Technical 1.6 Cabrio

Currently reading:
Technical 1.6 Cabrio

Joined
Oct 13, 2009
Messages
430
Points
148
Those of you who have been on this forum for a while may recall the problems I had with my Cabrio a couple of years ago which turned out to be the connector for the cam sensor. At that time I had the ECU tested and passed fit. Being a 1.6 the ECU is tucked safely behind the centre console rather than in the engine compartment and with no leaks in the heater matrix remains dry.


I thought the problem had returned, but I have since ruled it out and can confirm that the sensor itself is ok. A couple of weeks ago, the car would not fire instantly and would turn over a couple of times before firing and when warm would take even longer to fire. Once running, it was fine. It now will not start at all, or only very rarely. I have checked all the wiring and the ignition and fuel relays, which appear to be working, but there is no electronic pulse at the injectors. Yesterday it started and ran smoothly, so after a short while I switched it off and tried to start it again immediately, but nothing. Being a 1994 model it doesn't have an immobiliser.


I have concluded that I must have a failing component somewhere in the ignition, but what and where?
 
Today's update.


Tried the car this morning and it started and ran smoothly. Tried it again a bit later and it started normally. Switched it off and on again and it ran well. A little later I started it and ran it for about 20 minutes. Switched it off and on again and it refused to start.
 
I have the same car
Does your EML comes on when driving?
Fuel pump working only at cranking the ignition, unlike the 60/75 models.

Mine won't fire instantly as well when hot, I keep cranking it for 2-3 seconds but it always start.
I had a faulty crankshaft sensor, but it made me problems when I was driving and not only at start.

I'd first check fuel pressure, fuel regulator, all wiring that goes to the coil, sensors etc.
is voltage ok?
 
No, the EML does not come on. All wiring has been checked on the ignition circuit, but I do wonder if it is fuel related. If it is fuel related would I still have no electrical pulse at the injectors.
Further update today, it is working perfectly. Starts on the button whether cold or hot! Dare I take it out on the open road?
 
not very familiar with the 1.6 system, but normally lack of fuel/fuel pressure would not stop the injectors firing - not unless there is somekind of pressure sensor for the fuel the ecu can see - which on a fiat of this age i kinda doubt really..

Wiring diagram would be super helpful to work out how it all works for sure but from messing with other cars generally the ecu is switching the earth on and off to pulse injectors so it maybe a plan to check for power at the injector wiring - this kinda stuff is always miles harder when the fault is intermittent... But as you say there is no pulse at the injector i'm thinking it has to be either a fault with the wiring for them or the sensor that triggers the ecu to fire them (usually a crank/TDC sensor, does the 1.6 have a crank sensor as well as the cam one?) or its wiring. That is where i would start at least
 
not very familiar with the 1.6 system, but normally lack of fuel/fuel pressure would not stop the injectors firing - not unless there is somekind of pressure sensor for the fuel the ecu can see - which on a fiat of this age i kinda doubt really..

Wiring diagram would be super helpful to work out how it all works for sure but from messing with other cars generally the ecu is switching the earth on and off to pulse injectors so it maybe a plan to check for power at the injector wiring - this kinda stuff is always miles harder when the fault is intermittent... But as you say there is no pulse at the injector i'm thinking it has to be either a fault with the wiring for them or the sensor that triggers the ecu to fire them (usually a crank/TDC sensor, does the 1.6 have a crank sensor as well as the cam one?) or its wiring. That is where i would start at least
 
Thank you Blu, you have confirmed my thinking about the fuel system. The 1.6 only has a crank sensor and I know that is fine. I was using an aftermarket one, but now have an original equipment Fiat sensor which has been tested.
The Porter guide includes the 1.6, which Haynes doesn't, so I have been able to identify and check the wiring and all connections.
I have looked at the Tempra section of the Forum, as they used the same 1.6 engine, but not found the same problem, although the two relays which sit next to one another in the engine bay serving ignition and fuel circuits, have been known to cause problems. If I can identify the correct relay type, it may be worth replacing them both.
 
Car had been running ok for a while if I started it regularly. However, having sat in the garage for a couple of weeks it now refuses to start. I was able to confirm that the fuel pump control relay was not working. However, swapping it with the ignition relay proved that the relay was not at fault. Tested the live feed to the relay and that is fine, so tested the negative side. This is where the fault appears to lie - there is a black and white wire which runs from the negative side of the relay to the ECU rather than to earth as on the ignition circuit. I tested the wire for continuity and it is fine. Having previously sent the ECU away for testing and getting a clean bill of health (it is a GM unit), I can only assume there is an issue somewhere between the ECU and the fuel pump which is preventing the ECU from completing the circuit.
Does this make any sense to anyone out there?
 
Operation "let's smarten up Bertie" has commenced. The main problem is lacquer fade and peel around the windscreen and bonnet. Today I tackled the windscreen surround. Unfortunately, I didn't take any 'before' photos, but I'm sure most of you a familiar with the appearance of lacquer fade. I removed the lacquer and rubbed down the old paint, applied new paint and lacquer and lightly flatted back. I will leave it a week or so before polishing, but am quite pleased with the result so far. Next job is the bonnet!

