1993 2.0 inj Espace barely starts

[Anders Dinsen]

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

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

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

[roy4matra]

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

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

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

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).

Had a quick look at the knock sensor today, I didn't remove it but it does look very 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 very good. More and more this looks like something is causing the ignition timing to retard.

Paul

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

[renaultbiler]

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.

[voyager]

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

[voyager]

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.

[roy4matra]

Hi,
Just took it out for a run.
After about 4 miles the problem went, very suddenly and did'nt come back.

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