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MEFI adjustment ideas for rich idle on a Procharged motor?

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Old 08-10-2012, 03:37 PM
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M1 on 502mpi

Yes, you have to change the harness. Crate Engine Depot is where I bought mine. Looks like the price has gone up about $100 since I purchased mine. Mefi4a
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Old 08-10-2012, 03:38 PM
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Originally Posted by JRider View Post
I am running my intercooler off the sea pump but I am using a pressure relief valve to feed it (nothing through the chiller at idle). I am also feeding the cooler off the intake side of the pump with the use of a check valve. Plumbed in this fashion the check valve will open at higher speed and the cooler will be force fed. This also lets the sea pump feed the motor at its full capacity at speed. I have the pressure relief valve set so it is barely dribbling through the cooler at idle and when I put the throttle on it opens immediately (I had to change a spring in it). One advantage of this is that there is no drag from an external pickup. I run a 120* stat and the guage reads just over 130*. I do not run a sea strainer but I do run a Y type strainer before the pressure relief valve.

Idle will not be the best without a thermistat and will turn to terrible if you are running water through the cooler full time.
Different (upstream of thermostat) feed will be necessary if thermostat is installed right? Not in front of the motor but IIRC closed thermostat would kill intercooler flow the way Procharger designed their housing.
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Old 08-10-2012, 04:13 PM
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M1 on 502mpi

Yes, you have to change the harness. Crate Engine Depot is where I bought mine. Looks like the price has gone up about $100 since I purchased mine. Mefi4a
Thanks for the link. Interestingly that dealer is just up the road from me.
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Old 08-10-2012, 05:25 PM
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http://www.crateenginedepot.com/ECM-...10030C631.aspx

I service many of the purchases that come out of Crate Engine Depot

www.mefituning.com
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Old 08-11-2012, 02:08 AM
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Give us the numbers for your MAP/BPW/RPM table in the idle region.

I can't see a reason why you can't tailor the idle AFR. I've got a MEFI 1 and can set idle AFR any where from 10.0 all the way to 17+ and stall.

Chances are your idle characteristics don't sit exactly in one cell in the BPW/MAP/RPM table, which is typical. For instance, my motor idles at 700 rpm when warm at about 50 kPA. This sits right in the middle four cells on a MEFI 1. In cases like this you need to make small changes to all four cells to help smooth out the BPW output. So if I was a little rich at idle I would reduce the BPW in all four surrounding cells by a small amount, or at least in two of the cells. Too big of a difference between the cells in this region can result in fairly large AFR swings. I'd bet you have the 40 MAP column too lean, which is typical because the motor rarely ever sees that range except heavy decel at the upper rpm range so it's not likely to be tuned correctly on initial attempts.

As others have mentioned what do you mean by changing the step? Are you manually adjusting the numbers in each cell or hitting the adjust button on the table that pops up when viewing the BPW/MAP/RPM table? If its the latter the increment set on that window is probably too large. I go to each cell and change the values manually, say from 2.35 ms to 2.42 just as an example. You should be changing the values in tenths or 100th's.

Last edited by Trash; 08-11-2012 at 02:34 AM.
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Old 08-11-2012, 02:33 PM
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Originally Posted by Trash View Post
Give us the numbers for your MAP/BPW/RPM table in the idle region.

I can't see a reason why you can't tailor the idle AFR. I've got a MEFI 1 and can set idle AFR any where from 10.0 all the way to 17+ and stall.

Chances are your idle characteristics don't sit exactly in one cell in the BPW/MAP/RPM table, which is typical. For instance, my motor idles at 700 rpm when warm at about 50 kPA. This sits right in the middle four cells on a MEFI 1. In cases like this you need to make small changes to all four cells to help smooth out the BPW output. So if I was a little rich at idle I would reduce the BPW in all four surrounding cells by a small amount, or at least in two of the cells. Too big of a difference between the cells in this region can result in fairly large AFR swings. I'd bet you have the 40 MAP column too lean, which is typical because the motor rarely ever sees that range except heavy decel at the upper rpm range so it's not likely to be tuned correctly on initial attempts.

