Possible EA82T injector/MAF transplant?

[All_talk]

I’ve been thinking and cipherin again… On MAF based systems the fuel output (injector pulse width) is computed mainly from the MAF output voltage with other sensor inputs used as modifiers. So if you had a MAF that allowed more flow for the same voltage output range and a match set of injectors with a higher output for the given pulse width, the ECU should still maintain the A/F proportions, right?

 

What about fitting the EA82T with the MAF and injectors from the EJ22T? I believe they have the same input and output range and have about 50% more flow, which should give us about 180HP worth of fuel and air with NO fuel cut.

 

I’ve got some numbers but I don’t have time to post them right now, I’ll try when I get home.

 

Mounting the EJ injectors would have to be sorted out (or equivalent barbed injector could be used), and the fuel pressure would have to be adjusted, but I think there might be something to work with here. I wish I had some EJ22T parts to test and play with.

 

Discuss…

Gary

[All_talk]

Some math...

 

EJ22T

injectors - 275 cc/m @ 43 psi

26.2 lb/hr @ 43 psi

29.1 lb/hr @ 53 psi (10 psi boost)

MAF - 200 g/s

1587 lb/hr

 

1587/29.1 = 13.6:1 A/F

 

EA82T

injectors - 180 cc/m @ 36 psi ? (not sure on the test pressure)

17 lb/hr @ 36 psi ?

18.9 lb/hr @ 44 psi (8 psi boost)

MAF - I dont have any numbers for the max MAF rating so I back figured a ball park with a 13.5:1 A/F 18.9 x 13.5 = 1020 lb/hr

 

So the EJ stuff will flow about 50% more. Now there are some MAJOR assumptions involved in all this that will have to be tested, namely that the MAF voltage output range is the same and curve is similar to the EA82T’s MAF and that near idle both engines flow about the same. As long as the both ECUs use a similar output curve for the MAF voltage range the A/F should hold and the fuel pressure could be used to fine tune. I scaled the mass flow for the EA82T to see how much additional boost would be needed to fully utilize the extra flow provided by the larger EJ parts.

 

1000 lb/hr @ 1.54 bar (8 psi boost) goes to 1500 lb/hr @ 2.31 bar (19 psi boost)

 

Now 19 psi is not going to happen with the stock turbo, but with some other mods to increase flow (and a good IC) we should be able to run 12-14psi (about all the stocker is good for) with plenty of fuel. And with the TD04 or the like, I think somewhere in that 160-180HP range is possible.

 

Thoughts? Opinions?

Gary

 

[bushbasher]

why not just swap the whole legacy turbo engine control onto an ea block?

[Vanislru]

Do the ej injectors mount the same as ea?

[All_talk]

why not just swap the whole legacy turbo engine control onto an ea block?

 

Might be a good way to go if I wouldn't require a major rewire.

 

I wonder if the N/A EJ22 is MAF, I think it has the same injectors but I thought it was a MAP control, anybody know?

 

Gary

[Caboobaroo]

The earlier EJ22 NA motors are MAF controlled.

 

Maybe I should look into putting an EJ22T ECU in my car like bushbasher suggested since I was going to suggest this as well...

[All_talk]

Do the ej injectors mount the same as ea?

 

No, and thats a real problem to be sorted unless we can find some hose barb injectors that flow about 280cc/s. '81 to '83 Datsun 280ZXT injectors are suppose to flow 265cc @ 45psi.

 

Gary

[All_talk]

This was pasted from this thread: http://bbs.legacycentral.org/viewtopic.php?t=20750

 

This conversation started in PM, but it may be of interest to others so I’ll post it here.

 

Do you know the voltage output range of the stock MAF? I understand it tops out at the 5V reference, but what would it be at idle? I’ve seen your graph, can we correlate output voltage to it? I also under stand that max flow is 200g/m at 5V, true? Do you have any idea what would be a typical flow at idle?

 

Do you know the injector pulse width at idle (typical range)? And is injector flow fairly linier with changes in pulse width?

 

What all this is leading to is I’m hoping to use the EJ22T’s MAF and injectors in the earlier EA82T, this would give an additional 50% flow and eliminate the fuel cut issues that occur with any attempt to increase flow (additional boost or otherwise). This would require both ECUs to have similar architecture and input/output ranges, the ECUs are one generation apart so it might be possible. I think I can check the range of the EA82T MAF with a voltmeter, is there any simple way to read the injector pulse width? Maybe some type of RMS voltage, or is an oscilloscope the only actuate way?

 

Lastly, are the N/A EJ22 MAF and injectors the same as the turbo, if not, what sort of flow are the capable of?

 

Thanks for your time

Gary

 

NEXT POST

 

Here is vrg3's responce

 

I've been searching the site for some info on the stock EJ22T system and you seem to be in the know.

 

Quote:

Do you know the voltage output range of the stock MAF?

 

 

I don't understand what exactly you mean by this question... The signal can range from somewhere around 0 volts up to somewhere around 5 volts, and the meaning of the signal is given by the transfer function graph that I've posted and you've seen.

 

Quote:

I understand it tops out at the 5V reference, but what would it be at idle?

 

 

At idle the signal usually sits somewhere around 1 volt.

