Sodokat

Well here is the vig guys. Pulled the sensor and when you would flick it, it would show a decreased temperature (this makes sense for an internal short on the sensor but only under vibration). So I put in a real Delphi sensor, and the issue went right away. I still think that the sensor is not far enough into the flow to be getting a good reading so I might tinker some more with that. Here is the interesting part. My logging ability also came back to the computer. I went on a longer drive, probably 10 minutes, and didn't once lose connection. I do seem to have a little bit of an issue breaking up at higher RPM, but now that I have logging back, I can look at that more closely.

I will try the a couple more things with the USB cable. I just don't understand why it would get worse over time, I was thinking degradation of a ground? Who knows but I will check the transmission one next. My mistake on the spark plug wording, it is whatever the non copper one that the owners manual call out. I followed your/ ATS instructions on plugs so I will be sticking with copper, engine idles much better imo at least when cold. I was fidgeting around with knock control which made it helpful to see realtime data on the laptop. I can do it with logging but it takes a bit more time. Also was doing some freeway eco tuning from the passenger seat where it is very useful to edit tables real time

I will double check that tonight and report back, on the wiring jiggle. I will also look again at the noise to see if it looks cyclical with the rpm. Yea I didn't mention that, but after this issue started I figured I would try new plugs so I switched from oem iridium back to NGK v powers. The car seems to like the copper plugs more. I know there was an update on the firmware, but I am pretty sure I have the latest. I tried a ferrite cable for the USB, I might try another laptop as well. The connection drop is quite annoying. I read up on a couple other threads that had similar issues with 3sgtes and this ECU. Any suggestions there?

Greetings, I have been running my G4X on my '92 MR2 turbo for about 6 months now. When I first got the car running I didn't have any issues with connection drops while PC logging or at least they were very rare. The rate that I would see a 1407 connection drop steadily increased over time until it is now at the point the connection only holds if the engine is not running or below 3k RPM. Strangely I have also started to see one of my sensors misbehave at the same RPM threshold as my ECU disconnects from the laptop. Almost exactly 3100 RPM both the ECU will disconnect and the sensor will start to increase in voltage (decrease in registered IAT temp). The sensor's data if plotted shows a large jump in voltage and a lot of noise, the readout for the sensor drops about 40 degrees and varies around +/-15 degrees at about 10HZ The sensor is a standard GM IAT fast response sensor (Delphi IAT). I know that its position is not optimal for airflow, it lives in the stock cold start injector location and is a little shrouded, but it is showing a 30-40 degree drop in IAT when I get above the "breakup" RPM. When I get a little bit higher than that it seems to lose some of the signal noise. Things I have tried so far: Cleaning all the grounds to the intake manifold, checking to make sure my sparkplugs were firmly connected and not leaning on any other wires, I am in process on trying another IAT sensor as a double check (the old one had correct continuity and increasing in voltage seems illogical for a sensor with a bad connection.) Does anyone have any suggestions? I can use the ECU logging to grab whatever data but neither the 5V reference or the other sensors seem to show any erroneous behavior. Thanks in advance, Caleb

Excellent, thanks for the feedback. I was having a little bit of a miss when I drove it around the parking lot. It wasn't idling well so I didn't get the chance to log it, but that will be my next step. If I wanted to setup a relay to run my wideband controller (and later whatever other junk I get), suggested method is to use one of pins as a switchable ground for the signal side of the relay correct? Rather than switching on a power source for the signal.

I guess a little bit of an update to this, I got the car repinned. You can look at my google sheet here to check that out. It wasn't too bad, there are some small differences between the US late gen 2 and the 205, but it was pretty obvious when looking at the references. I did use a pair of pliers, although I should not have. I paid the price when one of the wires came loose and it was nearly impossible to get the terminal out. All is well though the car was idling this weekend but I have a few issues to solve. First I have a map provided by the distributor but it seems a little odd to me, it was setup for multi fuel which is great, but I am not planning to tune for 85 for a while so my plan was just to switch to modelled. That being said the fuel table is a bit weird. I am attaching the file, but I think the shaping is incorrect. The car ran really rich at idle and then got super lean right off idle. I may just smooth it out and work from there. Second problem, I think I either have the RSC RSO (ISC Open/Closed in Link verbage) pins mixed up. When I was closed loop idle the car would get into the top edge of idle range and then the control would go to zero, which would cause the idle to spike. I think it should go the other way so when it went to zero the ISC would close and the idle would drop. Plan is to pull of the idle valve and check its function outside the car. Third thought, should IAT correction be off for modelled fuel type? I think I read that elsewhere on the site. Fourth, I have some question about the injector table. These are pretty big imo, 1200cc, so I don't know how much trouble I will get with idle. It has a dead time set from the distributor for my injector, but the short pulse width adder is not filled out. I don't really know how critical that is. Sounds like it probably isn't too big a deal unless I had a little bit larger injectors. Appreciate everyone's help, and I apologize for knowing basically nothing. Holmes Map Mod.pclx

I am working on a excel file with a pinout conversion tonight, hopefully will have it done before the pinning tool shows up. Managed to source more of the small and large pins from digikey but I am going to YOLO the crimping tool because I don't think I need to spend $700 on one. Question about the architecture of the V1 and V2/V3 ECU, aside from the pin configurations are there significant differences in the ECU itself? I know the early and late gen 2 MR2s can run on the either ECU just by reconfiguring the pins. By that logic I am guess your ECU has similar amperage, voltage, triggering etc on the respective pins. A little bit circular but my question is for example are the knock circuits the same but different pin position on the two ECU models?

Perfect, thank you both. My plan is to document where I am pin wise and where I'm headed and then make the swap. Should be relatively straight forward, but probably worthwhile to document so future self can figure this out.

The issue I think is that the st205 ECU came in the late 92 model. According to this (ECU PN 17390) site https://www.shoarmateam.nl/content/3sgte-engine-ecu-layout/ I have what they call SW20 2 for the US market. So it has AFM stock, swinging gate style. But the triggers and a few other things live in the 205 position on the ECU connection. The difference in pinout can be seen in that site but basically a few things are swapped. There is actually more difference between the early and late gen 2 than the gen 3, at least in terms of pinout. I could be dead ass wrong, which I often am but I think I made a big mistake not reading the ECU PN when I ordered....

Greetings, I have a 92 MR2 and I believe I have made a mistake documented on this forum before. I purchased a Link ECU G4x, but I asked for the 185 version, not realizing that my car is a "Late Gen 2" and therefore should get the ST205. I already have the ECU installed in the car and I purchased it from the dealer asking specifically for that one, so I am not confident there is a chance for exchange. The ECU is already in the car and has been unlocked/powered on. I have read two different threads that detail similar adventures, (https://forums.linkecu.com/topic/12962-mr2-3sgte-setup/ and https://forums.linkecu.com/topic/14014-3sgte-swapped-celica-wont-start/ . Assuming I can't exchange the ECU, it sounds like I can probably re-pin the harness to the ST185 specs and go from there. One of the above threads has a pin exchange excel sheet showing the required changes (although it is for a Celica instead of an MR2, but I think the differences are minor). I will reach out to my dealer on Monday and see what they say, but otherwise I will probably start an excel sheet and plan to re-pin. Any advice from people who have had a similar experience? Thanks for your time! EDIT: I discovered this because the 34 and 42 pins were swapped when I found that the MAP sensor was reading 0 volts. Hopefully nothing got fried having it connected to the wrong thing, but there were no warnings or anything on the ECU when I connected, just a lack of MAP signal.