General Non start

[judderbar]

Sounds like this repair has become expensive already. What has been replaced so far?

 

[GrandePunto PL]

Sounds like this is a classic example of "parts cannon method" in action. No systematic approach. Result = not much progress.
This is the case where you should start using oscilloscope to peep the CAN lines (if there is some garbage, noise, proper levels).
Plus endoscope to check the cylinders, valves. Things like that (not just sparkplugs/coils jugglery).

Punto2 "eLearn", check the electrical structure (some modules can spoil each other).
https://aftersales.fiat.com/elearns...h&sectionName=Descrizioni&validityName=1.2 8v

 

[PuntoHowTo]

Oscilloscope is pointless but other than that I agree no systemic approach, apparently everything suggested has been tried, weird symptoms that make no actual sense, ie a misfire that apparently doesn’t change no matter what you disconnect, 2002 Punto, probably not even worth the time or money spent on it so far let alone wasting anymore time on it. Likely better off buying a £500 car off Facebook market place that works.

one of the biggest barriers to solving this is to use proper diagnostic tools.

So far we have established that compression is ok, there is spark and fuel. Apparently the timing is ok so given that the car should run.

I’m not sure what the obsession with the fuel and the fuel tank is all about unless you’ve done something there you’re not telling us about, like filling it with diesel?

Symptoms seem to stay the same or similar no matter what any of us suggest so at this point I’d just wash my hands of it.

If it needs a new ECU then aside from the fact you’re already written the car off with the time and money spent so far, a new ECU is definitely going to be more than the car is worth and apparently nothing else is working despite fuel, spark and compression all being present so I’d be inclined to think a new ECU is not the solution either.

 

[GrandePunto PL]

Real diagnostics with oscilloscope would tell you that sparks are there, but the ignition and combustion process is improper.
Engine is not just "burning fuel" like a stove (continuous flame): the burning process/cycle follows specific waveform.
Same for injectors: maybe you think they "work", but are sticking randomly. Again: current waveform will show that.
Compression is kinda "OK"? Guess what...it's a waveform (you grab it using pressure transducer), not just a number. Intake (vacuum) and exhaust too.
No pressure gauge will tell the intermittent problem with the valves for example (until it's critical, very low or no compression).
Speaking of gauges: where is the classic, old-school vacuum gauge check? Doesn't matter now, if it's useful at this point, (he should) just do it.

PS
This is nothing "new" nor "controversial". Diagnoscopes/oscilloscopes were always out there. Example textbook from the 1970's !

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[curly43]

Sounds like this is a classic example of "parts cannon method" in action. No systematic approach. Result = not much progress.
This is the case where you should start using oscilloscope to peep the CAN lines (if there is some garbage, noise, proper levels).
Plus endoscope to check the cylinders, valves. Things like that (not just sparkplugs/coils jugglery).

Punto2 "eLearn", check the electrical structure (some modules can spoil each other).
https://aftersales.fiat.com/elearnsections/main.aspx?nodeID=3118746&languageID=2&markID=1&modelID=2000003&valID=2000308&prodID=2003013&modelName=Fiat - 188 - Punto Classic&langDesc=English&sectionName=Descrizioni&validityName=1.2 8v

Ok so how do we check the can lines

 

[curly43]

Here is me endoscope pics

 

[curly43]

Sounds like this is a classic example of "parts cannon method" in action. No systematic approach. Result = not much progress.
This is the case where you should start using oscilloscope to peep the CAN lines (if there is some garbage, noise, proper levels).
Plus endoscope to check the cylinders, valves. Things like that (not just sparkplugs/coils jugglery).

Punto2 "eLearn", check the electrical structure (some modules can spoil each other).
https://aftersales.fiat.com/elearnsections/main.aspx?nodeID=3118746&languageID=2&markID=1&modelID=2000003&valID=2000308&prodID=2003013&modelName=Fiat - 188 - Punto Classic&langDesc=English&sectionName=Descrizioni&validityName=1.2 8v

Link don’t work

 

[curly43]

Did you compare dry, then wet?

