Tracing cold start issue

[burlybryan]

'82 FI 2000

I've had a cold start issue since I got this car last year and am working through troubleshooting. Jumpering the cold start injector indicates it works, but its not getting a signal. I pulled the thermo time switch plug and checked for voltage at the harness pins when cranking and there is nothing. From what I've read, the ECU should be sending power to the TSS which then signals the cold start injector to operate. Do I look to the ECU (or chase a wire break) next or would it make sense to start at the ignition wiring?

Thanks for any insight.

Bryan

[majicwrench]

Did you actually check the signal at the cold start valve?? With a noid light?? Or pull it and watch for spray with engine cold cranking??
Keith

[burlybryan]

There is no signal or voltage at the cold start injector harness when cranking. I jumpered a wire from a battery to the injector (negative to ground) and it clicked - and the resistance across the injector pins is pretty much on par with normal (4.5 ohms) - at least from what I know. Prior to this, when troubleshooting in fall, I did pull just the injector and check for spray when cranking, but there was nothing. That let me to test it's wiring - which showed no voltage.

Since the TTS is supposed to be "upstream" from the cold start injector - and it has no voltage at crank, I figure the problem lies beyond the TTS.

Thanks for the thought.

[So Cal Mark]

the ecu doesn't supply power, it switches the ground side. The FI system is usually powered through the dual relay

[burlybryan]

Thanks for correcting me Mark. So would it make sense to trace the wiring back to/through the relay looking for an interruption?

[rlux4]

A lot of time the connectors have been changed, have you checked that the wires close to the TTS are not spliced?
Your confusion about the source of the wire is understandable. The light blue with white stripe wire does come from the dual relay, but it starts at the ECU then goes to the dual relay, then to the cold start valve and TTS. The other wire (light blue with red stripe) is a direct connection between the TTS and cold start valve.
Page 8 of Brad Artigue's electrical diagram has the FI circuitry.
http://www.artigue.com/fiatcontent/wiri ... 0_1982.pdf
Ron

[burlybryan]

Thanks for the reminder about Brads wiring diagrams Ron. I stripped back what appears to be the original wiring hardness cover to the TTS and both wires are white. In any event, there is conductivity between the harness pins on the TTS and the Cold start injector. Also, the injector harness shows about 5 volts when cranking - which I assume should be 12v (?). Maybe it's lower due to association with the TTS - and the fact that it's about 62º in the garage. At rest, measuring the TTS to ground reads 35 ohms.

I did find that the blue/white wire at the A/#1 fuse location has been cut and spliced with 2 segments of lighter gauge wiring. Weird. Gonna get rid of the splice and reconnect the wires directly.

I'm going to check for fuel pressure leaking down when the car sits as well. This could help explain long cranks too.

[dantye]

I just tested the Thermo-Time Switch per the Artigue Manual; engine cold. It says it should show voltage at the cable for 1-8 seconds while the engine is cold. Mine only shows voltage momentarily and none as soon as the engine starts. When measured with an ohmeter (ignition off), the Thermo-time switch shows closed. This doesn't seem right - like it is being controlled through the dual relay by the AFM fuel pump switch, only in reverse, I.e.: whenever the fuel pump is on, the cold start valve off. Anyone have experienced observations on this?

[rlux4]

Dantye, my cold start valve turns off as soon as the engine starts to run. This is during present, moderate temperatures. I've never checked it during very cold weather.
It sounds like yours is doing the same? It's on only during cranking?
Ron

[dantye]

Dantye, my cold start valve turns off as soon as the engine starts to run. This is during present, moderate temperatures. I've never checked it during very cold weather.
It sounds like yours is doing the same? It's on only during cranking?
Ron

Yes. This car is not particularly hard to start, but it just won't run right until the engine is up to operating temp. Until the temp is up, the engine tends to stall when you put a load on it. Runs fine after it is warmed up, whatever the weather. In addition to the thremo-time switch, I have checked for air leaks, adjusted the idle speed and throttle position sensor settings per the Artigue manual. While the throttle position sensor adjustment did help the "back-off from acceleration to cruising speed" issue, the low power during warm-up still exists. Next I will check the actual spray from the cold start valve (although I don't see how that could be the problem) and the AFM ohmeter readings, but I probably will leave it "as is" before I will spend $500 for a new AFM.

[burlybryan]

I've had the chance to test a few components via Brad's handy reference. With my digital and analog voltmeters I'm getting 10+/- volts at the CSI and primary injectors. Steady voltage with no pulse though which could mean ECU. I'm skeptical though because once started it runs great. Pulled the CSI and re-confirmed (I pulled it last fall) no squirt. I'm going to look for a used CSI next.

I can't contort myself to get the DVM on the TTS with the engine cranking though.

[dantye]

... I can't contort myself to get the DVM on the TTS with the engine cranking though.

I have an old style volt meter, and it has small pin leads that will stay in the TTS-to-CSI connector, so I just lay the meter on the windshield wiper and I can see it while I crank the engine.

BTW: You might like this: http://www.meetup.com/Auto-Italia-Minne ... /53397462/

[Dawgme85]

Don't know if this is the same as your issue (i.e. carb vs FI), but my 77 has had a cold-start problem for quite some time. It has a recent valve job, head work, carb work, electronic ignition (Pertronix), etc., and still would take 15-20 seconds of constant cranking (new battery, too) to start when cold. Almost instant starting when warm, however.

Then, last week I was looking over the Service Letters on Brad Artigues website (http://www.artigue.com) and came across one regarding Engine Hard Starting (SL551-20, specifically, Item #8). Part of the suggested remedy was to clean the connection between the battery ground strap and the body. I did this to mine and it appears to have solved the problem. Now, one stab of the throttle and it starts in about half a revolution when cold...

Might be worth a try.

Good luck,

LeRoy

[burlyb]

Thanks for the tip Dawgme85!

I'll check that one again. I've already gone through every conceivable ground on the car trying to track down a lighting issue (finally found - RF, LR running light circuit not connected at fuse box).

I've concluded the cold start injector isn't functioning. Good fuel pressure, power, etc but no spray. Going to send it and the rest of the injectors off for cleaning.

[burlyb]

Resurrecting an old thread. Car still won't start when cold. This time around I've jumpered the cold start injector to the battery and it sprays fine (doesn't fire when cranking though). I tested the temp sensor at the ecu and it reads 5,000 ohms at 40 deg F - which seems in range. Continuity between (new) thermo sensor and cold start injector. Lastly, I measured the voltage to the cold start injector and it reads 4.8 volts when cranking. Apparently, this must not be enough voltage for it to operate. Is this the correct voltage and if not, what should it be?

Thanks as always

Bryan
'82 FI 2000