My daughter's Punto Mia (02) died the other day and had to be towed home. The guy who towed it thought it was the timing belt - well luckily it wasn't. It turns over, but doesn't start - no life at all. I attached an ELM327 to the diagnostic port and got error codes P0170 (Fuel Trim) and P1325. Anyone got any useful ideas before I take it down to the local Fiat dealer?
Currently reading:
Technical Dead Punto Mia
I dont know about the error code, but if the Mia is an 8v then its a 'safe' engine. Ie if the timing belt goes you just slap a new one on and no damage is done.
Helped me sleep better a night (when approaching 60k and weeks away from payday!)
Helped me sleep better a night (when approaching 60k and weeks away from payday!)
Lowtechguy
Member
The seond one is "Knock Sensor Circuit Low Input "
Fuel trim is the ecu's ability to adjust the fueling.
So first I would delete the codes and try to restart, if it does (which it should) I would look at the live data fuel trims - possible both lambdas are broken.
I would also check the tail pipe for evidence of cat break down.
The knock sensor - I have never heard of one breaking so it is possible it is either unplugged somehow or the wiring is damaged.
This is part of the loom so if the wiring does look damaged (the knock sensor is bolted to the block near the alternator bracket) I would replace the loom and knock sensor to be sure.
Fuel trim is the ecu's ability to adjust the fueling.
So first I would delete the codes and try to restart, if it does (which it should) I would look at the live data fuel trims - possible both lambdas are broken.
I would also check the tail pipe for evidence of cat break down.
The knock sensor - I have never heard of one breaking so it is possible it is either unplugged somehow or the wiring is damaged.
This is part of the loom so if the wiring does look damaged (the knock sensor is bolted to the block near the alternator bracket) I would replace the loom and knock sensor to be sure.
D4nny8oy
Established member
Firstly lets end the myth- deleting errors won't fix anything! This is the recovery driver's usual thought which then hinders the Fiat tech's diagnosis as all the fault data is lost.:bang:
Faulty lambda's won't stop an engine running. It will default to a limited operating strategy to get you home/ to a garage. It will still start!:bang:
A faulty knock sensor won't stop it running. It adjusts ignition timing to run as lean and fuel efficient as possible. If it fails- limp home mode! It's also not hard-wired into the loom!:bang:
Anyway, rant over. Check the usual things-
Is there fuel in the tank? Sounds silly but it's happened before!
Does the fuel pump prime? If not has the inertia switch been triggered?
Does it turn over as normal? Too fast- no compression (cambelt ok? you sure?) Too slow- bad battery/earth/etc
Is there a spark? (remove a plug lead & spark plug and rest on engine and crank)
A common fault is a failed crank (RPM) sensor- no spark, no injection. Only way to be sure is to check RPM and air pressure readings whilst cranking.
Lowtechguy
Member
Sorry for not explaining myself properly then.
I did not attempt to say deleting a code fixes anything, however if those codes are preventing him to start it is something to try, he knows the codes so can advise someone else if someone else is working on the car.
The knock sensor on the mk2 I can assure you is part of the loom I have removed 2 looms when I did an engine swap within the last 3 weeks.
I would be surprised if a broken pair of lambdas would prevent starting but shagged loom wiring would...
Thanks for covering the other basics though.
I did not attempt to say deleting a code fixes anything, however if those codes are preventing him to start it is something to try, he knows the codes so can advise someone else if someone else is working on the car.
The knock sensor on the mk2 I can assure you is part of the loom I have removed 2 looms when I did an engine swap within the last 3 weeks.
I would be surprised if a broken pair of lambdas would prevent starting but shagged loom wiring would...
Thanks for covering the other basics though.
D4nny8oy
Established member
These are your exact words!
A stored fault doesn't prevent starting- faulty sensor/ earth/ fuel/ timing does. Knowing the errors is nothing, as the ECU records the exact circumstances the fault occured under, ie Engine temp, RPM, Air temp, Pressure, and more importantly WHEN. Those two faults may be months old and have no relevance to what's happening now, which a Fiat tech could realise, thus saving time and money testing Lambda's/ Knock sensors/ etc.
This is a Punto Mk2 knock sensor- notice the lack of a wiring harness?