No

 

[PuntoHowTo]

Real diagnostics with oscilloscope would tell you that sparks are there, but the ignition and combustion process is improper.
Engine is not just "burning fuel" like a stove (continuous flame): the burning process/cycle follows specific waveform.
Same for injectors: maybe you think they "work", but are sticking randomly. Again: current waveform will show that.
Compression is kinda "OK"? Guess what...it's a waveform (you grab it using pressure transducer), not just a number. Intake (vacuum) and exhaust too.
No pressure gauge will tell the intermittent problem with the valves for example (until it's critical, very low or no compression).
Speaking of gauges: where is the classic, old-school vacuum gauge check? Doesn't matter now, if it's useful at this point, (he should) just do it.

PS
This is nothing "new" nor "controversial". Diagnoscopes/oscilloscopes were always out there. Example textbook from the 1970's

I can tell a proper spark is there with a calibrated Eyeball 1.0

I can used my hearomatic ears to tell me if there is propper combustion.

I can use a £20 timing gun if I’m really inclined to check that the spark plugs are firing at the right time, and I can use a plastic bottle and a watch to tell me if there is any issues with fuel delivery between one cylinder and another.

Decent pressure transducers are not cheap, a proper good quality oscilloscope is not cheap, you can’t read the can lines on an oscilloscope…. Well you can if you have a high enough sample rate you can literally watch the binary going back and forth but that doesn’t tell you where it came from or what it says. But I can read all that information with something like MES, so why bother? Oh and you’re assuming that the person even knows how to use one as the vast majority of people wouldn’t even know what an oscilloscope even is.

We are talking about a a 2002 fiat Punto which is fairly worthless in the UK, you can go and buy another road worthy one for less than the price of all the kit you’re proposing to use, and weigh in the dead car for a hundred quid or so with the scrap man. Looking on Facebook market place right now is a running and driving 2005 Mk2b for £350 and a 2007 Grande for £400 both within 20 miles of where I live. Going further a field I found a 2008 grande ready to go with MOT for £200

No lay person needs an oscilloscope, and it is never a useful suggestion especially on a non professionals forum.

By all means feel free to spend your days playing with one, but it’s not worth the time spent on a car that costs less than a couple of days work to even those on a minimum wage.

 

[curly43]

I can tell a proper spark is there with a calibrated Eyeball 1.0

I can used my hearomatic ears to tell me if there is propper combustion.

I can use a £20 timing gun if I’m really inclined to check that the spark plugs are firing at the right time, and I can use a plastic bottle and a watch to tell me if there is any issues with fuel delivery between one cylinder and another.

Decent pressure transducers are not cheap, a proper good quality oscilloscope is not cheap, you can’t read the can lines on an oscilloscope…. Well you can if you have a high enough sample rate you can literally watch the binary going back and forth but that doesn’t tell you where it came from or what it says. But I can read all that information with something like MES, so why bother? Oh and you’re assuming that the person even knows how to use one as the vast majority of people wouldn’t even know what an oscilloscope even is.

We are talking about a a 2002 fiat Punto which is fairly worthless in the UK, you can go and buy another road worthy one for less than the price of all the kit you’re proposing to use, and weigh in the dead car for a hundred quid or so with the scrap man. Looking on Facebook market place right now is a running and driving 2005 Mk2b for £350 and a 2007 Grande for £400 both within 20 miles of where I live. Going further a field I found a 2008 grande ready to go with MOT for £200

No lay person needs an oscilloscope, and it is never a useful suggestion especially on a non professionals forum.

By all means feel free to spend your days playing with one, but it’s not worth the time spent on a car that costs less than a couple of days work to even those on a minimum wage.

Cheers boy but I don’t give up and will get it going no matter what, I’ve had the car from new + I’m intrigued to what the fault is.

 

[curly43]

Sounds like this repair has become expensive already. What has been replaced so far?

Plugs
Leads
Coils
£100 worth of fuel
Map sensor
Fuel pump
4 x injectors + fuel rail
Purge valve
Ecu
Ref: ecu it is a plug and play although has the same multi misfire it has cured the throttle response as my original ecu you had to blip the throttle several times to get it to rev up ,now this ecu the throttle responds normally

 

[PuntoHowTo]

Cheers boy but I don’t give up and will get it going no matter what, I’ve had the car from new + I’m intrigued to what the fault is.

