Technical Jerkiness after trip to Scotland

[AnthonyH]

My Evo chucked a check engine warning at me not long ago. The engine has been a tiny bit jerky at low speeds for a while, but I'm on a break and after taking a trip to Scotland the jerkiness has gotten worse. It's now misfiring at motorway speeds. I'm about 150 miles away from home and wondering if I'm going to get back without needing to be towed.

The car revs up ok and will go through the whole range. It does have some kind of exhaust blow noise coming from the engine when it is cold, but that goes away.

I don't have any tools so the best I could do is take off the HT leads one by one, and they're all still working. Is there anything else I can check?

 

[GrandePunto PL]

Not much you can do without any tools (especially OBD2/MES and basics like a multimeter, fuel pressure gauge).
If you attempt to drive long distance while misfiring, you'll kill the exhaust (sensors + cat.) or worse (valves, pistons).

What was done to the car recently? Any "repairs"? How was the last MOT (exhaust gas analysis, barely Passed)?
Google says, there is no minimum speed limit in theory, but driving too slow on motorway is dangerous.
You must judge, if you can make it home (how slow you must be, to avoid misfiring)... Risk calculation.

 

[AnthonyH]

It'll drive at normal speed i.e. 70mph, so I don't need to worry about driving on a motorway at 30 mph.

I've already decided to drive it home tomorrow, its 150 miles...I don't think the car will breakdown but it is possible. I have a replacement for this car that I'm currently repairing so I'm quite happy for the car to simply die. It's at 116,000 miles and I've been deliberately putting lots of miles on this car because these puntos are very unreliable so leaving the car behind isn't a problem.

It had a new clutch a couple of months ago, and a front subframe last year. MOT is due next month. If I were to guess I'd say it's an O2 sensor, something simple like that.

 

[Zardo]

My Evo chucked a check engine warning at me not long ago. The engine has been a tiny bit jerky at low speeds for a while, but I'm on a break and after taking a trip to Scotland the jerkiness has gotten worse. It's now misfiring at motorway speeds. I'm about 150 miles away from home and wondering if I'm going to get back without needing to be towed.

It's a classic... ;-)

 

[GrandePunto PL]

these puntos are very unreliable

Not true. Fiat is an unlucky brand. Those cars are neglected, abused beyond belief, then your first reaction (in case of failure, malfunction) is to dump it, junk it. THAT shows what's your mindset, who you are (how you treat a car and other stuff, how much you "care"). Punto OWNERS are not reliable.
Car is not a toy (or TV set, or refrigerator). It is something more (needs more attention). It's one category higher than household appliances.

Then we can talk design flaws, manufacturing errors, recalls. Yes, there are many.

 

[AnthonyH]

It's a classic... ;-)

Thank you. That's hilarious, I'm sat in a hotel room watching TV so that was a great!

We watched Car SOS earlier and my son managed a joke about me spending 2 weeks trying to remove a rusty bolt, buying 8 different tools to try to get it done...and then the guy off the TV coming along and taking the bolt off in 30 seconds I laughed a lot, missus too.

 

[varesecrazy]

My Evo chucked a check engine warning at me not long ago. The engine has been a tiny bit jerky at low speeds for a while, but I'm on a break and after taking a trip to Scotland the jerkiness has gotten worse. It's now misfiring at motorway speeds. I'm about 150 miles away from home and wondering if I'm going to get back without needing to be towed.

The car revs up ok and will go through the whole range. It does have some kind of exhaust blow noise coming from the engine when it is cold, but that goes away.

I don't have any tools so the best I could do is take off the HT leads one by one, and they're all still working. Is there anything else I can check?

Worth uncoupling the earth cable overnight,

ECU will go back to Factory settings

Then relearn as you drive

It Might improve things

 

[AnthonyH]

Worth uncoupling the earth cable overnight,

ECU will go back to Factory settings

Then relearn as you drive

It Might improve things

Now there's an idea, will do.

 

[AnthonyH]

I disconnected the battery. I have 3 cars and 2 of them are needing work and not driveable, mmm, I hope my working GP doesn't fail...

 

[AnthonyH]

I got home OK. I felt jerkiness a couple of times, but keeping the revs constant throughout the journey helped.

I took it out again to try to recreate the problem and it occured firstly when in second at 2000 revs at a constant 20mph. Then again when accelerating to 4000 revs and 30mph up a moderately steep hill. I haven't had any dashboard lights and no repeat of the check engine warning.

I'm not sure what to do now.

 

[PuntoHowTo]

You need to invest in MES and a good cheap little laptop on which to use it

 

[AnthonyH]

You need to invest in MES and a good cheap little laptop on which to use it

I think you're right. I bought the cables ages ago in the belief that the software was free, then whatever problem I had went away so i didn't buy the software. I cleared the ECU last night, so there might not be any codes on there, not really sure!

 

[PuntoHowTo]

Codes should still be stored.


General rule of thumb is if the engine light is flashing then the ECU is recording a misfire

 

[AnthonyH]

Codes should still be stored.


General rule of thumb is if the engine light is flashing then the ECU is recording a misfire

The engine light didn't come on, i got a loud bleep and a written message coming across the dash saying "check engine" when the engine was misfiring badly. The engine management light does work, well at least it comes on when i turn the igntion and goes off when I start the engine.

Regardless, i think there will be some codes stored there either now or soon lol.

 

[AnthonyH]

Actually no, the engine management light doesn't work. It doesn't come on at startup like it should, i've never noticed and got mixed up with my GP, where the engine management light does come on and go off properly when i start the engine.

So anyway, most likely the engine management light would be on, if the dashboard light worked properly.

 

[varesecrazy]

Actually no, the engine management light doesn't work. It doesn't come on at startup like it should, i've never noticed and got mixed up with my GP, where the engine management light does come on and go off properly when i start the engine.

So anyway, most likely the engine management light would be on, if the dashboard light worked properly.

There Is a FREE version of MES..

JUST download that and go from there

It has limited connectivity, but should provide accurate engine codes on a 199

 

[AnthonyH]

There Is a FREE version of MES..

JUST download that and go from there

It has limited connectivity, but should provide accurate engine codes on a 199

Hmmm, righto I'll try again.

I managed to connect to all of the 199 modules in the car but it wouldn't give me any codes or give me any useful car information. The best I could do was a simulation to get an idea of what the software would do.

 

[PuntoHowTo]

I continue to use an older version which doesn’t require a subscription, back when you could pay once and use forever.