Technical Jerkiness on light throttle, esp when cold.

[koalar]

With lights on main, rear screen, fan on full, etc, the reading at the battery drops to 13.3 and when I rev the car to approx 3000rpm, it goes up to 13.85 - a little shy of 14 but it's consistent, if the I let the revs drop and then press the accelerator, it jumps straight back to 13.85. So I think that's good enough.

That's the alternator eliminated

It measures .019V so I guess we can move on!

I will post some updates when the code reader arrives in a day or two and I can check for codes and live data, or if the problem reappears and I can detach the breather pipe and see what effect that has.

Thanks everyone for your fantastic input so far!

That's the gearbox earth strap eliminated

Well done on going out there and actually measuring them correctly

 

[Mike1alike]

With the multimeter on volts one lead on the battery negative, one on the engine block

Crank the car, if you have a good ground the reading should be just under 0.2V

I'd say there's a more accurate way to check the grounding: First read the voltage on battery terminals, then move the (-) probe to chassis, then to gearbox and/or to starter motor body. If the readings are the same as on battery, the cable is ok. If not, the earthing cable is not ok.

Would this be made worse by wet weather?

I had the same problem you described on my Punto and it also was made worse by wet weather. You got close to it when you replaced the TB seal. The fix is to replace the intake manifold gasket seals especially the ones between manifold and CH, shown in my picture. I got them in set, not at all expensive, including the seals for everything that is attached to intake manifold: TB, all the sensors. When those ones on CH get worn out, you can't really see it on diagnose because I think the ECU stabilizes the vacuum pressure by opening less steps the IACV. But you can totally feel it in the way the engine runs because ouside air gets in there and when the air humidity is high that affects the good running of the engine. That thing is really puzzling because you get no stored errors and most of the times, on dry atmospheric air the engine runs quite nice with no problem.

 

[PacoJones]

The fix is to replace the intake manifold gasket seals especially the ones between manifold and CH, shown in my picture. I got them in set, not at all expensive, including the seals for everything that is attached to intake manifold: TB, all the sensors.

Thanks for the input - I'll see what the code reader/live date shows, but certainly replacing those gaskets is cheap enough, about £15 for a set from what I can see.

Looks like there are about 6 bolts holling the inlet manifold on? Anything to be aware of when removing it?

 

[Mike1alike]

As for the very oily intake manifold and MAP sensor, that is a different problem that I think I very recently solved on my Punto, after I had it for many years and I was told by a mechanic that that is "normal behavior" for Fiat.
So, doing some work on the CH, I also got to clean the rocker cover and was looking for a fix to this oily intak as I never rest assured that that's quite normal behavior.
And I discovered that the oil channels up in the cover were clogged. Did that by pushing diesel into the oil channel with a big syringe and managing to unclog it so.
The mechanics: the oil pump sends through one chanell oil under pressure up in the cover and it should go to the camshaft in those 3 points of contact where shaft sits on head. The brackets have orings for contact with the cover so that oil should go straight in to camshaft, no spilling around. And also, up there, beside those channels that carry oil to camshaft are other little openings that shoot oil to the valves areas and also near the oil channel is the system that collects the vapors and carries them to intake through the breather.
Having the oil channel blocked, first of all the lubrication of the camshaft is not done. That leads to overheating of camshaft and head in that point and premature burning of oil. Exces vapors gets carried inside the intake and most likely also are oil drops if there is spillage up in the cover.
I think that my engine was like this when I bought it because I noticed the over burning marks left on the shaft and on the head. Also, untill now, I always had a problem with oil consumption, it was pretty much or even more so.
And for the oil on the spark plugs, it can get on from inside. That's why I got to do work on the head, firstly to replace the valve stem seals. They were really worn out on all valves, probably due to improper lubrication on the camshaft and surroundings and over heating. With them in that state I had a lot of oil going inside the combustion chambers, part of it getting burned during engine running, but also part of it being spilled on the plugs threads during compression. I don't think that is the case on yours, @PacoJones by the way your plugs look, but I'm saying it is posibil for oil to get on the plug thread from inside and that is how.

 

[Mike1alike]

Looks like there are about 6 bolts holling the inlet manifold on? Anything to be aware of when removing it?

Two of them bolts (beside the 6) hold the cooling liquid temperature sensor, so before taking them down is better to take some coolant out of the system so it wouldn't spill there. When you're done, do the refill and breathing the air out.
Other than that, just to have some patience doing the job. With the proper tools it is an easy job. For the downside nuts I used this kind of spanner, little angled at one side and accessed it from above, throughout the manifold channels.