You sure about that?

I mean you’ve done a dry compression test with a 34% difference between cylinders and you’ve not even done a wet test…..

If there is something fundamentally wrong with the engine, swapping sensors and playing with ancillaries is going to be fairly pointless.

 

[curly43]

I did a rad pressure test and put the endoscope in the bores and found nothing,lost 1/2 psi in 3/4 of an hour

 

[judderbar]

Did the above but each cylinder has the same note/ rpm change,did it with plug leads at both ends then at the injector leads, still the same , so can not verify what cylinder or cylinders the misfire is on as they all are the same.

How can it be possible when you prevent a cylinder from producing power you cannot tell which cylinder is contributing mostly to the problem?

As you say they are all the same. How can that be possible?

Are you certain the ignition timing and the valve timing are correct? Have you had the crankshaft sensor pulley wheel off? The hole in the pulley must align with blob on the metal you are bolting to. With my eyes I had to put white paint on the blob to make sure it is correct.

What about the valve timing? What method did you use?

And how about some pictures and a video of you trying to start this engine so we can hear what it sounds like?

 

[GrandePunto PL]

Plugs
Leads
Coils
£100 worth of fuel
Map sensor
Fuel pump
4 x injectors + fuel rail
Purge valve
Ecu

Moderators, make this thread sticky. This is gonna be a Masterclass - how NOT to "repair" the car. Anti-Guide.
And you, study the "misfire parts cannon" examples: https://www.youtube.com/results?search_query=misfire+parts+cannon
Plus, try all remaining basic tests, like auxiliary belt drop (to see if it's the alternator resisting the engine - bad alternator can stall it).
And don't listen to "old-school" experts above (who can judge the combustion/ignition/injection events just by ear and eye). I'm out.

 

[curly43]

How can it be possible when you prevent a cylinder from producing power you cannot tell which cylinder is contributing mostly to the problem?

As you say they are all the same. How can that be possible?

Are you certain the ignition timing and the valve timing are correct? Have you had the crankshaft sensor pulley wheel off? The hole in the pulley must align with blob on the metal you are bolting to. With my eyes I had to put white paint on the blob to make sure it is correct.

What about the valve timing? What method did you use?

And how about some pictures and a video of you trying to start this engine so we can hear what it sounds like?

Ref: crank pulley all aligned properly as you have said with the little pin.
Ref : valve timing, was one tooth out when I checked very difficult even with mirror to line up cam pulley,she started and drove fine for 2 months till I broke down.I’ve since spent 2 hour double checking and putting it spot on still multi misfire.
Ref: individual cylinders, when I remove leads or injector plugs one at a time the engine rpm drops the same on each one.
Cheers judderbar

 

[curly43]

I suspect the can bus error is not important. I get a U code on my scanner but the car always runs ok

Puntohowto said it could be the Crank sensor is faulty because if the ECU does not know the engine is turning you will get no code. Now you are saying you are getting misfires but you evidently you do not get a misfire code.

So the same thing applies. Check or replace the crank sensor.

Replaced the crank sensor and the cam sensor still multi misfiring

 

[curly43]

Replaced the throttle body housing today , still multi misfiring

 

[Mike1alike]

Fuel pressure is 3 bar and a new Bosch fuel pump.

That could be a problem. On my Punto, same as yours 1.2 8V, the original fuel pump, I have 3.5 bar fuel pressure. I saw discussions about it and it turns out there are on the market fuel pumps that give both 3.5 and 3 bar. So you might have gotten the wrong fuel pump that could be causing you the current problem.

 

[curly43]

That could be a problem. On my Punto, same as yours 1.2 8V, the original fuel pump, I have 3.5 bar fuel pressure. I saw discussions about it and it turns out there are on the market fuel pumps that give both 3.5 and 3 bar. So you might have gotten the wrong fuel pump that could be causing you the current problem.

Food for thought cheers mike