MatraSport Forum

Help please.
My 1993 Espace 2.0 inj has never let me down, until now.
It was running fine then one morning a few days ago it started first time as always but after about 20 seconds it started to shudder and stalled. It was as if it had run out of petrol.
I put a gallon in and tried to re start. It does start but only with full throttle and then it runs so bad that it doesn't generate enough power to pull away. Taking my foot off the throttle causes it to stall imediately.
Below are the new bits fitted since.
Rotor Arm
Distributor Cap
Plugs
Plug Leads
Crank Possition Sensor (Old one was in a bad way with frayed wires)
Injectors

The fuel pump definately apears to work as I can put my hand on it as I turn the ignition on and feel it run for a couple of seconds.

To sumarise, It has a verry good regular spark, but although it will start it will barely run.

I've tried clamping off the fuel return pipe in case the pressure regulator is sending all the fuel straight back to the tank.

Could this be a faulty fuel pump ?
Does the fuel pump have it own pressure regulator built in ?

Can anyone give me any ideas please.

You may be looking in the wrong area.  You didn't say if you have an injection warning light on? (amber light lower right with the zig-zag symbol)  This should come on with the ignition and then go out when the engine starts.  The fuel injection system has a temperature sensor next to the temp. sensor on the right front of the cylinder head, for the computer and dashboard temperature gauge respectively.  This provides the injection computer with the information on engine temperature and allows it to control the additional air valve which regulates the starting and idling.  If the sensor or the air valve has failed, these can prevent the engine starting.

The valve can get clogged with carbon which prevents it rotating to open and close, and is easy to check - remove it from the vehicle and roll it back and forth between your hands quickly.  The valve should make a clicking noise as it rotates inside against the stops.  However, sometimes they can be free and still have failed - I had one on mine like that.  If the valve is stiff and clogged you may be able to clean it with some fuel, but as it is a sealed unit you can only do so much.  The plug is a 3 wire with spring latch.  Sometimes the spring has not locked on and the plug can come off.  The centre wire should have ignition voltage when it is switched on and the outer two wires go back to the computer as they are earth switched by the computer to control the valve.

The temperature sensor has a resistance that varies with temperature.  With the vehicle cold, what is the resistance?  It should be around 290 ohms at 20 degrees.  At 90 degrees it would be about 410 ohms.

The fault could also lie with the map sensor (absolute air pressure) or air temperature sensor, or throttle switch, or any broken or poor wiring connection but the most likely place to start would be the coolant sensor and air valve, and worth checking first.

Roy

Hi,
Thanks for the input. I've just fitted a new MAP sensor and no change. Im gonna check the other parts you mentioned now.
I'll post a reply with the results.

Hi,
Just tested the resistance of the coolant tempterature sensor and its resistance is 13k ohms cold. I asume that the car must think it's in the arctic and would prob make mixture way too rich.
Am I thinking right here ?

Hi,
Sorry foregot to mention no warning light on dash, but I dont ever recal having seen one.

Hi,
I took one of the pipes off of the idle control valve and it moves freely and if I rotate it by hand as I turn the ignition on it rotates itself OK.
I think that the throttle possition switch is prob OK as I have adjusted it's possition in the past to compensate for idling problems and it makes quite a diference to the idle speed so apeared to be working.
This car has always left a black sooty mark on the road under the exhaust outlet when cold and the plugs always run sooty. I guess that those two point towards mixture too rich in the past anyway.
It did recently pass it's MOT and although the MOT inspector did coment on the black sooty mark from the exhaust, the CO was fine when hot.
Would love to feel heat from this engine now as it's driving me crazy.
As a matter of interest do you know what the resistance of the air temp sender should be ?

0 deg C: 254 - 266 Ohm
20 deg C: 283 - 297 Ohm
40 deg C: 315 - 329 Ohm

... according to ETAI Revue Technique, Renault ESPACE depuis 1984 (great book if you know just a little bit of french).

Roy mentioned that the idle speed valve is sealed, which is correct of course, but with a little care, it can be dismantled and reassembled if you need to. Here's a photo of one I took apart on the 1987 J11 I used to have:

(http://dinsen.net/espace/teknik/j11-j63/isv1mini.jpg)

Hi,
Well, I bought a new engine management tenperature sender and fitted it.
Still the same.
What would be the possible efects of a faulty knock sensor ?
I seem to recal reading somewhere that a faulty knock sensor can cause severe retarding of the ignition timing. I've got a good spark but is it at the right time ?
I don't have a timing light and cant afford to buy one at the moment particularely as the cheapest I can find around here is over £40.

I guess that at this point I need to answer 2 questions.
1 - is the spark corectly timing
2 - is the fuel pressure right

Merely as a matter of interest the new engine management temperature sender straight out of the box has the same resistance as the old one

I foregot to mention not only is it the same resistance but the resistance falls as I warm it reather than rising.

That is way too much resistance. and since you say later that it falls as you warm it, you have the wrong type sensor by the sound of it.  What was the Renault part number?  Later cars do have a reverse CTN resistance type sensor i.e. they start at high resistance and drop when heated.  The early cars have a CTP sensor with low resistance that rises with heat.  The V6 uses the CTN sensor and you may have been given one of those by mistake.

