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1988 Spider Quadrifoglio
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Discussion Starter #1
I'm beginning to suspect that my thermo-time switch (L-Jet) is opening too early and taking too long to close again, giving me trouble with warm starts. Has anyone ever had one fail this way?

a related but seperate question: Has anyone ever measured the flowrate on the cold start valve? I'm not sure it matters that much, just curious.
 

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I had mine fail in a similar (I suppose opposite) way as it was causing trouble with cold starts. I verified the CSI was working by unbolting it and having it squirt into a bottle while someone cranked. I confirmed the TTS was failing by following the L-Jet diagnostic guide (around page 25) and measuring the ohms across the two pins, and between ground and each pin. My readings were off, so I ordered one from APE for $40 or so. Solved my problem!

L-jetronic Spider diagnosis (1982-1989)
 

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I'm beginning to suspect that my thermo-time switch (L-Jet) is opening too early and taking too long to close again, giving me trouble with warm starts. Has anyone ever had one fail this way?

a related but seperate question: Has anyone ever measured the flowrate on the cold start valve? I'm not sure it matters that much, just curious.
if you suspect warm starts are being affected by the CSI, why not just unplug it when the car is warm, then see if it starts better?
That will soon tell you if the CSI is causing your poor warm starts....or if something else is the problem.
 

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Discussion Starter #4
It's definitely something in the CSI circuit. CSI fires when the car is cold, and cars starts quickly. If the car has run for a few seconds, is shut off, it does not start easily. I did explore the circuit - the CSI is not getting a ground through the TTS during these hard just-off-cold-warmish starts. I suspect the TTS is opening the circuit at too low a temperature. I think I may have to pull it off the car and bench test it.
 

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if you suspect warm starts are being affected by the CSI, why not just unplug it when the car is warm, then see if it starts better?
That will soon tell you if the CSI is causing your poor warm starts....or if something else is the problem.
Come on Dom. That is too easy! :LOL:
Seriously, great and simple idea
 

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Discussion Starter #6
why not just unplug it when the car is warm
My problem is that the CSI does NOT spray when the car is still cold, but has run for a few seconds. It needs to be cranked for a long time. Hot starts are immediate.
 

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I’m guessing but I would think it would take a couple minutes of running for the coolant to actually absorb any meaningful heat. Have you done the ohm tests from the Ljet article?
My own experiences with symptoms like this is that the spark plugs are unhappy from not getting a good heat cycle from a real drive.
 

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Discussion Starter #8
Yes resistances cold and hot are within spec. It's the transition in between that's the problem. I believe the TTS is supposed to open at 35 °C, or 8 seconds of cranking. I'll have to see whether it's actually opening at a lower temperature.
 

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My problem is that the CSI does NOT spray when the car is still cold, but has run for a few seconds. It needs to be cranked for a long time. Hot starts are immediate.
OK, well that wasn't clear, as you said:
I'm beginning to suspect that my thermo-time switch (L-Jet) is opening too early and taking too long to close again, giving me trouble with warm starts

The TTS can't really open too early. It opens when you crank the starter (this warms up the bi-metallic strip inside the TTS, which makes a contact and grounds the CSI) and when it is cold outside.

but If I get it now, your CSI works with the first cold start. But, you turn off the car after a few moments then try start it again and the CSI won't spray......correct?
Have you physically tested that? (ie. quickly removed the CSI before trying to start it again after the 1st time to see if it still sprays)
or are you only assuming that, because the car is just very difficult to start right after the first cold start?
If you are only assuming, there could be other causes.

If you say the ohms values for the TTS check out fine, then perhaps double check the bosch plastic connectors both on TTS and CSI...clean them up (toothbrush and contact cleaner), make sure the pins are contacting solidly.

as those TTS things seem to be gold dust new maybe remove it and clean the probe (from what I have read they are a real pita to remove as there is simply notta lotta room there!)............could be the probe (sitting in the coolant) has some build up on it.

Thermo Time Sensor and L-Jet Guide Revision

not sure what to suggest otherwise.
 

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Discussion Starter #10
Sorry if I wasn't clear, my bad.

CSV is brand new. I'm sure it's spraying. Thanks for the suggestions. I think I have to remove the thing to test it to inspect and test it properly.

I think I will eventually tear out the L-Jet and replace it with a programmable efi. The rarity and expense of parts is not going to get any better.
 
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