Yes they're a b*****d to disconnect sometimes, it's easier to unbolt it first then get both hands in there to separate the large grey connector from the sensor.
Lowtechguy
Member
These are your exact words!
A stored fault doesn't prevent starting- faulty sensor/ earth/ fuel/ timing does. Knowing the errors is nothing, as the ECU records the exact circumstances the fault occured under, ie Engine temp, RPM, Air temp, Pressure, and more importantly WHEN. Those two faults may be months old and have no relevance to what's happening now, which a Fiat tech could realise, thus saving time and money testing Lambda's/ Knock sensors/ etc.
This is a Punto Mk2 knock sensor- notice the lack of a wiring harness?
Yes they're a b*****d to disconnect sometimes, it's easier to unbolt it first then get both hands in there to separate the large grey connector from the sensor.
I know full well what it looks like thank you, but you do plug into the loom and if the two wires are damaged coming from the sensor there maybe a problem wouldnt there.
I know what I typed also, I can read dispite my spelling sometimes, however such codes "MAY" prevent him from starting, I have not come across such codes but I know that if the ecu thinks there is a "major" problem it wont start to prevent damage, for example disconnect the throttle position sensor, it will log a fault and wont start.
However this thread is becoming counter productive so I leave it to you to help the guy if he still wants help.
D4nny8oy
Established member
Don't get me wrong, I'm all for people helping other people, and I'm not saying you don't have a clue or that I have all the answers, just that what you've been saying doesn't quite add up, whether it's how you've worded things or what info you've heard.
Saying a knock sensor is part of the loom is like saying every engine sensor is part of the loom. If he was to order an engine loom, it wouldn't come with the knock sensor attached. Yes, a faulty engine harness could account for a non-start, but it would take more than a lambda/ knock sensor wiring fault to prevent so.
Regarding the error codes- If any were serious enough to possibly cause engine damage the programming is clever enough to ignore the sensor giving false readings, and substitutes a predefined figure into the map to provide the 'limp home mode' when it needs to. You could disconnect every sensor on the loom, crank the engine to store multiple serious errors, reconnect everything, and the next turn of the key it will start ok.
I really hope the guy finds the cause (it's been 3 days now ) and gets back on the road.
Saying a knock sensor is part of the loom is like saying every engine sensor is part of the loom. If he was to order an engine loom, it wouldn't come with the knock sensor attached. Yes, a faulty engine harness could account for a non-start, but it would take more than a lambda/ knock sensor wiring fault to prevent so.
Regarding the error codes- If any were serious enough to possibly cause engine damage the programming is clever enough to ignore the sensor giving false readings, and substitutes a predefined figure into the map to provide the 'limp home mode' when it needs to. You could disconnect every sensor on the loom, crank the engine to store multiple serious errors, reconnect everything, and the next turn of the key it will start ok.
I really hope the guy finds the cause (it's been 3 days now
) and gets back on the road.Lowtechguy
Member
Don't get me wrong, I'm all for people helping other people, and I'm not saying you don't have a clue or that I have all the answers, just that what you've been saying doesn't quite add up, whether it's how you've worded things or what info you've heard.
Saying a knock sensor is part of the loom is like saying every engine sensor is part of the loom. If he was to order an engine loom, it wouldn't come with the knock sensor attached. Yes, a faulty engine harness could account for a non-start, but it would take more than a lambda/ knock sensor wiring fault to prevent so.
Regarding the error codes- If any were serious enough to possibly cause engine damage the programming is clever enough to ignore the sensor giving false readings, and substitutes a predefined figure into the map to provide the 'limp home mode' when it needs to. You could disconnect every sensor on the loom, crank the engine to store multiple serious errors, reconnect everything, and the next turn of the key it will start ok.
I really hope the guy finds the cause (it's been 3 days now
Hmm, that really helps the guy.
Nice post.
I stand by my previous comments which so far you have not prooved to be wrong.
There's been an lot of banter here and I'm grateful for all the suggestions. Anyhow here's the prognosis - let's hope this stands as a warning to others:
Clearing the engine codes didn't do anything for me and I agree that this can certainly hinder diagnosis by a dealer - so I printed them out before deleteing.
