MSPNP MSPNP specific Megasquirt related discussion.
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MS PNP2 noob question

 
Old 11-14-2017, 07:33 PM
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Default MS PNP2 noob question

Hey all,
So i'm looking to get another car and found naturally aspirated 1994 one with Megasquirt PNP2 + custom intake with IAT for AFR. I've never messed with aftermarket ECU's, so have 0 knowledge on this. My issue is that I'm in Cali and will need to pass SMOG. Car comes with original ECU and stock intake with MAF, CAT is still in place. Do i understand this correctly (from what I've read so far) that I can put those ECU+Intake+MAF back and I *should* be able to pass if CAT is good?

Thanks!
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Old 11-15-2017, 03:48 PM
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The original emissions equipment needs to be intact and functional. It's a 1994, so you want to make sure EGR is still there too, along with the charcoal canister.
And yes, obviously the stock intake, MAF, and a CA approved cat must be there. With the stock ECU in too, so that the check engine light functions and it drives like stock.
If there is a MS in it, is there a wideband o2 with a gauge as well? the stock ECU needs the original/normal o2 sensor in place and hooked up. There's only one on your car, on the header. Usually, the smog tech checks the o2 sensor visually, and they may ask if they see some other one hooked up that shouldn't be there.

the IAT is wired using two of the wires from the MAF, so you have to reverse that when reinstalling the MAF. also that has nothing to do with AFR, that's all from your o2 sensor.

Personally, i'd just call up a friend, send him my information, and go drive my car.
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Old 12-05-2017, 01:14 PM
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Ok,
So i just got around to removing MSPNP for smog, removing IAT/AFR sensor and custom intake. I see that there is a vacuum line connection to MSPNP, but there is no such connection on stock ECU.

1) Do I just fold it several times to pinch and zip tie this line for SMOG to stop vacuum leaks or should i really find where it's going first?
2) I'm not sure where it's connected in the engine bay, but assume something else may have been connected to this port/nipple before MSPNP was installed. Is there a standard place for MSPNP vacuum tap/source?
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Old 12-05-2017, 01:27 PM
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The vacuum line runs to your ECU because the ECU (Megasquirt) has an internal MAP sensor. It uses the MAP value to calculate load and fueling. It probably pokes through the firewall somewhere, so just look for a vacuum line coming out of it. It goes on the intake manifold usually in the center or near the back side, it seems to be a common understanding that right behind the TB is not ideal.

Your stock ECU doesn't use this, it uses the MAF (did you reinstall the MAF with stock intake?) and other values to determine fueling, etc.

That vacuum line was added to a port that was previously blocked off or used for something else. Assuming all your EVAP and smog components are in place, you should be able to simply block it off again with a cap from your parts store. I keep a box of them in my car because they come in handy.

edit: to answer your question more clearly, no I would not fold it over or pinch it off, I would temporarily remove it, because its not original equipment and may look odd to the smog tech. you may be able to tuck it off to the side so you dont have to snake it through the firewall again if you intend on re-installing the MS. I would still cap the nipple on the manifold.
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Old 12-05-2017, 01:30 PM
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Originally Posted by pakmx5 View Post
The vacuum line runs to your ECU because the ECU (Megasquirt) has an internal MAP sensor. It uses the MAP value to calculate load and fueling. It probably pokes through the firewall somewhere, so just look for a vacuum line coming out of it. It goes on the intake manifold usually in the center or near the back side, it seems to be a common understanding that right behind the TB is not ideal.

Your stock ECU doesn't use this, it uses the MAF (did you reinstall the MAF with stock intake?) and other values to determine fueling, etc.

That vacuum line was added to a port that was previously blocked off or used for something else. Assuming all your EVAP and smog components are in place, you should be able to simply block it off again with a cap from your parts store. I keep a box of them in my car because they come in handy.
Yes, I've re-installed MAF with OEM intake and tubing. Putting all EVAP equipment back now too.

I'll try to trace the vacuum line and see if it was used by something else.
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Old 12-05-2017, 01:34 PM
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Nice, let us know if you run into any issues. but you should be fine.
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Old 12-05-2017, 03:13 PM
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99% of PNP installs use a T to get a manifold signal from one of the ports. 99% chance, all you need is to put a cap on the extra nipple while you have the factory ECU in place. Go read the pnp install guide, it will make a lot more sense.
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