As others have mentioned what do you mean by changing the step? Are you manually adjusting the numbers in each cell or hitting the adjust button on the table that pops up when viewing the BPW/MAP/RPM table? If its the latter the increment set on that window is probably too large. I go to each cell and change the values manually, say from 2.35 ms to 2.42 just as an example. You should be changing the values in tenths or 100th's.
I pretty much agree with you except I feel IF you have a area in the BPW table you are working on and lets say you air fuel ratio is 11-1 and you want it at 13 at that point I look at the ms in the table at that map setting and lets say its at 5.0 ms I would divide 13 x 11 =1.18 then I would go to the top of the table enter 1.18 as a multiplier, high light the cells you want to modify and definately do the ones above and below the map you are in and then hit multiply vs just adding a little tiny bit at a time here and there (I still do that too but only after I have it real close), Smitty
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Old 08-11-2012, 02:47 PM
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I pretty much agree with you except I feel IF you have a area in the BPW table you are working on and lets say you air fuel ratio is 11-1 and you want it at 13 at that point I look at the ms in the table at that map setting and lets say its at 5.0 ms I would divide 13 x 11 =1.18 then I would go to the top of the table enter 1.18 as a multiplier, high light the cells you want to modify and definately do the ones above and below the map you are in and then hit multiply vs just adding a little tiny bit at a time here and there (I still do that too but only after I have it real close), Smitty
That is certainly another way to skin the cat, perhaps in a more eloquent fashion.

I'm not at all familiar with the boost reference regulator he's using, but am assuming it should not interfere with idle (no boost) situations. Is there a way to disconnect or isolate the boost reference regulator at idle to ensure its not messing with the idle AFRs at least during the tuning process?
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Old 08-11-2012, 06:27 PM
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That is certainly another way to skin the cat, perhaps in a more eloquent fashion.

I'm not at all familiar with the boost reference regulator he's using, but am assuming it should not interfere with idle (no boost) situations. Is there a way to disconnect or isolate the boost reference regulator at idle to ensure its not messing with the idle AFRs at least during the tuning process?
I am running the same regulator as he shows to hold my base pressure but using a second regulator to control the boost pressure. I do NOT attach a vacuum source to my primary regulator as it DOES screw with the idle fuel pressure vs loaded fuel pressure. All these regulators boosting fuel pressure under boost are cobbled up at best, these days there are better alternatives then there used to be- such as the right size injectors. I bought 80# high impedance injecters for my boat this year, I am taking the boost regulator and my boost actuated voltage booster on my fuel pump off when I go to the bigger injectors as I can just do everything with bpw and boost multipliers and hold a steady fuel pressure. Haven't had time to do it yet as I am still working bugs out of my freshend motor I just got back in boat last month, Smitty
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Old 08-13-2012, 12:51 AM
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1000RPM: 3.05 4.09 5.37 6.53 7.63 8.61 9.83 11.41
800RPM: 2.50 3.54 4.76 5.55 6.71 7.93 9.09 10.68
600RPM: 2.50 3.30 4.33 5.37 6.23 7.39 8.54 10.31

Tried to upload screenshot but errors occured registering for image hosting (over and over) so I give up for the night

Minimum "step" is .06 as hexidecimal values are converted to decimals. I used function muliply/divide by 1.1 for rows (RPM)to rough the tuning in, tried minimum step on idle but did not apply functions to more than one row at a time so I will try that.

I can't tune into boost with MEFI2 so I'm not sure that disconnecting the vacuum hose from the fuel pressure regulator is a good idea but you guys are quite knowledgable so I will test that at idle and see what happens.

Thanks for all your input so far!
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Old 08-13-2012, 05:03 PM
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Originally Posted by yellowjacket View Post
1000RPM: 3.05 4.09 5.37 6.53 7.63 8.61 9.83 11.41
800RPM: 2.50 3.54 4.76 5.55 6.71 7.93 9.09 10.68
600RPM: 2.50 3.30 4.33 5.37 6.23 7.39 8.54 10.31

Tried to upload screenshot but errors occured registering for image hosting (over and over) so I give up for the night

Minimum "step" is .06 as hexidecimal values are converted to decimals. I used function muliply/divide by 1.1 for rows (RPM)to rough the tuning in, tried minimum step on idle but did not apply functions to more than one row at a time so I will try that.

I can't tune into boost with MEFI2 so I'm not sure that disconnecting the vacuum hose from the fuel pressure regulator is a good idea but you guys are quite knowledgable so I will test that at idle and see what happens.

Thanks for all your input so far!
What are the MAP column values for the above table?

What is the BPW as shown on scanner pro, at idle, warm motor with your rich AFR of 11.X? Idle RPM (I think you mentioned 700) and idle MAP kPa are needed too. This will help us see where it sits in the table and make adjustments from there.

Last edited by Trash; 08-13-2012 at 05:07 PM.
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