Block and ecu ID help please

[Hazzid69]

Hey team. 

I recently bought a 1998 R34 which has been 25DE swapped from factory 20. Had some running issues so started doing some digging. The ecu says it’s a 23740 AA010. The closest I’ve found to that is a 23710 AA010 which says it’s for a 20DE. So just wanting to confirm ecu is correct for a 25. Next hurdle i hit was engine number. I got 2 numbers on the bottom passengers side of the block. First which I believe to be the number in need is 5L3 but can’t seem to match this to anything. The second is 90188 not sure if this helps any. 

 

Any my help would be appreciated cheers guys

[KiwiRS4T]

According to this site

http://jp-carparts.com/nissan/partlist.php?maker=nissan&type=81&cartype=&fig=226

your ecu is for an RB20DE auto AWD

That is not to say that this is the cause of your running problems.

[Hazzid69]

1 hour ago, KiwiRS4T said:

According to this site

http://jp-carparts.com/nissan/partlist.php?maker=nissan&type=81&cartype=&fig=226

your ecu is for an RB20DE auto AWD

That is not to say that this is the cause of your running problems.

Thanks mate. Now just need to figure out the engine number. I would assume the fuel and air mapping would be different between a 20 and a 25. So would possibly make it run a bit average 

[Hazzid69]

Couple of pics just in case it helps

[Rusty Nuts]

5L3 block is a RB20de block out of a Stagea 1997 to 1999. Its not a RB25. So should run fine on the 20de ECU. Shirtfront the seller he is a liar.

Edited August 25, 2019 by Rusty Nuts

[BK]

How about you check your actual engine number ? You know on the drivers side towards the front, it will start with RB something. Rusty nuts sounds like he's right as I've never heard of an 5L3 block. There is a 5L7 stagea block that appears to be a 25 though.

[KiwiRS4T]

The fact that the ecu is not original but for an AWD auto would support the theory that its from a Stagea  and an RB20 at that. You would think that if it came from an RB25 the matching ecu would have been fitted.

[Rusty Nuts]

I'm not theorizing or guessing, Nissan make it easy for us when it comes to block part numbers, the 6th 7th and 8th numbers are the casting numbers, no guesses or theories required. The part number of this block is 110005L300    RB20DE

[BK]

yes your correct with the way Nissan codes blocks, just never even heard of a 5L3.

[Rusty Nuts]

7 hours ago, Hazzid69 said:

The ecu says it’s a 23740 AA010

This ECU is from a HR34 Skyline N/A RB20DE auto 4speed 2WD NON-HICAS. So correct for the RB20DE you have. If your R34 is built after May 1998 then it is the ECU that came with your car.

Edited August 25, 2019 by Rusty Nuts

[Hazzid69]

Oh god the plot thickens. Haha.  I’ll post a few pics from the top of engine as from looking at it I was sure it was a 25. Could a 25 head be whacked on a 20 block

[Hazzid69]

So good having so much knowledge around. Cheers guys

[Rusty Nuts]

2 minutes ago, Hazzid69 said:

Could a 25 head be whacked on a 20 block

More likely 25 valve covers and valley covers

[Hazzid69]

Bugger. Might have to take it to my local and see if someone with more knowledge than me to have a poke around and figure it out. Will be disappointed if it is as it was sold to me as a 25. 

[GTSBoy]

Wouldn't the test be as simple as;

A: is it slow?

B: is it REALLY f**kING slow?

If A, then RB25DE, if B, then RB20DE. Right?

[KiwiRS4T]

I am sure Steve is right. But if they haven't been messed with the RB20DE injectors should be yellow (RB25DE should be red) .

If you can find a way to measure it the 25 stroke is 2mm more than the 20 at 71.7 (the 20 is 69.7 and the 25 bore is 86mm and the 20 78mm.Doubt very much anyone would put a 25 head on a 20 but who knows....

[Hazzid69]

So yes I managed to get hold of my mechanic mate that’s built a few rbs and it’s a 20DE neo. So will just have to be a runner while i gather bits and bobs to either drop a 25 or 30det into it. Bit gutted as I only bought it as it was advertised as a 25. Cheers for all your input guys. Such a primo forum