Stalls/dies on return trips

[Button]

Hello! I have an issue with my 1982 FI Spider with symptoms that present in an interesting way. The last two weekends here in NC have been warm and great for cruising, so I've taken the Spider about 30 minutes from home. On the return trip, she gave me the dreaded start than immediately stall treatment. If I started the car and revved the engine, and kept the revs up, the engine would keep running, but letting the revs go below 1,200 or so would lead to a stall. I could get the car in gear and limp home, but if I let of the gas to shift between 1st and 2nd the car would stall.

I have been reviewing Brad's guide (which is amazing), the L-Jetronic guide posted on highperformancestore.com, and the this forum in general. Based on those guides, I'm guessing my problem could come from:

1. Air Leak

2. Bad grounds (I'm not 100% sure I understand this effect or where all the grounds on the Spider are located)

3. Bad sensor(s)

4. AFM Flap issues (I checked this, and the flap seems to travel easily and spring back without problem)

5. Fuel pump (I think this probably works fine since I've been able to drive the outbound journey with no incident)

6. Bad injectors?

7. Bad Auxiliary Air Valve - I pulled the AAV and let it cool for a while. I also cleaned it out with some carb cleaner. Once it was cool it opened up about this wide:



Is this as wide as it should go?

I'm somewhat flummoxed why the car will run ok for 30 minutes, but if I park it for 30 minutes and then try to drive it again, I get these issues. Does that info help point to one symptom or another? Any chance the ignition coil somehow gets overheated (can that even happen?) or there is some other ignition system failure once the car has been driven for a while?

[Odoyle]

Check your throttle position sensor, make sure the sensor is rotated clockwise until you hear a small click. Once you hear that click tighten down the two flat head crews which hold the sensor in place. I was having a similar issue with my 83 and was able to get it to idle smoothly at 900 RPMs after adjusting my TPS.

[wizard124]

From the symptoms you describe, it doesn't point to a coil or ignition problem. Sounds like an air/fuel ratio issue at low RPMs.

Could be leaning out. Look for air leaks/cracks in the snorkel. Take locking pliers and close off the brake booster vacuum line, the AAV line.

Check timing and vacuum advance function.

No, the opening in the AAV doesn't get any larger.

[4uall]

for what's it worth There should be 4. One on inside of each fender, one under dash and one in trunk rear lights

http://www.fiatspider.com/f08/viewtopic ... it=+ground

[KevAndAndi]

Check the coolant temperature sensor, because that's an important one that can cause the engine to stop running.

To paraphrase Brad: Test via connector on ECU - terminal 13 to ground. @68 deg = 2k to 3k ohms. @176 deg = 250 to 400 ohms. If 0 or less, replace sensor. If infinity, check for wire break; if wires OK, replace sensor.

Our car was starting and stalling, albeit from a cold, not warm, start. The sensor had questionable test results, so I replaced it yesterday. I have not yet refilled the cooling system, so when I do, I'll let you know if it solved my problem.

IMHO, if your sensor is 30 years old, it should be replaced regardless of how it appears to be performing. It's cheap and easy to R&R.

[Button]

Thanks for all the suggestions! I think problem one is the air leak caused by my broken air intake boot that you can see in this photo. I feel like a dope for not noticing it right away.



My first step will be ordering a new intake boot because this one is completely broken around the joint that heads to the AAV.

I'm not entirely clear how the car would run reasonably fine for a while with the air leak caused by broken boot, and then suffer the effects of the air leak... but I'm going to fix this first and then see where we are.

The testing procedure for the coolant temp sensor is very helpful KevAndAndi, thanks for pointing it out. I think I will replace this as well because I have no idea if the PO ever did. Is there a good link that describes what this sensor actually does?

[KevAndAndi]

Yep, looks like a new air snorkel is in your future. Also, remove the idle speed screw and check the o-ring. A hard, shrunken o-ring can cause a heap of trouble, idle-wise. You might also want to check and see if the AAV aperture closes when the device gets hot. I confirmed this in the oven. Arguably, it's more important for the AAV to close when hot than to be open when cold.

The CTS lets the ECU know the coolant temperature so that the "brain" can adjust the fuel quantity supplied, which is going to be different for a cold engine than for a warm one. I found that right after starting, when the engine began to stumble, it would suddenly idle fine if I unplugged the CTS. This was suspicious, and it was old, so I replaced it. I also know that there are issues with my AFM, but I'm taking it one step at a time.

[KevAndAndi]

You mentioned having the Artigue guide and the Hiperformancestore article, but if you don't have this one, you should, to complete the collection:

http://www.njfiats.org/joomla/images/st ... BoschL.pdf

[RRoller123]

That is fantastic, didn't have that one either.

[Button]

Somehow I had part of that guide... and I always wondered about the rest. Thanks!!!

You mentioned having the Artigue guide and the Hiperformancestore article, but if you don't have this one, you should, to complete the collection:

http://www.njfiats.org/joomla/images/st ... BoschL.pdf

[Button]

Update: I received a new intake boot from autoricambi.us and installed it without incident. The rubber on the new boot is much more flexible than the old one I removed, which I hope bodes well for its longevity under the hood:



I took the spider for a ride last evening and she seemed to perform well. I did not have time to give a full test from a long journey, but I'm cautiously optimistic.

Flush with the confidence of a successful installation, I decided to use the remaining light to set my idle properly because the spider was idling low. While I was doing that, I discovered that my accelerator stop screw was stripped. Since that is an altogether different issue, I've started another thread on that new adventure.

[Button]

Gave the spider a decent shakedown run this weekend and no symptoms. I'm cautiously optimistic that plugging the air leak and setting the idle properly will keep her running well.

[RRoller123]

I love it when a plan comes together!