Small Renault - SPI problem I think.

[52classic]

It's not the first time that PH gurus have helped me out with this one!

Renault Twingo '93 and a part of the family now. 1300 pushrod engine which runs like a sewing machine. Primative SPI system with no diagnostic plug. (that we can find)

Thoroughly warmed up it starts and runs beautifully. Smooth tickover, clean exhaust, no exceptional oil or water consumption or contamination.

On a cold start it will fire first turn but if it doesn't 'catch' then it becomes very tempramental.
Turning over it will eventually fire on a couple of cylinders and smokes like hell all the while.
Coax it on the throttle and you can get it to run and then tease it into life. Runs lumpy with erratic tickover but settles down when warm.

I suspect it is over fuelling because this performance is accompanied by a smell of petrol and a sooty ring under the exhaust. Plugs are fuel soaked too.

Replaced the idle control valve and plugs/HT leads. Now running out of ideas.

Last time, PHers diagnosed an air leak to cure a fast tickover which worked a treat so its back to the font of knowledge once again.

Advice much appreciated.

Edited by 52classic on Wednesday 1st September 10:34

[annodomini2]

Crank/cam position sensor, lambda sensor, if it has any of these

ETA: Temperature sensor

Edited by annodomini2 on Wednesday 1st September 13:23

[bob1179]

Sounds like it could be the Lambda sensor, however, if it is shot, the car won't run properly full stop, especially if it's using Bosch Monojetronic fuel injection.

[52classic]

Thanks lads, Crank sensor has been cleaned but doesn't mean it's working properly.
Will try to find a good S/H Lambda over the weekend.

Temp sensor would seem to be directly related but no mention of it in the data on the car. One probe within the top of the SPI body - a circle about 15mm dia with a vertical, central, bulb shaped probe about 10mm long. Maybe that's it!

MOT yesterday, just scraped the emissions test with the engine thoroughly thrashed en-route to the test centre. (couple of brake flexis to do but that's not bad for a 17 year old car with 250000 Km)

[annodomini2]

52classic said:

Thanks lads, Crank sensor has been cleaned but doesn't mean it's working properly.
Will try to find a good S/H Lambda over the weekend.

Temp sensor would seem to be directly related but no mention of it in the data on the car. One probe within the top of the SPI body - a circle about 15mm dia with a vertical, central, bulb shaped probe about 10mm long. Maybe that's it!

MOT yesterday, just scraped the emissions test with the engine thoroughly thrashed en-route to the test centre. (couple of brake flexis to do but that's not bad for a 17 year old car with 250000 Km)

Have you cleaned the electrical contacts to the crank sensor aswell, also replace the connectors as renault ones are quite prone to corrosion.

Crank sensors are known to fail aswell.

[Mr2Mike]

52classic said:

Temp sensor would seem to be directly related but no mention of it in the data on the car. One probe within the top of the SPI body - a circle about 15mm dia with a vertical, central, bulb shaped probe about 10mm long. Maybe that's it!

The symptoms do point quite strongly to the ECU temperature sensor, this is quite a common issue. The sensor is not likely to be in the throttle body itself, but screwed into part of the coolant circuit, usually in or near the thermostat housing. You are looking for a sensor with a brass hex shaped body (for a spanner), a plastic upper and a connector with two wires coming out of it.