 

[koalar]

No idea what we are talking about

There's no coolant in the inlet manifold

You have to disconnect a few things like the evap but nothing complex

We don't have symptoms of an inlet manifold, engine raising to 2k during idle

You can't undo the bolts with a spanner

If you want to test for an air leak here try like this

 

[PacoJones]

If you want to test for an air leak here try like this

It was on my list of things, forgot to do it earlier, have just tried and the engine stalls immediately. Vacuum seems pretty strong.

 

[Mike1alike]

At mine, the temperature sensor sits together with the manifold on the CH with a sideways interlocking mechanism. I can take off only the sensor, but can't take the manifold without taking the sensor too.
Surely some details differ on Panda, but the main idea stands.
I could undo the downside nuts with the spanner.
Testing it for air leak doesn't really get you anywhere as it is very tight and just the humidity that gets in that ways makes the difference. I tested for air leaks that way when I had the problem and it didn't show anything. Thought about replacing those gaskets as they were kind of old (probably the original ones that came with the car) and that fixed it.

 

[PacoJones]

@koalar The Code Reader turned up this afternoon, I ordered a CReader 3001 and received a Kingbolen YA200, but have plugged it in and it appears to work. I can track live data from various sensors, but there were no stored codes.

I have to drive about an hour tomorrow, 30 mins each way, so can do some measurements if you can let me know what would be useful. Though the car is running absolutely fine at the moment!

Going back to the possibility of wet conditions having an impact, my feeling is that it's not related, I don't remember rain being a factor on previous occasions. I think it just happened the other day at the same time as it had been raining. I took the car out yesterday in pretty horrendous rain and drove through every puddle I could find, got home, parked it up for a couple of hours and drove it again and it was absolutely fine both times.

 

[The Panda Nut]

Felicity (Mk1 Panda Parade) had a wire mesh flame trap in her breather pipe which used to block up regularly because she did short journeys most of the time. I got fed up clearing it out so just left it out and never had a problem thereafter. Non of the more modern ones - Pandas or my boy's Punto - had them.

I think thats a telling post. I feel if flames have got to that point you are already in a pile of trouble Any issues from ours and I will remove them. I still have my flame arresters but have fitted catch cans to 2 of our 1.2's, These have made a big impact on cutting this problem out. They need emptying very regularly. Almost all the catch is water with (now) just a trace of oil. Interestingly changing the oil from Castrol Edge to quantum C3 premium has reduced the amount of oil in the catch can by 90%. Im actually pretty staggered at the change as the stuff in our 2016 was alarming me with its heavy mayo content. It is now really just water. Getting rid of the water in the crank case and breather stops mayo build up completely and keeps the MAP much much cleaner. I checked Mrs Panda Nuts manifold and MAP at service. The manifold was still spotless and the map OK- but it responded well to cleaning. This car is now as sweet as my 100HP was. I always said that was quietest and smoothest 4 cylinder engined car I have ever driven. Ruby now runs it very close and is a real pleasure.

 

[koalar]

inlet manifold pressure should be around 1000 mbar engine off, Google will tell you the exact pressure for your location

Measure the inlet temperature should be whatever Google says at your location

Start the engine and let it idle the inlet manifold pressure should drop to 290-330 mbar

Look at the long and short term fuel trims together they should be around 0

For example one could be -20 the other +20

 

[PacoJones]

OK, atmospheric pressure and inlet manifold pressure before starting the engine are the same, approx 1010 mbar.

Ditto for intake temp - same as ambient (1 degree C this morning).

On starting the car, inlet manifold pressure was 360 mbar at idle but after the car had been run and was fully warmed up, it was 270 mbar (again at idle).

Looking at the fuel trims, the combined total is always above 0, it probably averages around +20. The STFT occasionally goes negative but the LTFT basically never does.

 

[Pugglt Auld Jock]

I'd say there's a more accurate way to check the grounding: First read the voltage on battery terminals, then move the (-) probe to chassis, then to gearbox and/or to starter motor body. If the readings are the same as on battery, the cable is ok. If not, the earthing cable is not ok.

Hmm? there's no load being applied to the circuitry doing this? Needs load to properly check for poor earth, no?

