That really was a long struggle. Congrats on your persistance. 
What make of plug, out of interest?
What make of plug, out of interest?
Technical Persistent misfire problem, tried loads - need advice!
- Thread starter ST60SX
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Technical Persistent misfire problem, tried loads - need advice!
It was a Bosch Super 4. These are ones with the 4 ground terminals so you supposedly don't need to gap them.
I've been thinking about why it went wrong. I presume the resistor has been breaking down for a while. The higher the resistance the longer it takes for the spark to complete. I guess the fuel has been getting ignited, just not in the most efficient manner. If this has been happening for a while I think I'm lucky it didn't blow a hole in a piston.
I've been thinking about why it went wrong. I presume the resistor has been breaking down for a while. The higher the resistance the longer it takes for the spark to complete. I guess the fuel has been getting ignited, just not in the most efficient manner. If this has been happening for a while I think I'm lucky it didn't blow a hole in a piston.
Phew! If you'd said NGK I'd have had to appologise to a lot of people!
I've always found NGK to be utterly reliable (and cheap), and only my 450 Desmo Ducati preferred anything else -- for some reason it ran best on the Pink Lodge plugs.
ST60 I envy you. My spark plugs are 2 weeks old and at the time the problem would appear from time to time.Since then it is constant.My problem is not the plugs....i think. I was just advised over the phone(overseas again) that it might be the fuel pump.Two days ago the local garage insisted that it is injector 1 and 4....Got them changed.Same story.So tomorrow will attemped to figure out if my fuel pump is bad.Please, advise an easy way to check and where to find(underneath back seats?).ST60 I believe it is the air intake sensor I was talking about. I meant when taken off , it looks like half a pen with a el. bit in it.Was told to take and proper wash it.Anyway, guys help with the fuel pump!
The fuel pump is under the back seats, yeah. Three screws hold a silver cover plate. The pump has two pipes, flow and return.
Before fiddling with the pump run the car and remove the fuel pump fuse while its running (the fuse is under the cover above and to the right of the airbox). Also remove the filler cap to repressurise the tank. This should alleviate pressure in the system.
Remove the two pipes from top of the pump, they are held on by clips and should pull off once the clips have been move upwards.
The pump is held into the tank with a large plastic ring. It will be tight.
Good luck.
Before fiddling with the pump run the car and remove the fuel pump fuse while its running (the fuse is under the cover above and to the right of the airbox). Also remove the filler cap to repressurise the tank. This should alleviate pressure in the system.
Remove the two pipes from top of the pump, they are held on by clips and should pull off once the clips have been move upwards.
The pump is held into the tank with a large plastic ring. It will be tight.
Good luck.
On the Mk2 there is a valve on the fuel rail to which a guage can be attached.
You can check the injectors simply by taking them out one at a time. (Wear goggles, no smoking). They are pulsed on the earth side. Worthwhile checking the connectors and wiring visually.
Personally, I doubt it's the fuel pump. They're very reliable. Wiring to it, perhaps............
You can check the injectors simply by taking them out one at a time. (Wear goggles, no smoking). They are pulsed on the earth side. Worthwhile checking the connectors and wiring visually.
Personally, I doubt it's the fuel pump. They're very reliable. Wiring to it, perhaps............
Pogo
New member
I had the same prob a few years back as you and it turned out to be the C02 sensor, got a new one @ £26 replaced it myself and bingo no more probs.
Worth a try!
Billy
Worth a try!
Billy
The fuel pump looked good.Did not check the pressure though . Had a ten mile drive and on a couple of occasions "it" cleared and the car went back to its best. Unfortunaly there is no patern whatsoever when and why the car is going to stutter.
Sprayed clean all the sesors I could see . Just read about that Lambda sensor in the latest thread.......It is crazy to replace every part I hear about though, isn't it?
Friend keeps saying...It is a lose wire(plug) somewhere and the trick is to find it.
Crazy machines
Sprayed clean all the sesors I could see . Just read about that Lambda sensor in the latest thread.......It is crazy to replace every part I hear about though, isn't it?
Friend keeps saying...It is a lose wire(plug) somewhere and the trick is to find it.
Crazy machines
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Inconsistant faults are the worst, always are, always will be
Forwell could be a Shafing wire or a Sloppy plug somewhere causing a lack of power
Lamba sensors are sensors on the exhaust/manifold/manicat
ziggy
Forwell could be a Shafing wire or a Sloppy plug somewhere causing a lack of power
Lamba sensors are sensors on the exhaust/manifold/manicat
ziggy
Pogo
New member
It the sensor on the exhaust down pipe right hand side, it has two wires the are crimp on. Black and white i think.
