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aussiemr2
18-08-2011, 18:34
I know this has been talked about many times but here goes :-)

When we wire up the 3vz ecu as per Pauls excellent wiring guide we are using the existing Mr2 circuit to power the main EFI relay, but look what i found in a Toyata training manual in regards the mrel circuit

http://www.twobrutal.co.uk/forum/images/recovered/2011/08/198.jpg

The bit on the left applies to us with the 3vz, i will be giving it a go and see if there are any side effects of doing this

stevehall
19-08-2011, 12:54
Interesting find, I wonder if this will cure my start up stall problem. Only thing is I did my own wiring and kept no records :-S

aussiemr2
19-08-2011, 13:08
I dont think it would be hard to retrofit this to an existing install, only needs 3 wires moving
Finds like this are like hens teeth, Toyota are more secretive than the government :-)
I also have a manual ecu but I would be curious if it would fix the stall issue PW's POCVIP fixes

stevehall
19-08-2011, 13:17
I'm not sure if it will deal with that stall, because the problem that was designed for was stalling once the engine was running, sometimes when pulling up at lights etc. It would certainly explain why my install starts 2nd time everytime, but often stalls 1st time, every time.
Definately going to give this a try, just need to dig out the old wiring diagrams.

aussiemr2
25-04-2012, 17:55
UPDATE!!!

I just did this mod and will try it out over the next couple of weeks

Since I have done my swap I would get a stall coming up to lights or junction maybe once a day and after starting again would not happen again
This is with a 1996 Manual Ecu so we can rule that out as causing the problem
This gives me a pretty good base to work from the see if my fix works

Luckily we also own a 96 camry so I had a listen to the Iscv when engine is shut down and sure enough it winds back for a couple of seconds after shutdown

So I think the reason that the problem never happens again after a stall is the ignition is still feeding the Ecu so it winds back the Iscv to default position
It cannot do this if you shut the engine off because you disconnect the ignition feed to Ecu

To make this work on the Mr2 I had a look at both wiring diagrams and noticed a problem that possibly Paul Woods mentioned before about the engine not shutting off properly if the Mrel was used
This is related to the way the Mr2 COR relay is wired so this needs binned and the Camry one used instead as it has an extra pin on one of the coils that gets a direct feed from Ignition

So to make this work I have used the Camry COR and rewired 2 wires on the 4th connector on ECU, now when I turn engine off I can hear Iscv wind back and the idle seems more consistent
I have not taken it for a drive yet but will give it some testing later in the week


I could try and do some sort of write up for people if this does indeed work, it does involve cutting a few wires on bottom of engine bay fuse box and you will need the Camry COR and one of the pins from its connector on the Camry loom under the dash but it only took me about an hour to do after spending all day studying both wiring diagrams


Paul Out

cdwood2010
25-04-2012, 18:49
Very nice work, and very interesting indeed!

Yes, a write up would be great, I know that will help a lot of people carrying out 3VZ swaps, possibly others given the logic involved.

I might have a look at this for build #4, as I'm using non standard loom bits it will be a good excuse to dig a bit deeper than normal and look at what I have.

Top man.

Chris.

Paul Woods
25-04-2012, 19:28
Very interesting Paul, Mrel could well be the reason for the "one off stall" issue, it doesn't affect the POCVIP'd cars obviously, but an electrical solution is long overdue.

Keep us posted if it works out for you.

aussiemr2
25-04-2012, 19:39
I was never happy to do the POCVIP mod as I dont have a welder so the electronics tech in me wanted to get to the bottom of this problem once and for all

Pauls wiring guide is excellent if you want to get your swap running quickly and easily, but it is just that "A Guide" and takes a lot more work to get everything as how Toyota would have wired it

I have a fully functional cruise control, A/C works using original 3SGE idle up valve, 3VZ ecu still receives A/C on signal from A/C Amplifier to do initial idle up and Ecu feeds A/C off signal on Wide open Throttle back to A/C amplifier
I also fully wired up my diagnostic connector so I can still test ABS, Cruise and Fuel Pump
This all took a lot of extra work but needless to say I do not have many wires left unconnected on Camry loom which I completely stripped back before install and pulled all the unneccessary stuff out

The only thing left to work out is the 5v feed Paul sends to the Spd pin on Ecu, I want to see if I can make the Spd signal from dash compatible with this as this does have an effect on ISCV operation

Paul Woods
25-04-2012, 19:47
The only thing left to work out is the 5v feed Paul sends to the Spd pin on Ecu, I want to see if I can make the Spd signal from dash compatible with this as this does have an effect on ISCV operation

Ah, i already tried this and couldn't get it to work, the Speed input on the Camry ECU is looking for a very funny signal, neither the Mr2 speedo (gearbox) , nor the return signal from the clocks will work, it's definately looking for something else. Locking the SPD signal with 5v was the only answer we could find, without that 5v lock you get a horrible jerk on acceleration as the auto ECU retards the timing bewteen it's "ghost" gearchanges at set RPM's, obviously with the transmission now being manual our new gearchanges don't match the auto events, hence the bad jerk.

