AFM and Idle Issues (With Some Fuel Pump Issues Thrown In)

[bradartigue]

Don't worry about the AFM door, it isn't time to worry about that yet.

The car should idle at 750 RPM with the idle speed screw fully seated - the throttle stop screw sets primary idle (750RPM) and the idle speed screw the final 100 RPM.

[toplessexpat]

.... and also just because the rev counter says XXX rpm, it could be a couple of hundred out either way. Use some common sense when setting the rpm - some timing lights will provide this information too and are a worthy investment (although they won't work correctly with some aftermarket ignitions).

Also - don't under estimate using the ECU pin outs as a diagnosis tool.


A few notes back Brad suggested an ordered diagnosis approach - use it and report back each step!

[KevAndAndi]

Thought I would post an interim update on this thread, which I hope to bring to a successful conclusion soon. With the brutal winter, I did not put in a lot of time in the garage, despite the fact that my wife bought me insulated overalls.

I still need to do an orderly troubleshooting process on the idle, but so far my scattershot efforts have produced some results. Because I found that the clamp attaching the AFM to the air snorkel had some broken threads, and it was not enabling an airtight seal, I bought some new Norma Torro clamps for the air intake system. I removed the auxiliary air valve (AAV) and air snorkel.

The AAV inspection revealed that at room temperature, the disc inside was open as far as the initial, small "pie-shaped" opening. Putting the AAV in the freezer did not budge the disc; I believe the cold temperature should have opened the orifice completely. I was able to move the disc using a screwdriver, but it snapped back to the "tiny pie" position. There did not appear to be any crud inside that was restricting the mechanism. Instead, I believe the bimetallic strip is malfunctioning. Putting the AAV in the oven at 150 degrees did cause the disc to close the orifice completely, so it is working in that direction. I tried messing with the adjustment screw during my various tests, but I was never able to get the AAV to open completely. Therefore, I left the adjustment screw at a setting to make sure the AAV closes at operating temperature. I can live with the AAV as is, because the car will virtually never be driven during cold weather. From a performance standpoint, it is far more important to make sure the AAV closes completely. I reinstalled the AAV and while I was at it, replaced the worn short hoses on either side of it with blue silicone hoses. They are a bear to get on, but (or, should I say, "therefore"?) require no clamps.

I had previously done a propane test that had not revealed any air leaks, but since I received the new clamps, it was time to remove the snorkel and inspect it to be sure it was free from cracks. I used a long refrigerator "snake" brush to clean the interior and I cleaned the cruddy exterior, as well. I then used Meguiar's Ultimate Black cream on the exterior, and the result was that the snorkel looks like new. I couldn't find any defects other than at the fitting where the metal elbow tube is attached (the one going to the AAV). The end was brittle, such that trying to re-fit the tube caused splitting of the snorkel's plastic that would have continued had I persisted. I backed off and used a knife to cut a few millimeters of brittle material off the end of the fitting, to get to more pliable material. I was then able to re-fit the tube, and clamp it down, with no splitting.

So, the AAV is back in place, working well enough for my purposes, and the air snorkel is purty and clamped down tight.

I'll post again in the near future to close this thread with the final results of the idle troubleshooting and adjustment.

[KevAndAndi]

I noticed something interesting today. To recap: One idle issue that I've had is that the car starts right up, idles fine for a few seconds and then the RPMs dive, either resulting in a stall or a rough, too-low idle. If I manually rev it during the warm-up period, it eventually will idle just fine.

I have begun to suspect a bad coolant temperature sensor. So I unplugged it and started the car. No RPM dive; idled fine, well into the period when it normally would have stalled. I only ran it for 30 seconds or so.

Does this necessarily mean that the coolant temperature sensor is bad?

[76was124]

I have begun to suspect a bad coolant temperature sensor. So I unplugged it and started the car. No RPM dive; idled fine, well into the period when it normally would have stalled. I only ran it for 30 seconds or so.

Does this necessarily mean that the coolant temperature sensor is bad?

That was the coolant sensor you unplugged? Did you jumper it out or just unplug the connector?

I must be wrong, as I thought the temp sensor, located in the coolant T between the radiator and the head, wouldn't allow the car to start if unplugged? Or maybe that's only when warm without the help of the cold start injector? Was the engine warm when you did that?

[KevAndAndi]

I have begun to suspect a bad coolant temperature sensor. So I unplugged it and started the car. No RPM dive; idled fine, well into the period when it normally would have stalled. I only ran it for 30 seconds or so.

Does this necessarily mean that the coolant temperature sensor is bad?

That was the coolant sensor you unplugged? Did you jumper it out or just unplug the connector?

I must be wrong, as I thought the temp sensor, located in the coolant T between the radiator and the head, wouldn't allow the car to start if unplugged? Or maybe that's only when warm without the help of the cold start injector? Was the engine warm when you did that?

I simply unplugged it with the engine cold. I just did it again to be sure. Started up and idled OK. As soon as I plugged the coolant temp sensor back in, the RPMs dived.

I know I have other issues to sort out with the AFM, etc., but I'm hoping to find out whether this behavior means that the coolant temp sensor is bad and I should definitely go ahead and order one. Or does it not necessarily mean it needs replacing?

[wizard124]

Do a search on the AAV. You have some misconceptions on its operation.

