I have a C3, why would I want a P4?
Thread Starter
Junior Member
Joined: Jan 2005
Posts: 62
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From: Sonoma County, CA
Car: '63 Nova Wagon these days
Engine: 3.1L V6
Transmission: 5-speed
I have a C3, why would I want a P4?
Hi,
I'm trying to come up to speed on the ECM and what the posibilities are for tuning my 3.1 MPFI (has '86 2.8 MPFI electronics). I am starting to understand some of the basics about the ECM variations.
I'm a little clueless on the differences between the C3 and P4. I think I've read that the C3 has a tiny bitty 6801 and the P4 has a somewhat more manly 16 bit processor (HC11). Is this a big advantage for engine control?
What occurs to me so far is that my 1227302 ECM is only a 160 baud box while the P4 boxes are 8192 baud. To me this means that the P4 box will provide more frequent updates than my C3 box. For 0-60 type tuning (road dynamometer) that seems to give a big advantage to the P4. Am I thinking correctly on that? Is there more advantages of the P4 than that?
Any tutorial or references would be appreciated.
My first engineering job was working with 6801 processors and my second was designing a system with the 68HC11. I'm pretty familiar with both of these, should be fun to play with the machines once I come up to speed.
Frank
I'm trying to come up to speed on the ECM and what the posibilities are for tuning my 3.1 MPFI (has '86 2.8 MPFI electronics). I am starting to understand some of the basics about the ECM variations.
I'm a little clueless on the differences between the C3 and P4. I think I've read that the C3 has a tiny bitty 6801 and the P4 has a somewhat more manly 16 bit processor (HC11). Is this a big advantage for engine control?
What occurs to me so far is that my 1227302 ECM is only a 160 baud box while the P4 boxes are 8192 baud. To me this means that the P4 box will provide more frequent updates than my C3 box. For 0-60 type tuning (road dynamometer) that seems to give a big advantage to the P4. Am I thinking correctly on that? Is there more advantages of the P4 than that?
Any tutorial or references would be appreciated.
My first engineering job was working with 6801 processors and my second was designing a system with the 68HC11. I'm pretty familiar with both of these, should be fun to play with the machines once I come up to speed.
Frank
Last edited by Geyservillebob; Feb 5, 2005 at 12:39 PM.
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From: Chasing Electrons
Car: check
Engine: check
Transmission: check
As you mentioned the P4 runs at a faster speed (CPU clock) and provides a faster ALDL line. If you want to use the ALDL for tuning, road dyno, or such, the 8192 baud interface is a must: 64 bytes of data 11 times a second vs. 20 bytes of data every 1.8 seconds.
The other major difference is in the actual code. The '86 ECM code is simple compared to the '90-'92 code that came in the 3.1 f-body's. Although sometimes simple can be good.
If the car is just a driver and is working properly the benefits of a P4 are not that great.
RBob.
The other major difference is in the actual code. The '86 ECM code is simple compared to the '90-'92 code that came in the 3.1 f-body's. Although sometimes simple can be good.
If the car is just a driver and is working properly the benefits of a P4 are not that great.
RBob.
Thread Starter
Junior Member
Joined: Jan 2005
Posts: 62
Likes: 0
From: Sonoma County, CA
Car: '63 Nova Wagon these days
Engine: 3.1L V6
Transmission: 5-speed
RBob,
It is just a daily driver but I want to learn to tune. For now I'll probably just limp along with the 160 baud.
I do have a WBO2 and a GTECH and am pretty adept at electronics. I can probably rig some kind of triggered logging aid to help me deal with the 160 baud and/or just collect a lot of data and try to correlate it.
Maybe after I come up to speed I'll revisit some kind of P4 ECM swap.
I'm also wondering if it is possible to reprogram the 6801 in the C3 to increase the ALDL rate.
Frank
It is just a daily driver but I want to learn to tune. For now I'll probably just limp along with the 160 baud.
I do have a WBO2 and a GTECH and am pretty adept at electronics. I can probably rig some kind of triggered logging aid to help me deal with the 160 baud and/or just collect a lot of data and try to correlate it.
Maybe after I come up to speed I'll revisit some kind of P4 ECM swap.
I'm also wondering if it is possible to reprogram the 6801 in the C3 to increase the ALDL rate.
Frank
