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Frontier KA24DE to D21 4x4 swap. No more KAZ24.


HRH

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Correct.  Better atomization of the fuel.  Also, a lot of times stock injectors are maxed out past 75% throttle if the factory cheaps out.  I'm not sure it's that case with Nissan, but the head does flow better and never got the 1 hole injectors in the year range system I'm using.  1 hole with the 2001 frontier, but also green, so slightly higher poundage.  I should check and see whether the fuel pressure regulator was limited to the same amount on the '01.

 

On the Cherokee, Buddy's stock injectors were maxed out at 75% of throttle.  I need to have him hook up the data logger to my system and see what mine is doing.  I suspect Nissan didn't max them out, but I don't know.

 

Short of it is, she idles smoother and runs better throughout the rpm range.  And why not, those injectors were designed for the KADE in the mid-90s.

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I have noticed a hot start problem.  Seems when she firsts starts in hot (90) degree weather, there's not enough fuel, and she spits and sputters.  I need to disconnect the IAT and see if that problem goes away.  Considering just getting a nistune ecu and fixing the entire problem, but still haven't wanted to pony up the dough.  Other than that, it seems she's getting a bit better overall mileage.  Only filled up once though, need to drive her a bit more.

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Mileage is definitely getting better.  Acceleration is better.  I have found if I pin it and go, it seems to suck more gas.  Had her up to 95 the other day, it takes a while, but she can get there.  Not bad for a 3950 pound brick.  Got 17.75 mpg the last fill up which included some 95 mph runs and 70 mph to work and back.  And also included towing the wood chipper to and from the rental place.  So far, this tank looks to be more near the 20 mpg mark while keeping it at 65, below 3000 rpm on freeway cruise.  Haven't had any hot enough weather to cause hot-start issue, so deciding not to worry about that.

 

I have to register tabs again, just the mail.  Says I need to emissions test, so we'll see how well the truck does with that.  Shouldn't have any problem.  Good thing the emissions station couldn't tell a KAE from a KADE. ;)

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Ok, so updates on mileage.  This is from going back and forth to work, which is mostly highway, but still has the Sunset hill to go up which sucks mileage because I can't pull it in 5th, have to wrap it up to 3500 in 4th.  Or I could go slower, but yeah, no.  So this week I was really conscious of keeping it at exactly 65 mph on the speedo, which with our 4% correction factor for bigger tires, is 67.6 mph.

 

Mileage was 18.6, which isn't too bad considering it's been quite cold in the morning, more like fall.

 

I took a trip over to CDA yesterday, granted had a HUGE tailwind, so kept it at 65 on the way there.  On the way back, I still had the headwind, though it had died a little.  Consequently I kept it at 62.5 mph, which is previously where max mileage was attained, short of going 50 in 5th gear because that just doesn't work on the freeway.  Anyway, not quite even, but managed 21.26 mpg for that back and forth trip.

 

It got me to thinking about mileage and aerodynamics.  Beginning to think about making a tonneau cover for the bed again.  Wish I would have kept the camper shell I sold when I bought the truck, but oh well.

 

Anyway, that is all.

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So it seems the truck is indeed getting better mileage with the addition of the hard shell tonneau cover I was lucky enough to find at Spaldings!  Still need to fill up, but I'm guessing 21 mpg for around town + freeway driving, which will be great.  I noticed when I drove it up to work last Friday, the wind didn't push the truck around at all compared to what it usually is, so perhaps the hardbody is one of those that benefits from a covered bed area or tailgate net.  I know there's a reason they put bed covers on in NAS-Truck.  Stands to reason it would aid higher speed aerodynamics.

 

The only annoying thing is the instant I put the cover on, I wanted to go get a tree and realized that wasn't going to happen.  I wanted to put the dog in the bed if she's wet from the river.  That's not going to happen either. ;)  So, there are some drawbacks.  But if it maintains better mileage through winter it will still be worth it.

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Ok, so filled up the truck tonight.  Mixed driving, and I do mean mixed, 19.79 mpg!  Not bad for in town and highway!  I put the tonneau cover on at 54 miles of 208.  Only been commuting to work the last three days, the rest has been driving around town for errands during my vacation, a lot of drive throughs wasting gas.  Anyway, now I'll get to see how she is for mostly just highway going to work and back.  Either way, for an average mix, that's pretty darn decent.  I think the tonneau cover helped a lot.  More testing will confirm.

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  • 4 months later...

Alright, truck works fine, but obviously needs refinement since the original system parameters don't work that well with the DE manifold.  The Frontier manifold doesn't have the butterfly flap for the intake, which affects low speed performance.  No small runners to speed up the intake charge.  So it has decent power in the mid-range, but not that great at large throttle loads down low.  If you half-throttle it, power is better at low rpm.

 

Anyway, finally doing what I probably should have done in the first place.  Ordered a Megasquirt system.  Have to assemble it partially. I got the PNP option that comes with the correct connector block, just have to solder a few wires and whatnot, then get the tuning software and a data cable, and bingo, the laptop will be used to interface with the new ECU.  I suspect massive gains in driveability and hopefully fuel mileage.