Note there are two different coolant sensors depending on the engine fabrication number, so can you please supply that.  It is on an alloy plate attached to the block near the exhaust manifold.

Roy

Hi,
The details on the plate on the engine are as follows.
J7R 3 768
F446026

The oval plate details are as follows,
J636
23 720 061
TJ 577 E2
T014985

The new temperature sender does respong the same as the old one that has been on the car for some time.

Had a quick look at the knock sensor today, I didn't remove it but it does look verry old. I seem to remember reading that a faulty knock sensor can retard the timing.

As a matter of interest I tried using easy start direct into the air intake while cranking. It made no diference. The fuel pressure is good so it the compression. The spark is verry good. More and more this looks like something is causing the ignition timing to retard.

Paul

A faulty knock sensor can theoretically do all sorts of things to the timing, but you should be able to run the engine without it. I suggest you disconnect it for the moment. The ECU should detect that it is not there any more, and run with a fixed ignition advance curve. The engine should be able to run.

- Anders

Hi,
Many, Many thanks for the help.
This morning I disconnected the knock sensor and it sprang into life.
Slightly lumpy but it is verry cold out there and the engine was absolutely cold, plus no knock sensor.
I'll fit a new knock sensor asap.

Thanks again for the advice.
It's nice to see that there are genuine people out there who will take the time to help a stranger.

Paul

A stranger with good taste, that is :-)

But that is what this forum is all about. I'll keep my fingers crossed for the knock-sensor being the culprit.

/Lennart

Lennart is right, we only help people who love Matras (it's beginning to sound like a religion? ;D )

I'll keep my fingers crossed that the new knock sensor will cure the problem. You have attended almost everything else, so you should be close now. Have you tried giving the car a run 'till warm? How does it behave then? Advance means a lot when the car is cold (as cold air burns slightly slower than hot meaning that the car benefits from a bit more advance, but the engine management should be able to cure that by increasing the idle speed slightly on the idle valve) but the lumpyness could indicate that there was another problem too. Maybe an air leak somewhere? I'm just thinking... there could be a million reasons (at least more than 5 ;) ) for a problem like yours, but usually there's more than one (just my personal experience)!

- Anders

Thanks for the information.  What part number temp. sensor did you get?  With your details I can now check it against the official Renault parts list.  It should be 77 00 737 571


That certainly made me think it may be right, but an incorrect one could have been fitted previously and the engine set up incorrectly to compensate.  Not as likely but I have seen these things in the past.  However a J7R engine definitely should have a CTP sensor (resistance starting low and going high with heating).


I was going to suggest disconnecting the knock sensor, if you thought it was retarding the timing too much or permanently, but I see you have now tried that successfully.  A knock sensor simply detects when a cylinder is pinking or knocking and retards the timing to stop it.  So when you are starting up it is not really necessary.  If it is not connected when running, then any pinking will continue unless you back off the throttle, to ease the cylinder pressure.  If the fuel grade is wrong the system cannot accommodate it.  But you could certainly try running it without the sensor connected until you get a new one.   But don't let it pink too much...

When you fit the new knock sensor, you MUST torque it up correctly.  It works by pressure and if the torque is too low or too high, it will not work correctly.  The knock sensor should be 82 00 680 689  and oddly I cannot find the torque setting at this moment, so note how tight the old one is to remove and do it up a similar amount.  I'll let you know if I find the setting.

Finally, you said it ran roughly after starting without knock sensor - could that be owing to wrong coolant sensor?

Roy

Had a mild case of your symptom on our old 1993 2.2 - when cold it would always stop 2-3 times before it slightly came to life.

Leaking rubber sealings around injectors + Broken inlet manifoild gasket was the main problem then, this (gasket) later reappeared and my mind took it as a common weakness on these engines. Solution was to use a pro liquid gasket.

I might add that the car had 600.000km on the clock so in our case we accepted grumpy behaviour, but it always ran well when hot.

Hi Everyone,
Well, the new knock sensor arived and is now fitted.
It's alive !!!!!
It runs, more poky than ever.
But.
There is one curiouse thing.
It starts and runs but the power is a bit uneven. Rather like having a lack of power from one cylinder. I hav'nt done a compression test since getting it running yet but last time I did 1 all the cylinders were pretty even and that wasn't long ago probably only 2000 miles.
It is verry tappety though.
Tried most of the usual stuff.
Firing on all 4.
Injecting fuel on all 4.
Just seems uneven on power.
Could it be sloppy tappets ?

Paul

Hi,
Just took it out for a run.
After about 4 miles the problem went, very suddenly and did'nt come back.
Theres only 2 things that I can think of that might cause that.
1
Something bridging a spark plug gap. Eventualy burned away.

2
An electrical bad connection. Eventualy made connection.

Either way, would be impossible to locate once the problem goes.
I'll keep an eye on how it goes.

But for now it's all good.

Does that engine have hydraulic tappets?  That would account for the rattle initially, and after the four miles they have all filled with oil, so it is now quieter, and the valves are opening correctly, so it now runs correctly.

If they are not hydraulic (can't remember without checking the manuals) maybe one was sticking at first...

Roy