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Question about 870 ECM's

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Old Feb 16, 2005 | 09:15 AM
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Ovrclck350's Avatar
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From: Longview, Tx
Question about 870 ECM's

Is it possible in the tuning to switch to batch fire instead of a CS setup?

Is it possible to change the injector constant?

I think my injector's are leaking b/c it's flooding when I leave it sitting which makes for a hard start everytime I kill it. I have a spare set of LT1 24#'s I'd like to put in, but I dont' know if I can just throw them in without any ECM modification which I guess will be my 3rd question although it may not belong in this forum. Can I just throw them in without any problems?


Thanks in advance for any help.
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Old Feb 17, 2005 | 06:32 AM
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
To get rid of the cold start injector you will need to upgrade to a '165 ECM and use MY '89 code ($6E).

There probably is an injector constant in the current code. However, I can't guarantee it. I am not familiar with the '870 code at all.

Going from 22#'s (350ci engine, correct?) to 24#'s isn't too big of a jump. The BLM will correct for it. Although it will be richer under WOT and open loop conditions.

RBob.
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Old Feb 17, 2005 | 04:26 PM
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Actually I read last night that the 85's came with 24's stock, so I may be good in that respect.

Thanks for your help.

So there isn't a batch fire operation possible under the 870?
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Old Feb 17, 2005 | 06:12 PM
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From: Chasing Electrons
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Originally posted by Ovrclck350
Actually I read last night that the 85's came with 24's stock, so I may be good in that respect.

Thanks for your help.

So there isn't a batch fire operation possible under the 870?
Yes to the 24's in '85. A little known and easily forgotten fact, GM used a lower fuel pressure and a larger injector.

It wasn't until the '89 code that GM added cold enrichment to the ECM. TPI is batch fire no matter if a CS injector was used or not. Batch fire just means that all 8 injectors fire at the same time (in a batch).

RBob.
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Old Feb 17, 2005 | 10:45 PM
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From: Longview, Tx
Thanks for the help

I was thinking of the enrichment.
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