Modifying an NA ecu for turbo idle controls

Stinky · Post by **Stinky** » Wed Jun 21, 2006 10:46 am

I figured you guys might be able to answer this question. It should be pretty easy for someone that knows electronics. I'm trying to get na ecus to work with the turbo idle controls and code. After comparing the circuits I found the D801 seems to be the only difference. After pulling a similiar diode off of a parts ecu and putting it in the test na ecu the idle controls seem to work just like a stock turbo. Now for the question. How can I determine what kind of diode it is so I can buy replacements instead of ripping them off of another ecu? It's a black and white round diode with some small blue dots. I'll post a pic soon.

vgwagon · Post by **vgwagon** » Sat May 19, 2007 2:50 pm

Have you found anything out about this yet.
I'm looking to run the 97 pathfinder upper intake on my 88na computer to and still be able to utilze the iacv/aac that the 97's use.
Also, what part of the ecu code needs to be changed in order for this to work?
Thanks

Matt · Post by **Matt** » Sat May 19, 2007 9:06 pm

diodes to my knowledge have particular characteristics such as reverse allowed voltage and voltage dropped on forward voltage

i would probably just try a 'garden variety' 1N400x diode and see how that goes since the part you have pictured does not have part markings

Fusion Ed · Post by **Fusion Ed** » Sat May 19, 2007 10:19 pm

You could simply measure its characteristics and find something similar

URG8RB8 · Post by **URG8RB8** » Sun Jun 03, 2007 4:49 am

This is my first post, so hopefully it will be useful. I had a similar problem unexpectedly arise when I discovered the '88 turbo ECU I ordered from E-bay some time ago was actually a N/A ECU. I would like to keep the idle controls in tact until I make my move to Florida and be done with all of the smog crap for good. The original D801 diode is a Silicon fast switching, soft recovery diode. It is a NTE 571 equilvalent and has the following specifications: Maximum forward voltage drop: 1.78VDC @ 3A, Max forward average current: 3 A, Max peak current: 65 A, Max peak reverse voltage: 100 VDC, Reverse recovery time: 150 nS. I looked at several electronic shops to find this component and came up empty, so I found a good alternative that is availbale. You can use the NTE 569. It was only $1.19 at Fry's. I will miss this store in Florida. It has the following specifications: Maximum forward voltage drop: 1.25VDC @ 3A, Max forward average current: 3 A, Max peak current: 100 A, Max peak reverse voltage: 600 VDC, Reverse recovery time: 200 nS. I have posted some pictures below. I also added a few shots of the resistors that should be removed for the Z32 or '93 Cobra MAF upgrade/install.

URG8RB8 · Post by **URG8RB8** » Sun Jun 03, 2007 4:58 am

I was unaware of the three picture limit. Here are the rest of the pictures.

URG8RB8 · Post by **URG8RB8** » Thu Jun 28, 2007 8:24 am

Jason (from Z31 performance) brought up an important feature missing from the NA ECU & suggested that I post here seeking more information. The NA ECU does not contain the knock sensor daughter board. How much of a disadvantage is this as far as Nistune is concerned? Can a knock sensor daughter board be retrofitted to a NA ECU? If this should be posted as a seperate topic, please feel free to move. Thanks.

Matt · Post by **Matt** » Thu Jun 28, 2007 7:34 pm

That is correct. As far as I am aware the turbo/non turbo ECUs are identical apart from this (and the mod above... for Z31)

The ROM images themselves for RB30ET which I have analysed side by side are almost identical. It is mainly the settings (constants) which are different (things like indicating knock sensor fitted etc, flag DTC code for knock)

With the knock sensor circuit board if you fit this to an NA ECU and use a turbo base ROM image, then you should be able to detect knocking and the ECU should pull the timing

I have had a look through some of the RB30 code which does do something with timing when the knock sensor input has been flaged as 'active'. I belive it pulls back timing based from a counter value but I dont totally understand how the subroutine works. Uncommented assembly code is very difficult to folow sometimes

RB30/VG30 code for these ECUs is JECS ECU and code

But on the HR31, CA18, HCR32, Z32 etc which have Hitachi ECU and code these have the two knock tables and have some knock counter comparison table in them too. Only the Z32 location of that table is readily known but the others should be able to be investigated further

URG8RB8 · Post by **URG8RB8** » Fri Jun 29, 2007 10:42 am

I am pretty sure from your response, that it is possible to add a knock sensor daughterboard to a N/A ECU. This brings up another question. Are all Z31 turbo ECU daughterboards the same or do they vary by model year? I have a '84 & '86 turbo ECU which I could scavenge the daughterboards from, if they are the same from year to year. I hope this is the case.

Matt · Post by **Matt** » Fri Jun 29, 2007 12:37 pm

The knock sensors for Z31s I believe are all the same, the daughterboards should be also. They are just a frequency filter