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Discussion Starter · #1 ·
I recommend you buckle up, this is going to be a looooong read. Or tl;dr at the bottom (y)

Just got my Gen 5 swap up and running the other day. Having never owned a 3S, I can't say for sure but it seems to drive really well. No hiccups at idle, goes through all the gears nicely (no WOT as I'm babying the motor and clutch for the first 500 miles) and coolant temp stayed right below half way. Car boosted nice and steadily (no BOV), overall I've been smiling like an idiot for the past few days.

As I'm waiting for a new B Pipe to arrive, I'm going over all the fault codes that the ECU is throwing, and this is where my puzzlement lies. I pull 63 codes using a JOBD scanner, many of which are unbeknownst to even google (U15F2, looking at you). Trying to reset the ECU ( through either the JOBD scanner, pulling the EFI fuse or disconnecting the battery) has failed to result in clearing any of the 63 codes. Some of these codes are for systems that are no longer part of the motor/car, such as P0101 (MAF circuit), P0753 & P0758 (AT Shift Solenoids), and the ever silly P0000 ("no codes" code...but in reality there are 63) many are the gibberish codes which are probably a result from the lack of fancy Calinda systems in the MR2 chassis.

I have two codes specifically that are nagging me, the code that's most worrisome is P0008, Engine Position System Performance Bank 1. From my research this is a fancy way of saying that the ECU is seeing a discrepancy between the position of the Cam and Crank (or not being able to see it at all). It's bothering me because I could have sworn I nailed the timing of the motor (see picture below). Cam marks line up to the dimples on the valve cover, the arrow on the oil pump was pointing to the right most side of the flat tooth on the crank timing gear, everything was replaced and torqued to spec, and loctite applied where necessary. With what seems like such a sever fault, I'm baffled as to why my car would drive so well (could be the case that I haven't driven ran it enough to make the problem apparent, but I also don't want to let it get to that point if I can avoid it).

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I had a little spare time last night and went to start some disgnostics. I checked the resistance of the Crank Position Sensor and at dead cold read 1365 ohms, which matched up to what some other members on the board here have measured. I went to test continuity on the connector side to ECU and was getting no dice. To be honest I'm not sure I was testing correctly, but I put my power lead from multimeter into the port of the ground wire of the connector, then took my ground lead and tried grounding it to the chassis. When I didn't get a beep, I tried grounding my lead to the motor. Still no dice. As electronics are my literal kryptonite, I'm not sure if I was testing for continuity properly (was following along a youtube video). Should I have tried checking for continuity at the ECU connector instead of grounding it to the chassis/engine? Any electrical gurus that can provide tips for this process would be greatly appreciated.

My next plan of attack is to test the Crank Position Sensor resistance warmed up, the Cam Position Sensor (both cold and warm), change the oil (have only started the car a handful of times and drove ~2 miles since completing the swap, but who knows what crud I knocked loose) then check the timing itself. In regards to checking timing, I had read somewhere that I can use an old plug wire, attach one end to the plug and the other to the coil, and clamp a timing gun to that added wire. Can anyone confirm this?

Other than the above mentioned steps, does anyone have suggestions for trouble shooting the P0008 code? Don't want to ruin a good thing by running the car while it's throwing this code.

The other code that bothers me, though this one is more annoying than anything, is the P0110 code, for the IAT. I'm currently using a TCS intake pipe, which obviously does not make use of a IAT sensor. Is it worth finding a place to install one anyways? If so, where would you recommend installing and then wiring it up to? The harness I had converted by Doug at Wiregap did not have a plug for one so I thought nothing of it, and maybe I should keep it that way?

Anywho tl;dr looking for tips and tricks to diagnose the P0008 code, and any advice on if I should and where to install an IAT somewhere before the turbo, Gen5 into a 91 NA chassis.
 

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I'm no expert on the Gen5, but one thing caught my eye here:

Some of these codes are for systems that are no longer part of the motor/car, such as P0101 (MAF circuit),
How is the stock ECU running the motor if it's supposed to have a MAF and doesn't? Or does the Gen5 not use a MAF? And if that's the case, why would it throw a code for it?

Regarding trouble shooting, to check continuity you should be checking from one end of a wire to another. What you did might work if the sensor ties into chassis ground on that pin (I have not looked at the wiring diagram, this may be what it does). But if that side of the sensor goes straight to the ECU, you probably need to disconnect the harness from the ECU and test from the sensor connector to the ECU connector.
 

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Discussion Starter · #3 · (Edited)
Thank you for confirming my suspicion about testing the connector wiring improperly! I've found a ST246 Caldina workshop manual that's been roughly (i.e. very roughly) translated to English and will be digging through the wiring diagram to find the correct pin.

Edit: Gen 5s do not make use of MAF from factory.

On a side note, have you had the occasion to install an IAT before, or ever come across a P0008 code?
 

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Intake temp is frequently handled in the MAF on some engines, although I'm not sure how it'd work with a turbo engine that could very easily have an IAT very different from the air box temp.
 

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Discussion Starter · #5 ·
Another member on the forum had the same issue, the ST246 uses an IAT in the intake tract. The intake pipe I have doesn't have a space for one so I'll PM the member and ask about his solution to getting the IAT installed and wired. Out of all the other Gen 5 swaps I've seen, I've yet to see an IAT on the intake, and as I said the car seems to run great without it. The major concern is the P0008 code.
 

