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General Dredded P0300 after timing belt change

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General Dredded P0300 after timing belt change

E

Entwine

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Jun 1, 2010
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My Punto 1.2 8v 53 plate was running fine however mileage had gone over 60k so thought I would be proactive and get it replaced at my local garage.

They changed it and all was fine until I hit around 76-80MPH then the ECU light flashes sometimes for 30 seconds sometimes for about 10 seconds, then goes off. On one ocasion it came on and stayed on, took it back to garage they reported P0300 code, multiple cylinder misfire.

The garage stripped the belt again to double check no problems and to be honest the car is running as smooth as it always has.

Anyway had the plugs and leads changed and the problem still persists, however the car itself is running really smooth.

Anyone got and ideas? Someone has suggested a faulty sensor, which one, how much and where do you get them from.

Any help would be greatly appreciated.


Thanks in advance
P0300 victim.

p.s. no jokes about going staying under 70MPH....
 
Hmmm, the code was cleared yesterday when the plugs and leads were changed. Any further suggestions?

Thanks in advance
 
Needs the ECU self adaptive parameters resetting and Phonic wheel learn procedure performing. (Dealer job unless the local garage's software is upto it)

https://www.fiatforum.com/punto/232195-eobd-dashboard-light-flashing-amber-around-70mph.html

Local garages may be cheaper, but if they'd called the local Dealer (or searched on here) they'd have had the answer I'm giving you in seconds, and saved themselves the time and hassle of replacing working plugs and leads and rechecking the belt. ;)
 
Hi Danny thanks for the update, you mentioned the self adaptive parameters need resetting, is this required? As I tried the phonic wheel reset today but the problem remains.

Thank in advance
 
How did you do the phonic wheel learn without resetting the parameter in the ECU with the diagnostic machine? Can't be done any other way.
 
Hi Danny,
Do you need to reset the self-adaptive parameter with the ECU software first? as I followed your procedure:

"Start engine and warm-up until the temp needle reaches normal/top rad hose is hot. With the vehicle stationary and out of gear, floor the throttle and then release as it passes 5,000rpm (only has to be for a split second) and allow to idle. Repeat this 2 more times, and the EML should stop flashing. Job done."

Sorry in advance if it is a stupid question.

The EML has come on and stayed on twice, so I took it back to local garage and they showed me in the software where it stated multiple cylinder misfire but they were stumped. They cleared the error off the ECU "no engine warning light - hmm, is this clearing the self-adaptive parameter?", but I have driven it since then without doing the phonic wheel and the light flashes again around the same mph.

Thank in advance
Frustrated

p.s. Thanks to all who have posted so far, it really is appreciated.
 
Entwine said:
Hi Danny,
Do you need to reset the self-adaptive parameter with the ECU software first? as I followed your procedure:

"Start engine and warm-up until the temp needle reaches normal/top rad hose is hot. With the vehicle stationary and out of gear, floor the throttle and then release as it passes 5,000rpm (only has to be for a split second) and allow to idle. Repeat this 2 more times, and the EML should stop flashing. Job done."
Click to expand...

That's the phonic wheel learn procedure, and can only be carried out when the parameters have been reset- you'll know this because the EML will flash constantly with the engine running until the wheel learn is done.

Deleting the errors/disconnecting the ECU does not reset the self adaptives.
 
Solved

Thanks to everyone who posted.

After much back and forth between the garage who performed the belt change I contacted a local Fiat specialist who flatly refused to accept a phonic wheel learn was required post cam belt change and to prove the point they then stated they would check the timing for free.

They did and guess what the timing was out by one tooth.
No more ECU flashing light and the guys did not charge me anything (so I gave them something anyway).

Just to add, the Fiat specialist did state that the local garage had used the old mark with tip-ex technique and they would not be able to line the cracks back properly without using the proper locking tool (don't ask me)

At least it is over.
 
Last edited:
Entwine said:
Solved

Thanks to everyone who posted.

After much back and forth between the garage who performed the belt change I contacted a local Fiat specialist who flatly refused to accept a phonic wheel learn was required post cam belt change and to prove the point they then stated they would check the timing for free.

They did and guess what the timing was out by one tooth.
No more ECU flashing light and the guys did not charge me anything (so I gave them something anyway).

Just to add, the Fiat specialist did state that the local garage had used the old mark with tip-ex technique and they would not be able to line the cracks back properly without using the proper locking tool (don't ask me)

At least it is over.
Click to expand...

Then how come Fiat state that the phonic wheel learn procedure is to be performed "when any action is performed on the timing belt or related components"? ;)

Granted the issue in your case was caused by the original garage failing to time-up one of the easiest engines you can wish to work on.
 
Danny I agree with you, I nearly had an argument with the Fiat specialist regards the phonic wheel learn and he was not having any of it. Then again I could not really call him or question him as I am not a mechanic and he did find the fault, but I guess he would have resorted to completing the phonic wheel learn if the timing was found to be correct.

Who knows? Glad its fixed.

One other small problem (the local garage had slowed it down to try and here if the timing was out) the idle seems to be very slow and periodically sounds as though it comes close to cutting out, is this just a case of increasing the idle?

Thanks as always.
 
I'm with the above specialist. A new timing belt should not require a phonic wheel learn? If the new belt is fitted properly, as far as the ECU is concerned, nothing has changed. So there would be nothing to relearn. Arguably, if the timing was out a PWL could serve only to mask problems caused by the wrong timing.

But, if I had an engine that had been timed wrong, I probably would do a PWL, because who knows if one was done by the mechanic who fitted the timing out.

Regarding timing marks when I did my HGT (I know its set differently) I used the flywheel marker and locking blocks, but also checked it against the #1 piston position. Good job I did because the flywheel mark was out by about 6mm circumferentially. I also rechecked it (with blocks and piston position) after tensioning the new belt.
 
Last edited:
Entwine said:
One other small problem (the local garage had slowed it down to try and here if the timing was out) the idle seems to be very slow and periodically sounds as though it comes close to cutting out, is this just a case of increasing the idle?

Thanks as always.
Click to expand...

Idle is not adjustable (it's ECU managed via the idle stepper motor). With all the messing around, the ECU may have 'learnt' the wrong setting. Quickest/easiest way to get it to learn again is to simply-

Switch ignition on and wait 1 minute,
Switch ignition off and wait 1 minute,
Start engine and leave to warm up.

After that it should have learnt the position it needs to be in.

WhiteSei said:
I'm with the above specialist. A new timing belt should not require a phonic wheel learn? If the new belt is fitted properly, as far as the ECU is concerned, nothing has changed.
Click to expand...

You'd think so, but we've proved it's true in the past with people returning with the "general ignition failure" issue @ motorway speed when the Tech involved forgot to reset the parameters after correctly fitting the belt.

A small difference in the length of the rubber belt, or a slight difference in belt tension, will cause the two signals to slowly alter in synchronisation over time, which the ECU accepts. Then the next turn of the key they are back in line again, so the ECU suspects a fault because it hasn't been told to relearn the position because the belt has been changed.

Anyone with a 1.2 16v, HGT or JTD with sprung-loaded tensioners will see that during the belt change after 3/5 years that the belt has altered and the tensioner is no longer indicating at the correct tension point. ;)
 
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