Small Renault. Fuel injection problem

[52classic]

Our family fleet includes a '93 Twingo I. Normally very reliable but just recently!!!....


Simple little pushrod engine similar to Renault 4 & 5 and what looks like a Webber Carb but is probably some sort of early SPI set up.

Just started to display tickover problems. From start, revs rise to about 2K, then as it warms up it starts to 'hunt' as if the throttle was being blipped every 2-3 seconds. Drives normally in all respects but just won't idle.

Checked coolant level (thought a temp sensing problem) cleaned any sensor that I can find. Disconnected the battery for an hour or so (resetting ECU) Changed the Idle Control Valve and next step will be to change the Throttle Position Sensor.

I recall a similar problem with a Metro in which the answer was a farcical procedure to reset the Stepper Motor, however I can't remember how this worked.

Thought I'd consult the PH gurus before starting to throw stuff!

[annodomini2]

Have you checked the following:

1. Battery Earth onto the engine?

2. Crank position or more commonly known as the TDC sensor (usually on the top of the gearbox) if it has one

Edited by annodomini2 on Monday 30th November 20:44

[fatjon]

classic air leak symptoms. Look for split vaccuum pipes and leaks below the throttle body up to the head. Bit of washing up liquid solution will help as it bubbles up round the leak.

[52classic]

Thanks lads! Earth OK Crank sensor cleaned and refitted but no difference.

Vac leak is an interesting idea. Next bit of good daylight and I'll check it.

[Andoo]

Another way to check for vacuume leak is WD40 sprayed in the area you suspect.

The engine will either conk out or the revs die down for a bit when you hit the spot.

Small bursts at a time though, don't go mad with the stuff

[52classic]

Good news update..... It's fixed!!

Thanks again lads and especially Fatjon who was right on the money.
Yes indeed a detached vacuum pipe running from under the throttle body via some sort of flame trap and into the rocker box. Can't see what it was supposed to do but it is doing it again now. A real PH victory then.


Must say this Twingo is a brilliant little car. 9 years on the family fleet now and there's always a cheap solution when things go wrong with it, which they rarely do. Lot to be said for simple engineering.

[phumy]

fatjon said:

classic air leak symptoms. Look for split vaccuum pipes and leaks below the throttle body up to the head. Bit of washing up liquid solution will help as it bubbles up round the leak.

You may have been on the money with the problem but i doubt very much you would see bubbling around a hole on a vacuum pipe.