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When is the cold start injector on? by Shonyman32
Started on: 07-22-2013 05:24 PM
Replies: 5 (164 views)
Last post by: armos on 07-22-2013 08:43 PM
Shonyman32
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Report this Post07-22-2013 05:24 PM Click Here to See the Profile for Shonyman32Send a Private Message to Shonyman32Edit/Delete MessageReply w/QuoteDirect Link to This Post
Me and my dad are having an argument about the cold start injector.
When does the cold start injector fire on the v-6?

Is it only active during cranking or does it spray until a certain temp?
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92wastheyear
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Report this Post07-22-2013 05:28 PM Click Here to See the Profile for 92wastheyearClick Here to Email 92wastheyearSend a Private Message to 92wastheyearEdit/Delete MessageReply w/QuoteDirect Link to This Post
Just during cranking
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Shonyman32
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Report this Post07-22-2013 05:31 PM Click Here to See the Profile for Shonyman32Send a Private Message to Shonyman32Edit/Delete MessageReply w/QuoteDirect Link to This Post
Thank you very much.
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92wastheyear
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Report this Post07-22-2013 05:34 PM Click Here to See the Profile for 92wastheyearClick Here to Email 92wastheyearSend a Private Message to 92wastheyearEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Shonyman32:

Thank you very much.




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Marvin McInnis
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Report this Post07-22-2013 07:06 PM Click Here to See the Profile for Marvin McInnisClick Here to visit Marvin McInnis's HomePageSend a Private Message to Marvin McInnisEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Shonyman32:

Is it only active during cranking or does it spray until a certain temp?



1) Power applied to starter (cranking only)
and
2) Coolant temperature below a preset threshold ... below 95° F per the '88 FSM.
and
3) Within a variable time-out limit which depends on coolant temperature ... ~8 seconds max at -5° F per the '88 FSM, warmer => shorter time-out.

[This message has been edited by Marvin McInnis (edited 07-23-2013).]

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armos
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Report this Post07-22-2013 08:43 PM Click Here to See the Profile for armosSend a Private Message to armosEdit/Delete MessageReply w/QuoteDirect Link to This Post
Only while cranking, AND when the cold start injector switch is closed due to being below some temperature.

How long the switch stays closed depends on temperature, as Marvin mentioned. What really happens is that the switch is self-heating. After enough seconds it will heat itself to the point that the switch opens.


I saw a video demonstration on youtube from the owner of one of the fuel injector refurbishing shops. In it, he argued that one of the main reasons for using a cold start injector was that the early style port injectors don't atomize the fuel very well. This does seem plausible, because as far as I'm aware, it seems that when GM started using Multecs is when they also stopped using the CSI.
If it was just a matter of programming the ECM to spray more fuel during cold cranking, that just doesn't make much sense to me. It would be trivial to program the ECM to do that. But I admit, GM hasn't always made sense.
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