Idle question

[henry]

Hello,
My FI does not maintain Idle in cold start, and if I raise the RPM, to 5.000 for example, when warm up it goes up to 10 to 11.000???

[rlux4]

Did you do anything to the car just before this started, or has it been doing it a while or just start doing it?
The components involved in cold starts are the thermo/time switch, the cold start valve, the temp sensor in the coolant T, the aux. air valve and to a lesser degree the temp sensor in the AFM. Ignition timing can also be an issue. You can check the thermo/time switch by pulling the connector at the cold start valve and putting a noid light on it, see if it stays constantly lit for 6-8 seconds or so. The cold start valve can be checked by pulling it and start the car when cold. Point the valve into a container and crank the car, see if it sprays a good steady mist.
The temp. sensor in the coolant T can be diagnosed by putting it in warming water, the resistance should go down as the temp raises: 7,000-12,000 ohms at 14°, 2,000-3,000 ohms at 68° and 250-400 ohms at 176°.
You can also lie to the ECU by putting a resistor of about 350 ohms in the connector for the temp sensor.
Brad Artigue has a good FI tune up guide in his "Fiat maintenance and modification manual". You'll find it with a lot of good FI info at: http://www.artigue.com/fiat/tuning-book

Ron

[henry]

Thank you very much, great help, I'll start checking.

[76was124]

I hope its okay to hijack an old thread, but figured the information might as well stay together.

I have a somewhat similar problem (although haven't adjusted the idle or gotten to a warm engine state yet)....the car starts great and purrs for about 3 seconds around 1800RMP and then stalls, or stalls immediately within the 3 seconds on giving it throttle. Is it safe to say its still a cold start circuit issue, or should I also be checking fuel injectors at this point ?

Some background:
The car is an 82 FI 2000, has undergone valve job and engine rebuild, so this is the 1st time start up since then, and it has been sitting 5 years since the engine was rebuilt, and probably another 4 or 5 since it last ran.

I before I started the tear down, I did run gas stabalizer through it (at 10 years later though, if the injectors aren't fouled, I might be a case study for the stabalizer manufacture ), I had also drained nearly all the fuel from the system. I'm expecting the FI need cleaning too, but was pleasantly surprised it started at all when I cranked it yesterday, so before I yank the injectors, I want to be sure I have everything else working correctly. I'm pretty sure I have the firing order correct, and timing close enough in that the 3 seconds of idle sounded and felt pretty smooth.

I'm thining its the thermo timing sensor, but didn't know if there other things I should check first based on the specific symptoms I described.

Thanks for the help in advance.....love this forum.

[76was124]

Bump

[rlux4]

Unless it's pretty cold where you are the thermo-time switch isn't going to play a very big roll in getting your car to run good. The car will start without it, but if it's cold out it may run rough for a few seconds. Injectors that have sat for that long are almost assuredly stuck. Plus it's a good bet that the injector seals have dried out and gotten hard, so it would be a good idea to replace them anyway. At that time, with the injectors out you can crank the car and watch how they act. They should squirt a good, fine mist in pulses.
Ron

[76was124]

Okay, so then the cold start valve providing 3 seconds of fuel is normally long enough for the fuel injectors to kick in? Or do I have a misunderstanding about the cold start valve too and the injectors provide all the starting fuel except in the cases of very cold conditions?

[rlux4]

On my car the cold start valve shuts off as soon as the engine fires up. It's very warm where I am. I haven't checked it in the winter when the temps can get down to freezing, but I plan to, just out of curiosity. I'm betting that if I disconnected my cold start valve the car would start and run fine in these 100° temps.
Ron

[76was124]

At 100 degrees you are probably right, wouldn't need the cold start valve. I read somewhere it kicks in when the coolant temperature is below around 95 degrees. The manual from the link in an earlier reply in this thread says it should run 2 to 8 seconds. So that pretty much confirms it, my 3 seconds is within that range, and as you suggested next step is to service the injectors.
Thanks

[RRoller123]

Just FYI. My 80 FI wouldn't start a short while ago, kept turning over (engine cold). It has always started fine. Realized I had left the CSI disconnected from some maintenance I was doing earlier. Outdoor temperature was about 80F. Mine clearly needs the CSI working at all temps, but I can't say this is normal for the FI cars.

[76was124]

Makes sense I think at 80 degrees (with a cold engine) CSI is needed.
Thanks

[bradartigue]

Just FYI. My 80 FI wouldn't start a short while ago, kept turning over (engine cold). It has always started fine. Realized I had left the CSI disconnected from some maintenance I was doing earlier. Outdoor temperature was about 80F. Mine clearly needs the CSI working at all temps, but I can't say this is normal for the FI cars.

If your car needs the CSI working at all temps then your thermo-time switch is crapped out and you are primarily running off the cold-start. I can't imagine a car like that running very well, the main injectors would hardly pulse and the #1 plug would be fouled worse than the rest.

At 80 degrees the CSI won't fire for long at all. It is necessary but not for continuous operation.

[76was124]

Not sure, but I took his comment to mean "needed at all temps to start"

[RRoller123]

Correct. Injectors and rail refurbished, car runs great. Just needs the CSI to start when the engine is cold and the outside air is 80F.