WTF...I need some help before I shoot my MR2

Mark_Dorman · 11-13-2009, 05:20 AM

So everyone knows I've been working on my V6 swap. Well...I finally got everything done. So the big moment came to start her up...and she didn't run. She cranked/turned over just fine. After a quick diagnosis we determined that the problem was with the fuel system. Here are the tests I ran and the conclusions:

1. Voltage to the Fuel Pump - works fine.
2. Continuity between the MAF and the COR (circuit opening relay) - Check
3. Continuity between the COR and the Fuel Pump - Check
4. Continuity between the EFI relay and the COR - Check
5. Voltage to the EFI relay - Check
6. Voltage to the Fuel Pump (while cranking and on) - Failed
7. Voltage to the COR from EFI - Failed
8. MAF operation - Check
9. Voltage to MAF - Failed
10. Voltage to ECU - Check

So after messing with the wiring trying to figure out what is going on (car will run for about 5 seconds if I prime the fuel pump...then it dies), I came up with nothing. I tried rewiring a few things to get voltage to MAF and no dice. I also triple checked all the wiring and made sure the COR was wired up correctly. Anyone know why the MAF isn't sending a signal to the COR to keep the fuel pump on, or simply why the COR won't keep the fuel pump running??? Thanks guys

4v6 · 11-13-2009, 08:09 AM

Check that the plenum is earthed correctly.

It seems ( and i did it myself on the gt4) that there are a bunch of 3 or 4 brown ground wires on a ring terminal that *should* terminate on the lower bolt of the acis, sometimes they end up being bolted to the rocker cover by mistake cos that looks like where theyd go but electrically it dosent work so the car will run for a few seconds then it dies.
Have a look and see.

Jason.MZW20 · 11-13-2009, 10:50 AM

Yep, you've gotta make sure you have the grounds bolted to the factory locations for the critical connections (ECU based). And if they're rusted or dirty, clean them (super important). I sanded a couple of mine that looked questionable. The ones on the chassis should be the worst off because they're as old as your car if you haven't changed them. I also used the free ground cables from my old 5SFE harness and the new 1MZ harness for extra engine/tranny to chassis grounding. I'd rather not have my electrical system ground to the throttle cable and start a fire, you know?

On EFI engines, the ECU controls the grounds for the fuel related components, so triple check those grounds, especially the intake plenum as Tony stated because that's where Toyota chose to put the critical ECU grounds.

DaveMush · 11-13-2009, 10:25 PM

depending on what engine you are using, check the ecu inputs/outputs for MREL and IGSW

Mark_Dorman · 11-14-2009, 05:49 AM

So it had to do with the power not getting to the MAF. Like Dave just said...the MREL signal wasn't working off the V6 harness. I ended up tapping the wire off the MR2 EFI relay and hooking into the V6 MREL wire that runs to the MAF. Starts up just fine now and is working. Now to finish her up. Thanks for your help everyone

masagsxr · 11-14-2009, 06:18 AM

Oh wow... I've been waiting for this. (The swap I mean)

Hey Dorman... It was a running car you took the engine from to do the swap right? Hhhmmmm. Let me do some research and I'll let you know what I find.

something about maf
http://www.autoshop101.com/forms/h34.pdf

edit:... nevermind.... i was researching and stuff while I was trying to reply... Good job.. Now we need to see that beast

o6spdracer · 11-14-2009, 03:26 PM

Congrats Dorman, now you don't have to shoot her!

Mark_Dorman · 11-14-2009, 03:31 PM

Thanks Guys

I just have to finish doing the coolant flush, gear oil, and clutch fluid

o6spdracer · 11-14-2009, 03:34 PM

Git 'er done!

Jason.MZW20 · 11-14-2009, 05:47 PM

Quote:

Originally Posted by Mark_Dorman

So it had to do with the power not getting to the MAF. Like Dave just said...the MREL signal wasn't working off the V6 harness. I ended up tapping the wire off the MR2 EFI relay and hooking into the V6 MREL wire that runs to the MAF. Starts up just fine now and is working. Now to finish her up. Thanks for your help everyone

Interesting. On most Toyotas, the MREL circuit is exclusive to the ECU and EFI main relay (not the MAF). It allows the ECU to power the relay and also provide power after the engine has been shut off to reset a stepper type ISCV. The way it's wired in the Camry/Solara isn't compatible with our relays, so I chose not to wire it in. Our MR2s use a single contact, ignition switch controlled EFI relay. Engines that use the MREL signal use a single (or dual) contact, ECU controlled EFI main relay, and the relay is wired as such.

