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

[Mr.PFloyd]

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.

It has to do directly with this thread considering you think that egr has only to do with cost savings. Find me a direct link about that, that doesn't just use your "economics logic", and i will be happy. one thing i hate is misinformation.

 

[Poodles]

/facepalm

Hasn't this been beaten to death enough? Case in point Toyota added EGR to even the JDM spec on later engines.

A good example of what happens when EGR is missing is Geo Metro 3 cylinder engines where the EGR passage gets clogged and it burns valves. Now we have larger valves that don't get burned as easily, but do you REALLY want to subject your engine to that all the time?

 

[suprafredde]

The fact is if you remove the EGR, the exhaust gas is replaced by air with the same amount of fuel injected...

Shouldnt the afm meassure the extra air going in and adjust the fuel?
Always thought that it was the timing that screwed the engine if egr was removed.

suprafredde

 

[jdub]

Shouldnt the afm meassure the extra air going in and adjust the fuel?
Always thought that it was the timing that screwed the engine if egr was removed.

Timing is affected...the ECU advances timing in the EGR operating range.

The amount of air sensed by the AFM is the same...the ECU does not know the EGR is not there. Keep in mind air volume is sensed at the air filter...EGR exhaust gas is introduced at the manifold, diluting the air.
No exhaust gas = more air by volume in the manifold = more air introduced into the cylinders for a given valve opening time.

Basic injector duration is determined based on intake air volume (sensed at the AFM) and engine speed, plus other sensor corrections. The volume of fuel injected is the same as if the exhaust gas/air was present in the manifold.

 

[MarkIII4Me]

For the love of god people, do I need to start a new thread now to answer the questions I posed in the FIRST POST OF THIS THREAD? There are numerous threads already of why a JDM ECU is needed on a 7M engine not running an EGR or Stand-alone. If you have something to add to that I recommend posting it in those threads. I stated that I was aware of needing a JDM ECU in the FIRST POST.

I appreciate the number of responses in this thread, and there's some good info being exchanged, but the fact is that I've read through 3 pages with none of my questions answered. At least not with any reasoning behind them.

I still want to know if I need a JDM MT ECU or a JDM AT ECU to run with my AT wire harness. I'd also like to know the exact part number of said ECU so I can buy the correct one.


I was unaware of the JDM ECU's speed limiter tho.
Will running an HKS VPC take car of the JDM ECU's speed limiter?


I'm not trying to be a moderator here (because obviously I am not); nor am I singling anybody out. I'm just trying to keep the thread I started on the right track to acquire the knowledge originally requested in order to purchase what is needed to get my car running correctly.

Thank you all for your knowledge and contributions.

 

[jdub]

Ummm...I thought I answered your questions pretty well...like I said in Post #9, compare the pin-outs on the Auto vs Manual tranny to determine compatibility with your harness.
You're going to have a tough time getting a part #...I can't help you there.

A VPC will not defeat the JDM speed limiter. I answered what will work in post #15.

I apologize for some of the posts in your thread and understand your frustration...some folks just can't seem to accept the facts or resist taking cheap shots.

 

[MarkIII4Me]

Ummm...I thought I answered your questions pretty well...like I said in Post #9, compare the pin-outs on the Auto vs Manual tranny to determine compatibility with your harness.

Are you talking about comparing the pin-outs on the AT and MT ECU's or the harnesses? Either way, I'd need one of each to compare; which I don't have. I was hoping someone would just know.

A VPC will not defeat the JDM speed limiter. I answered what will work in post #15.

Ah ha, I just reread your post. I thought you wrote FCD (which the VPC eliminates the need for). I've never heard of the SLD before. I'll have to look into those. Thanks for that jdub

 

[jdub]

ECU pin-outs...like this one for the 1990
(gotta let you figure something out)

http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?S=FI&P=31

 

[MarkIII4Me]

ECU pin-outs...like this one for the 1990
(gotta let you figure something out)

http://www.cygnusx1.net/supra/Library/TSRM/MK3/manual.aspx?S=FI&P=31

Gotcha. difference I'm seeing from auto to manual is the NSW (Neutral start switch) and the n/c (clutch switch). As far as the ECT, I won't even be using that, so that's no biggie. Tell me, why shouldn't I use a JDM MT ECU then? It looks like it's what I need.

 

[the t3d]

'cause it's probably going to be harder to find

 

[MarkIII4Me]

'cause it's probably going to be harder to find

Well lucky me. I found one JDM MT ECU and two JDM Auto ECU's.

Part numbers for reference:

Late model grey plug JDM Manual ECU# 89661-14231 / 175000-2690

Late model grey plug JDM Automatic ECU# 89661-14230 / 175000-1462

 

[jdub]

Couple questions:
You are using an USDM auto ECU with an auto harness on a manual tranny, correct?
You have the A/T neutral start switch bypassed now?

If yes to both, I would stick with an auto ECU.

 

[the t3d]

Couple questions:
You are using an USDM auto ECU with an auto harness on a manual tranny, correct?
You have the A/T neutral start switch bypassed now?

If yes to both, I would stick with an auto ECU.

that's what i said, 'cause that's what i have:icon_bigg

-t3d

 

[MarkIII4Me]

You are using an USDM auto ECU with an auto harness on a manual tranny, correct?

Correct.

You have the A/T neutral start switch bypassed now?

No. The vehicle is still in the build up stages. The engine and MT tranny are installed, but I haven't even fired the engine up yet. I have not rewired anything. The other day I cut both the plugs and wires that go to the clutch from a junker to wire into my car. I thought it would be easier to just get a MT ECU and wire then in.

Am I wrong?

I'm currently bidding on a MT JDM ECU that ends in less than 10 hours, so if I need a Automatic ECU please speak up now.

Thanks.

 

[jdub]

You can do it either way. Most guys just bypass (jump) the neutral start switch plug when using an auto harness.

 

[MarkIII4Me]

What about the cruise disengage switch?

 

[jetjock]

If you jump the NSW at it's harness connector the cruise control system will not operate. You'll either have to open it up again upstream or mod the NSW circuit elsewhere to prevent cancellation. Same difference...

 

[MarkIII4Me]

I guess I'll just get the JDM Auto ECU. Does that have the speed limiter as well?

Can anyone point me to a post that describes exactly what wires need spliced where to bypass the NSW and retain cruise control?