View Full Version : St185-St205 electronics conversion

01-23-2013, 06:08 AM
Is there a thread anywhere about this?
What all is needed?

01-24-2013, 03:44 AM
205 ECU, injectors, ignitor, map sensor, a 185 to 205 jumper harness (or you can repin), inlet air temp sensor. If I remember correctly, I think that is it. I'm not sure if there is a thread here but the info is available over at MR2OC. I'm going to do this but still have to get the harness, map sensor and injectors.

01-25-2013, 04:53 AM
Is there any down sides to doing this?
Would you be running higher stock boost because of the 205 ecu?

01-25-2013, 05:14 AM
Boost isn't effected by the conversion. The boost level is controlled by the wastegate actuator. It's a vacuum pod that opens the wastegate at a specific boost level. You can control that with a boost controller.

From what I've heard, there doesn't seem to be a downside. The engine runs better and the AFM is eliminated. I'm pretty sure Luni did this conversion on his MR2. I know there are a few other All Trac guys floating around that have done it as well. As soon as I can put some cash together I'm going to do it.

01-25-2013, 01:52 PM
Wow I knew that it wouldn't be affected because its ran off the wastegate, I don't know what I was thinking.
Do you have a link to that conversion thread?
Or Luni did you happen to do a write up on it?

01-25-2013, 09:27 PM
I did a write up on MR2OC.

There are several threads on here that Ive touched on.

Dont do this mod unless youre going to do something with your cams, you need Gen3 cams or you need at the very least an adjustable cam gear on the exhaust side. The thing falls on its face in the top end of the revs. Smooth as silk, driveable as hell, but now top end power. You will LOSE power up top if you dont address the cam timing difference.

01-26-2013, 03:22 AM
Would I need intake and exhaust camS from the 205?
Or would the hks cam gears work?

01-26-2013, 04:33 AM
you don't need either, the 2nd gen cam gear is almost identical to the 3rd, look up my thread on cheapest exhaust cam retard. By simply retarding a tooth on your belt and moving the dowel on your cam gear to advance the timing forward and you get the same effect (tho obviously not as easily changed) as buying an adjustable gear or 3rd gen cam. I did this while I was putting in my clutch and ct20b and it works awesome, the top end pulls hard all the way even on stock waste-gate pressure. I would also like to suggest doing something to your fuel rail or pump or both also. I did dual feed stock rail and supra pump. Assuming your on a budget which everyone is... this is probably the best option, unless you really need to be able to adjust your cam timing for tuning every last little HP or something...

01-26-2013, 05:23 AM
^You can do that too I suppose.

Ive never messed with the dowel on the cam so I dunno. BD says it works so I say go for it.

01-26-2013, 05:33 AM
I think my car already has an upgraded fuel pump, not 100% sure tho.
The guy I bought it from gave me a list of upgrades but don't know where its at.
He told me he was running 17 psi... Don't believe it because it still has stock injectors and tmic.

02-10-2013, 04:45 AM
What is the difference as far as the intake cam? Has anyone here done the gen 3 and coil on plug?


02-14-2013, 02:34 PM
Can we get some links to those threads I have a terrible time finding things with searches.

02-14-2013, 11:40 PM
Lift on gen 3 cams is taller, and the retard is different. The cam gears themselves are the same. Look at finding a good set of gen 3 cams, that will solve everything, they aren't that hard to come by and they aren't that expensive.

Over on GT4OC they are quite common to find, Ill see if I cant source you a set for cheap.

EDIT: Found THIS (http://compare.ebay.com/like/350708129168?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar)

Then sell the Cyl Head minus the cams, might be suprised what you can get for a bare gen 3 head :)

02-20-2013, 03:17 PM
Okay so I have been sourcing this out and it looks like its about 400 to do a gen 3 electronics upgrade and its about 400 for a coil on plug upgrade. If you do both at the same time you reduce the cost to about 600-650 depending on how much you can get used parts for. This guy on mr2oc sells COP kits designed for gen3 ecu, you source coils and plugs etc. http://www.mr2oc.com/showthread.php?t=444574

There are several guys with gen 3 cams for sale around 100 bucks on mr2oc if you want to get some. You can get a gen 3 ecu here easily also. This guy has both for sale http://www.mr2oc.com/showthread.php?t=459344&highlight=gen+3+cams

02-24-2013, 07:59 AM
Good info on the COP setup BD.

My Gen3 EFI conversion thread: http://www.mr2oc.com/showthread.php?t=292842
I got ALOT of my info from Ishii in his thread: http://www.mr2oc.com/showthread.php?t=240177

Neither are TOTALLY complete, but honestly should give you the gist of what you need to do. Ive performed the conversion on BOTH my MR2s, and as well for a buddy of mine here in Utah, so 3 times.

05-12-2013, 02:34 PM
Well Just wanted to update this thread and let you guys know I got the conversion done. I went with a Gen3 mr2 ecu to avoid intercooler sensor issues I read about with 205 ecus. If you have a JDM Gen2 ecu it is super simple to change over, other than the wiring in the engine bay, you only have to re-pin a single wire on the ecu. The Coil on plug was significantly harder. I think I might do a write up thread on all of it if anyone shows interest. NoddE still has a few kits to sell, if anyone is interested post up.