Our EFI main relay is solely controlled by the ignition switch, so it is always energized by the switch, and not the ECU itself. It's wired in such a way that it would require some good knowledge of the circuit to change it to an ECU controlled setup.

I would've thought the MAF would be wired to the +B power source like all of the other components, unless your harness had some kind of factory theft deterent system?

Mark_Dorman · 11-15-2009, 04:29 AM

I could have wired it into the +B on the 4th ECU plug but I wasn't sure if the FC would work if the engine died if it were hooked up there. I simply copied the design off the camry's EFI relay where the white and black wire was spliced so one went to ground and the other to the MAF. I was also doing a manual conversion while I was doing the V6 swap but I'm not sure if the auto MR2 body harness played any role in the different wiring.

Jason.MZW20 · 11-15-2009, 10:33 AM

Quote:

Originally Posted by Mark_Dorman

I could have wired it into the +B on the 4th ECU plug but I wasn't sure if the FC would work if the engine died if it were hooked up there. I simply copied the design off the camry's EFI relay where the white and black wire was spliced so one went to ground and the other to the MAF. I was also doing a manual conversion while I was doing the V6 swap but I'm not sure if the auto MR2 body harness played any role in the different wiring.

FC is used by the ECU during engine operation, not shut down. It cuts the fuel injectors momentarily during idle and while driving during light loads or coasting to save fuel and keep the engine running smoothly. The ECU controls the grounds to the injectors, so no matter how it's wired, FC will always work.

Mark_Dorman · 11-16-2009, 02:37 PM

oh...good to know. Well...guess I made it a little more complicated than I needed to. Thanks for the info. I'll make a note of that for the next V6 swap I do (hint hint, wink wink...Colin aka Honda_BAR

).

11-13-2009, 05:20 AM	#1 (permalink)
Mark_Dorman So long MR2's... Join Date: Apr 2008 Location: Pasadena, CA Posts: 4,666 Thanks: 97 Thanked 86 Times in 82 Posts Blog Entries: 1 iTrader Rating: (26/100% )	WTF...I need some help before I shoot my MR2 So everyone knows I've been working on my V6 swap. Well...I finally got everything done. So the big moment came to start her up...and she didn't run. She cranked/turned over just fine. After a quick diagnosis we determined that the problem was with the fuel system. Here are the tests I ran and the conclusions: 1. Voltage to the Fuel Pump - works fine. 2. Continuity between the MAF and the COR (circuit opening relay) - Check 3. Continuity between the COR and the Fuel Pump - Check 4. Continuity between the EFI relay and the COR - Check 5. Voltage to the EFI relay - Check 6. Voltage to the Fuel Pump (while cranking and on) - Failed 7. Voltage to the COR from EFI - Failed 8. MAF operation - Check 9. Voltage to MAF - Failed 10. Voltage to ECU - Check So after messing with the wiring trying to figure out what is going on (car will run for about 5 seconds if I prime the fuel pump...then it dies), I came up with nothing. I tried rewiring a few things to get voltage to MAF and no dice. I also triple checked all the wiring and made sure the COR was wired up correctly. Anyone know why the MAF isn't sending a signal to the COR to keep the fuel pump on, or simply why the COR won't keep the fuel pump running??? Thanks guys

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11-13-2009, 08:09 AM	#2 (permalink)
4v6 http://www.Typ-85.co.uk Join Date: Jun 2007 Posts: 184 Thanks: 2 Thanked 24 Times in 14 Posts iTrader Rating: (0/0% )	Check that the plenum is earthed correctly. It seems ( and i did it myself on the gt4) that there are a bunch of 3 or 4 brown ground wires on a ring terminal that should terminate on the lower bolt of the acis, sometimes they end up being bolted to the rocker cover by mistake cos that looks like where theyd go but electrically it dosent work so the car will run for a few seconds then it dies. Have a look and see.

