Please Help....

I am having problems. The car is heavy on fuel and idles erratically. Adjusting the mixture makes no difference and I do not know what to do. I was told by a Renault Dealer that R11 GTA need a new carb. I promptly went and bought a new one but the problems is still here. Could this be a timing problem?? or something else....

Have you checked the ignition HT cables? Old cables cause problems sometimes.

I assume your car has the electronic AEI ignition box. These do go wrong sometimes, and can be a bit tricky to test. There's a procedure for testing in the Haynes repair manual, unfortunately I don't have it with me now. One test I remember, however: With the engine running, disconnect the hose that goes from the inlet manifold to the ignition box vacuum capsule. If engine revs don't drop, get a new ignition box.

I drive a Renault 19 GTS that didn't pass its emission test. Mixture screw didn't have much effect and it idled erratically (although the fuel consumption wasn't particularly high). It turned out to be the number 3 cylinder had burned a valve. So it was a head off job and some machining.

Having a compression test run on all cylinders gives an indication to the engine internal condition. If the compression in one cylinder is clearly lower than the others, then there's probably something wrong inside the engine.

Erratic idle often indicates there's an air leak somewhere. It's possible that the inlet manifold gasket is leaking. Or some of the vacuum hoses has perished. Or then some vacuum passage is blocked.


Finding the cause for this can be tricky, I hope you find a cure.

Hi pals! I read your response about testing the ignition box, I have a R-Fuego with a pretty similar carb (Weber 32 DARA) and pretty similiar ignition box (if not the same) and I did this test, of course the car was cold/warm and the revs didn't changed, have to try with the car fully warmed up to see what happens, maybe this can figure out why It hasn't idled right since 30k kms! I even rebuilded the engine and it got a lot better but I know that it can be even better.

Do the timing should be advanced as the rpms go up?

I forgot to mention:

If any of you thinks the ignition box vacuum capsule is faulty (or for any other reason),
DO NOT,
DO NOT,
DO NOT TRY TO REMOVE THE CAPSULE FROM THE IGNITION BOX to test it,
even if it conveniently seems to be fitted with just a collar held by two screws! Removing the capsule from the ignition box renders the very expensive unit useless!!

I've been told that there are very thin electric wires that connect the capsule to the ECU. When you try to remove the capsule, these wires break and there's no way you can solder so thin wires back together. I don't know how it's been done when it was manufactured, but definitely not a DIY job. Even experienced car electricians can't tackle it.

I have taken the power module apart to clean it but never the vaccum capsule. I have tested the module giving me the right values but I think the vaccum capsule is working bad. In fact if you remove the two torx screws and the plate that hold the capsule it will still be stiff enough to make you think that it will not came out. The car is perfectly driveable but sometimes is hard to start form cold or starts at the first attempt but fails to keep the idle or idles very very erratically, sometimes it will backfire thru the carb when accelerating when cold.... I know these aren't carb problems and everything in the ignition department has been changed or checked.

There must be some sort of a diaphragm inside the capsule that the manifold vacuum acts on. This has made me think maybe it's that the diaphragm gets 'tired' with age, just like the diaphragm in a carburettor accelerator pump?

Or maybe there's some capacitor or regulator on the ECU printed circuit that goes bad?


I'm also suspecting the ignition unit on my car, but a new box is so expensive I'll probably struggle on with the current one as long as it works somehow... Depending on where you buy it here in Finland, the price varies from about 600 to 900 euros. That's a lot if the car (Renault 9) is worth the same. But a Fuego is so nice car it's probably different...

Yes, I tested the electronic AEI ignition box and the engine did drop its revs. I checked the vacuum pipes for any blockages and they where fine. I also did a compression test on all cylinders and they are all the same, around 11 bar with no noticeable difference between them.

I have ordered new ignition HT leads and am waiting for them to arrive. If they are not the problem I am stuck for a solution.

Could this be cause by broken gaskets on the inlet manifold?

A broken gasket on the inlet side will cause a leak that would ruin an engine in 2 or 3k miles because of the lean mixture so check that. Apparently your problem is ignition related so check ht leads and other components like rotor and dizzy cap.