st205 into st185 swap faq/ and parts compatibility

toayoztan

Moderator
I feel this is a pretty useful thread. Can a MOD sticky this?

And perhaps stick this thread in the FAQ/Archive forum? It'll be nice to keep this easily accessible in there. (I guess if it's in that forum, it won't need to be stickied)

Bryan
 

aus jd 2703

New member
Hey guys I started her and she runs:)
one problem I'm having is the boost gauge isn't working at all. Has anyone else had thisproblem? Is it due to the 205 map sensor?
Cheers
 

CMS-GT4

Active member
My boost gauge works, but I can not remember what controls it. I think it might be related to the vsv or map sensor.

Did you disconnect the turbo vsv for a boost controller?
 

aus jd 2703

New member
no i didnt disconnect the vsv or map i thought....
ill double check to day (i still have the cars on stands so cant really hit boost so ill just turnb the ignition on and used a compressor with regulator to apply 14 psi).
any suggestions would be appreciated
 

CMS-GT4

Active member
MixMaster":1fz2so3d said:
On pg 13 you mentioned a new ecu fixed your code 54 problem and that the 3rd gen mr2 ecu would not start the car.
Were you able to use the mr2 ecu or did you wire up a fix on the 185 harness to get rid of code 54.
I'm using a fmic, 185 wiring and 205 electronics.

Thanks for any help. Great info congrats on the swap.


I ended up selling the mr2 ecu and buying a new st205 ecu. It turns out my previous 205 ecu had issues with its INT function. I sold it cheap a while back for someone who wanted to make it work for their project. I used the code54 solution found in the code 54 thread.

EDIT:
viewtopic.php?f=9&t=17368&hilit=code
 

aus jd 2703

New member
I unplugged my map sensor and the gauge didn't change any ideas how to fix that? Ad my bgb said it should show full boost when disconnected.
 

CMS-GT4

Active member
I am not sure. I know there is a thread on these boards that has discussed the stock boost gauge not working. I would search around a bit, as its not really covered in this thread. Hopefully someone can chime in that has experience with it. Hopefully its a simple solution.
 

KORacing

New member
just completed this conversion on a 90 alltrac thanks in big part to this thread. I came up with a slightly modified fix for the code 54 that didn't use a bulb, but two 1/4 watt 10k resistors in parallel (equals 1/2 watt 5k ohm load). On the intake temp sensor, at the AFM connection I put a 10k resistor across the THA and E2 pins and code 24 went away. Thanks for the great info. Would be nice to see this information in a more concise format -- I may use the information here to create an article on the swap.

BTW, I used the 90 4 wire o2 sensor with the 90 engine harness just fine.

Cost to do this conversion again (not including parts): $2200

On this customer car we also installed a front mount IC setup with custom pipe, painted and installed a CS front bumper, and installed a Street Brawler billet 58mm turbo kit (gen 3 of course), custom air intake with the battery still in stock location, and a Blitz spec R boost controller.
 

CMS-GT4

Active member
Glad it helped. I might condense it some day whenever I finally finish my car.

EDIT: Maybe you might help me. I notice a slight dip in idle when I hit the gas. Any idea what to check for? Everything is stock but the intake, and turbo back exhaust.
 

aus jd 2703

New member
Won't not running a tha sensor throw the ecu offas it's a VE based map? I'm looking forward to putting mine on the road just gottamake a custom intake hose and water lines for the wta ic
 

KORacing

New member
CMS-GT4":13yimcyg said:
Glad it helped. I might condense it some day whenever I finally finish my car.

EDIT: Maybe you might help me. I notice a slight dip in idle when I hit the gas. Any idea what to check for? Everything is stock but the intake, and turbo back exhaust.

If your TPS adjustment is correct, then I'd say that it's likely that it's running a little rich or lean right at throttle tip-in causing a slight hesitation. Could be due to a incorrectly reading temp sensor (air or water), o2 sensor, etc. Hard to say what it is if you are running all the used JDM parts. Fuel pressure correct? Not a lot of info from the stock ECU...

I actually started the car we swapped with a Hydra to see what the temp sensors were reading to see if things looked normal before starting it with the stock Gen 3 ecu, but not really an option for most people...
 

KORacing

New member
aus jd 2703":141iuzv8 said:
Won't not running a tha sensor throw the ecu offas it's a VE based map? I'm looking forward to putting mine on the road just gottamake a custom intake hose and water lines for the wta ic


The THA is probably much less critical to running than the THAM (manifold air temp sensor) as that is the sensor used primarily in the speed density calculation. My guess is the THA is used as a correction for ambient conditions as it is pre-charge cooler temperature and ultimately, it is the temperature of the air in the manifold (post charge-cooler) that is critical to how dense the air going into the engine is.
 

