C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

CODE 41- EST - ok...i'm lost now.

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Old Apr 20, 2005 | 12:45 AM
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Default CODE 41- EST - ok...i'm lost now.

Car won't stay running. it turns over and starts easily, but then the RPMS drop and it dies out. no black smoke from the exhaust, all ignition components are new. got a code 41 for the electronic spark timing

funny thing is that I can tap on the throttle and it will run and rev up , but it backfires some and if I try to hold any RPM level it dies.

is that somthing that can be replaced or repaired, or is it in the computer's brain and needs to be hacked out?

Is there any easy way to troubleshoot it?
what does it look like?
anyone had this problem before?

any ideas?
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Old Apr 20, 2005 | 01:41 AM
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EST is simple on a 93... check your knock sensors.
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Old Apr 20, 2005 | 02:18 AM
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The actual EST on 90+ was part of the calpack, pre 90 it was a black module in the engine bay.
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Old Apr 20, 2005 | 12:27 PM
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well at least I have a more specific target to shoot at now... I went to the dealership and copied some pages out of their tech manual on this code and I'm about to go outside and follow their troubleshooting flowchart.

looks like a bad ECM or bad connections is the only way this code would show....I really hope it's just a bad connection...
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Old Apr 20, 2005 | 02:08 PM
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I went back and read some of your other threads and here is what I think. NAPA may have sold you the wrong ICM, get one from the GM Dealer. Next I am worried that the rotor may be contacting the distributor cap that you installed. Last I read your car was in the shop, it is possible someone over-reved the engine and bent pushrods but your car threw a code and that is where I feel your problem lies, in the ignition system.
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Old Apr 20, 2005 | 02:11 PM
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Originally Posted by Morley
The actual EST on 90+ was part of the calpack, pre 90 it was a black module in the engine bay.
that is correct - hense, the focus on the knock sensors themselves.

I was unaware there was a problem from before.

if the EST is throwing a code, and there is a chance of bent metal, that could set off the knock sensors. If they are weak, or, getting too much information, it could throw the code.
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Old Apr 20, 2005 | 02:23 PM
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WELL i think i found the problem...

I went through the GM tech manual troubleshooting guide for code 41 step by step and when I got to the end, all fingers were pointing at my BRAND NEW ignition control module (ICM)

I was suprised and so I went to look for the recipt. found it, looked at it, and sure enough it was AUTO ZONE part number DR174...ICM for a

*drumroll*


94 impalla SS


being that they are year specific.... I think I found the problem.

Going to go to auto zone now...wonder if they'll have security escort me out.
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Old Apr 20, 2005 | 02:33 PM
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That is correct a 94 ICM is the wrong part, I just so happen to have the GM part # for a 1993 LT1. 010483131
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Old Apr 20, 2005 | 05:05 PM
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Originally Posted by crheinish
That is correct a 94 ICM is the wrong part, I just so happen to have the GM part # for a 1993 LT1. 010483131

exactly what the dealership said
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Old Apr 20, 2005 | 07:05 PM
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hell, yea... that is not gonna work, yo.

hope your up and running ASAP!!!!
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Old Apr 21, 2005 | 01:06 PM
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YAHOOOOOO!!!!


it's ALIVE!

started right up after installing the new module... 120 bucks from the dealership... but it runs like a champ now!
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Old Apr 21, 2005 | 02:02 PM
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Originally Posted by crkemppainen
YAHOOOOOO!!!!


it's ALIVE!

started right up after installing the new module... 120 bucks from the dealership... but it runs like a champ now!
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