Any benefit for me going from a US AT ECU to a JDM MT ECU?

[MarkIII4Me]

Here's the deal. My 90T Supra was originally a AT and has now been converted to a manual. The engine now also no longer runs EGR and will using a VPC piggyback.

Ok, since I'm not going to be putting an EGR on the engine, I'll be needing a JDM ECU so the engine won't lean out on me.

Questions are:

1) Is there any benefit to me getting a MT JDM ECU over an AT one? Does it make it any easier for wiring up, (***excuse my terminology, but I don't know what these sensors are officially called***), the reverse brake light, clutch cruise control sensor, clutch depression sensor (to start car), etc.

2) As long as it's a grey plug ECU, does it really matter what year it comes out of? Does anyone know the exact ECU# I should be looking for. I've found several on ebay advertised as late model JDM manual ECU's, but they all have different numbers. So I'd really like to know.

3) If I do go MT ECU, will I have any issues using my AT engine wiring harness?


Thanks a bunch for any info you can provide. I'm dying to fire this baby up already.

 

[shaeff]

Yes, simply because the JDM ECU is not tuned for EGR. If you had EGR, there would be no point to switch.

 

[adampecush]

just out of curiosity, what is the part number for the JDM ecu?

 

[tbcmorris]

And a MT over an AT one will give the benfits of easier install



Do MT an AT cars have the same Redline??

 

[MarkIII4Me]

Yes, simply because the JDM ECU is not tuned for EGR. If you had EGR, there would be no point to switch.

Yes, but should I go JDM MT ECU or JDM AT ECU? Since even tho the car is now a manual, I'm still using the original AT engine wire harness.

just out of curiosity, what is the part number for the JDM ecu?

I'm wondering the same thing.

And a MT over an AT one will give the benfits of easier install

How so?

 

[tbcmorris]

The differences between auto and manual wiring for the trans??

 

[tbcmorris]

Wait nvd.....brain fart sorry

 

[MarkIII4Me]

So nobody knows? I really would like to get this engine fired up, but I'm not trying to buy several different ECU's in an attempt to figure this out for myself.

Someone on here must know!

 

[jdub]

1) You will need a JDM ECU if you do not have an EGR on the engine. You will have to deal with the speed limiter that is built in the ECU if you plan on running the car on the track.

2) A grey plug ECU should work.

3) Take a look at the pin-outs for the AT vs Manual ECU to see if they match up. I would use an AT ECU to avoid any possible harness issue.

Personally, I would put an EGR on the engine and avoid all this. There is no benefit in removing the EGR and all you will do is cut fuel economy. Not to mention spewing one of the worst emission gasses there is out your tail pipe.

 

[the t3d]

wait. so i have a JDM motor...it's fully built, pretty much done. i got the manual turbo harness off a member on here along with the ecu(from a different member). i'm not gonna be running the egr on it, so i HAVE to get a JDM ECU?

i'm curious...would the fuel mods help with it running lean due to not having the jdm ecu?

i've never heard of this before. does everyone have a jdm ecu that's not running the egr?

lastly...where the hell would you get one?


maybe i should just get an AEM standalone...=0)

-t3d

 

[tbcmorris]

You either need to run a jdm ecu, or install an egr.

 

[jdub]

wait. so i have a JDM motor...it's fully built, pretty much done. i got the manual turbo harness off a member on here along with the ecu(from a different member). i'm not gonna be running the egr on it, so i HAVE to get a JDM ECU?

That would be a very wise idea...that is unless you want to risk detonation at mid-throttle, high load conditions. Like I said, you will likely want to address the speed cut that is programmed into the JDM version.

i'm curious...would the fuel mods help with it running lean due to not having the jdm ecu?

You would have to add a lot of fuel at the mid-range...right where you don't need it to make power. It's much easier just to run the EGR.

i've never heard of this before. does everyone have a jdm ecu that's not running the egr?

Doesn't matter...and, it's been beat to death. The people that have removed the EGR do not understand how the TCCS works. It's a fool's mod.

lastly...where the hell would you get one?

Got me...eBay? I run the EGR...there is no point in removing it.

maybe i should just get an AEM standalone...=0)

That would work.