 

Assuming of course I can figure out how to operate the damn thing. ;)  But, it's about time I learned about aftermarket EFI systems.  I have enough books on the subject, time to stop being scared and just do it.  If the results are good, then I'll start thinking about putting one on the racecar.

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  • 7 months later...

Time for an update!  Still haven't found time to have the ECU assembled so I can fiddle with the management.  However, I began thinking about the reasons for poor fuel economy in the original '95 fat body D21 injectors in the 2001 fuel rail on the DE while running factory '92 efi.

 

I pulled the '95 injectors out of a fuel rail and manifold I had sitting around the garage for about 5 years prior to installing the KA24DE from the Frontier.  And more than likely, though I put massive amounts of injector cleaner through the truck, I'm betting they weren't operating very well.

 

With the 240sx/Altima injectors, there was a big problem with hot start up during hot weather.  There was also some idle fluctuations when the truck was half warm when you hit the brakes coming to a stop.  The truck would drop to 500-700 rpm up and down for about 3 seconds until it regained composure.  I suspect just not enough fuel at lower rpm due to the nature of the fuel injector, or possibly where it sat in the fuel rail as it was different from other injectors.  Although, as I write this, I just had another thought regarding the tightness of the little rubber cushion on the top that sandwiches the top of the fuel injector.  I'm not sure if that is a relief valve on the top that must be fully depressed.  I need to look at the injector again.  In fact, I may cut one apart to see exactly how it operates.  A used one of course. ;)

 

Anyway, it came down to thinking I probably had poor spray patterns on the injectors that worked better with the original system, so I ordered some remans from rockauto since new ones my cost were too damn expensive.  Installed those today, and cut and soldered the old fuel injector harness pigtails on yet again.  (Bah, too many changes for injector connecters!) but started it up and seems to have more power.  Filled it up tonight and will continue testing for mileage tomorrow.  We shall see.  Hopefully it will run better but not have any worse mileage since these injectors have been rebuilt.

 

If anyone needs a set of 240sx injectors with only about 10,000 miles on them, let me know.  Nothing wrong with them, bought them new about a year or two ago.

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  • 2 weeks later...

Definitely has more power and runs better with the "original" '95 injectors in '01 manifold with '93 system.  ;)  Last tank was 17.75, which isn't too bad considering I did a bit with the trailer and I kept staying at Rose's house last week, which is a 1.5 mile trip to work roughly, which isn't really worth starting up the truck, but in these cold mornings, I've done it anyway.  And of course, it doesn't warm up by the time I'm there and that kills the mileage because it's still in closed loop.  Also been going faster than normal to work, so I'm about 10 miles shy of good mileage at half tank right now, but considering I've been cruising at 70-75 to work instead of 65, it's not surprising.

 

I did find the guy I normally send my ECUs at NAPA to for fixing is happy to build the MS ecu I have, probably somewhere around 100-150 to put it together and test it to make sure everything is functioning correctly.  So I'll probably do that one of these days here and then maybe fiddle with that after winter so I can actually tune the motor for the mess of parts.

 

If I were to cut out the intake butterfly valve section off the '93 KAE manifold and weld it to the DE manifold, I bet it would run near perfect, just like the effects of adding a cam with the better headflow of the DE.  Wished I could have just used the '93 manifold, alas the intake ports are different between KAE and KADE.  For right now it still does burnouts though, so we're good! :D

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Open loop. When cold the O2 is cut out of the circuit, no feedback control. You mean the vacuum operated butterflies with the notches in them? I found out that they are only closed at near idle and force a turbulence in the intake port for better mixture control.

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Oh damnit, you're right.  I hate that.  I think it should be closed when cold because it's not open to interpretation from the 02 sensor, alas the engineers disagree.  Anyway, hauled the trailer with a couch up to Rose's yesterday, against 20 mph headwinds.  That sucked.  Had to go to 3rd wide open all the way up Sunset Hill just to maintain 65.  Wasted a lot of gas between then, but surprisingly, only dropped to 17.5 mpg.  And that's after a couple days of the short trips wasting fuel up in Cheney.  So had I not been hauling new sofas and old sofas with an 850 pound trailer all over in high winds, I probably would have gotten closer to 18.5 or thereabouts.

 

Yep, the butterfly intake.  It generates a turbulent air charge that then swirls in the combustion chamber.  Works really well for the 12 valve KAE.  It also slows the air at near idle speeds so it's the effect of having a small runner intake which is better for down low torque.  It's an ingenious little system.  If they just would have put non hydraulic valves in it, the KAE would have gotten a much better following.  At WOT or more than about 3000 rpm, there's a vacuum switch that operates it to full open for full throttle power.  Right now I have a slight hiccup just off load like going down Sunset Hill.  If I'm just barely off throttle the truck will buck because it has too much air from the large intake of the KADE Frontier motor.  Once I get the custom ECU in and start fiddling, I should be able to tune that out and have it run perfectly.  As it is now, I have to either let off the gas entirely, or go down the hill slightly faster so it stays above a certain load.  Works almost perfectly other than that.

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  • 3 years later...

You know I have 236,075 on the truck now.  Same DE, it went in with 116k at 188k miles. So that's 164k on the engine now.  Still needs better management, still haven't done it.  She starts and runs every day, so meh.  Eventually I'll get around to it.

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