Perplexing idle issue

[dmg36054]

I've had the 81 fuel injected spider a little over a month now, and typically it starts up pretty well. Not perfectly, but it does start. It runs nice and smooth for several seconds, so I'm assuming the cold start bits are working as they should. At this point the idle drops waaaay down, and it barely runs.

Conventional wisdom here seems to point to the auxiliary air valve. I took it off last night, looked inside, and saw that the opening was a lot smaller than what I was expecting. Further reading on the forum indicates that the opening is normally not very big anyway, so I guess it is OK. I clean it out really good with carb cleaner, and I'm able to move the disk with a small screwdriver, then it returns to its original position.

I throw it in the freezer for 30 minutes, and it opens up considerably. So it is moving relative to temperature. Now I'm not sure if it is bad or not.

I get home today, and try to start the car with the auxiliary air valve off. Completely off. I read on the Mirafiora website that one can do this, with the expectation that it would idle really high. It would never crank. I installed the valve, and it finally cranked. Once the idle started dying down as it always does, I disconnected the hose between the air valve and the plenum, and the engine died. I tried this a few times. So, apparently letting this much extra air in is not a good idea.

I throttled it up some to keep it running (with the air valve attached), until it would stay lit on its own. Once it is warm, it runs OK. So, it is running pretty good, I'm looking around the engine bay, then it just dies. Nothing extraordinary, just dies.

I crank it several times, and it ALMOST starts. I finally get it running again, and I notice the idle is about 1000 rpm, then it goes up to about 1300 rpm for a few seconds, then back down to 1000 for several seconds. Eventually it evens out around 1000 rpm, but at this point I realize I'm not getting anywhere.

What are the chances my auxiliary air valve is bad, even if it appears to be opening and closing relative to temperature changes?

Any ideas about the slightly erratic idle?

I plan on going through the fuel injection system this weekend, looking for air leaks, but after a cursory look it all seems fine.

[124JOE]

is you AMF sticking?or a vacume leak?
ofcorse im just guessing as i have a carb

[majicwrench]

All your idle valve does is open and shut. If it is doing that it is OK. They do not move quickly, any sudden change in RPM is not because of the AAV.
ALL the air going into the intake has to go thru the AFM. The ductwork has to be secure. Even a crankcase leak (like taking the oil fill cap off) will allow unmetered air into the system. Get it all tight.
Gonna be a little generic here, cause I am not familiar with Spider FI, but if it is like most systems, you can adjust the mixture slightly with the big screw on the AFM. It may be under a plug. Back in the day at Nissan, most needed to be richened slightly as they got some miles on them.
Keith

[thefiatek]

Check for vacuum leaks, especially the brake booster line and around the plenum. Don't adjust the airflow meter, they don't go out of adjustment. You could also have a head gasket starting to go between 3 & 4 or a leaky exhaust valve.

[So Cal Mark]

I'd suggest you find a copy of the FI manual and check all of the settings. Keith is correct about the aav, it doesn't sound like your problem. Most of the FI cars I see with similar problems have had someone tinker with the settings, especially the idle stop screw which changes the tps setting

[vandor]

..., but if it is like most systems, you can adjust the mixture slightly with the big screw on the AFM. It may be under a plug. Back in the day at Nissan, most needed to be richened slightly as they got some miles on them.
Keith

The Spider is the same way, there is an allen plug under the round plug. To remove the plug drill a hole in it and pry it out.

To check the Throttle Position Sensor setting, with the engine off start opening the throttle (from the engine compartment). As soon as it start moving, you should hear a click from the TPS. To check that the TPS is working correctly disconnect the electrical plug and with an ohm-meter check for continuity between the center pin and one of the side ones. Now move the throttle all the way open, and there should be continuity between the center pin and the other side pin. There should be no continuity between any of the pins in any intermediate position.

[So Cal Mark]

good procedure from Csaba, but it's important to make sure the idle stop screw hasn't been moved before setting the tps

[dmg36054]

This is why we have such a great forum here, guys. Lots of advice and people willing to help each other keep these things running.

I have Brad's manuals, so I guess my Saturday is now spoken for, except for 2:30 until 6:00 when Auburn is playing football.

I'm getting ready to pull the engine and transmission, clean them up,and fix whatever is broken and/or leaking. I suppose it is better to go ahead and work on this problem now and get it resolved, instead of trying to get it fixed after the engine is back in.

Thanks guys. Hopefully I'll find the source of the problem. These FI systems don't appear to be dificult, but everything has to be right.

[So Cal Mark]

if you're going to pull the motor, I'd do it first. You may find some air leaks or poor connections that can be cured during the installation. While it's apart you might consider having the injectors cleaned and matched and put new seals on them

[dmg36054]

Mark, who can do the injector cleaning? Is it a DIY job, or a "by others" job?

[So Cal Mark]

I use a pro, who can test injector flow and pattern.

[bradartigue]

A few things to consider:

- Don't use the book I wrote just on FI (2003 or something like that). It has some errors but still appears to be floating around. Use the one on my website, http://www.artigue.com/fiat as it has the diagrams and such.

- Make sure everything not FI related is set correctly. The timing has to be right. The plugs have to be clean and/or new. The ignition stuff should be in good shape. The fuel you are using shouldn't smell like varnish (use a full tank of the best fuel you can get from the local pump).

- Read the section on setting the FI idle. It is not a simple turn-the-screw-and-set-the-throttle-plate like on a carb. The primary idle setting is an air bypass on the plenum body, which elevates the idle to a certain amount, then you set the throttle plate. Before doing that I'd clean the heck out of the idle orifice by removing the screw.

- You will bang your head against the wall if you approach the FI system from the AFM. Even what you can adjust on there isn't going to make the car do anything like you are describing. Focus on airflow (leaks, ancillary devices (anything w/vacuum), and the aux air regulator). A bad AAR will cause the car to idle high when hot (stuck open) or low when cold (stuck closed). This is why you tune FI with the engine warmed up if possible, it eliminates the AAR and cold start injector IF they are working as designed.

- Major causes of problems - forward temp gauge, air leaks, faulty injectors, bad AFM, bad fuel pump. Secondary - bad AAR, bad thermo-time switch, bad pressure regulator. Tertiary - bad O2 sensor.

- Bad O2 sensor will NEVER cause the car to run notably bad, not matter what the guy at Auto Zone says.

- Cracked injector seals will give you fits

- Cracked injector tips will give you fits.

- If you suspect injectors then test them in a jar. Should have a nice pattern (this is described in the FIAT shop manual).

- FI motors don't smell like fuel, if so then you have a leak in an injector seal or a cracked injector tip.

My .02 anyway....

[dmg36054]

Thanks for chiming in, Brad. Good to hear from you and nice of you to take an interest. Yes, I have your older FI guide, and a newer guide for the entire engine, with a section on FI. I assume that is your latest one.

I noticed yesterday that the connection of the small hose (that goes to the AAV), to the "big hose" has been puttied together with some sort of rubbery substance. This may not be connected to the problem, but it might, as it could be drawing in unaccounted for air. and long term it can't be good. Csaba is sending me a new "big hose."

Hopefully I can get to it this weekend. The Cayman needs new brake rotors and pads for the front, so that is first priority. Interesting how the rotors and pads for the Cayman cost half as much as I paid for the entire spider.