RC ECU to ST185 JDM Q's

M

MetalSlug

New member
I have a few questions regarding an ECU and AFM swap, I have searched the forums and found useful information, but not all that I need.
What parts do I need for an rc ecu swap? I already have the Air flow meter and the ECU, and can get the wiring loom also, is there anything else that I need?
I saw a 205 to 185 writeup and it said something about injectors? I assume I don't need to upgrade the injectors as they are the same in the RC as the JDM.
Is there any hidden dangers of upgrading the ECU? I have a FMIC on the way, but at present I'm running the stock IC, If anyone was going to comment on chance of detonation on higher boost.
I noticed the plugs are completely different on the RC as you can see from the pictures below. Is there any rewiring needed, even if I get the harness?

I'd like it to be as plug and play as possible.

Heres a comparison of the AFMs, RC on the left and JDM on the right.
2633264_15_full.jpg

Below is the JDM AFM Plug
2633264_16_full.jpg

Below is the RC AFM Plug
2633264_17_full.jpg
 
Gary ST165

Gary ST165

New member
MetalSlug":fajwfnet said:
Is there any hidden dangers of upgrading the ECU?
Click to expand...

yes a lot of hassle and cost for virtually zero gains.


what is the part# on you current JDM ECU?
>>> If it is a 92-93 JDM ECU then it is almost a pointless swap.



my best advice is to fill up with the highest octane fuel available and crank up the boost until factory fuel cut.
 
M

MetalSlug

New member
Apart from all the hassles, are there any other parts I'd need other than the AFM, ECU and Harness?

The JDM ECU part number in my car is 89661-2B280
The new ECU part number is 89661-2B310, definitely from an RC

I was swapping it out as I got the AFM and ECU for dirt cheap, and they do have better fuel maps and higher boost cut. It's not just for the performance, it's so I can learn at the same time.
 
W

WarTowels

Active member
Why not just get a regular JDM ecu, that would require no afm or conversions of any kind. If you got the correct year 90-91, 92-93 it will be plug and play.

-Towels
 
M

MetalSlug

New member
I already have the JDM ECU, I'm in NZ and thats all we get over here, but I wanted the RC ECU for the better fuel maps and higher fuel cut.
I haven't done many mods to the car, so the ECU would complement it nicely, without going too overboard (and better on my wallet).
Current mod list as:

Higher flowing air filter (old picture)
2459214452a5029423893l.jpg

Vent to atmosphere release valve
2459214452a6825712810l.jpg

Exhaust dump pipe
2459214452a6825712842l.jpg

3" all the way through
2459214452a6825712921l.jpg


I am getting a front mount intercooler soon, and once that is installed was planning on running higher boost, hence the new ECU.

I thought the RC ECU was an improvement over the JDM, but may have been mislead, I have always heard about how it was more aggressively tuned and such.
 
H

Hotrodhendrix

New member
Nice car man.

He already has the stuff. Even if its not much of a gain he already has everything to do it. Why wouldnt he?
Im not sure what else besides the AFM wirring you would need. I cant think of anything...

Anyone else want to answer his question?
 
S

ST185pinjo

New member
I think you will be getting the engine warning light. Because you don't heve the WtA IC ecu. You can sort this, but will be extra work.

I have unpluged this for my always on for the ic-pump, but it is stlii hooked up. Maybe if you dont hook it up there will be a CEL.
 
Gary ST165

Gary ST165

New member
MetalSlug":3kliuoxd said:
The JDM ECU part number in my car is 89661-2B280
Click to expand...


89661-2B280 is a late spec / revision ('91 08 - '93 09) ST185 JDM ECU.

It shares the same twin board ECU architecture / design, as found on the RC/CS and rev2 SW20, and then subsequently carried across to the ST205 and rev3 SW20.

The on board maps, will not be significantly different to those found on the earlier RC ECU..

You will notice very little difference in performance. Factory fuel cut is reported to be 16-17 psi on the 89661-2B280 ECU. (can you confim fuel cut level from your experience?)


I still think this is a pointless swap. If you got the RC parts cheap, then sell them and put the money towards a fully reprogrammable ECU and bin the AFM once and for all.
 
G

Gary

Moderator
Gary ST165":25ldit07 said:
You will notice very little difference in performance. Factory fuel cut is reported to be 16-17 psi on the 89661-2B280 ECU. (can you confim fuel cut level from your experience?)
Click to expand...

That's about right.
My USDM 93 ecu does that.
I have hit 15 psi several times. No fuel cut.
 
M

MetalSlug

New member
I suppose this forum should be moved over to the parts for sale section, lol.

So my JDM ECU is just as good as the RC? What about the larger AFM? Any reason to still do the swap?
I've never hit fuel cut, but might test this later, I have an MBC sitting in front of me, never installed it as I assumed there would be no point (boosting at 10PSI, and thought fuel cut was 12)

Thanks for all the info, I don't know where I went wrong, but it's good to be pointed in the right direction.
 
L

l0ch0w

New member
well... most peoples fuel cut hits around 10, can vary though. But seriously, the boost cut thing isnt a big deal. Check the power primer for a link on how to make a radio-shack 7 dollar fuel cut defender deal... As for ECU, its too much money and hastle for like 10 horsepower, when you can get much greater gains from just installing a fuel cut defender, and boosting more.
 
G

Gary

Moderator
l0ch0w":38bmvw9h said:
well... most peoples fuel cut hits around 10, can vary though.
Click to expand...
Well, I don't think "most" people hit fuel cut at 10 psi.
If you hit fuel cut at 10psi, there is something wrong with either your car or your boost gauge.
Stock boost is 7-11 psi.
 
M

MetalSlug

New member
I have the wiring harness for the ECU too now. I'm focusing on getting the intake air colder before I start increasing boost. I just acquired some FMIC pipes and I'm in the process of purchasing an intercooler, joiners and and RC front bar. I'll post pics when its all up and running ETA 2 Months (I'm incredibly lazy) :?
 
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