I'm not sure that there is an answer to the SPD signal issue using an Auto ECU, i really do think you'd need to start with a USDM manual trans ECU.

aussiemr2
25-04-2012, 19:53
I do have a 96 M/T ECU :smile:

Paul Woods
25-04-2012, 19:55
Great, in that case have you tried just running without the 5v lock? It could well work, we've never had a manual ECU to try that on, all our UK cars are autos.... bumhole.

aussiemr2
25-04-2012, 20:02
I have not tried without but I have a Toyota technical document relating to the ISCV operation and it does mention using SPD to adjust ISCV stepper motor

I also have a document that talks about the reed sensor used in the clocks should be 4 pulse per revolution of speedo cable, might try to set up some sort of portable oscilloscope to Camry and MR2 SPD signal from Dash and see if there is any difference in output

Maybe you could not get it to work because as you say the Auto part of the ECU retards the timing when it thinks it needs to change gear

Possibly the signal from the dash clocks is correct but does not work properly on A/T ECU's

Paul Woods
25-04-2012, 20:05
I think there is a very strong possibility that that is exactly what is going on, the Auto ECU is definately retarding timing at its supposed gearshifts, it does that to lessen the shock on the transmission.

The Mr2 dash reed signal going back to the ECU is a 4 pulse per revolution type, we know that much, so i suspect your MT ECU will just work with the Mr2 speed signal.

Fizzy
26-04-2012, 02:36
Wasn't this SPD issue discussed before with the resistor position change within the auto ecu? On mine it was changed and I had the spd signal going into the ecu which got rid of the jerks around the expected gear change rev points. It also seemed to sort out my stall issues and I ended up using a stock idle control valve too. So in theory if a proper manual ecu is used there shouldn't be a problem...?

Interestingly I believe mine was using the camry main relay (it was using the original camry plastic relay bracket in the boot rather than the one in the standard mr2 fuse box) - wonder if that made any difference, but I guess it would depend on how it was wired up.

Unfortunately since the car has been broken up and engine sold a while back I can't check. :icon_neutral:

Paul Woods
26-04-2012, 08:00
While the resistor position change seemed to overcome the timing retard i never liked the dyno graph dip it produced at a certain RPM, which wasn't present without the resistor mod, there was more going on there than just switching to manual so i was never a fan of doing it that way.

aussiemr2
26-04-2012, 09:46
I mainly want to do the SPD to make sure the ISCV circuit is operating properly as it does lookup both IDL and SPD to determine when it should kick in
Having a manual ecu means the resistor mod is unneccessary in my case

aussiemr2
08-05-2012, 17:22
Been running like his now for couple of weeks and idle is solid as a rock at 950ish rpm with no stalls at all
Before the mod sometimes idle would hover around 400-500 rpm and I knew it would stall at any moment
Only other difference that has crept in now is if I lift foot off throttle on overrun engine braking seems a lot stronger than before like the car litterally jerks back a bit but not sure if this is electrical or maybe my throttle plate is closing too far
I did a few other tidy up things at the time including connecting the charcoal cannister so unsure exactly what could have caused this change, maybe its normal but I didnt have it for the first few months

What was the hickup that happened with wiring the spd wire Paul?

Paul Woods
08-05-2012, 17:26
The hiccup was when the SPD was connected to the Mr2's speed signal, the ECU would retard the timing and cause a horrible stumble at its preset gearchange points.

