Hunting at idle

[porschedavid]

1983 PORSCHE 3.2 CABRERA
Started to play up at idle revs go up and down, ok when driving until you stop and it goes back to idle,seems to of started since garage put on new oil breather pipes

[old man neri]

Originally Posted by porschedavid

1983 PORSCHE 3.2 CABRERA
Started to play up at idle revs go up and down, ok when driving until you stop and it goes back to idle,seems to of started since garage put on new oil breather pipes

Maybe they knocked loose one of the many vacuum hoses back there.

There are a lot of 3.2 idle issue threads out there. They usually go something like this:

1) Check for vacuum leaks,
2) Clean out your ICV.
3) Sensor problems - Idle Switch contact, CHT, O2, etc.
4) Base idle/CO adjustment.

[911SauCy]

To check for obvious vac leak, get back there, with car running and fog aome carb cleaner around the hoses etc. If idle changes, further pinpoint that area.

If not, does it do it when idling cold or just when hot? If just when hot, get a 3mm (maybe 3.5mm) and adjust ur idle mixture on the CIS head, hunting IIRC means too lean at idle?

[Jack Stands]

Does the car have the original CIS Injection or has the engine been replaced with a Carrera (1984 on) engine with Motronic injection?

[danco_]

Do you know when the last time your Idle Control Valve has been cleaned or replaced? Idle hunting is a product of unmetered air entering throttle body and throwing the ECU for a loop where it's constantly trying to correct for air flow.

also known as pure anarchy.

[porschedavid]

IT does it hot or cold
i cleaned icv valve
its has the later engine in it.It it the first of the later model

[76FJ55]

I didn't think the 3.2 was available until the 84 model, but either way. When I first got my 84 it had a hunting idle as well. I chased a lot of item, with my initial investigation discounting intake gasket leak. what i ended up finding in the end was that the carb cleaner test isn't effective in finding leaks at the lower intake gasket below the phenolic spacer. It seems that due to the cooling fan pressurizing the cooling shroud the carb cleaner doesn't make it to the lower gasket surface since the pressurized cooling air blows it back up out of the gap between the shroud and intake runner. I had to use the thin red straw on the bottle of carb cleaner and force it down into the gap to get the cleaner to get the areas where the gaskets were leaking.

[tcar]

Originally Posted by porschedavid

IT does it hot or cold
i cleaned icv valve
its has the later engine in it.It it the first of the later model

So an '84 engine (motronic) in an '83 CIS car?

[DRACO A5OG]

Originally Posted by porschedavid

started since garage put on new oil breather pipes

Check to insure they did not place clamp on the breather notch or at the wrong place on the tank. Quite easy to mis-align the breather side when engine is in the car.

[porschedavid]

It was one of the first 1984 model ,it was registered November 1983.
What do you mean by (clamp on the breather notch or at the wrong place on the tank)

[old man neri]

I wonder if they remember to swap over that little metal restricter in the upper breather hose. It shouldn't affect the idle with the oil cap closed though.

[porschedavid]

No they didn't put the restrictor back,i bought a new one and fitted it idle was no different

[DRACO A5OG]

Part #34 is the Breather Cap, one of your Hoses attach to connector then goes to your oil tank connector.

The notch is a round beebee sized detent that sits towards the front, almost everyone misses this one and inadvertently place the clamp right on top of it, no amount of tightening will keep the hose from leaking and spewing out oil to boot.

The other thing is the loverly wrench may have dislodged one of the vacuum lines in the back as well.

Question? Why did you have this hose replaced, did they claim it was leaking?

Brain fart, if it was leaking a previous wrench or owner may have adjust the idle/afr to compensate for the vacuum leak so the new hose may cause idle to be too rich. Just a thought. I have seen allot of this crap going on with my buddy's off idle.

Break a Leg '83 built 3.2 Brother :-)

[porschedavid]

I did think that when they put new pipe on it made the fuel mixture settings out.Bu t i was not sure if you can alter it yourself.Does anyone know how to alter mixture to make it run not so rich

[porschedavid]

What i have also noticed is when i remover oil filler cap idle returns to normal

[DRACO A5OG]

To do it right, you need a AFR reader like a LM1 or LM2 after she is completely warmed up to insure the DME is not going to alter the settings when cold.

Option, you can use your volt meter connected to the O2S to get a voltage reading when hot. Not as accurate but you can get close.

After AFR adjustment you need to jumper the ICV via the BC socket on the left side of the engine bay to set BASE IDLE.

For the AFM, use a 3MM allen key and turn out ( LEFT ) to lean

For the idle 7MM socket, if not chipped, go to 780-800 RPM ICV jumpered.

[DRACO A5OG]

BTW, where you located OP?