98.5 hardware running 01 PCM

biggy238

biggy238

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Aug 3, 2008
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I have an employee with a 98.5 that is running an 01 PCM. IIRC he had to modify a tone wheel to make It work, and I honestly don't remember why that's what he has, but here's the deal: He's running a smarty and the truck will run strong, but you can cycle the key with the thing in motion and it will run with nearly another 50hp on tap.
I'm not knowledgeable on the 24V electronics some I'm really curious about what's happening, but it sounds to me like the key cycle is changing sensor rationality.

Let me know what you think.

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The ‘98.5 has a crank sensor and the ‘01 has a cam sensor.
 
I know on the destroked tone rings you had to slot the holes to line up tdc on the piston and the tone ring to make one run correctly or at least in our case. The truck is such a cluster F........ it seems so much easier to source the correct ecm lol.
 
I will ask about the correct PCM. Probably him being a cheapass

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Hhmmmm
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I guess that changes things

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zstroken said:
I thought the 98.5 had a crank AND cam sensor, the later ones eliminated the crank sensor.
Click to expand...

You’re correct, ‘98 and ‘99 had both. ‘00-‘02 only had the cam sensor. However, the cam sensor in the ‘98 and ‘99 was not involved with the fuel system, just diagnostics.


biggy238 said:
I guess that changes things
Click to expand...

You lost me there. ‘98-‘02 had an ECM AND a PCM.
 
My truck has an 01 motor/ecm and a 99 chassis, might have to try the key trick.
 
BigPapa said:
You’re correct, ‘98 and ‘99 had both. ‘00-‘02 only had the cam sensor. However, the cam sensor in the ‘98 and ‘99 was not involved with the fuel system, just diagnostics.









You lost me there. ‘98-‘02 had an ECM AND a PCM.
Click to expand...
He's saying 98.5 PCM and an 01 ECM are on the truck

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BigPapa said:
You’re correct, ‘98 and ‘99 had both. ‘00-‘02 only had the cam sensor. However, the cam sensor in the ‘98 and ‘99 was not involved with the fuel system, just diagnostics.
Click to expand...

Close, but the year break was '98.5-00 with both crank and cam sensor, and '01-02 with just cam sensor. The MAP sensor is a giveaway, the early years had a triangle plug and the later years had a flat plug. Also the fuel filter housing changed, and the valve cover, and the power rating.
 
Yes, I was thinking about this last night after my post. Seems I remember that 2000 was actually a split year, early ’00’s had both and later build dates only had the cam sensor. Just can’t remember for sure.
 
Is it reasonable to believe the MAP sensor is behind his complaint? What he is describing sounds to me like the barometric pressure is being fooled after the key cycle while it's in motion.

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