Dfz Engine Won't Start

[kachel 5]

Hi, my cti won't start anymore after running well. Fuel pump is running, sparkplug cables gives power (tested with screwdriver in it on the inletmanifolt). I have cleaned the injectors a couple of months ago. I have sprayed brake cleaner in the inletmanifold during starting, it gives a few puffs then but no more....... what else to check?

[Leslie green 111]

If it runs with brake cleaner then maybe you are getting no fuel pressure either due to a faulty pump or relay so id take a rubber fuel hose of at the inlet manifold and stick the end it in a large plastic bottle and turn the ignition on and see what comes out ...

[dcc 855]

Compression test

Fuel pressure test

Not sure if these use distributor but if so worth checking points and rotor arm.

 

Next would be plugs, fuel filter, ecu temp sensor, afm etc...

[kachel 5]

I have pulled out the injectors. (the rubbers o-rings are still attached ;-))

The injectors don't give a drop of fuel. Does the ecu give 12v to the injectors or does it earth the injectors?

There is fuel in the rail.

[welshpug 1,661]

12v to injectors comes from relay, ecu pulls these to earth.

[kachel 5]

Thanks wp, from the tachometric relay?

[welshpug 1,661]

yes.

[kachel 5]

Does the tachometric relay give 12v AFTER starting? I ask because my multimeter does not measure 12v at the injection connectors when i have the starting key in position 2. This is also the case with my other d6b gti which does run well.

[Anthony 1,003]

I don't have the Motronic 1.3 wiring schematic to hand, but as far as I know the injector power will be along the same lines as Jetronic (D6B) - they'll only be powered when the fuel pump is powered, ie when the engine is turning over.

 

The actual mechanism for switching the relay is quite different though - the ECU will switch it on Motronic, whereas it's switched by the coil pulse on Jetronic.

 

If you've got a spark on Motronic then that suggests that the ECU is working and seeing a signal from the crank sensor when the engine is turning over, so it should be firing the injectors as well.

[MrAndy 10]

To clarify this to my self... Is the tachymetric relay included in all the cars?

 

- In my 1988 1.9 model I can find it below the battery.

- In my 1989 Motronic with catalysator 1.9 model I can not find it anywhere? (I have searched it below the battery, next to the ECU and other places, but not recognized it yet.)

 

-A-

Edited September 25, 2017 by MrAndy

[petert 588]

It's near the ECU, on the vertical panel, foot well, in front of the upper door hinge. It's a regular relay, not a true tachymetric relay like the Jetronic version. It will have large wires, #1A and #76 running to it.

 

Motronic will only prime the pump if its getting a pulse from the crank angle sensor.

Edited September 25, 2017 by petert

[MrAndy 10]

Thanks!!

[kachel 5]

So i have measured if there is 12v during starting on the injector connectors. Only for like one second there is 12v and fuel comes out the injectors. After the second it's dead during starting. Where to look?

[kachel 5]

I think the reason for not having 12v on the injectors i can find in:

 

Tachymetric relay

ECU

 

But do the other measurement parts (airflowmeter, SAD, temperature sensor, throttle position sensor) also give 12v to the injectors or just a signal?

[welshpug 1,661]

nothing else is connected to the injectors, they are all connected to the ecu.

[kachel 5]

Thanks WP, so i should find the error in the ECU?

Or does the Tachemetric relay decides if the ecu gets 12v for the injectors?

Or do the airflow meter, SAD, temp sensor and throttle position sensor send signal to the ECU to give the injectors 12v?

[kachel 5]

WP gave already an answer in this topic, sorry. 12v for the injectors comes from the relay.

[kachel 5]

Today i unplugged the tachymetric relay and put it back again. The engines gets fuel again! It's running well now. I hope it isn't a cable breakage. Time will tell.

[jackherer 543]

The tachymetric relays are prone to dry solder joints, prise the cover off and you'll probably see what I mean...

[kachel 5]

Ok, i will chek it, thanks!