I had the same problem you described on my Punto and it also was made worse by wet weather. You got close to it when you replaced the TB seal. The fix is to replace the intake manifold gasket seals especially the ones between manifold and CH, shown in my picture. I got them in set, not at all expensive, including the seals for everything that is attached to intake manifold: TB, all the sensors. When those ones on CH get worn out, you can't really see it on diagnose because I think the ECU stabilizes the vacuum pressure by opening less steps the IACV. But you can totally feel it in the way the engine runs because ouside air gets in there and when the air humidity is high that affects the good running of the engine. That thing is really puzzling because you get no stored errors and most of the times, on dry atmospheric air the engine runs quite nice with no problem.

Oh dear, that gives me another reason to buy a smoke tester!

 

[Mike1alike]

Hmm? there's no load being applied to the circuitry doing this? Needs load to properly check for poor earth, no?

Not this way. This way you are technically measuring the battery voltage, first directly on the terminals for comparison, the second moving the voltmeter (-) probe to the other end of earthing cable. It really shows you if there are problems. Of course, you can do the measurements with the engine running too, but nothing changes in regard to what you're looking for (good or bad earthing cable), just the voltage would be higher, as the alternator puts out.

 

[Pugglt Auld Jock]

Not this way. This way you are technically measuring the battery voltage, first directly on the terminals for comparison, the second moving the voltmeter (-) probe to the other end of earthing cable. It really shows you if there are problems. Of course, you can do the measurements with the engine running too, but nothing changes in regard to what you're looking for (good or bad earthing cable), just the voltage would be higher, as the alternator puts out.

Yes, but there's no heavy current being pulled? So the earth cable could be poorly connected or, more likely corroded and thus substantially frayed but still able to pass enough current to indicate voltage on the voltmeter? Mind you I'm a "thick old school grease monkey" so I'm probably missing something - like some little grey cells!

 

[AnthonyH]

Caveat - I've not read this conversation.

But has this guy checked the temperature sensor?

The heading says the vehicle is a problem when cold, so this would seem to indicate its a temperature sensor problem.

 

[Mike1alike]

Mind you I'm a "thick old school grease monkey" so I'm probably missing something - like some little grey cells!

I don't think you are missing any grey cells, I think you're fine. What I can tell you about that voltage reading is that when I had problems with the earthing cable I did the voltage reading and it revealed more than 1V drop of voltage on the body and engine compared to on the battery terminals. Can't really remember if that was with the engine not running, but I think it was too, and it was for sure with the engine running. After that reading, on closer look I discovered that many of the cable's wires were broken on the contact point on the body and cable was also full of green stuff there. I've put a new cable on and since then on all the voltage readings I did I got the exact same numbers on the body and engine as on the terminals.

 

[Pugglt Auld Jock]

I don't think you are missing any grey cells, I think you're fine. What I can tell you about that voltage reading is that when I had problems with the earthing cable I did the voltage reading and it revealed more than 1V drop of voltage on the body and engine compared to on the battery terminals. Can't really remember if that was with the engine not running, but I think it was too, and it was for sure with the engine running. After that reading, on closer look I discovered that many of the cable's wires were broken on the contact point on the body and cable was also full of green stuff there. I've put a new cable on and since then on all the voltage readings I did I got the exact same numbers on the body and engine as on the terminals.

Maybe more than one way to skin this particular "cat" then

 

[koalar]

270 mbar is a very good vacuum seen by the MAP sensor in the inlet

+20 on fuel trims is a little on the high side, ideally they should be within 10%

If you raise the revs to around 3k and hold, do the fuel trims stay the same, lower or rise

 

[koalar]

Yes, but there's no heavy current being pulled? So the earth cable could be poorly connected or, more likely corroded and thus substantially frayed but still able to pass enough current to indicate voltage on the voltmeter? Mind you I'm a "thick old school grease monkey" so I'm probably missing something - like some little grey cells!

I was ignoring this advice

So often I advise someone to do a voltage drop test under load, and I get well it measures 0 ohms

All these wires measure close to 0 ohms
All these wires will measure battery voltage at the end if not under load

The correct method is to check is via voltage drop under load

As per Delphi and just about every auto electrician

Here a auto electrician, that teaches at a collage



Here's my car with a faulty earth

It's a very simple test, and is 100% accurate at the time of testing, so will catch nearly all cases

If the block to the battery negative is under 0.2V while cranking, take a minute of your life, the gearbox cable is fine, you can just move on


@PacoJones did the test, let's move on

I very much doubt this would have be the cause but seeing as the symptoms improved with the new battery it was worth eliminating, although this could just be coincidence as it intermittent anyhow