Engine won't run

Hi everybody

I am new to this board which I am following for some time with great interest. I own a GTA turbo for many years which is my daily driver.
Unfortunately I have some engine problems recently. My engine is very hard to start and only keeps running above 3000 RPM. Below it starts to shake and quits immediatelly. I guess its fuel related? Can anybody give me some hints?

Thanks Mike

Is the engine management light on? (and does it definitely work firstly?).

That will tell you if its a sensor prob - the coolant temp sensor can cause hard to start and poor idle problems when the engine is cold as the engine mgt system substitutes a value of 80deg if it cant get a reading. That means that fuelling is reduced quite a bit from what it should be for starting and idling on cold.

All the sensors affect the fuel map in some way and they normally substitute values that are appropriate for a warmed up and running engine if they are knacked - so that can impact cold start and idle.

Crank angle (TDC) sensor is another favourite - that doesnt show up as an ems fault I dont think, but it has given people loads of starting problems - normally second start of a hot engine though.

Fuel pump wiring has also been responsible for numerous problems - do a search and you'll see. Recommendation from those in the know (well DG anyhow) is to get rid of the capacitor and the connectors and solder the fuel pump wiring together. The Renault fuel injection manual estimates that the fuel delivery is reduced by 10% for every volt lost.

Apart from that - just check the obvious - plugs, leads, distributor cap & arm etc..

It's our group catchphrase but "check your earths!"

Seriously the main lead from the battery negative to the chassis is directly underneath the battery and in a 'gulley'. Over time it corrodes and the connection becomes very poor.

Unbolt this and clean with wire wool or emery paper until it's sparkling. Sometimes the bolt is so corroded that it won't even tighten up. I remounted mine onto the left hand suspension turret. If the earth's weak it'll only run properly when the engine is being revved and it's kicking out power from the alternator.

It could be dizzy or HT leads or one of half a dozen other things but check the earth first and start from there.

Hi everybody

I am new to this board which I am following for some time with great interest. I own a GTA turbo for many years which is my daily driver.
Unfortunately I have some engine problems recently. My engine is very hard to start and only keeps running above 3000 RPM. Below it starts to shake and quits immediatelly. I guess its fuel related? Can anybody give me some hints?

Thanks Mike

First question, is it running on all 6 cylinders...?

I second Darrenbiggs comments. A poor battery to chassis earth is one problem I've had.

I would also add, check the condition of your alternator. A faulty alternator caused my GTA to cut out if I had a a couple or more electrical systems turned on. Put a voltmeter across your battery (after checking the earths!) and turn on every electrical device possible. If the voltage drops and the car cuts out, it points to your alternator.

Thanks for all the hints!!
The engine control warning light is not on when the engine is running (and it is working). I have installed a second ground from the battery to the right suspension turret. It is also running on all 6 cylinders (when running...). I already have replaced the coolant temperature sensor.
I think I will try to measure the fuel pressure and go from there...?

Mike

Is your car lambda controlled with the anti-pollution system?

Lampda controlled yes, but I don't know about the anti pollution system. Its is a Swiss edition.

Try disconnecting the lambda sensor. The sensor works on part throttle and idle, and switches over to just reading the map in the chip at a certain revs/load.. If the lambda sensor is faulty, then it may be running the engine very lean low down and then stall, hence why you can only get it to run above 3000...

Just came back and tried with the lambda probe disconnected. It didn't help unfortunately.
I also measured fuel pressure between the fuel pressure regulator and the injectors and it was indicating exacltly 3 bar (just as it should be). I connected a vacuum hand pump and was able to reduce the fuel pressure by the amount of the negative pressure produced by the vaccum pump.
I also checked the vacuum hose which is running to the ignition box from the manifold and it could held the vacuum perfectly.

I guess it is more ignition related then...?

My engine is running again! It was the rotor of the distributor which was burnt through. Amazing that it was running sometimes with high RPM's.

WOT A SURPRISE, an electrical fault