Cinqeucento Fuel Injector Warning Light

Sounds like a Lambda fault to me.

Fairly common issue on that generation of Fiat, but only about 35 quid for a pattern part.

Romeo'

The light wouldnt go out at all last night, then I prodded the Low Tension plug on one of the HT coils and it cleared up. The light is back on again this morning so I'm going to check the Lambda sensor with my oscilloscope - Do you happen to know if the sensor should pulse correctly even if there's a fault elsewhere?

Romeo'

quoted text -

Out of curiosity I prodded the LT wire again and the light out again! This sounds to me like a bad connection - come to think of it the light has come on at least 3 times while the car was making a (slightly bumpy) turn. Still gonna check the Lambda today though.

It will get to the stage where even though you have fixed the fault the light will stay on as the ECU will need the fault code cleared.

The warning light now ligths up fairly constantly. When on I get no signal whatsoever on the Lambda sensor black wire. When the warning light decides to go out the Lambda works more or less as it should i.e. pulsing 0.2~0.8v at 1 second intervals (with a slight kick at about 0.5v every other cycle or so).

Correction...

When the Fuel Injector Warning Light isnt illuminated the Lambda voltage is about 0.1v - 0.8v (not 0.2 - 0.8 as previously stated)

(when the F/I Light is on there's no voltage at the Lambda sensor whatsoevr)

I had this on something and it had a loose fuse that fed the lambda sensors

the schematic shows that the coils,injector and hego are all fed from the same relay, so that rules out the fuse, however there may just be a bad connection somewhere. I would probably check wiring and plugs very carefully first. This is all assuming you have a four wire hego sensor. there should be battery voltage across pins 3-4

thanks for your interest. A box near the ECU has 2 fuses & 2 relays which I pushed firmly home. I checked all the connectors in the engine bay including the ones on the injector, coils (LT & HT) and when the engine was running smoothly no amount of prodding & poking could make the warning light come on. The sensor is a 4 wire and I'm going to check the voltage tomorrow and (as I've already removed it once) remove it to see if it heats up (using a thermocouple type thermometer). Running smoothly it's obvious all plugs are firing but when the warning light comes on maybe they're not - I'll check that too. I'm convinced it's either a bad connection or someting blocking the injector perhaps and wonder if it's worth dosing the fuel with Injector Cleaner. When this is all sorted I will post the final conclusion - so many threads start and never close!

With the engine running (normally) I measured 13~14v (alternator voltage) at the sensor. To do this I disconnected the heater plug before the engine hadnt even warmed up - and it made no difference to the tickover.

There are TWO ignition coils. Resistance (cold) across the LT contacts is 0.7ohm & 1.0 ohm. Across the HT output cyl 1/2 & cyl 3/4 is about

Today I pick up an identical injector from the local car breakers. It ran okay (bit lumpy though) but after a few goes the warning light came back on.

I located the crank sensor and put my 'scope on it. The waveform at tickover was -3 to +6v and higher with more revs

Can anybody tell me if high primary values on the coil has any adverse effect on the spark. 2 colis ~ one is about 0.8 the other is about 1.0 ohm. According to info on the net it should be more like 0.5 - 0.6 ohm

Have you nulled the leads on the meter?

Thanks & good point - now why didnt I think of that? That's why I'm here I suppose.

I'll re-check tomorrrow, but if the reading IS correct does it make a difference and is it affected by the temperature of the coil itself?

I joined a Fiat Forum and a couple of people have suggested the MAP sensor might be the cause

Only in as much as it means there's something faulty in the coil

Yes. but only 0.393%per deg c. You can see it with a multimeter.

Try cleaning it.

valve

SUCCESS !!!!!!!

Thanks Duncan,

The multimeter doesnt zero in that range but taking one reading from t'other means the primaries are within spec.

There was no blockage / leak in the vacuum hose, but I found that prodding the MAP Sensor and giving the nipple a suck and replacing the hose had a direct correlation to the fault. I went to the scrappers and got a replacement MAP Sensor, since fitting it the engine hasn't missed a beat.

Hope this thread proves usefull to others!