I took the car to a garage and they done fault finding check on it and quoted me £100 to fix it!
No thank you! But on the print out they highlighted the CO2 sensor as the problem, and the rest is history!
Billy
Ziggy you are Bang on man. It is dodgy plugs or wires 100 %, the problem is they are bustard to find.I tried , changed , touched everything. It works as a clock and then it doesn't. You go to a garage and they are ECU , Coils......there aren't good mechanics nowadays, you agree guys?
Hi Guys, back here again after Sat & Sun taking my Punto Apart. Still not fixed, but I believe I am a step closer.
I have checked now everything suggested. At one point on Sunday with my car running "bad" I disconnected my Coil 2 and the car did not change its stutter. So the problem was with that coil. The thing is they tried 2 brand new ones in the garage I went to, as their comp. said coil. So it is defenetley not SPARK PLUGS, LEADS, COILS...AND NOT THE ECU AS I HAVE 2 SPARE ONES.So I am convienced it is the cabels between Coil 2 and the ECU.I should probably mention here that a year ago I had problem with my Steering and was advised that it is either ECU or the pump. I must've unplugged th 5-6 plugs from the ECU 10 times( in the end obviously it turned to be the pump).I now think that I must have damaged one of them plug ....the one that leads to the Coil2 . So, GUYS PLEASE ADVISE ON WHERE DOES THE CABEL FROM THE COIL GO.DOES IT JOIN ANY OTHER CABELS OR DOES IT GO TO THE ECU ON ITS OWN? CAN I GET A NEW ONE AND JUST PLUG IT IN THE ECU AND COIL ON THE OTHER SIDE....AND LEAVE THE DEAD ONE WHERE IT IS?Will attempted the opperation the coming Saturday, so please advise.
Hope my BAttle here helps someone.
I have checked now everything suggested. At one point on Sunday with my car running "bad" I disconnected my Coil 2 and the car did not change its stutter. So the problem was with that coil. The thing is they tried 2 brand new ones in the garage I went to, as their comp. said coil. So it is defenetley not SPARK PLUGS, LEADS, COILS...AND NOT THE ECU AS I HAVE 2 SPARE ONES.So I am convienced it is the cabels between Coil 2 and the ECU.I should probably mention here that a year ago I had problem with my Steering and was advised that it is either ECU or the pump. I must've unplugged th 5-6 plugs from the ECU 10 times( in the end obviously it turned to be the pump).I now think that I must have damaged one of them plug ....the one that leads to the Coil2 . So, GUYS PLEASE ADVISE ON WHERE DOES THE CABEL FROM THE COIL GO.DOES IT JOIN ANY OTHER CABELS OR DOES IT GO TO THE ECU ON ITS OWN? CAN I GET A NEW ONE AND JUST PLUG IT IN THE ECU AND COIL ON THE OTHER SIDE....AND LEAVE THE DEAD ONE WHERE IT IS?Will attempted the opperation the coming Saturday, so please advise.
Hope my BAttle here helps someone.
dumbledore
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Unplug the ECU and the coil2 wire and see if you have connectivity between the two. You will need to work out the correct connection. If the connectivity looks OK then the ECU may need attention. Most probably some dry joint there needs re-soldering. Have a look and let us know if this fixes it. Saying that I have also a slight intermittent misfire like you describe especially on a dump morning with a cold engine and half throttle. Also I think my engine and age of the car is similar to yours. 1999, MK1, 1.2 8V.
I really think it is the wiring, as I have 2 spare ECU. It must be it.If not I have to give up. Right, I will greatly appreciate any help with the wiring.Where does the cable from the coil lead to?Does it join the cable from coil1 or does it go to the ECU on its own( If it goes to the ECU at all)?Does it join anything else on the way?Anyone with Elecrtical(wiring)Diagram?Will be great help, all the wiring as you know goes in them curly hoses , so if you do not know what goes whrere........
Will attempt on Saturday and update after.
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It might be easier to get a spare loom from the breakers. A good look with magnifying glass should show any dirty contacts.
The ECU itself can be opened up and look for dry solder joints on the coil driver transistors with the magnifying glass.
If the engine is started with both plugs disconnected on one spark pair the back emf can blow the ECU coil driver transistors. Spark energy is normally drained down by the plugs, but when both are disconnected, that energy has nowhere to go.
The ECU itself can be opened up and look for dry solder joints on the coil driver transistors with the magnifying glass.
If the engine is started with both plugs disconnected on one spark pair the back emf can blow the ECU coil driver transistors. Spark energy is normally drained down by the plugs, but when both are disconnected, that energy has nowhere to go.
