Technical Engine management light, engine running poorly...

[dumbledore]

Was working on adjusting the handbrake cable and when I decided to give my punto mk1, 1.2 8V, a test drive the engine started poorly and the managment light stayed on. So something went wrong suddenly. What can die like that without warning?

I understand there is a diagnostic socket what do I need to read the codes?

 

[fingers99]

Mk1s have a different system to modern OBD2 compliant cars.

An alternative is to measure the values of the sensors with a multimeter.

The Mk1 uses the same sensors as the early Seicento: all the nominal values are in ther Seicento Technical Manual in the Downloads section (towards the front of the manual).

But -- if running rough -- the usual culprits are the ignition leads. Do the start it at night, bonnet open, air filter off, look for blue flashes trick.

 

[dumbledore]

I think I may have fixed it. I disconnect the battery, unplugged the ECU and sprayed some WD40 on the connector, put it back. Started fine end engine management light went away. So hopefully is OK.
However, the initial work I done on the rear brakes changing the handbrake cable is not right. I went for a test drive, and while on the move I hear a knocking sounds from the rear wheel I have done the work. I can also feel the knock through the handbrake as well. I am puzzled now. I will have to dismantle the brakes and see what is wrong. Also the handbrake acrion is not effective on this wheel too so may be this has something to do with my problem. Before replacing the cable there was no noise so I messed something up for sure.

 

[fingers99]

If you're reluctant to buy the Haynes, there are bootleg copies out there on most of the file sharing and peer to peer networks.

 

[dumbledore]

If you're reluctant to buy the Haynes, there are bootleg copies out there on most of the file sharing and peer to peer networks.

I have the Haynes manual which I study normally. This is how I figured out that there is diagnostic socket to read the codes. But now my immediate problem is the knock from the rear wheel that started after replacing the handbrake cable. Used Haynes for guidence but something went wrong.

 

[dumbledore]

Managed to find the cause of the noise from the rear. Ended up to be the cables. When I pull the handbrake cable as hard as I could in order to check one of the wheel not working the cables jumped out of the fixing bracket. As a result they were touching the wheel and the cables were bunging on the underside while driving. Put then back in the bracket and with a cable tie make sure they don'r come out again. So this is fixed. Now how do I fix the handbrake, I will start another thread for that as this is well off topic now.

 

[dumbledore]

Original topic still on. Test drove my car today and after about 10 miles luckily near my home the engine light came on. Also noticed some dodgy burning smell when this happened. Managed to get it home with the engine light going off a couple of times. At home I decided to do some more investigations. I started the engine and was idling poorly with the engine shaking. This indicated that it was running on less then 4 cylinders. So decided to measure the coils primary resistance and one was showing 0.8ohm and the other 1.6ohms so clearly not the same. Decided to go and get some new ones and have a go.

I now fitted the new ones and seems fine. Done another 10 miles but the engine management light stayed off.

Now the symtoms I seen and the dodgy smell do point to at atleast one of coils not working correctly as the smell may be unburned fuel. However, the smell is not typical of unburned fuel, but the CAT may alter the smell in a way I am not familiar?

 

[fingers99]

The cat is very hot -- will try to burn the fuel.

 

[dumbledore]

Yes, this was my thought. However, the way is burning it is strange as it make a distintive burning smell. It definetelly does no smell like unburned fuel.
I tried the car a few more time and it seems to behave. However, I measured now the old coils out of the car and at normal temperature and they appear OK and measure the same. So not sure if they were the cause of my fault but time will show.

 

[fingers99]

They do seem to break down when hot.

Smell is probably just the cat getting super hot.

 

[blu73]

you won't get unburt fuel smell from the back, as soon as the CAT warms up its hot enough to ignite petrol and so any petrol down the exhaust burns off in the CAT, this is how fuel damages CATs - they get so hot they melt if petrol is going down the exhaust for prolonged period.

 

[dumbledore]

However, I measured now the old coils out of the car and at normal temperature and they appear OK and measure the same. So not sure if they were the cause of my fault but time will show.

Well I used my car this week for my usual commute and had no issues anymore. So I can only assume the coil (at least one of them) had it. Even they measure OK off the car in the car when things warm up old coils internal wiring may could be iffy causing the problems I had. So hopefully this was it.

 

[Elxpunto90]

Have you checked to see if cable is catching the rear wheel rim at the back you might need to fiddle with cable where it anchors to the chassis