11-13-2009, 10:50 AM	#3 (permalink)
Jason.MZW20 Pig Snout Join Date: Jul 2006 Location: Victorville, CA Posts: 1,373 Thanks: 15 Thanked 111 Times in 102 Posts Blog Entries: 6 iTrader Rating: (2/100% )	Yep, you've gotta make sure you have the grounds bolted to the factory locations for the critical connections (ECU based). And if they're rusted or dirty, clean them (super important). I sanded a couple of mine that looked questionable. The ones on the chassis should be the worst off because they're as old as your car if you haven't changed them. I also used the free ground cables from my old 5SFE harness and the new 1MZ harness for extra engine/tranny to chassis grounding. I'd rather not have my electrical system ground to the throttle cable and start a fire, you know? On EFI engines, the ECU controls the grounds for the fuel related components, so triple check those grounds, especially the intake plenum as Tony stated because that's where Toyota chose to put the critical ECU grounds.

11-13-2009, 10:25 PM	#4 (permalink)
DaveMush Mr2 V6 #8 Join Date: Aug 2005 Location: Syracuse, Ny Posts: 413 Thanks: 0 Thanked 14 Times in 11 Posts iTrader Rating: (0/0% )	depending on what engine you are using, check the ecu inputs/outputs for MREL and IGSW

11-14-2009, 05:49 AM	#5 (permalink)
Mark_Dorman So long MR2's... Join Date: Apr 2008 Location: Pasadena, CA Posts: 4,666 Thanks: 97 Thanked 86 Times in 82 Posts Blog Entries: 1 iTrader Rating: (26/100% )	So it had to do with the power not getting to the MAF. Like Dave just said...the MREL signal wasn't working off the V6 harness. I ended up tapping the wire off the MR2 EFI relay and hooking into the V6 MREL wire that runs to the MAF. Starts up just fine now and is working. Now to finish her up. Thanks for your help everyone

11-14-2009, 06:18 AM	#6 (permalink)
masagsxr Cage Fighter Join Date: Sep 2008 Location: Norwalk, CA Posts: 3,534 Thanks: 1 Thanked 81 Times in 81 Posts iTrader Rating: (1/100% )	Oh wow... I've been waiting for this. (The swap I mean) Hey Dorman... It was a running car you took the engine from to do the swap right? Hhhmmmm. Let me do some research and I'll let you know what I find. something about maf http://www.autoshop101.com/forms/h34.pdf edit:... nevermind.... i was researching and stuff while I was trying to reply... Good job.. Now we need to see that beast

11-14-2009, 03:26 PM	#7 (permalink)
o6spdracer Nothing Clever Join Date: Jan 2007 Posts: 2,187 Thanks: 1 Thanked 112 Times in 107 Posts iTrader Rating: (1/100% )	Congrats Dorman, now you don't have to shoot her!

11-14-2009, 03:31 PM	#8 (permalink)
Mark_Dorman So long MR2's... Join Date: Apr 2008 Location: Pasadena, CA Posts: 4,666 Thanks: 97 Thanked 86 Times in 82 Posts Blog Entries: 1 iTrader Rating: (26/100% )	Thanks Guys I just have to finish doing the coolant flush, gear oil, and clutch fluid

11-14-2009, 03:34 PM	#9 (permalink)
o6spdracer Nothing Clever Join Date: Jan 2007 Posts: 2,187 Thanks: 1 Thanked 112 Times in 107 Posts iTrader Rating: (1/100% )	Git 'er done!

11-15-2009, 04:29 AM	#11 (permalink)
Mark_Dorman So long MR2's... Join Date: Apr 2008 Location: Pasadena, CA Posts: 4,666 Thanks: 97 Thanked 86 Times in 82 Posts Blog Entries: 1 iTrader Rating: (26/100% )	I could have wired it into the +B on the 4th ECU plug but I wasn't sure if the FC would work if the engine died if it were hooked up there. I simply copied the design off the camry's EFI relay where the white and black wire was spliced so one went to ground and the other to the MAF. I was also doing a manual conversion while I was doing the V6 swap but I'm not sure if the auto MR2 body harness played any role in the different wiring.

11-16-2009, 02:37 PM	#13 (permalink)
Mark_Dorman So long MR2's... Join Date: Apr 2008 Location: Pasadena, CA Posts: 4,666 Thanks: 97 Thanked 86 Times in 82 Posts Blog Entries: 1 iTrader Rating: (26/100% )	oh...good to know. Well...guess I made it a little more complicated than I needed to. Thanks for the info. I'll make a note of that for the next V6 swap I do (hint hint, wink wink...Colin aka Honda_BAR ).