Stanza ECU in D21 hardbody

[HRH]

EDIT: Found some hiccups. Besides the idle not being correct, in light mid-throttle application, there turns out to be a bit of a dead spot around 2800 rpm and 3500. Under full throttle, it's not that noticeable, but like 3/8s throttle, it's pretty bad. Another problem is since the IAC valve can't accommodate the ECU, on/off throttle response is rather abrupt. Consequently, I'll be putting the D21 ecu back in and just upping the ignition timing. See where that gets me.

 

So I got a wild hair up my butt while I was trying to figure out the hardbody hesitation which turned out to be separating tires. It got my curiosity going about other ECUs that would provide better power and or ignition curves than the stock D21 ECU. Not to mention the possibility of better mileage.

 

I was going to try an Altima ECU even though it's a double cam. The ECU doesn't know the motor is a double cam. But I happened to be at Pull and Save the other day and saw a '92 automatic Stanza which came with the KA24E. So I grabbed the ECU for amusement. Only cost me $25. Anyway, got home and put it in, lo and behold, WAY better response and a leaner fuel map!

 

I haven't done a mileage test yet, but it certainly has better passing power. There is a lean pop every so often under certain off-throttle conditions, but nothing to worry about. Temperature stays the same, everything seems to be in perfect working order.

 

Talked to Jeff (Icehouse) regarding the differences, his thoughts were the trucks came with a richer fuel map so if you were hauling a big heavy load up a hill, the extra fuel would cool the motor so it wouldn't overheat. Makes sense, however, given I've upped the power anyway, I figure I'm not going to have an overheating issue. If it does I'll wire a fan override toggle in the cab. Right now it's controlled by a water jacket thermo-switch, so I don't worry about it. Later today I'll go to the ORV park and climb some steep hills for further testing.

 

So the only thing left to do is make it mount correctly. The hardbody ECU sticks up off the floor because the bottom plate has fingers on it. Good idea in a truck, where wetness is an issue. Anyway, went to switch the bottom plate, but go figure the Stanza ECU case is slightly shorter with a deeper bell on it's bottom plate. I was going to swap the boards in the case, but they security screwed in the board on the D21 case, and it was going to be a significant pain getting those out without a lot of effort.

 

In the end, I ended up putting it back together and then taking the bottom plate off the D21 ECU. It just so happens it fits into that bottom plate just fine. So I ran a bead of blue silicone all around the pan for vibration and dust sealing, and put it back in the truck.

 

It raises the ECU about an 1/8", but I think it will still have sufficient clearance to fit under the passenger seat. I'll be checking it here shortly.

 

I'll update this thread with mileage and performance conditions later on. That is all, enjoy!

 

 

 

 

 

 

 

 

 

[MicroMachinery]

Very interesting. I don't have a D21, but good info, nonetheless.

[HRH]

So I might have figured this, but just went about trying to reset the parameters to get optimal ECU function. That is I knew the hardbody was set correctly to base function.

 

Idle with TPS and IAC disconnected, adjust actual throttle plate to 650 rpm.

With TPS disconnected, adjust timing.

Adjust actual idle with TPS disconnected via IAC screw only. (Should be 750 +-50 and should go up to 800 +-50 after TPS is reconnected. Turn ignition off each time you reconnect or disconnect TPS is recommended.

 

So the problem is when you disconnect the TPS to do this with the Stanza ECU installed, the idle jumps to 1500 rpm. Adjusting the IAC screw all the way down only gets you to about 1250. So it does exactly the opposite of what it's supposed to do. With TPS disconnected, idle should drop by 50 rpm or so.

 

Oddly, re-connecting the TPS sets idle back down to about where it's supposed to be. So in turn, I've been adjusting the IAC idle adjust screw (air bleed basically) with the TPS connected. I gather the hardbody IAC doesn't operate within the parameters of the new ECU.

 

Anyway, that brings you to the problem of timing. Adjusting the timing is supposed to be done with the TPS disconnected to get an accurate reading. Unfortunately unless you know what it's supposed to be at 1500 rpm, you can't set it right. It seems to be at about 23 degrees given the setting with the old computer was at 8 degrees.

 

I tried setting it with the TPS connected, but the ECU overrides the value, so you have no reference point for actual. Ended up putting it back to where it was at 8 degrees, known by the dirt mark in the baseplate from where I turned it.

 

Anyway, with a bunch of dicking around, got it pretty good. Idle is not exactly rock steady, which is probably to be expected. I'm sure I'd have better luck if I installed the entire car intake and wiring harness system on the truck. However, I'm not going to do that. Worst case I'll put the truck ECU back in and re-set to factory parameters.

 

I may find a Stanza FSM and see if there are some set procedures that carry over. I doubt it, as probably the idle system is just plain different. I can handle a not-so-perfect idle though for better fuel economy and performance. We'll see what happens after I drive it around for a week and get a few ideas of the quirks.

 

Hey! Look at that! This post was 4400!

[HRH]

So I'm putting the D21 ECU back in for the reasons in post 1. With the full system/harness from the Stanza, I have no doubt it would work fine. With this system however, it's a little too quirky for my duties as a daily driver.

 

But at least I tried it right?! ;)

[HRH]

Back to normal now, funny how it's so easy to set a KA system back to perfect according to the manual. Done it enough I don't think I'll ever forget it. Set timing at 12 degrees, reset everything for that spec. Truck runs fine, but definitely slower. Oh well. Until I megasquirt it or something I'll just accept it the way it is. Driveability is back to 100% though.

[HRH]

So I went out to the ORV park anyway to give Gracie II a workout before winter and see if anything needed attention. All was good, and even climbed the steepest hill at the far end of the park! Woo hoo! (Farthest left one in the pic. Looks less steep than it is.) I have a video of climbing it, may try and upload that to youtube.

 

 

Here we go:

 

[deathrace2000]

Interesting information. I am actually running my D21 off of a 240sx ECU at the moment.

[HRH]

Manual or automatic ECU? I'm almost wondering if for some reason the Stanza ECU I had was making fuel/spark cuts/slow downs for the AT to shift? Doesn't seem like that's logical, but not sure. What intake system are you using on your D21, or rather, what year and how much of 240sx system are you using?