CMS-GT4

Active member
KORacing":3q4zp45c said:
CMS-GT4":3q4zp45c said:
Glad it helped. I might condense it some day whenever I finally finish my car.

EDIT: Maybe you might help me. I notice a slight dip in idle when I hit the gas. Any idea what to check for? Everything is stock but the intake, and turbo back exhaust.

If your TPS adjustment is correct, then I'd say that it's likely that it's running a little rich or lean right at throttle tip-in causing a slight hesitation. Could be due to a incorrectly reading temp sensor (air or water), o2 sensor, etc. Hard to say what it is if you are running all the used JDM parts. Fuel pressure correct? Not a lot of info from the stock ECU...

I actually started the car we swapped with a Hydra to see what the temp sensors were reading to see if things looked normal before starting it with the stock Gen 3 ecu, but not really an option for most people...

Thanks.
I will check the TPS when I get the car back.
 

lalojamesliz

New member
back from thedead 8) thank you Coldiron for posting all of your problems and solutions on here. im buying another st205 gen3 swap (my first one got parted out) but his time i will be installing it in my 91 all-trac. i currently have gen3 electronics on my gen2 engine with a berk jumper harness with my original 91 harness so i hope it will be mostly a plug & play since my gen2/gen3 engine with a gen3 MR2 ecu runs like a champ. i plan on buying new belts, this kit http://www.berktechnology.com/shop/prod ... ry=related and a new oil pump if it needs it. i already have hks 256 cams (might trade for some 264's), arp head studs and a new gen3 hg. i dont want to remove the head unless i have to for some reason. i have a gen3 engine top half i was going to install along with a st205 trans i also have but everyone tells me it would be easier to just swap in another engine/trans instead of operating on my gen2. my current mods are a st205 I/C with the pump and I/C fan always on with the engine,ct20b,upgraded intake and a mandrel bent 3'' exhaust with a 3'' dp. my current power band sucks with power only in the mid rpm's since i have my stock cams and gears so i hope this will make a big diffrence at 16-17 psi like i run right now.
 

soarer.jzz30

New member
I just put in my gen3 swap in my 90 all-trac. I actually took apart the 185 harness for the sensors to the gauges and cruise and A/C control and electrical stuff. Then ripped apart the gen3 harness for the engine control parts of the harness. the taped down all the sensors, and flipped the gen3 wiring to the other side. Then cut and extended the wires that were short. Once finished I mated the 185 and 205 harnesses, the grounds and everything so it would bee like OEM. That way I don't have to re-pin much of anything except the fuel pump relay signal to the 22 pin. and the circuit opening relay on the 16 pin. there were only minor discrepancies. I really think this method is easier and less of a headache partly because you are actually getting a legit harness out of it. And not having to modify an old worn harness to suit the needs, then re-pinning everything. Instead combining the needed harnesses from both cars. It took about 30 hours of labor to actually get this done though, so for time sake it is not the best method, but now I know my harness very well and am not afraid of getting in there when I might need to. Much more confidence ATM when it comes to this now.
 

CMS-GT4

Active member
I updated the first post. I added info I remember and added quotes of useful info from this thread. While I suggest people still read the whole thread and since there may still be some things missing. For the most part, the first post should have enough info to get you started on your 205 swap.
 

turbocelica

New member
Okay trying to finish up this swap got the car running today, still have a few vaccum things to take care of so i figured id post pictures to find out where these go, also i need a stock bypass valve and throttle cable bracket if anyone has one. The line in question are circled and what are those two sensors? i found them in a bin of alltrac/ supra parts and not sure if need to be hooked up. The only codes I have are 54 and 23.


 

CMS-GT4

Active member
First pic. I forget what it's meant for. The closest to the intercooler I used for my boost gauge. I capped the other.

2nd looks like your ac idle up. Bgb should detail where it goes. I used the 205 one.

3rd pic not sure.
 

phattyduck

New member
First pic = both vacuum lines go to the EVAP solenoid and canister. If you are keeping the USDM evap system, you don't need both lines. Cap the port closest to the firewall and connect the other port to the evap cannister through the one-way valve (so that air can only flow in to the engine). You will also need to put a 1k ohm resistor in the plug for the VSV that would be used in the JDM evap system (I believe its a blue plug and should be down near the canister).

Second pic = ST185 A/C idle-up, as described. You will want to use the ST205 idle-up valve instead (vacuum ports from the back of the intercooler to the the solenoid and from the solenoid to the manifold). You then have to get the A/C wiring right to get it all to work...

Last pic - doesn't look like anything ST185 or ST205 related.

-Charlie
 
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