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Gen 3 4 and 5 are all speed density meaning they use the MAP sensor and intake manifold temp sensor to calculate incoming air volume. Any mention of a MAF sensor in parts diagrams is for other engines that were used in the caldina.

My harness from wiregap was wired for the intake air temp sensor and is installed in my intake.

I think you need to use a Japanese market obd2 reader not just a JOBD. My regular US market code readers don't work with my car but I have a launch diagun iv that allows me to set it to japanese market mode and that does work. You can also use torque but you have to input a custom string that has been documented here on the forum.
 

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Discussion Starter · #7 · (Edited)
Appreciate the info, I have seen an image posted by a member here of that initialization string, maybe my JOBD is just reporting the P0110 with a generic description. If you don't mind my asking, which intake are you using?

Edit: Also forgot to mention that Jp-carparts listed the MAF specifically for the ST246, which is the only third gen Caldina variant with the 3SGTE. That's not to say the site couldn't be wrong, but certainly something to consider.
 

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I have a gen3 MR2 ARC intake it is just a big aluminum box.

The site is wrong no 3sgte uses a MAF meter. Gen 1 and 2 use a vane air flow meter which is different from a hotwire MAF sensor. Gen3 4 and 5 have nothing in the intake that determines incoming air volume. The temp sensor in the air filter measures ambient air and it can run without it.
 

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Discussion Starter · #9 ·
Duely noted! I'll just learn to live with the code for the IAT, and I'll double check that the MAP sensor is functioning normally to make sure the Mass Air code is just a fluke. I do love me the look of the Arc intake box, very OEM+ look.

I'll be going to diagnose the car further this afternoon and I'll post back here with my findings. All the previous information I've found about P0008 on the forum leads to dead ends and OPs that never ended up reporting back.
 

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Honestly I'd buy a compatible OBD2 dongle and use torque to read the codes. I think the JOBD reader really only applies to the gen4.
 

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MAP sensor is located under diagnostic port. Follow vacuum line to TB.

IAT is located in plenum under TB for the gen 3. Generally this is replaced with a GM type if running aftermarket EMS as stock Toyota sensor is not very responsive.
 

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MAP sensor is located under diagnostic port. Follow vacuum line to TB.

IAT is located in plenum under TB for the gen 3. Generally this is replaced with a GM type if running aftermarket EMS as stock Toyota sensor is not very responsive.
No on gen4 and 5 the MAP is mounted to the intake manifold. On gen5 the temperature sensor is screwed into the side right above the IAC.

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Discussion Starter · #13 ·
On a Gen 5 you can't miss them, as JHarris has pointed out. I'm positive the IAT code is from a lack of IAT on the intake tract, but I'll check the manifold temp sensor as well for sh!ts and giggles.

In other news, I have an Elm327 arriving tomorrow and got the Torque Pro app with the initialization string set up so I'll be ready to go. In the mean time I will be checking continuity and resistance of crank and cam sensor circuits as well as checking the timing.
 

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According to the gen 5 service manual P0110 is for both the Intake manifold temp sensor (THAM) and the intake elbow temp sensor (THA) and most swaps don't run that one.
 

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Discussion Starter · #16 ·
Tabkola, that's what I suspected and thank you for confirming! Merryfrankster, if I'm understanding you correctly, I believe my ECU connectors would be 4 row headers. Ive included a snapshot of what I have. I checked continuity from both cam and crank sensors to the ECU last night, and both tests checked out fine using this diagram.
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Discussion Starter · #17 ·
Got an ELM327 Bluetooth dongle, and downloaded the Torque Pro app. I put the initialization string found on this forum into the app and connect to the dongle, but I'm getting an error on the app that says can't connect to ECU. I saw the initialization string works for the gen 4, but can anyone with a gen5 using the Torque Pro app confirm this string also works on their gen5. Maybe the adapter I'm using isn't compatible?
 

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Discussion Starter · #19 ·
Hmm that's the same dongle I'm using as well...J. Harris, are there any other options in the App you have selected/deselected? I tried the following for my init code:

ATIB 96 \n ATIIA 13 n\ ATSH8113F1 \n ATSP A4 \n ATSW00 with only a space between each line break. Wondering if my formatting is off, or if there was a preferred protocol to select but I currently have it set to fast protocol scan and the adapter flashes when communicating, so I don't believe the adapter is faulty.
 

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Thank you for confirming my suspicion about testing the connector wiring improperly! I've found a ST246 Caldina workshop manual that's been roughly (i.e. very roughly) translated to English and will be digging through the wiring diagram to find the correct pin.

As to the MAF question, you raise a good point. The ST246 does use a MAF sensor attached to the Air Filter Box, as seen in the diagram below (part 22204). How the motor runs without it, and how it does it so well is beyond me. When I bought the motor, none of the intake components were included, and there were no left over plugs from my harness 🤷

On a side note, have you had the occasion to install an IAT before, or ever come across a P0008 code?
That diagram is not of the ST246 intake system. That is for the 1ZZ version. The ZZT241.

This is the ST246. No MAF.
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