 

[MarkIII4Me]

The guy I bought my engine from was running stand-alone and capped off the egr by threading caps into the EGR ports in the back of the head. The engine is now installed (ref. avatar) and it would be a RPITA to get an EGR in there while the engine is still in the bay; not even sure it's possible. I only recently came across the EGR or JDM ECU threads and it's after the engine was installed.

So I have to get a JDM ECU I guess.

This sucks! I would have totally installed the EGR when I had the chance if I'd have only known. So is the final answer for me to get an Auto JDM ECU? Also, how do I go about addressing the speed cut? Where is it governed at?

 

[the t3d]

The guy I bought my engine from was running stand-alone and capped off the egr by threading caps into the EGR ports in the back of the head. The engine is now installed (ref. avatar) and it would be a RPITA to get an EGR in there while the engine is still in the bay; not even sure it's possible. I only recently came across the EGR or JDM ECU threads and it's after the engine was installed.

So I have to get a JDM ECU I guess.

yea i was wondering how much of a pain it would be to install an egr with my motor in it, so i'm probably with you man...JDM ECU

what's the speed thing you're talking about jdub?

-t3d

 

[jdub]

JDM ECU's have a speed limiter (speed cut) built in...I do not have personal experience with it, but I'm pretty sure it's 180 Km/h (112 MPH). You can get around it with an HKS Speed Cut Defender or cut the SPD input into the ECU.

Cutting the SPD input is not a good idea on an auto tranny. On a manual tranny you can get away with it. SPD is used for fuel cut off during decel with the TB plate closed, for timing corrections during idle due to changing load, and for adjustment to AFR during accel/decel. It looks like fuel economy type fuel trims more than anything.

 

[tekdeus]

There is no benefit in removing the EGR and all you will do is cut fuel economy.

If this is true, why would Toyota willfully not include it on JDM models?

For those that are worried, my car came with a JDM engine and seems to have a USDM ECU (I've never hit speed cut). It is tuned with an SAFC and I've never had any issues, although I do run the highest octane pump fuel I can find. My cruising AFR's are pretty much 14.5-15.0.

 

[tbcmorris]

Because the jdm ecu is tuned to not have it and the usdm is tuned to have it

 

[jdub]

If this is true, why would Toyota willfully not include it on JDM models?

For those that are worried, my car came with a JDM engine and seems to have a USDM ECU (I've never hit speed cut). It is tuned with an SAFC and I've never had any issues, although I do run the highest octane pump fuel I can find. My cruising AFR's are pretty much 14.5-15.0.

You know Brad - How many times is it going to take to convince you that the "I do it" -or- "my cousin's buddy does it and it's ok" doesn't mean squat. That amounts to a "testimonial" that has no basis in fact...we have had that conversation before. What you are saying means absolutely nothing. I really have no desire to slap you around again.

The fact is if you remove the EGR, the exhaust gas is replaced by air with the same amount of fuel injected...It's also a fact that exhaust gas in the mixture reduces combustion temps. With this combination (more air and a higher combustion temp) under load in the EGR operation range, care to guess what happens? I suppose you data log your AFR, EGT, and knock? Like I said before, this horse is been beaten to death. Just because you do not use an EGR with an USDM ECU means you are once again displaying limited knowledge of how the TCCS works...something else you have demonstrated in the past.

BTW - Toyota did not use an EGR on JDM models simply as a cost savings measure. That is why the JDM ECU is tuned for it. That line of reasoning has nothing to do with how the engine performs without one installed on the USDM version.

 

[Mr.PFloyd]

BTW - Toyota did not use an EGR on JDM models simply as a cost savings measure. That is why the JDM ECU is tuned for it. That line of reasoning has nothing to do with how the engine performs without one installed on the USDM version.

Nice deleted post. Again, find me an article where it states not having EGR on Jdm's was for cost savings alone.

 

[jdub]

Nice deleted post. Again, find me an article where it states not having EGR on Jdm's was for cost savings alone.

I deleted the posts because it was borderline trolling...something you are well known for.

It doesn't take a rocket scientist to figure out that the cost of X number EGR valves, modulators, coolers, and associated fittings will result in a production cost savings when Japan's emissions laws did not require the same NoX reduction as in the US , or did you skip economics in high school?

Like I warned you in the PM, this has nothing to do with the subject of this thread. I suggest you heed that warning.