328 idling problem

On the US version - there are two hoses coming from the fuel distributor. one goes to the air bypass valve that is mounted under the coolent tank, and the other goes through a fitting with a bolt in it. That bolt is how you adjustthe idle.
Euro car may not have this? If not, I guess you adjust the idle with the throttle plate by-pass. It is on the bottom of the throttle body.

BUT the thing is - you shouldn't have to change the idle setting. Something else went wrong in the car. And bumping up the idle is just masking the problem. It is better to fix the problem.
Some of the start-up things, like the air by-pass, cold start valve, warm-up regulator - none of these (if not working) should cause it to stall.
So I don't know where to start. I'd probably take the air filter off and check the fuel metering plate. You can push on it a little - it should have a dampening type resistence to it. If dirt got in there and is holding it open- that could do it. I'm just going by experiene on that one - I had an air injection check value go - part of its flap burnt up and came back into the air box - and then got caught on the metering plate.
Sorry couldn't help more - I am just trying to contribute what I can.

 

Paul -- Please describe the problem a little more. When you say: "It will not maintain its idle when warm, dropping to 500rpm and then stuttering to a stall." does that mean:

1. As soon as it is warm, the idle is always low/stuttering/bad, or

2. When warm, and during decelleration to a stop (i.e., the throttle plate fully closed and vehicle speed decreasing), the RPM undershoots past the 1000 RPM down to the low (500) RPM (and sometimes stalls) when you push the clutch in?

 

Check that you have spark on both banks of the engine when she is warm. Have an assistant try to maintain an idle, and remove an ignition wire from the plug when the car is running. Do one bank at a time. Complete remove of the wire is not needed. Just lift it enough to hear "snapping" type noise. If you do not hear the noise..the investigate further

 

Paul -- Definitely confirm spark presence (or not) per Tom's suggestion when the problem exists, but if are you saying that cold-running is good/perfect, one other clue might be "when" the problem starts to occur. Does it

1. Always occurs at the same coolant temperature during warm-up (like 65~70 deg C -- the switch over point from open-loop to closed-loop injection), or

2. Does the water temp reach the normal equilibrium (full-warm) and then the problem occurs shortly thereafter?

 

Thanks for answering Paul, but I shouldn't have even brought up the open-loop vs closed-loop operation issue -- I forgot we we're talking about a standard/Euro-version (no Lambda) 328.

But your response sure seems to describe something more likely ignition-gremlin-related as Tom suggested rather than something injection-gremlin-related -- good hunting...

 

plug extenders? Yank the plug wires and check for holes burned through the plastic pieces that connect the plug wire to the plug.

Alternatively, pull back the boot on the spark plug wire sealing the well and when it's dark you'll see if arcing is occuring inside the well due to a bad extender.

To stall, though, you'd need a few bad ones.

did the problem start after filling up the petrol?

 

Bingo!! We have a winner.
It showed up after fill up and it has been getting progressively worse with additional fill ups at the SAME station. Sounds like water in the tank.
Disconnect a fuel line, turn the key to the on position and, and pump some fuel into a glass jar. If there is water in the system, it will be very obvious. It will look like clear jello on the bottom of the jar. Bad fuel has been enough to bring small planes out of the sky upon take off.
If you have water in the fuel get it out NOW, before it starts rusting everything in the fuel system. As a precaution I would replace the fuel filter as well.

I may be wrong, but it cost $0 to check and I bet you will find H2O.

Good luck,
John

 

One more thing. If you do find water in your fuel, go down to the station and pump a few gallons into a gas can. Then check to see if there is water in their tanks. If so, they should be made aware so others can be notified.

If you were a hard ass, you might ever have them pay the bill at the Ferrari dealer for draining and treating the fuel system.

Again good luck,
John

 

you'd think if there was something other than gas in the tank you'd have the problem regardless of engine temp, engine speed, etc even at start up....
but who knows.

I don't have a euro model 328, but you said it starts fine when cold all the time?
And then as the temp comes up the idle drops too low? Once that happens does it ever correct itself? In other words when it gets into this mode of too low and idle does it stay like that (in the failed mode)?
when it stumbles and quits does it start up again like it normally did, or do you have to sit there with numerous attempts (does it start back up easily)?
Can you make it idle perfectly if you adjust it with your foot or hand on the accelerator? Does the car drive normally when at operating temp (other than idle)....?

 

I just went through some idle/starting issues on my 328. Its a US spec.
It evidently was a aux air valve and throttle body problem because since I cleanded everything I haven't had any problems and the car idles perfectly hot or cold now.

If on your car if it runs well hot or cold and starts well hot or cold.
And you can make it idle perfectly with your foot. I think I'd take the fuel/air route first.
May be your getting air into the engine that is not passing the sensor plate somehow, check for vacuum leaks. Or the throttle body is just crapped up with not allowing a good idle. let the car warm up and un-plug the cold start injector. I'd look for simple things first. Make sure the intake part of the system is clean, like that sensor plate on the fuel distributor make sure it moves easily. Mine was gunked up because a clamp was loose and air was bypassing the filter a little. I'm not really familiar with euro model cars. Try some simple things first then you might have to have the system pressure checked while in the failed state.

I had to go out and buy a bunch of tools for this antiquated system on my car and ask for a lot of help.
I'm not sure if I read that your problem correctly, the idle issue happens while your into a drive? And not the first time the car comes off high idle when warm after a cold start? Once it idles bad, it never corrects itself. that's good, you'll be able to figure out what's up.