Heating it in an oven, does not ensure its operating properly. The internal coil heats the bimetallic arm that closes the air plate. Check for coil resistance and voltage from the plug.

The air plate doesn't open. It is spring closed against a stop. Prying it will cause you $$.

[76was124]

See this on temp sensor
http://www.fiatspider.com/f08/viewtopic ... or#p142462

[KevAndAndi]

Do a search on the AAV. You have some misconceptions on its operation.

Heating it in an oven, does not ensure its operating properly. The internal coil heats the bimetallic arm that closes the air plate. Check for coil resistance and voltage from the plug.

The air plate doesn't open. It is spring closed against a stop. Prying it will cause you $$.

Wiz, I have done quite a bit of reading about the AAV. I'm confused about the two things you said were misconceptions:

(1) My understanding is that the internal coil of the AAV merely supplements the engine heat that closes the air plate, and so if the plate closes in the oven, the internal coil is kind of irrelevant.
(2) When you say the air plate doesn't open, what do you mean? Do you mean that it doesn't open completely? Some claim that it does (which would make sense given the diameter of the hose). Some say it only opens as far as the first "triangle" (as mine does). Others say it opens to a half-moon shape.

Also, as your post came after my post describing what occurs when I unplug the coolant temp sensor, are you saying that the diving of the RPMs in fact may be caused by the AAV?

I appreciate your comments; just trying to sort out the context and precise meaning.

[KevAndAndi]

See this on temp sensor
http://www.fiatspider.com/f08/viewtopic ... or#p142462

Thanks. There's some helpful info there. Though I note he was having quite a different problem: Unplugging the coolant temp sensor caused his engine to stall, and with the sensor in, the RPMs climbed as the engine warmed.

Anyway, I think I will just go ahead and R&R my sensor.

[KevAndAndi]

Double post deleted.

[76was124]

, and with the sensor in, the RPMs climbed as the engine warmed.

Anyway, I think I will just go ahead and R&R my sensor.

I had/ have this problem too. Didn't fully solve it, but had replaced the temp sensor for lack of any other ideas. For me, it didn't make a difference.

The car wanting to stall between the period the ARR closed, and the engine fully up to temp seemed to be related to the idle dropping momentarily enough to make the dual relay start to drop (below 600-700 RPMs) which created a cascading event of injector intermittent firing and RPM dropping and so on until I gave it throttle, or it stalled.

I saw the most improvement by following Brad Artigue's tune up manual and setting the target RPM to around 1050 vs the factory spec of 950. I still get a slight climb in RPM when Going from warm to hot, but not enough to worry about. The warm (vs HOT) idle stays around 950RPMs after the AAR closes and climbs to 1050 or so when HOT.(190f).

While not being able to get it to spec bothers me a little bit, the fun of driving it and knowing it starts and runs very reliably makes up for a little lost pride. Besides, it is hard to blame the car, as I'm older than the it is and have some peculiarities of my own that I didn't use to.

If you don't have Brad's tune up guide , you can do an Internet search on Artigue and FIAT and you'll find his site or a link to it from a forum thread.

[wizard124]

Do a search on the AAV. You have some misconceptions on its operation.

Heating it in an oven, does not ensure its operating properly. The internal coil heats the bimetallic arm that closes the air plate. Check for coil resistance and voltage from the plug.

The air plate doesn't open. It is spring closed against a stop. Prying it will cause you $$.

Wiz, I have done quite a bit of reading about the AAV. I'm confused about the two things you said were misconceptions:

(1) My understanding is that the internal coil of the AAV merely supplements the engine heat that closes the air plate, and so if the plate closes in the oven, the internal coil is kind of irrelevant.
(2) When you say the air plate doesn't open, what do you mean? Do you mean that it doesn't open completely? Some claim that it does (which would make sense given the diameter of the hose). Some say it only opens as far as the first "triangle" (as mine does). Others say it opens to a half-moon shape.

Also, as your post came after my post describing what occurs when I unplug the coolant temp sensor, are you saying that the diving of the RPMs in fact may be caused by the AAV?

I appreciate your comments; just trying to sort out the context and precise meaning.

Go here, i tore into an AAR: http://www.fiatspider.com/f08/viewtopic ... hilit=+AAR

[KevAndAndi]

I'm reactivating this thread because today we received our car's AFM that Fuel Injection Corp. returned to us rebuilt.

I probably won't have time to reinstall it until next week, so I won't have an answer on whether it solved the idle problems until then. However, merely on an aesthetic basis, they did a great job. It literally looks like new.

This is what it looked like before I shipped it to FIC:



This is what it looks like now:



The whole thing was media blasted, cleaned, and re-caulked. All electronic parts were replaced. The door, which had been hyperextended, now has no gap when it is in the resting position. FIC thoroughly tested the unit, setting the air bypass screw (and plugging the hole to discourage tampering), adjusting spring tension, and fixing the fuel pump electrical contact arm.

Even if the AFM reburbishment doesn't prove to be the "magic bullet" that some have reported when replacing their bad AFMs, it was worth it as the cost was reasonable and now we can be relatively confident that we have an AFM that is good for the next 100,000 miles. (And the warranty is 18 months with unlimited miles.)

Will report back later.

[bradartigue]

I'm not reading if you replaced the temp sensor or not, but if you suspect it at all, replace it. It can cause a lot of problems if it "thinks" you car is colder than it is.