D21 ECU

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666d21
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D21 ECU

Post by 666d21 » Wed Mar 22, 2017 12:50 pm

Alright, so this is my first post here, but I'm certainly no newb lol. Question. I have a 93 d21 that I'm hoping to go turbo with here very soon. Will need a tune for the ecu. Obviously.

My truck seems to hit fuel cut or similar in 3rd gear at roughly 68 mph. Is this indicative of an issue I'm unaware of, or is this something that will be just tuned out? It's driving me nuts....looked everywhere for months have found very limited information on the subject. Thia

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Nomad
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Re: D21 ECU

Post by Nomad » Thu Mar 23, 2017 3:07 am

Hi, a couple of questions to get a bit more info.
About how many revs does 68mph in 3rd gear equal?
Does it miss fire like a rev limit or just not rev any further, like it runs out of puff?
1995 D21 Navara Dual Cab
Socketed U12 ECU
Tuned ROM/NVSRAM

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Re: D21 ECU

Post by 666d21 » Thu Mar 23, 2017 3:21 am

Truck doesn't have a tach. Haven't installed one yet. I'd estimate about mid 5k rpm. It hits 68 mph, then it's like you unplugged the coil wire, you can stab the throttle all you want,it just won't do anything for a second or 2. Shift to 4thc and it'll pick right back up.

I had read somewhere about a limiter of some sort at 68 mph so I assumed this is what it is.

If you accelerate at less than full throttle, you can continue past 68 as well. It's very strange. I can take it to over 100 in 5th, so it can't be a load issue.

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Nomad
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Re: D21 ECU

Post by Nomad » Tue Mar 28, 2017 2:49 am

FYI, U12 Stanza's with KA24E's have a high speed fuel map that is used over 68mph. This map is very rich and can make the car feel like it is loosing power, but not to extreme. Makes it use more fuel though!
The D21 hi speed fuel map is very similar to the primary map, so it shouldn't give the symtoms you are experiencing.
Have you done a diagnostic test on the ECU and checked for error codes?
1995 D21 Navara Dual Cab
Socketed U12 ECU
Tuned ROM/NVSRAM

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Re: D21 ECU

Post by 666d21 » Wed Mar 29, 2017 11:14 am

Yeah. Should have been more clear. Covered all the bases. Codes, good connection, etc. I do believe tho, that the ecu is out of a 240, not a d21. And when I hit 68, or so, it literally shuts down. Have to go below 68 or grab 4th gear to continue accelerating.... very strange to me.

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Re: D21 ECU

Post by Nomad » Thu Mar 30, 2017 2:43 am

Ahhh, an S13 240 (KA24E SOHC) ECU, I assume.
240's have a 5th gear switch that the D21 does not.
From the FSM, the 240 ECU is expecting 6-8 Volts on pin 45 (5th gear sw) when the 5th gear switch is NOT engaged. (0V when engaged)
Maybe because pin 45 is never getting this 6-8V, it is upsetting the ECU?
Worth investigating?
1995 D21 Navara Dual Cab
Socketed U12 ECU
Tuned ROM/NVSRAM

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Re: D21 ECU

Post by 666d21 » Thu Mar 30, 2017 6:35 am

That's what I was wondering about, but, I can hit the Rev limiter in 1st and 2nd gear.... I suppose I'll scope out the 45th pin and see what the deal is.

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Re: D21 ECU

Post by 666d21 » Thu Mar 30, 2017 6:38 am

At the same time, ive done the the speed cut out elimination by cutting the speed sensor wire, in hopes that that would fix it. But alas, no change

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Nomad
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Re: D21 ECU

Post by Nomad » Thu Mar 30, 2017 2:15 pm

Oops, I was a bit tired last night (Oz time) and was a bit wrong there.
The 5th gear switch just grounds/earths pin 45, so having no connection will make no difference at all.
Cutting the speed sensor wire may make it go into "limp mode" (max 2500rpm). That happened to me when my speedo stopped working.
1995 D21 Navara Dual Cab
Socketed U12 ECU
Tuned ROM/NVSRAM

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Re: D21 ECU

Post by 666d21 » Fri Mar 31, 2017 6:57 pm

It's certainly not in limp mode, and oddly enough, no speed sensor code. . Weird. May try chasing the 5th gear circuit

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Re: D21 ECU

Post by 666d21 » Fri Apr 21, 2017 9:59 am

So, after lots of trouble shooting, I still haven't found any issues. What would happen if I applied power or ground to pin 45? Simulating that 5th gear switch being there. Ideas?

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Re: D21 ECU

Post by p00t » Sun May 21, 2017 7:41 pm

Unplug the 4th and 5th gear switches on the transmission and your problem will go away.

Most switches will connect to ground when on. There is no way for the computer to detect if the are unplugged. Electrically they appear just like the switch isn't activated.
KA24DETT still alive
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Re: D21 ECU

Post by Aiden02 » Mon Jan 08, 2018 7:57 am

666d21 wrote:Truck doesn't have a tach. Haven't installed one yet. I'd estimate about mid 5k rpm. It hits 68 mph, then it's like you unplugged the coil wire, you can stab the throttle rembourser crédit all you want,it just won't do anything for a second or 2. Shift to 4thc and it'll pick right back up.

I had read somewhere about a limiter of some sort at 68 mph so I assumed this is what it is.

If you accelerate at less than full throttle, you can continue past 68 as well. It's very strange. I can take it to over 100 in 5th, so it can't be a load issue.
Hello, thank you for your response :)

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