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The mkiv Supra Owners Club

Engine will not fire (no Spark)


T2 MSW

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Got an issue I don't understand and has to be alarm/electrical related.

 

Car has been in to have the alarm serviced today as nothing works and due to it being so badly wired and what was diagnosed as a fault with the brain it was decided to pull it out and start again.

 

Did have a clifford concept 650 connected in drivers footwell which links in to main ignition power and the signal from the barrel. Also had some stupid intelistart system.

 

Alarm has been removed and the wiring put back to stock, I have also checked this and validated with the wires disconnected. One you get no crank and the other zero power to the ignition system.

 

Now the alarm + Intelistart has been removed the engine will not fire. Ive check all of the below. Car has plenty of fuel as the garage stinks of it, crank and power at the ignitor just no spark.

 

All fuses have been checked

Power at the ignitor

Disconnected the ignitor, tapped it and reconnected

Logged onto the ECU to see if there are any errors - none

Checked all of the wiring where the alarm fitter has been in footwell and can't find anything obvious out of place or that should be connected and not.

 

Car drove there perfect no problems this morning, no misfires or anything suspect. Taken the alarm out and it now won't run so it has to be electrical in my view. Anyone any ideas?

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Even if the plugs were flooded it would try and start. would cough and splutter. This just does not even attempt to fire, just turns over.

 

If I get time tomorrow ill be going over to the garage to take a plug out and check if it actually gets any spark at all.

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Garage is going to check for actual spark this morning. Car was left with battery disconnected overnight and tried again this morning. Simply just cranks over.

 

Does anyone know a quality auto electrician in the NW/Cheshire area as I'm 99.9% sure this is electrical post alarm being removed. Garage will need support to get it running again and I'm not picking car up or paying any money till it drives out as it drove in.

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They have take 3 wires that interfere with the starting system, ignition barel signal, ing power and a signal from an injector that wasn't actually connected to anything out. The two ignition wires have been joined back together as per stock. That's it.

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Ok think I have worked out what is going on. Just not worked out how to fix it.

 

Changed the ignitor its not that which is causing a problem.

 

However put the laptop on the ECU to see what the CPS sensor and outputs to the coil packs are doing. started logging everything, turned the key to start and the ECU goes off!!!

 

Engine cranks over but the ECU is off hence no fire. Only issue is I can't work out why. All the wiring from the key to the ignition system seems OK and I've got a multimeter on all the outputs. Everything is at 12v. Run out of light to check the ECU side and also need to work out the syvecs pins to check.

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To bypass the ignition system if I run a 12v feed from the battery to pins 19/20/21 (they are joined on the board so only need one) on the syvecs and that will allow me to test that the car runs. Anyone see an issue with this?

 

Looking at wiring diagram this could be EFI fuse 1 has gone?? Im sure I've checked all fuses.

Edited by T2 MSW (see edit history)
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could it be a bad relay contact,

thing is though you have removed the alarm so I would expect that its related in someway and the wiring is a miss at some point , sounds like you know what your doing wiring wize though , so work your way back from the ecu and find where the power sorce fails , remember this could also be a bad earth side of the wiring

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Need some help with this one now as Ive run out of Ideas. The ECU going off was a red herring as I had the fuse out for the IGN circuit.

 

Car has been left overnight so its not fuel on the plugs.

Checked all fuses

The two ignition wires from the barrel are correct and connected as stock. Both wires are at 11 volts on crank.

changed the ignitor, ignitor also has 12 v feed and ground. All coil packs have 12v with the ignition on.

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I thougt you said you had it started when you put a wire straight from the battery to the ecu

 

No I was asking if it would allow me to test if the car runs. But that does not matter any more as the issue was the ING fuse being removed.

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Owh ok,

Being that you drove there and removed the alarm and now it does not start it must be related to the wiring in the foot well, you maybe over thinking things with it mike,

There must be a wire that went into the alarm for it to stop the car starting that has not been attached back to the original wiring, you may have to check with a meter the wiring from where the alarm was to the ecu and ignition.

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What should the input from the crank position sensors and cam sensors look like on the syvecs? if the ECU does not get a signal from the CPS then it would stop the engine firing wouldn't it??

 

Yes thats right it would not know when to spark if it didnt have the crank signal, im not to sure about the cam sensors though

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Ive done that. The alarm cuts two wires from the connector that plugs into the ignition barrel.

 

1) Black/white which going from the starter wiring diagram on page 47 in the wiring diagrams is the main wire from the ignition switch. This has been connected back to the black/white wire in the loom

2) Black/orange which is the charging system and again has been joined back to the black/orange wire in the loom.

 

These are the only two wires that are cut to install the alarm.

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Yes thats right it would not know when to spark if it didnt have the crank signal, im not to sure about the cam sensors though

 

Does anyone know what the crank position signal should look like to the ECU. Ive logged the input and its just sits a 6.21 volts

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Ive done that. The alarm cuts two wires from the connector that plugs into the ignition barrel.

 

1) Black/white which going from the starter wiring diagram on page 47 in the wiring diagrams is the main wire from the ignition switch. This has been connected back to the black/white wire in the loom

2) Black/orange which is the charging system and again has been joined back to the black/orange wire in the loom.

 

These are the only two wires that are cut to install the alarm.

 

Maybe the wires have been pulled out at the barrel end while they was being reconnected to the loom?

This is where I would spend most my time trying to fix this issue mate.

The 650 manual says it cuts in the starter and ingition signal

Edited by mellonman (see edit history)
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If the wires had been pulled out the starter would not turn over which it does or I would have no lights on the dash at all which I do.

 

if I disconnect the wires that have been cut I either get no crank or no lights so I'm confident the wiring is correct. It's only two wires to check.

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Does anyone know what the crank position signal should look like to the ECU. Ive logged the input and its just sits a 6.21 volts

 

 

The CPS connects to an Analog bipolar input on the syvecs so the output will be a voltage above and below the reference ground, basically like an AC waveform, not sure if you could check that on multimeter only a scope.

 

Would it help you with the wiring if I email you a spreadsheet of the engine loom, I have recently logged every wire from the ECU connector to all the other related connectors so I could make a new loom. If your interested pm me your email address :)

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