Bertie%20windscreen%20002_zpskrvbprrp.jpg


Bertie%20windscreen%20001_zpsbhfgyarc.jpg
 
Having successfully stopped oil leaking from the rocker cover with a new gasket, it was time to turn my attention to the sump gasket (having a new driveway laid in September - do not want oil drips).
Removal proved nice and simple and the sump came away easily. However, removing the old gasket was a case of a little at a time, as it was stuck fast to the sump cover. Eventually I removed every trace of the old gasket and cleaned the inside of the sump. I am pleased to report that there was no trace of any sludge in the sump, just clean oil, so a wipe was all that was required. I have noticed that newer Puntos suffer from rusty sump covers. No such problem here.
New gasket fitted (with a thin layer of silicone gasket sealant) and gently, but lightly tightened. We now have a leak free Punto.
 
After months of reliability, I went to get fish & chips this evening, stopped at the cash machine at our local BP garage, got back in the car and it would not fire. Walked home, went to chippy in other car then watched F1 Grand Prix. Just been back to the car and it fired up instantly and drove home! It will probably be fine now for months, but I know it will do this again and my wife is afraid to trust it.
banghead.gif
 
Following the episode at the garage in September, the car has been running fine, that is until last week. The car had been parked on the driveway for a few days and when I tried to start it, it would not fire. However, one morning I tried it and it fired, but in the evening nothing again. Over the weekend I tested every connection I could find in the ignition circuit, but all seemed fine, but still the car wouldn't start.


This evening I tried the car and it fired and ran perfectly. I have tried it twice more and it has fired on each occasion. The difference today is that it is about -3 degrees outside and the car is covered in frost, whereas prior to today it has been largely damp. Could the problem be dampness related?


I also suspect that the crankshaft connector may benefit from replacement. Does anyone know if such a connector is available and where I can obtain one?
 
Well if you think its damp related I'd start with checking spark?
Since the 1.6 doesn't fuel prime when mine has been sat for a few days it does take a few extra seconds of turning it over for it to fire up, lift up the rear seat bases, get someone to turn it over and listen to the fuel pump, is it making noise? Obviously you'd have to try this when it decides not to start...
 
all the connectors are standard style weatherproof connectors, i can't remember exactly what type of connector that one has but you basically need some crimping tools and the correct connectors - they don't really need to be the same just have the right number of pins but getting the same type is beneficial if you come to replace a sensor one day.

Just stick waterproof connector in ebay and loads come up, like this one for example http://www.ebay.co.uk/itm/1-2-3-4-5...ors-Set-Superseal-Pair-Car-Boat-/251994363428
There is lots of videos on youtube about fitting these kinds of connector so just have a search ;)
 
This post contains affiliate links which may earn a commission at no additional cost to you.
I don't like admitting defeat, but I am close. After a couple of days working perfectly, today it wouldn't fire. Not to worry, I was going to replace the connector for the crank sensor anyway. Job done (soldered rather than crimped), but no joy. Tested the crank sensor itself ( I have a spare), but it is fine. Tested ignition and fuel relays, both are working, but no joy. Replaced coil pack - no joy.


I cleaned the fuses in the engine bay (under the screw down black cover), but it made no difference. I removed the fuse on the ignition circuit and put a multimeter across the contacts while my wife cranked the engine. Result was no reading whatsoever, so it looks like I have a dead ignition circuit, but why?
banghead.gif



Being a 94 car, it pre-dates the red key and immobiliser, so I can't blame that. I have previously sent the ECU away for testing, but it came back with a clean bill of health. I have checked that the heater matrix is not leaking onto the ECU, but all is well there. Could there be a poor earth somewhere?
 
Went out to the car, covered in frost this morning to take a look at the ignition switch. Before I did anything I tried the key in the ignition. It fired immediately and ran beautifully. How am I going to find out what is wrong with it if it randomly works?
confused.gif



While the engine was running I fiddled with each electrical connection to see if it faltered or stopped, including the ignition switch, but everything worked sweetly. I drove it into the garage, then switched off the engine and started it again immediately, but nothing. It turned over as normal, but wouldn't fire. I've since been back out and it fired up perfectly.
 
Intermittent faults are the worst!!
I think, if i have understood all the posts correctly, the ignition switch is a red herring. Sounds like when its not started it has at least turned over, which would rule out the ignition switch itself and points towards something fuel or spark related - I suggest next time it does it to keep letting it turn over for a while and then whipping a plug out to see if its wet and ergo you have fuel, you will then at least be able to rule out a fuel issue. Bit harder to test spark with it being intermittent, of course if there is no fuel it could be both still but you can fix fuel and if it still does it there is an issue with spark as well.
I kinda suspect a dodgy earth on the engine loom myself, may be worth just going through and cleaning them all thoroughly and ensuring good contact - on the fire engined cars what you describe is classic earth issue on the body to gearbox ground lead, not sure where it is or if there is multiple earths on the 1.6 - the test is usually to put a jump lead from battery -ve to somewhere on the engine block or gearbox but with it being intermittent thats not much help really.
 
Last edited:
Thank you for that advice, it makes sense. I have tested the electrics using a noid light which connects to a fuel injector. This has confirmed that there is no electrical pulse to the injector when it won't start. Next time I have the problem I will try the jump lead earth trick.
 
I take it the EML isn't coming on when it isn't starting? Bit weird if you aren't getting power to the injectors when it won't start. Not sure if this a good idea with a fuel injected engine but something I used to do with my carb'd Panda was spray some starting fluid (or WD40 if its all I had to hand....) in the intake, I assume this wouldn't hurt an injection engine anymore than a carbed one just for a few seconds. You could try that next time it won't start, if you spray some in and it coughs a bit then you'll know its got spark and its fuel related.
 
Back
Top