Locking the ECU at a set speed by giving it a fixed 5v signal did the trick, no more stumble. Of course you won't get that with a manual ECU, it's just a UK Auto problem we had to endure.

aussiemr2
08-05-2012, 17:39
So is the strong engine braking a thing you have come across?,it seems to be when I have mostly released accelerator pedal you can feel car decelerate quite strongly, more than you would expect
I did have throttle body stripped to clean and paint , could it be out of adjustment and maybe closing too far?, i did adjust the TPS before this latest round of mods as my Cruise control was not working and this was done using feeler gauges as per BGB
other than this it drive just fine with no hiccups between gears

jon.sole
08-05-2012, 18:00
I mainly want to do the SPD to make sure the ISCV circuit is operating properly as it does lookup both IDL and SPD to determine when it should kick in
Having a manual ecu means the resistor mod is unneccessary in my case

If you compare a MT and AT ECU from the same year and region you'll see that they are identical (including the ROM image in the CPU) apart from the MT ECU not having the extra AT components fitted and one of the mod resistors fitted in the alternative position.

aussiemr2
08-05-2012, 18:08
I actually have a 96 camry A/T that my wife drives, I should pull its ecu out some day and compare to my 96 M/T one

Paul Woods
08-05-2012, 19:42
I've never experienced this strong engine braking you speak of, unless i was in the wrong gear of course.... but under normal driving no, the engine/trans braking is normal.

aussiemr2
29-05-2012, 15:29
Been driving around for a couple weeks with this mod and so far so good
I have not had a single stall and after engine warms up rpm always idles between 750-950

Only thing I changed was connect Spd wire back to 5v source for now as this was the cause of the braking feeling I mentioned earlier

I will investigate this further later with an oscilloscope on both the camry and mr2 speedo signals to see what is different

cdwood2010
29-05-2012, 16:37
Nice work!

I'm sure if you wanted to make a document out of your findings Nik would be only too happy to host them
In our downloads section.

Chris.

bigcw
24-06-2012, 17:39
OK, I did this mod yesterday on my rev2 and thought I'd write a quick howto. As yet I've not driven the car - the Mrs was calling me in for dinner and it's p'd down all day today, but it certainly runs perfectly well in the garage and behaves the way I expect.

My car is a rev2 with 3VZ, originally done by Woodsport. Although I've thinned the loom out to get rid of all the non-used wires I've not changed any wiring from what Paul did during the original conversion, so I'd assume others from the same era are the same.

It's worth mentioning that this mod needs to be done on the car's original loom, not on the engine loom. The MR2 runs the EFI relay straight off the ignition feed and this has to be split and run into the boot so that the ECU has charge over it instead. It's not possible to do it purely by changing the engine loom.

Before you start, identify your 'D' connector on the ECU. It's the far right hand side on with 22 pins. On my car, pins 1, 12 and 13 were black with orange stripe which should help you identify which way around it is. All my pin numbers are on the D plug unless otherwise mentioned.

http://www.twobrutal.co.uk/forum/images/recovered/2012/06/241.jpg

First off let's check that you're not already wired for MREL. Hook up a multimeter between pin 13 on the D connector and ground. You should see 12v here with the ignition on that goes away when the ignition is switched off. On my car, Paul had fed this from the switched side of the EFI relay which is the way the original MR2 would have been but not the way it's done on the Camry. To confirm that yours is the same pull out your EFI relay (in the engine bay fuse box). If you still have 12v with ignition on and nothing with ignition off you already have this bit wired correctly.

Next step to check is the MREL feed itself. It's on pin 3 of the D connector. On my car it was just taped off so it was obvious that it wasn't connected, but if yours is use a multimeter to check contiunity with pin 1 on the EFI relay socket. If you're standing by the nearside wheel, pin 1 is on the far-right. If you have continuity here you're probably already set up for this mod.

Finally before continuing with the mod itself it would be wise to check a couple of other bits are wired correctly. Pin 2 should have 12v on it regardless of the key position which should disappear if the EFI fuse is pulled. Pin 12 should have 12v on it with the ignition switched on only which should disappear if you pull the EFI relay. If either of things don't happen it's probably best not to carry on unless you know what you're doing!

OK, so assuming you've got this far you'll need to hook up two wires, IGSW and MREL. To do so we need to modify the wiring underneath the engine bay fuse box. Undo the bolts that hold it in, turn it upside down, and remove the bottom cover. Inside you should find a black with orange wire that loops through the ignition relay, to the EFI relay, and then to the fan relay. Of course, before you take anything electrical apart, remove the battery negative lead to be safe. There are high-current feeds to the engine bay fusebox for the starter motor and if these touch the bodywork or engine during your work and you've not taken the negative lead off very bad things will happen!

http://www.twobrutal.co.uk/forum/images/recovered/2012/06/242.jpg

Now, cut the wires so that the EFI relay is isolated from the other two. Ideally you need to cut them to such a length that the two long ends have sufficient slack to solder back together, but that the two stubs that remain on the EFI relay are also long enough to solder to. If not, you're going to have to do some bodging to get everything to join up, but I'm sure you can figure that out!

