Fiat Uno Turbo Starting problem

[Yugo_Turbo]

I have Yugo with Fiat Uno Turbo 1301ccm turbo i.e engine from 1988.

I've tried to start it but it can't.
Fuel pump time relay, two cables from main ECU, and two red wires from distributor are connected to one relay which is connected to one switch which gives power, and than I press ignition button.

Problem is that injectors don't want to open. I have 2 + on injectors, and to open them one + need to become -.
So I probably need one - coming to main ECU.

Here are some pictures of conectors which are giving ECU power, is there anything missing?

Help please!





*Note

Airflow meter isn't there now,this is old picture.

[SteveNZ]

SO the ECU is not working, not providing a switching earth? This could be a few things. Do you know if its even getting power? There is a main engine control relay, this switches the ECU and fuel pump on.

Does it have spark?

[Julian]

Just from personal experience with this problem I would suggest seeing if you can get hold of another fuel rail (with injectors) that you know works. The ones originally used by Fiat are very sensitive to damp and if the fuel rail is left detached from the engine and exposed to air the injectors can quickly seize up.

You might be able to get them working again with the aid of a sonic bath but in the end it usually comes down to a set of 4 new injectors (and new seals to go with them).

[Yugo_Turbo]

SO the ECU is not working, not providing a switching earth?

Yes,there is no + and - when it needs to open,just + and one more + on injectors.

Do you know if its even getting power?

Is ECU getting power through wires on pictures above? :?:

There is a main engine control relay, this switches the ECU and fuel pump on.

Is that time relay?
Can you post the picture of it just to be sure I have it.

Does it have spark?

Yes it have,and sparks are totally dry,no sign of fuel after cranking.

Just from personal experience with this problem I would suggest seeing if you can get hold of another fuel rail (with injectors) that you know works. The ones originally used by Fiat are very sensitive to damp and if the fuel rail is left detached from the engine and exposed to air the injectors can quickly seize up.

This could be it,a month ago I deatached rail and injectors from intake manifold.They where out for about 2days,whithout fuel in them.
Can I shock injectors with +12v?

You might be able to get them working again with the aid of a sonic bath but in the end it usually comes down to a set of 4 new injectors (and new seals to go with them).

I'll try that too.

[Julian]

Without the aid of an oscilloscope I am not sure you would be reliably able to monitor the trigger signals to the injectors.

I believe the system is negatively switched so both sides of the injector circuit are kept at +volts until the fire signal is made and the earth side is driven to 0 volts for the duration of the injector pulse. All four injectors fire as a bank so there should be 4 pulses per cam cycle to each of them.

[Yugo_Turbo]

I believe the system is negatively switched so both sides of the injector circuit are kept at +volts until the fire signal is made and the earth side is driven to 0 volts for the duration of the injector pulse. All four injectors fire as a bank so there should be 4 pulses per cam cycle to each of them.

Yes,on both pins on each injector there is +,only when they are opened one + becomes -.
But problem is(I think so) is that my injectors are not reciving -volts when they need to open so they dont open at all.

So there should be 4pulses per cam cycle when I'm cranking the motor?

What you think the problem is,despite seized up injectors?


My friend had almost same problem wtih his NEW injectors on his engine.Then he has conected one injector serial to headlamp bulb,and connected it to +12v for about half a second,to shock injector.
He done it to all 4 injectors and when he refitted them,car started.
Could that be a problem?

How is main ECU getting mass?

[dvv]

Without the aid of an oscilloscope I am not sure you would be reliably able to monitor the trigger signals to the injectors.

Completely agreed! Sale, you can use my oscilloscope, if you like.

I believe the system is negatively switched so both sides of the injector circuit are kept at +volts until the fire signal is made and the earth side is driven to 0 volts for the duration of the injector pulse. All four injectors fire as a bank so there should be 4 pulses per cam cycle to each of them.

Julian, Yugo has ALWAYS had problems with its electrical circuits, for many reasons. In part, it's inheritance, the worst part of any Italian car is always its electrical system, and in part, sloppy local factory assembly.