I ascertained that the fuel system was OK (at least there was pressure in the system), that the timing belt was OK and that as far as I could tell the electrics were OK. So it seemed that there was something more serious . . .
Anyhow, I towed it down to my local Fiat dealer who was very helpful and agreed to diagnose the problem. There was virtually no compression and after removing the head it was obvious that the gasket had blown, the engine lost all its coolant and had basically melted! The inlet manifold was damaged, the head was warped and a couple of pistons partially melted. So I've ordered a reconditioned engine with 12 months warranty (not from Fiat as it would have cost more than the car was worth).
Why did this all happen - the 02 Punto Mia that my daughter was driving doesn't have a temperature gauge and she had no clue that it was overheating. Add to this that it was on the motorway - sudden death of an engine.
Clearing the engine codes didn't do anything for me and I agree that this can certainly hinder diagnosis by a dealer - so I printed them out before deleteing.
I ascertained that the fuel system was OK (at least there was pressure in the system), that the timing belt was OK and that as far as I could tell the electrics were OK. So it seemed that there was something more serious . . .
Anyhow, I towed it down to my local Fiat dealer who was very helpful and agreed to diagnose the problem. There was virtually no compression and after removing the head it was obvious that the gasket had blown, the engine lost all its coolant and had basically melted! The inlet manifold was damaged, the head was warped and a couple of pistons partially melted. So I've ordered a reconditioned engine with 12 months warranty (not from Fiat as it would have cost more than the car was worth).
Why did this all happen - the 02 Punto Mia that my daughter was driving doesn't have a temperature gauge and she had no clue that it was overheating. Add to this that it was on the motorway - sudden death of an engine.
Firstly lets end the myth- deleting errors won't fix anything! This is the recovery driver's usual thought which then hinders the Fiat tech's diagnosis as all the fault data is lost.:bang:
Faulty lambda's won't stop an engine running. It will default to a limited operating strategy to get you home/ to a garage. It will still start!:bang:
A faulty knock sensor won't stop it running. It adjusts ignition timing to run as lean and fuel efficient as possible. If it fails- limp home mode! It's also not hard-wired into the loom!:bang:
Anyway, rant over. Check the usual things-
Is there fuel in the tank? Sounds silly but it's happened before!
Does the fuel pump prime? If not has the inertia switch been triggered?
Does it turn over as normal? Too fast- no compression (cambelt ok? you sure?) Too slow- bad battery/earth/etc
Is there a spark? (remove a plug lead & spark plug and rest on engine and crank)
A common fault is a failed crank (RPM) sensor- no spark, no injection. Only way to be sure is to check RPM and air pressure readings whilst cranking.
D4nny8oy
Established member
Glad someone thinks so!
Sorry to hear about the overheating, sadly it's a common failure on the 1.2 8v engine. The cooling fan is often the cause as they tend to seize with dirt/dust getting lodged in the motor with the first warning being the gauge creeping into the red, and usually it only has to overheat once for the headgasket to fail.
If it's caught quickly (as soon as the gauge first goes high) you can normally get away with just a gasket. But if the engine continues to run hot it melts the plastic inlet manifold, as well as warping the head, and the costs escalate.
Models without a gauge have a red warning light to signify overheating which runs off the temp sender for the Fuel injection system. However if the engine boils dry, there's no coolant to measure- it's possible this is why it didn't come on. You can check it works by switching the ignition on and watching the lamps during the self-test.
Good luck with the new engine.
Lowtechguy
Member
fyi, clocks with a water temp gauge and a rev counter are a striaght swap, you just need to get the milage corrected at the dealer for around £30 otherwise it flashes.
Yes it is common for engines to overheat with no water in them...
Yes it is common for engines to overheat with no water in them...
We bought this Punto with 15,000 miles on the clock and it was oozing oil from the cam-cover gasket. The dealer was meant to fix it but he didn't. Eventually I changed the gasket and again - it didn't fix the problem. Also I had to replace the cooling fan as it was making a lot of noise. The car's annual mile is low so it's taken 2 years to die.
My conclusion is that the car overheated in a previous life and I endedup buying a problem!
Thanks again.
My conclusion is that the car overheated in a previous life and I endedup buying a problem!
Thanks again.
