[Mk2] [SC] calling all electical and tuning wizards, this will stump you

[TBDevelopments]

Right been down to perfect touch on wednesday to have a customers car mapped by them, after an hour of messing about and the car refusing the even idle properly and violently spluttering its way up the revs the conclusion was made that the power fc was duff and needed to be replaced. Upon getting back home we tested this ecu on another gen 3 (my own) and the problem seems to have resolved itself on my car, i tested a prospec power fc i have reserved for my own car and again it revved perfectly.

We tested the customers power fc on his car again, and refused to idle and spluttered up the revs, we swapped and fitted the prospec and it did the same, so we've come to the conclusion that its not the power fc at fault but the car its been fitted to seeing 2 different power fcs that work fine on one car refuse to work on this one.

The 2 test cars are both gen 3 M Plates, similar modification.

The custom car in question runs perfectly with no error codes on the standard Gen 3 ECU.

Done a signal test on the power FC engine sensors, all voltages match and respond the same as the other test gen 3 which operates perfectly. All relay acctivations are the same.

No diagnositc error codes on the standard ecu.

An apexi avcr has been connected to the trouble some gen3 in question but thats been removed to see if that caused a problem, nothing still the same.

This must be a simple problem otherwise the car wouldn't run perfectly on the standard ecu.

Any and all ideas are welcome, i've been through everything i can think of so another brains opinion is welcome.

Tim
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[greeny]

perfect touch could alter the map on the pfc ok? what map was stored on the troublesome pfc ? was it on a base map? Would it store changes?
Just a few questions!

[TBDevelopments]

they uploaded a few other maps to resolve the problem but nothing helped, we reset the power fc back to the base map.

The same power fc worked perfectly fine on my gen 3 but not on my customers gen 3.

We've tried 2 different power fc's both work fine on my gen 3, but both have the same problem on my customers Gen 3 so i can honestly say its not the power fc at fault or any aspects of its map or tuning. Its something on my customers gen 3 that it doesn't like, but not a big enough problem to effect perfect running of the standard ecu or even give an error code.

its the fact of the car runs perfectly on the standard ecu compaired to the power fc is whats stumped me, if it did it on the standard ecu then i could start tracking down the problem effecting both of them, but its like night and day. Standard ecu is perfecty, a good power fc won't even idle properly.

Tim
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[greeny]

All standard sensors on the rev3?

[TBDevelopments]

yes the customers car and my personal gen 3 are identical regarding sensors and ecu control.

Power fc works perfectly on my car, not on his.

Remember his car works perfectly on his factory ecu so i wouldn't have thought its a broken sensor or the standard ecu would run poorly as well or atleast throw and error code.

Tim
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[MR2lover]

Tim

I would check the earth under the inlet manifold and give that a good clean up then check all the other earthes.

The powerfc earths out through the following pins

E01
E02
E1

Just check the wiring of the earths too. The symptons you are describing sound very much a rev3 map sensor fault but if works fine on rev3 ecu then doubt its the map sensor so check all the wiring back to the ecu with a continuty check and see if there is any restistance if there is some then the power might not be liking it.

But would deffo check intake manifold earth first and that is where everything earth out i.e map sensor, ecu, sensors etc

[TBDevelopments]

i was thinking the same regarding the map sensor as it was the same when my map sensor failed on my gen 3.

i'll check the earths but i can't see it being that really, i also checked the Map voltage being recieved through the power fc on both cars and its identical so its not like the power fc is seeing a lower map input on daves car compaired to mine.

Tim
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[BenF]

I'm no expert on the PowerFC, but a bad / corroded earth may explain what you're seeing - There is obviously something different between the two cars.

A bad earth would check out OK with a multimeter, but as soon as any power/curent was flowing it would show as a non- 'ground' voltage.

Perhaps repeat the tests you've done, but monitoring the pins Ryan mentioned and check voltages there are still ground? Or, it could be a failing sensor somewhere...

[TBDevelopments]

see i thought of all those but that would also show up on the standard ecu if it was a bad earth or a failing sensor. but it works perfectly with the standard ecu, just not with a power fc.

Tim
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[luthor1]

switch out your engine wiring harness into the customers car. PITA I know, but it'll answer another bunch of questions.

[EarL]

switch out your engine wiring harness into the customers car. PITA I know, but it'll answer another bunch of questions.