http://www.twobrutal.co.uk/forum/images/recovered/2012/06/243.jpg

Next, take another length of black/orange wire and solder the two long ends together with your new piece. This will become your IGSW feed to tell the ECU when the ignition is switched on.

http://www.twobrutal.co.uk/forum/images/recovered/2012/06/244.jpg

...and of course use heat shrink to protect it. Note the two stubs left on the EFI relay are unconnected at this point.

http://www.twobrutal.co.uk/forum/images/recovered/2012/06/245.jpg

Next, take the two stubs left on the EFI relay and twist them together. Solder a length of red-blue wire to this and again protect with heat shrink. It will probably be a bit fiddly as the stubs will be short, but as you can see it's possible if you're careful. This will become your MREL feed back from the ECU to allow it to turn on the EFI relay under it's own command, independant from the ignition switch.

http://www.twobrutal.co.uk/forum/images/recovered/2012/06/246.jpg

Now you need to put your fusebox back together and run these two wires into the boot near to your ECU. I'll leave you to figure that out for yourself!

Final step is to connect the two wires to your ECU. The red & blue goes to pin 3 'MREL' (this was red/blue on my ECU but the diagram shows it as red/yellow for some reason) and the black & orange to pin 13 'IGSW'.

http://www.twobrutal.co.uk/forum/images/recovered/2012/06/247.jpg

To test, first of all put the battery -ve back and check for any blown fuses (EFI or IGN fuse most likely) or smoke signals. If all is well, make sure the car starts up as it should. When you switch off you should notice that instead of the EFI relay clicking off straight away it will be 2-3 seconds after the key is turned. You may also hear the ISCV moving back to it's startup position but you may need to disconnect the fan to hear it. Note that this only happens if the engine has run ie if you just switch the ignition on and off again the EFI relay will follow the key.

To really prove it, put your multimeter between pin12 and ground. If you just turn the ignition on and off you should see 12v on this wire in time with your key turns. However, if you start the car up and then switch off the 12v should remain on this pin for 2-3 seconds after the key has been turned off.

Exactly what benefit this will have on the running of the car is uncertain at the moment but we know that at the very least the ECU resets the ISCV position during it's shutdown process so it should aid starting the car the next time. The way I explained it to the Mrs was to compare it to her laptop in that to turn it off you tell it to shutdown first so that it can save all it's settings and be ready for the next startup rather than just pulling the power out which is what the stock installation does. Whatever it does I'm sure that Toyota would have done it this way for a reason so for the ease of doing this mod it's worth doing.

Hopefully that all makes sense. Any questions, just ask!

Chris

cdwood2010
24-06-2012, 18:18
Hi Chris,

Post that in a new thread and we can sticky it!

:)

C.

bigcw
24-06-2012, 19:27
Ok, just been out for a drive with this mod and the resistor change in the ECU. Works spot on and idles beautifully!

Will re- post when I get back to a pc.

Chris

Paul Woods
25-06-2012, 08:01
Nice write up Chris, remember to fit a standard, non "Pocvip'd" ISCV or it will mask your results as mine don't have any idle problems this way.

bigcw
25-06-2012, 11:26
I don't think mine was POCVIP'd anyway, unless you know different? It certainly used to stall on 'clutch down' approach to junctions now and again so I assumed it wasn't done, but I've not taken it apart to check.

Chris

Paul Woods
25-06-2012, 20:00
All Woodsport conversions get the ISCV modified, if you take yours apart you will see it, it should not have been stalling with this done, unless you've changed the ISCV in that time?

Not a single conversion of mine stalls with this mod, so if you're saying yours did with the ISCV modified then there is something odd going on there.

bigcw
25-06-2012, 23:09
Interesting. It certainly used to stall on approaches to junctions when you dip the clutch at the last minute. More often when it was cold, but sometimes when hot too.

Chris

Paul Woods
26-06-2012, 08:09
In that case it had another issue of some sort, or we simply forgot to modify the ISCV.

bigcw
26-06-2012, 12:23
Not sure on that one Paul, I'd have to take it apart to find out.

All I can tell you is that with the MREL mod and the 752 to 751 resistor move in the ECU the problem has gone away on my car.

Chris

Paul Woods
26-06-2012, 19:41
I appreciate that, what i'm saying is it is not normally a problem at all on any of our conversions because i modify the ISCV, yours is the first WS conversion i've ever heard of stalling, so i probably forgot to do it.