Cutting out...

Geoff, GTA's havent such luxuries as Lambda sensors!

See what I mean, I shouldn't be advising! Beware the new expert!! The engine harness is a disaster however that has not been mentioned as far as I could see when trying to find out about the problem for myself so I am just raising it's profile as it was certainly a major problem on my A610.

Just put a new distributer and rotor arm on (£131) and the bloody thing still cuts out. Only seems to do it after its been standing while warm for a few minutes... Any sugestions as to what to check next?

Have you swapped the engine computer for a known working one? and checked the idle speed valve for a mechanical defect - ie jammed - or swap with known working one - these are on 21's 25's and 19 16vs also if you don't have easy access to a spare. Does the engine speed rise to about 1500 rpm when you start and drop to about 950 when cold and 800 when fully warmed up? If it doesn't it could be computer problem ( it has happened to me) or theidle valve or even the coolant temp switch which i assumed you have changed. I am assuming that it only cuts out on idle and not under load and that you have all the ignition system in working order and checked on the renault system.I have also noticed that with the age of the parts some of the idle speed valves work better than others despitecleaning and lubricating in the same way .

If its none of these you'll have to put a bornier in the place if the injection computer and check continuity and resistance of the computer imputs circuits

might be of some help

Try these...

Ignition module can deteriorate with heat, and also the earth and power feed to it.

Main king lead from ignition pack

Map sensor wiring/plug and vacuum feed and sensor itsself.

Input sensor wise, the GTA engine will run with only the map sensor connected (though won't idle without idle speed control valve)

If you can't find the source of the problems easily, I have spare ecus, map sensors you can borrow, may be worth hiring the diagnostic unit too..

A few things to check there then!!! Thanks David. Don't know whether or not it makes a difference, but it cuts out under load the majority of the time - reallt good fun when you go to overtake!

Load, as in boost? or just part throttle? Could be map sensor related, has it happened since youve played with that electrical Ebay thingy, or it could be spark breaking down under load, so try some new leads.

Tips before you spend too much money!:

Bougicord leads (original fit)are available from EuroCarParts
Cap and rotor arm (£35 + £20 ) from most local motorfactors
MAP sensor, used on Saab/Volvo/Renault turbos from scrappies..
Ignition module - used on Clio/R19/R25/21...same unit.

Load, as in boost? or just part throttle? Could be map sensor related, has it happened since youve played with that electrical Ebay thingy, or it could be spark breaking down under load, so try some new leads.

Thanks again David. I started it from cold last night and the revs go straight to 900 rpm and stay there. It cuts outs on all aspects of load, whether on the turbo or not. It has been doing it long before the 'ebay thingy'. though the reading for the turbo boost on that gauge won't work, so im thinking that the map sensor may now be at fault....

Is it definately an electical cut out, or a fuel cut out? Under load the fuelling may be inadequate.

I had a perforated fuel pressure regulator years ago that caused issues.

The car would stall when hot as you pulled up at a junction for instance and had massive flat spots under load, that felt like the ignition was cutting out. Paul Sage swapped the ECU and ignition module temporarily etc but the syptoms would come and go so everything was put back again as before.

We simply couldn't work out what the cause was until the regulator popped in a big way on the driveway starting the car up. It hydraulically locked the engine with the massive dose of fuel it dumped into the bores.

Usually thats how they go- in one big pop. But in my case the tin diaphragm had tiny holes in it that were causing these weird effects simply by overfuelling.

Perhaps ben needs an ECU that can "record" activity during a test-run?

Ok, the story so far. Still cutting out, but i have booked it into AC Williams Renault next tuesday to get them to have a look at it. Will let you know what solutions this brings.
I was having a look at the wiring loom this morning and i noticed an unconected wire. It is located on the bottom of the engine sub-frame and comes off the same 'spur' of wiring that the reversing light switch wires do. It is a cream coloured wire (cream now, but could of been yellow or white 19 years ago). Any ideas where this should be conected, as i can't see anything to plug it into? Could this have anything to do with it cutting out?

Got the car back from Renault this afternoon and the results are as quoted...

"CHECKED ON THE XR25 SHOWED FAULT WITH C.O POTENTIONMTER. IT IS ACTUALLY MISSING FROM THE VEHICLE & WIRING HAS BEEN CUT AND BODGED AROUND IT. WE NEED TO ELIMINATE THIS FAULT FIRST BEFORE WE CAN KNOW IT IS THAT ALONECAUSING THE PROBLEMS. THEY WILL ALSO TRY TO RESCUE THE WIRING BUT IT MAY REQUIRE LOOM"

I have never heard of this C.O thingy, but i am guessing it needs to be there so i have ordered one to be fitted next wednesday. It costs £230 ish.

Does anyone know if this is likely to solve my problem or even if it makes any difference before i fork out £300 on parts and labour?

Just put a set of Bougicord leads, so i will give it a good run before next wednesday just to make sure they havn't cured it.

STOP! The c.o pot on the Alpines is used on all Renaults without lambda sensors, eg 25s, 21s, Espaces etc....all the same part. I threw a couple away the other day. It will costs you pennies from a scrappy, and is two wires - so save yourself £230!

It is a serious part, and your car will run badly without it. It controls the fueling enrichment percentage for idle and part throttle - for an MOT you need to adjust this to get the correct c/o level - so how your car passes an MOT is pretty clever....

I just went out side and unplugged my c/o pot, and used my diagnostic unit to see what happened. Most GTA's run a c/o voltage of around 1-1.2v, when you unplug the sensor, it senses a fault and drops to a 'get you home' voltage of 0.7v. This is a very lean state for idle and part throttle, and could be the cause of it cutting out - but....if its been like that since you had the car, then it would have always done it.