The cure is to double back a decent wire to the battery minus side, rather than rely on the bodywork to do the same. But this takes time and requires effort, so most people don't do it. That notwithstanding, it's always a good ide to use one of those rubber-based, chemically treated "tails" that you hang from somewhere; this is electrically conductive rubber, which theoretically ground the bodywork. In practice, it doesn't quite do the job, but it certainly improves things quite a bit.

The last problem, this time a general one, is electrical circuit noise. I won't go deep on this because I manufacture power line filters, it's my field and I could wax lyrical for days on end, but a quality power filter preceding the ECU is a GOOD idea. I am seriously considering producing such filters in the near future.

thank you,
Dejan V. Veselinovic (DVV)

[Julian]

All good comments!

The main thing here is that the ECU(s) *must* be getting at least some of the right signals otherwise you would not be seeing a spark. The wiring for the injectors is incredibly simple - just one wire for each side of the circuit. The injectors themselves are all wired together. One thing you do need to be careful of is the crank sensors - there is one on the nosewheel/pulley and one on the flywheel both need to be very precisely fitted in order to get the ignition and fuelling to work properly, if one signal is missing it is possible to get spark without fuel and vice-versa.

In terms of sloppy wiring the fuelling management side of the engine is not too bad on the Mk1 Uno Turbo - simply because it is all provided by Bosch, you can spot the difference because the Bosch wiring has numbered wires instead of colour coding.

If any of the wiring is suspect then that has to be the first thing you check - for all the old Bosch system isnt up to the standards of modern engine management it is still utterly dependent on the input signals from the engine. The eternal problem is "garbage in - garbage out". If those input signals are distorted or missing then you will not see much by way of results.

I can't comment on shocking the injectors into life - I have never tried to do so myself and I certainly do not know enough about them to know if it would or wouldn't work or more importantly damage them. I do know that the injectors used are easier to drive than the equivalents from more recent cars.

When you say MASS are you referring to the mass airflow meter? I am not sure I entirely follow what you expect by way of reply as the question is (to me) rather ambiguous. I assume you have fitted the MAF unit into the engine bay.

[Yugo_Turbo]

@DVV
Thank you,I'll call you for oscilloscope.

@Julian

The main thing here is that the ECU(s) *must* be getting at least some of the right signals otherwise you would not be seeing a spark.

One thing you do need to be careful of is the crank sensors - there is one on the nosewheel/pulley and one on the flywheel both need to be very precisely fitted in order to get the ignition and fuelling to work properly, if one signal is missing it is possible to get spark without fuel and vice-versa.

Yes,I think I already had problems with those two.
But they are connected to Ignition ECU(Maganeti Marelli) not ECU which controls fueling.
And,I say again,there IS spark,but fuel is not entering cylinder.
Injectors are not opnening.

I can't comment on shocking the injectors into life - I have never tried to do so myself and I certainly do not know enough about them to know if it would or wouldn't work or more importantly damage them. I do know that the injectors used are easier to drive than the equivalents from more recent cars.

OK,it's been done on DVV's car.
And that was doing a man who works in Bosch in Germany and a friend of mine.

When you say MASS are you referring to the mass airflow meter?

Sorry,my bad.
I meen Ground(- from batery).

Well Uno Turbo has VAF,so of course it's fitted,it can't work without it.

[dvv]

... I can't comment on shocking the injectors into life - I have never tried to do so myself and I certainly do not know enough about them to know if it would or wouldn't work or more importantly damage them. I do know that the injectors used are easier to drive than the equivalents from more recent cars.

Well, you can tell me all about mechanics, I just drive 'em, but electronics is more my field. In principle, there are two types of injectors, low and high impedance ones. Thus, the high impedance ones (12 Ohms and above) require less current and more voltage to click, but the feedback signal is also a volatge one; this is not cool, because its quality will depend on revs. Sure, they developed several schemes to overcome the problem, but that's not the real thing.

In contrast, low impedance (2...5 Ohms in general) injectors are harder to drive, they sometimes require added cicruitry because they are current driven, but they also use current feedback, which is inherently more linear than voltage feedback (even in audio) and gives you more precise control over the injectors.

