PCM Question
#21
08-28-2013, 12:28 PM
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If I could piggy back upon this thread.
I have a 90 vert I'm preparing to make a 360 swap into. I'll likely have a 94/95 dakota V8 donor truck for parts. I will be using a mopar performance crate 5.9L magnum for the swap (if all goes well...lucked upon one new).
If I understand your information, AZ, the 94 5.2L dakota was a returnless style system and its PCM/injectors will be tailored as such. So, my options are:
1) Swap the 94 gas tank/fuel pump/fuel lines/manifold/injectors/fuel rail into the 90 along with the PCM and call it day...
OR
2) Keep the return style and add the intrepid regulator? The second option I'm a bit unclear on what I'd have to do keeping it return style, and if there are any advantages?
3) Lastly, if I go with a 93 donor truck instead which is return style, would I do the same wholesale swap of manifold/injectors/PCM but keep the fuel system the same, and all is good? My concern is the injector change between 93 and 94. I couldn't find any flow specs on the two styles...Was it purely to accommodate pressure differences or is the lb rating different?
I have a 90 vert I'm preparing to make a 360 swap into. I'll likely have a 94/95 dakota V8 donor truck for parts. I will be using a mopar performance crate 5.9L magnum for the swap (if all goes well...lucked upon one new).
If I understand your information, AZ, the 94 5.2L dakota was a returnless style system and its PCM/injectors will be tailored as such. So, my options are:
1) Swap the 94 gas tank/fuel pump/fuel lines/manifold/injectors/fuel rail into the 90 along with the PCM and call it day...
OR
2) Keep the return style and add the intrepid regulator? The second option I'm a bit unclear on what I'd have to do keeping it return style, and if there are any advantages?
3) Lastly, if I go with a 93 donor truck instead which is return style, would I do the same wholesale swap of manifold/injectors/PCM but keep the fuel system the same, and all is good? My concern is the injector change between 93 and 94. I couldn't find any flow specs on the two styles...Was it purely to accommodate pressure differences or is the lb rating different?
First off you need to keep the year PCM you use with that year fuel injectors. It's not the fuel pressure rating, it's injector flow rating and the injectors are matched to the computer. Some years are the same but some years are different. To avoid confusion, just keep the same year PCM with the same year injectors.
1) Yes and no. Use everything you listed but you need to use a 94 5.9 computer.
2) Yes. You use the Intrepid regulator to up the fuel pressure to use the 5.2 PCM on the 5.9 engine.
3) Yes.
In short, if you run returnless you have to use a 5.9 PCM with a 5.9 engine. If you return you can run either a 5.2 or 5.9 PCM but if you run a 5.2 PCM you have to use the Intrepid fuel pressure regulator to up the fuel pressure to compensate for the larger displacement of the 5.9 engine.
#22
08-28-2013, 02:37 PM
If the difference warrants a change, is the ODBI pcm in 94 flashable? Is the EPROM the only difference? Would a chip swap or reburn allow me to use the 5.2 PCM or is it just more economical/feasible to find a 5.9 of the same year? And are 94 and 95's the same then to open up the search for one.
#23
08-28-2013, 03:36 PM
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I think you need to use a 5.9L PCM because the 5.2L PCM is tuned for the 5.2L, so it will have a different fuel mapping. You can get away with a 5.2L PCM on a 5.9L with a return system because you increase the fuel pressure, which forces more fuel into the cylinder at the same pulse width. On a returnless system you can't mess with the fuel pressure.
#24
08-28-2013, 03:48 PM
I think you need to use a 5.9L PCM because the 5.2L PCM is tuned for the 5.2L, so it will have a different fuel mapping. You can get away with a 5.2L PCM on a 5.9L with a return system because you increase the fuel pressure, which forces more fuel into the cylinder at the same pulse width. On a returnless system you can't mess with the fuel pressure.
#25
08-28-2013, 08:00 PM
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I think you need to use a 5.9L PCM because the 5.2L PCM is tuned for the 5.2L, so it will have a different fuel mapping. You can get away with a 5.2L PCM on a 5.9L with a return system because you increase the fuel pressure, which forces more fuel into the cylinder at the same pulse width. On a returnless system you can't mess with the fuel pressure.
#26
08-29-2013, 09:35 AM
So I secured a running '95 5.2L dakota...Which means, I either:
Wholesale swap everything from intake to fuel tank and find a '95 5.9L PCM
or
Keep return and use the 5.2L PCM and add the intrepid regulator
Assuming I have a 5.9L PCM and that's not a factor, any advantage/disadvantage either way?
NOTE: Not using the 5.2L engine from the donor, but a 5.9L crate
Wholesale swap everything from intake to fuel tank and find a '95 5.9L PCM
or
Keep return and use the 5.2L PCM and add the intrepid regulator
Assuming I have a 5.9L PCM and that's not a factor, any advantage/disadvantage either way?
NOTE: Not using the 5.2L engine from the donor, but a 5.9L crate
Last edited by robertmee; 08-29-2013 at 10:07 AM.
#27
08-29-2013, 11:06 AM
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So I secured a running '95 5.2L dakota...Which means, I either:
Wholesale swap everything from intake to fuel tank and find a '95 5.9L PCM
or
Keep return and use the 5.2L PCM and add the intrepid regulator
Assuming I have a 5.9L PCM and that's not a factor, any advantage/disadvantage either way?
NOTE: Not using the 5.2L engine from the donor, but a 5.9L crate
Wholesale swap everything from intake to fuel tank and find a '95 5.9L PCM
or
Keep return and use the 5.2L PCM and add the intrepid regulator
Assuming I have a 5.9L PCM and that's not a factor, any advantage/disadvantage either way?
NOTE: Not using the 5.2L engine from the donor, but a 5.9L crate
#29
08-29-2013, 12:51 PM
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#30
08-29-2013, 04:54 PM
Stock converter also? I'll probably run a higher stall converter and 4:10 gears eventually mated with the 400 HP crate 360. I'm still concerned that the injectors/flow curve combo won't be sufficient since the stock was around 260 HP, so I assume I'll need a tune/flash of the PCM anyway. That's why I was wondering if the 5.2 PCM could just be reflashed.
Do you know if gear changes are handled in the PCM of this era for correct speedo operation?
Do you know if gear changes are handled in the PCM of this era for correct speedo operation?