don't believe I have heard it before. 

I think that hissing sound went away when I turned the A/C switch on and the IAC flap open or closed.

[trentmeyer23]

Some models have it just below the butterfly.

[Michelin Man]

How big is this IAC passage?

Are you referring to the 12mm or so hole that is at 6 o'clock behind the butterfly? I believe that is clean and clear.

[trentmeyer23]

Some Toyota models use a 2-3mm hole, not sure about yours.

[Michelin Man]

Just had a chance to look at it again today and there doesn't seem to be another hole apart from the big one that goes down to the IAC.

I've investigated the hissing sound and it seems to be coming from the small hose that goes to the A/C idle up solenoid. After clamping both lines off the hissing noise was almost gone.

However, even with the line clamped still need to apply and hold throttle on a cold start. I've rechecked TPS resistance values as well as IAC resistance and all are still in spec.