The Stupid Engine Questions Thread

PlayingWithTBI

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Can anyone explain what the MEMCAL and CALPAK do?
The memory and calibration unit is a removable part of the ECM. MEMCAL is GM-talk for PROM and it contains a 27C256 ROM, PROM, or EPROM. It also houses back-up fuel control system which consists of an IC and some analog circuitry.

Calpak is the base "limp mode" calibration chip. In the GN's, it's the smaller chip under the ECM cover, as opposed to the PROM "Chip". It's basically a series of precision resistors in a matrix, which bypass and "hardwire" the engine's sensors and base functions.
 

C2164

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The oil pressure has always seemed high in my 2000 K2500 454. When cold it is 65-70 psi at idle on up. When warm it drops to about 45 psi at idle and 60 psi at higher rpm.

Running 5W-30 Mobil 1.

Only ask because I just saw in the service manual it shows oil pressure 10 psi at 600 rpm and 25 psi at 2000 rpm. I would assume that means "minimum" specification, but is obviously way lower than I ever see.

Just curious to know what others see. Could a pressure relief on the pump be stuck? If so it has been stuck for at least 17 years.
 

Intragration

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How many miles on your truck, C2164? 10 PSI at idle would be minimum, with a loose or worn out engine. I can't remember where mine is, but I want to say around 30-40 at warm idle, and so a bit higher on cold start or higher RPMs. This is with 10w30 at 240k miles. If yours has always been the way it is, I don't think you have anything to worry about.
 

df2x4

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The oil pressure has always seemed high in my 2000 K2500 454. When cold it is 65-70 psi at idle on up. When warm it drops to about 45 psi at idle and 60 psi at higher rpm.

Running 5W-30 Mobil 1.

Only ask because I just saw in the service manual it shows oil pressure 10 psi at 600 rpm and 25 psi at 2000 rpm. I would assume that means "minimum" specification, but is obviously way lower than I ever see.

Just curious to know what others see. Could a pressure relief on the pump be stuck? If so it has been stuck for at least 17 years.

My red truck ('97 C1500 4.3L) will sometimes peg the gauge at 80psi on cold starts but always settles to around 40. It's done this since it was new. I wouldn't worry about it.
 
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