 

Quote:

I’ve seen your graph, can we correlate output voltage to it?

 

 

Yes; the horizontal axis is the voltage (or the voltage times 32 or times 8 depending on what units I chose).

 

Quote:

I also under stand that max flow is 200g/m at 5V, true?

 

 

At 5 volts the airflow is around 200 grams per second (not per minute).

 

Quote:

Do you have any idea what would be a typical flow at idle?

 

 

I dunno, somewhere around 10 grams a second maybe?

 

Quote:

Do you know the injector pulse width at idle (typical range)?

 

 

Around 2 or 3 milliseconds.

 

Quote:

And is injector flow fairly linier with changes in pulse width?

 

 

Very roughly, yes. To do it a little more accurately you have to model the time it takes the injector to move from the closed position to the open position. This time is roughly proportional to system voltage.

 

Quote:

What all this is leading to is I’m hoping to use the EJ22T’s MAF and injectors in the earlier EA82T, this would give an additional 50% flow and eliminate the fuel cut issues that occur with any attempt to increase flow (additional boost or otherwise).

 

 

This seems like a cool idea in principle.

 

How does the EA82T's stock engine management control ignition timing?

 

Quote:

This would require both ECUs to have similar architecture and input/output ranges, the ECUs are one generation apart so it might be possible.

 

 

Weellll... I don't think that's true (the first part, I mean). If you change out the injectors and MAF sensor but keep the ECU, you're basically throwing the architecture out the window. You're going to mangle the input to the system (the airflow signal) and the output of the system (the amount of fuel injected) and hope you can make the two cancel out.

 

One difficulty you'll encounter is that hot-wire and hot-film MAF sensors typically have quadratic transfer functions, while injector flow is approximately linear. So, you can't just change out the injectors and sensor and get "correct" behavior all the time.

 

Also, doesn't the EA82T ECU have control over ignition timing? I would imagine it would compute load based on airflow and then determine spark advance using this load computation. If you make the ECU think there's less airflow than there really is, you may get undesirably advanced spark.

 

You might be able to make this stuff work out in the end though. You'll want good instrumentation, I think.

 

Another thing you might want to consider... I'll preface by saying I have no idea how the EA82T does its camshaft and/or crankshaft position sensing, but maybe you could look into the possibility of using an EJ22T ECU as well. The hard part would just be to get the right kind of crankshaft and camshaft position signals, assuming the EA82T does it very differently. But maybe you could hack up your crank pulley and a cam sprocket to give the right signals.

 

Quote:

I think I can check the range of the EA82T MAF with a voltmeter,

 

 

What do you mean by the range? Wouldn't you need some kind of flow bench to determine the transfer function?

 

Quote:

is there any simple way to read the injector pulse width? Maybe some type of RMS voltage, or is an oscilloscope the only actuate way?

 

 

Many quality multimeters (especially those designed for automotive use, of course) have the ability to display duty cycle and/or pulse width.

 

They do also make some very crude "injector duty cycle" meters that basically use a capacitor to integrate a square wave representing the injector drive waveform, and in that way display the average value of the waveform.

 

Quote:

Lastly, are the N/A EJ22 MAF and injectors the same as the turbo, if not, what sort of flow are the capable of?

 

 

90-91 5-speed N/A EJ22s use the same MAF sensor as the EJ22T.

 

90-91 automatic N/A EJ22s, and all 92-94 N/A EJ22s, use a MAF sensor made by JECS with a maximum flow reading of around 300 grams per second.

 

As far as I know, all N/A EJ22s use injectors that flow about 280 cc/min, roughly 75% as much as the turbo injectors.

 

Quote:

Thanks for your time

 

 

You're welcome. Good luck!

 

-Vikash

 

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I’ve been busy lately, but here are a few more thoughts…

 

IF the EA82T MAF’s signal ranges from 0 to 5V (I believe it does, still need to test).

 

IF the EA82T MAF’s transfer function follows a curve “similar” to the EJ22T (big assumption, and much harder to test).

 

Based on the 180cc rating for the EA injector the EA MAF should flow around 130g/s @ 5V.

 

MAF ratios: 200/130 = 1.54

Injector ratio: 280/180 = 1.56

Looks like the parts from the ’90-’91 N/A 5MT EJ22 are a good match.

 

The EA has a lower static fuel pressure 36psi vs. 43psi for the EJ, so I’m assuming I’ll need to raise the fuel pressure to the EJ 43 or so for the scaling to hold true.

 

I scaled the MAF’s transfer function of the EJ to get a similar function for the EA over the lower flow to see the trend in voltage differential.

 

 

The voltage differential increases with higher flow, I believe this will cause a leaner A/F relative to the balance set at idle. But the higher flow will most likely be due to higher boost pressures, which will raise fuel pressure and hopefully offset this.

 

The ignition timing on the EA82T is controlled by the ECU, but the crank/cam position is sensed by a module in the distributor, and because is adjustable I should be able to shift the whole timing map down. This will mean less total advance, but I should be able to find a balance that mitigates the over-advance due to the lower flow/load sensed. The EA82T also has a knock sensor, which provides up to 5deg of retard.

 

Thoughts

Gary

[Vanislru]

I'll have to reread this again a few times but at first glance it looks really good.