I don't think that's a viable option to be honest.

Any update on this Tim?

[TBDevelopments]

daves popping over after work tonight and we've going to have another look, try and few of the earths, atleast its something we can remove from the possible list then.

I can't see it personally as a bad earth would also show up on the standard ecu and cause problems. It runs just like when my map sensor failed on my gen 3, but it works perfectly fine with the standard ecu so can't be a problem with that.

And the power fc works fine in my car so can't be a problem with the power fc

Tim
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[TBDevelopments]

done a few earth checks tonight and they all seem ok. i ran the multimeter on the wires ryan suggested on off and engine running.

Wire check

E01

Off...... 0.0
Running .....0.0

E02

Off......0.0
Running......0.0

E1

Off......0.0
Running......0.12

I also tested the resistance of the wire, both again with the car off and engine running

E01

Off....... 00.3 ohm
Running.....9.6 ohm

E02

Off.......00.3 ohm
Running.....10.5 ohm

E1

Off.......00.4
Running......10.0 ohm

Hope this means something to someone, my thinking was if it was an earth fault it would show on the standard ecu as well, yet the standard ecu runs fine.

We also disconnected the wires at the ecu for the avcr that were previously connected, made no difference.

Any information would be great, paul port if you don't mind commenting as i know you've helped me with a wiring fault before.

Thankyou.

Tim
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[rossdymond3352]

all those values are neglegable mate, i have no idea, but i just id add my input about the resistance values

[TBDevelopments]

yeah i thought the same, just thought i'd post them so people can see what i'm getting.

i can't understand it personally.

Tim
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[jon]

Have you checked the G1 & G2 signals from the distributer to the ECU? They provide the CAM timing for the injectors.

The Toyota ECU can cope with G1 failing, and will fall back to using the G2 signal.
If the G1 signal isn't working due to bad wiring or faulty distributer the ECU can still run the engine normally, maybe the PowerFC hasn't got this fall back mode?

It's a long shot but might work checking!

For more info, have a look at http://www.autoshop101.com/forms/h25.pdf , page 8.

Cheers,
Jon

[LJS @ Rogue]

Have you checked the G1 & G2 signals from the distributer to the ECU? They provide the CAM timing for the injectors.

The Toyota ECU can cope with G1 failing, and will fall back to using the G2 signal.
If the G1 signal isn't working due to bad wiring or faulty distributer the ECU can still run the engine normally, maybe the PowerFC hasn't got this fall back mode?

It's a long shot but might work checking!

For more info, have a look at http://www.autoshop101.com/forms/h25.pdf , page 8.

Cheers,
Jon

I was thinking along similar lines but if either of the NE or G signals drop out it would flag a diagnostic code. I've had this before and the solution was a Link XLEM However, joking aside, I think the problem is the Dizzy signal amplification, where an out of tolerance air gap can weaken the reluctor level to a point the PFC can't cope with.

When we had this problem we swapped the injector ballast, fuel pump relay and ballast, ignitor, coil, map sensor and triple checked all the wiring and nothing made the slightest difference. The only thing we didn't change was the dizzy so swap this from your working car and see if this fixes it. Also check you have a good clean G- as this can cause similar effect as it's the ground for all the reluctor sensors. Do you have an oscilloscope as this will soon route out any signal issues?

Lyndon.

[MR2lover]

Ok tim i would now plug in the other ecu the one that you didn't do the resitance checks on and check the resitance then and see what they show and report back.

Also i would have thought you would have tried this but have you tried selecting the other map sensor options in the setting area. Could be selecting wrong one maybe

[TBDevelopments]

what should i be seeing on the G signals? 1/2 and -

I'll check those and see if there correct.

Tim
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[jon]

The BGB gives some resistance values & air gaps to check:

http://www.mr2-tech.com/bgb/mechanical/ ... stem/4.htm

Also if you have a oscilloscope you can check the G1 & G2 waveforms, G1 & G2 should give a pulse every camshaft rotation, G2 should be 180 degrees behind G1.

See http://www.autoshop101.com/forms/h36.pdf page 4 for a picture of the G & NE signals on Toyotas.

Alternatively if that all seems too much hassle, try swapping the distributor in your car into your customers car and see if the problem disappears with the PowerFC.

Cheers,
Jon