81 FI Fast Idle 1600RPM out of ideas

[RRoller123]

What happens when you rotate the TPS (after loosening) to the RIGHT.?

[sclebo05]

I'm always hard right for this test.

I pulled my TPS to test, following the diagram on this thread:
http://www.fiatspider.com/f15/viewtopic.php?t=9430

I get continuity between 2 and 18, but nothing, ever between 3 and 18. Also of note, my TPS is flaky, in fact I had to give it a whack to get it working at all. I'm wondering if it's working when in position or the engine is running.

Thinking I should order a new one, just to rule it out, this one is clearly original.

[ORFORD2004]

When you did the timing, you remove and plug the vaccum line?

[sclebo05]

While playing with the TPS, at one point rotating the TPS to the RIGHT started a surging. Looking over other forum posts, that may have actually been a GOOD sign, as I had the throttle bypass screw all the way in and it may have been the AFM door flapping to compensate for a lack of air.

I have everything apart at the moment, waiting for some new screws and hose clamps. I also have a second TPS inbound as my current one seems to have a rather loose center with a lot of play in it.

I'll post any new developments in a few days.

[Squidders]

Two things on this thread. The TPS maybe on its way out so the new one should make a difference and will need repositioning again when installed. Also the Tacho's on these cars are not that accurate so if you are getting 1000 or 1100 RPM it fine.

Also the AFM screw shouldn't be all the way in either.

[PhillySpider]

That AFM sounds and looks suspect to me. Perhaps swap with a buddy to check it out? I've got an extra one, but in Philly that doesn't really help you...

As for octane, my 1980 manual calls for 91...I can't imagine 93 would make much difference and is also what I run 90% of the time. I think Sunoco distributes 91 in stations around here, I put it in sometimes and don't see a change.

[RRoller123]

When you did the timing, you remove and plug the vaccum line?

+1 on that, it could throw the timing off and it may still be too far advanced.

[sclebo05]

OK, it's been almost a year, but I've decided to chase this a bit more. I have the idle down to 1000 - 1200.

The next thing I've discovered is that my vacuum advance unit gives no resistance against air flow. I could play it like a kazoo. Clamping the hose that leads to it yields no difference. Would this leak contribute to a high idle?

[sclebo05]

Clamping the vacuum advance and turning the ignition timing back from 12 degrees to 10 degrees puts me at about 1050 - 1100 RPM. Installed a gasket on the EGR unit (mine was missing). I've made many improvements since I started at 1600. Bypass screw still all the way in.

[tima01864]

I am chasing the same carrot. Mine idles high then cuts out, warms up all is fine. Replaced the sensor on the coolant tee and the pickup and control module as suggested. PIA setting the gap on the pickup, hidden under the vacuum advance. Did all this while replacing the timing belt and coolant. I took off the plenum cleaned it when I had the injectors cleaned and tested. I can adjust the throttle stop, very sensitive too much and the engine just dies, like you the idle screw with the oring is all the way seated. The one thing i noticed is that carbon has formed around the throttle plate shaft, idles on tach around 1000 1100. The catalytic converter is original, thinking that i should replace it, maybe has some effect.

[tima01864]

I think I solved this one on my car. I had the idle down to below 1000 RPM after adjusting the timing after a good run. Went out later the idle was back up 1200 1300 RPM.
looked to the distributor, gap was okay, The trigger shaft in the distributor was binding, sticking. put a little oil on the shaft, Engine started and did not cut out. Initially idle was high but came back down to below 1000 RPM. I may be on to something.

[tima01864]

Did for a while but no luck.

[spider2081]

were the seals on the fuel injectors replaced with new proper sized seals after they were removed for service. Were the seats for the seals inspected and clean before the injectors were reinstalled.

[tima01864]

Yes, The Injector service bought and replaced the seals. Did a complete overhaul on the injectors with new paint, filter basket and pintles. I cleaned the seats as well as i could on the manifold. The engine runs fine, I got the idle down to spec. after cleaning the centrifagle advance, got it working. After a run the idle went back up, The one thing I did accomplish was there was no stalling after startup.

[sclebo05]

Are we sure any of the above is related to my fast idle? Quit hijacking my thread, and get off my lawn you kids!