jdm 7mgte more power than usdm gte?????????

[jdmmilhouse]

i have a jdm spec gte in my 89. are their any differences in the two, besides the missing egr?

[MA70-3.0GT]

I'm afraid I'm not sure what the differences are (aside from reading somewhere that JDM's were a bit more agressively tuned than US or Euro markets, possibly due to tighter emissions law in America) but please could you possibly post a couple of biggish pictures of your engine bay, and more specifically ones of where your vacuum lines are running from/to? I'm working on an '89 JDM model myself at the moment & someone's been "playing" so any reassurance that I've got stuff back where it belongs would be brilliant.

Thanks in anticipation, Dan.

[cre]

Aside from the lack of the EGR system and the tuning to make up for it there is reportedly no difference. Toyota's published numbers are the same for all models of 7M-GTE engines of the same year. There is a guy over at SM who is reverse engineering the ECU though and has found that both the JDM and USDM maps are present in the N/A's ECU... no word yet on the Turbo's ECU. But, this does mean we may have the chance to test them out ourselves with the addition of one resistor. Even if the GTE's ECU doesn't contain both, I'm sure he'll publish the fuel and timing tables of each for comparison... should be pretty cool.

[cre]

Okay, I'm now somewhere where I can add a little bit of info to this.

The JDM 7M's use a Lamda sensor (also called an O2 sensor) the same as the USDM. The ECU uses this sensor to monitor and maintain an air to fuel ratio of 14.7. Given that the JDM ECU would actually have to pull timing any time that the EGR system is active the JDM 7M would make less power. Now, at WOT the ECU does not refer to the Lamda sensor and returns to the base fuel maps. If the maps are the same then the JDM would now make the same amount of power as the USDM engine. The JDM engine may be tuned differently across the board, but there's not really any more power to be made without a boost controller. There may be significant differences in responsiveness and that combined with the timing differences may result in very slightly different power curves, but the peak power will remain roughly the same.

[jdmmilhouse]

i thinks pics of my engine bay wont help, all of my emissions components have been removed so any open vacume has been pluggd

[MA70-3.0GT]

cre-: Given that the JDM ECU would actually have to pull timing any time that the EGR system is active the JDM 7M would make less power.

Shouldn't that be the USDM? JDM has no egr does it? Or do you mean that on the JDM it would have to pull the timing back in situations where the EGR would have been active if it were present?

Interesting note on the GE ECU's containing both J & US maps though, especially if it turns out to be the same for the GTE lump's brain. If there was any specific advantage to one map we'd be able to swap without spending 100's on a new ECU.
I suppose, as you say there isn't any real power discrepancies between markets, the benefits would be limited to USDM owners just being able to remove the EGR both physically & "mentally" from their car...

Though I wonder if the different maps are stored on seperate chips? That could be a significant breakthrough for people suffering an ECU software failure of some sort if they were able to simply add a link or extra resistor to make the ECU revert to another chip & hence start it working again, albeit in the other country mode.

P.S. milhouse, any pics of any JDM engine bay would be better than nothing. If you don't have the time or something then no worries, I don't wanna impose, but if your car's running OK as it is & all else fails I could try plumbing it as per yours... (That said, I had a play yesterday & I think it's just a fuelling problem now anyway. Think the injectors are gummed up & sticking/leaking, and the cold start wasn't even plugged in!)

EDIT-: no worries milhouse, cre came through with some cool diagrams of a JDM setup here http://www.toyota-supra.info/forums/...html#post74926 so I'm set.

Cheers, Dan.

[cre]

Originally Posted by MA70-3.0GT

cre-: Given that the JDM ECU would actually have to pull timing any time that the EGR system is active the JDM 7M would make less power.

Shouldn't that be the USDM? JDM has no egr does it? Or do you mean that on the JDM it would have to pull the timing back in situations where the EGR would have been active if it were present?

If the JDM had EGR it could run more aggressive timing such as the USDM does when the EGR system is active.

Originally Posted by MA70-3.0GT

Interesting note on the GE ECU's containing both J & US maps though, especially if it turns out to be the same for the GTE lump's brain. If there was any specific advantage to one map we'd be able to swap without spending 100's on a new ECU.
I suppose, as you say there isn't any real power discrepancies between markets, the benefits would be limited to USDM owners just being able to remove the EGR both physically & "mentally" from their car...

As I said, it may be worth it just for the properly tuned timing maps.

Originally Posted by MA70-3.0GT

Though I wonder if the different maps are stored on seperate chips?

Nope, same chip IIRC.

[SuperSpartan]

Whats the EGR system?

[cre]

It's a system which is used to reduce combustion temperatures (good for emissions reduction but also good for engine longevity). It just routes a small amount of spent gasses back into the engine to pull down engine temps. Most cars have it (despite popular belief) whether it's accomplished using variable valve timing or an external valve system... The use of an extremely aggressive EGR system is how Honda gets such outrageous mileage and is able to run an engine WAY leaner than what's considered a safe and practical level.

[batmmannn]

When ever I start to think I know something about cars, all I have to do is come here and read your posts and I quickly realize I don't know shite about cars....lol