Mine could have been shocked back to life because miy injectors are current driven, whereas Yugo_Turbo's are classic, voltage drive types. Shocking them to life is a very dicey proposition, anything might happen. What if you discover you need say over 14V for an effect? Or more?

Not recommended.

When you say MASS are you referring to the mass airflow meter? I am not sure I entirely follow what you expect by way of reply as the question is (to me) rather ambiguous. I assume you have fitted the MAF unit into the engine bay.

Language mishap. In Serbian, "ground" is termed "masa", so our young friend (just 16.5, believe it or not, so young and already turboed!) misused the term. He meant ground.

thank you,
DVV

[SteveNZ]

Without the aid of an oscilloscope I am not sure you would be reliably able to monitor the trigger signals to the injectors.

I believe the system is negatively switched so both sides of the injector circuit are kept at +volts until the fire signal is made and the earth side is driven to 0 volts for the duration of the injector pulse. All four injectors fire as a bank so there should be 4 pulses per cam cycle to each of them.

An LED test light is more than adiquate. A multimeter with a duty cycle function will work oo,

There will be 1 pulse per revolution.

[SteveNZ]

All good comments!

The main thing here is that the ECU(s) *must* be getting at least some of the right signals otherwise you would not be seeing a spark. .

I don't wish to pick on you Julian but this is incorrect. The Microplex ignition system is totally independant of the fuel injection. You can have spark but no injection but if there is injection there must also be spark, or at least a working spark signal to the coil.

So if there is no injector pulse, this is the problem. The injectors wont fire, siezed or free without injector pulse.

You need to check for power and earth. The fuel injectors get the same power supply as the fuel ecu, so the relay should be switching on at least. Check the coolant sensor signal wire for 5V, or about 2.5V (cold) when backprobed. This is a decent enough test for power. You need to check for earth too, the injectors cannot switch to earth without an earth! If the coolant sensor has 5V on both sides when connected there is no earth. When pluged in the coolant sensor should have voltage one side and 0.0V on the other. Any voltage on the negative side of the sensor is a bad earth.

If thats ok I would check for reference. The fuel injection system has only 1 reference with respect to injector timing. It has a simple wire running to the ignition coil (Mk2 UT is different). When the coil gets an earth, the fuel ecu starts its next injection event.

If the ecu is getting the correct reference, and has power and earth it should work, or at least give an injector pulse regardless of the other sensors.

[Julian]

I realised my mistake on the timing issue when I read through my post again this morning - I'm too used to working with my DTA system and had forgotten that the two systems were independent on the Mk1 Uno Turbo.

I won't go back and edit it - the subsequent posts won't make a lot of sense if I do but I would certainly be the first to admit the error.

[Guy Croft]

I think I have a idea what the fault is, I congratulate the poster on 'having a go' here, not easy.

But - I don't have a clear idea of the fault-finding regime. If I don't others don't either. Can someone now perhaps pull this together into a step-by-step please?

ie:

1. check 'A' - if OK go to step 2. If not go to step 4
2. Check 'B' - if Ok go to setp 3

etc


GC

[Yugo_Turbo]

Thank you DVV.

You need to check for power and earth. The fuel injectors get the same power supply as the fuel ecu, so the relay should be switching on at least. Check the coolant sensor signal wire for 5V, or about 2.5V (cold) when backprobed. This is a decent enough test for power. You need to check for earth too, the injectors cannot switch to earth without an earth! If the coolant sensor has 5V on both sides when connected there is no earth. When pluged in the coolant sensor should have voltage one side and 0.0V on the other. Any voltage on the negative side of the sensor is a bad earth.

If thats ok I would check for reference. The fuel injection system has only 1 reference with respect to injector timing. It has a simple wire running to the ignition coil (Mk2 UT is different). When the coil gets an earth, the fuel ecu starts its next injection event.

If the ecu is getting the correct reference, and has power and earth it should work, or at least give an injector pulse regardless of the other sensors.

Thank you.