205 Ecu Conversion

SuperWhite92

New member
Okay, there was one on ebay that I lost track of about 2 months ago. I don't even remember what company made it, but what it did was include the ECU, and a few sensors to replace the ST185 ones, so that you could run the 185 off the 205 ecu after rewiring, and such.

Anyone know what im talking about? Or am I totally off my rocker?
 

Gabtoks

New member
Well I don't know of any company who would make a "kit", but a few people here and there are selling all the parts. Depending on the price, it could be a good upgrade. If you need the list of parts necessary for this upgrade, you can find all the info, a few people made up a list.

Gabe
 

Gary

Moderator
You will need
205 ECU ~$300
Harness ~$200 (you can rewire it yourself, 17 wires more, and save on this)
igniter
map
mat
iat
radiator sensor (?)
disconnect , if there the 02 sensor heater and place an resistor , Tvis, Egr
 

sardgt4

New member
Well I have a 92 st185 with a 3rd gen mr2 ecu. Not sure how much the ecu will cost you id say $100-$350. As for wiring the 92-93 will only need about 5 wires to be moved. The rest are strait forward to the 3rd gen ecus. The ignitor is the same part # as any 5sfe celicas (94+), tercels, RAV4s mr2s, and camrys. There are 2 part #s and I have tested both parts and they work. I paid $15 or so for them. If you do not change this your rev limiter will be at 5500 rpms no other side effects. THe map sensor is like $280 but I didnt notice any change in my car after changing it. My theory is that 92-93 map sensors are the same as the 3rd gens because 90-91 st185s have 12psi fuel cuts and 92-93s have 15psi fuel cuts. I theorized that the difference in fuel cuts are due to the map sensor. I wouldnt waste your money on the map sensor since you have a 92. Save the $ and get a super afc or emanage or some other fuel controller. THe mat i used a GM one. The iat I used a resistor. Didnt really see anything else that needed to be done except disconnect the egr. If you get the st205 ecu I know that you have to put in a resistor for the intercooler water level so it doesnt go into safe mode. Hope this helps.

John 92 st185
03 g35 coupe


You will need
205 ECU ~$300
Harness ~$200 (you can rewire it yourself, 17 wires more, and save on this)
igniter
map
mat
iat
radiator sensor (?)
disconnect , if there the 02 sensor heater and place an resistor , Tvis, Egr
_________________
 

Gary

Moderator
sardgt4":18swbxa8 said:
Well I have a 92 st185 with a 3rd gen mr2 ecu. Not sure how much the ecu will cost you id say $100-$350. As for wiring the 92-93 will only need about 5 wires to be moved. The rest are strait forward to the 3rd gen ecus. The ignitor is the same part # as any 5sfe celicas (94+), tercels, RAV4s mr2s, and camrys. There are 2 part #s and I have tested both parts and they work. I paid $15 or so for them. If you do not change this your rev limiter will be at 5500 rpms no other side effects. THe map sensor is like $280 but I didnt notice any change in my car after changing it. My theory is that 92-93 map sensors are the same as the 3rd gens because 90-91 st185s have 12psi fuel cuts and 92-93s have 15psi fuel cuts. I theorized that the difference in fuel cuts are due to the map sensor. I wouldnt waste your money on the map sensor since you have a 92. Save the $ and get a super afc or emanage or some other fuel controller. THe mat i used a GM one. The iat I used a resistor. Didnt really see anything else that needed to be done except disconnect the egr. If you get the st205 ecu I know that you have to put in a resistor for the intercooler water level so it doesnt go into safe mode. Hope this helps.

John 92 st185
03 g35 coupe

That's a good info John, especially on 92-93 :D
Wanna do a write up?
5 more wires is not bad at all.
Do you have any problem with octane rating?
I check on MR2 board only to find that they sell ECU for ~$300. :(
 

sardgt4

New member
Yea it was 5 or 7 wires or so not many. At first I was using the wiring diagram from a 90 from the BGB and I had no spark. I moved like 14 wires or so ALOT of work. Then one of my buddies suggested just pluggin the damn wires in the ecu strait without moving anything and i got spark at the ignition. Then i figured the 92-93s had a different wiring diagram. Couldnt find the diagram online so I just used one off the 2nd gen mr2 and it worked. I have the 3rd gen ecu wiring schematics in japanese. I can send you a copy if youd like. Its very hard to decipher tho. I can just send you the cracked version (the pinouts I determined). You're gonna laugh if you see how dirty and beat up this piece of paper is. A few notes to add I used the 2 res off the afm for the AIT. The other 2 i just left dead alone. The map sensor just plug it in thats it. There no more egr so I used the wires off that for the MAT sensor. I made an adaptor to put the MAT into the cold injector location you will not need that anymore. As for upgrading to 550s I dont know if you need to because the car runs really rich and retarded for some reason. I had the super afc settings leaned out 30% at WOT on the high rpms and advanced the timing up to 20 degrees at one point. THe car ran awesome, but I didnt feel comfortable with the timing so advanced. It was good at WOT but at idle and low throttle it felt too advanced. A guy named Lindsley has the 3rd gen ecu too on his 92 alltrac in the eastcoast and he had reported similar results in leaning it out and whatnot too. I dynoed my car at 205 at the wheels at 14psi with the timing advanced to 15 degrees. The WB o2 sensor read real rich so I advanced the timing to 20 when I got home. THe car ran much much better. Ive been driving on this setup for 2 years with no problems. My car is currently down upgrading to a t3/t04e. I am done with it just need to sandblast the inside of the intercooler pipes to make sure theyre clean. I also took off the super afc and went with a emanage. I really need to tune it now. Just with the ecu alone you will not feel any power, you will have to get some sort of fuel controller such as a afc.

Hope this helps,

John 92 st185
 

Gary

Moderator
Thanks John. If it's not difficult for you, please send me both versions. I'll ask my Japanese friend to help me out.
 

sardgt4

New member
Sorry guys for the delay. I will do a writeup and send ecu schematics soon after tuning the emanage. I was busy with my new turbo. Just finished it today. It was a $500 very well spent. I have a few pics if you guys wanna see. Now i have to tune the emanage to get it running right. Lotsa things to do, no time and money.

John 92 st185
03 g35 coupe
 

Gary

Moderator
Don't worry John. Nothing's hurry.
I suppose to get a 3rd gen ecu but the seller backed off the deal.
May be he realized that it's too cheap for the ecu. :shoots:
 

5speedGT4

New member
Im bring this thread back from the dead!

Im about to do this swap, i got the ecu and sensors and such needed! Now i just have to figure out how to do this?

Any more info gary? anyone else?
 

5speedGT4

New member
eh, i kinda figured that out... im just looking to see if there are any other things i ought to know that i may not catch otherwise....
 

ChrisD

New member
I could easily, the problem is that I do not have a source for the plugs.

The conversion is pretty easy at the ECU end though. Only thing to keep in mind is that 1) TVIS will not work, 2) THAM has to be added, 3) THA has to be added, 4) need different turbo pressure sensor.
 
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