Technical Jerkiness on light throttle, esp when cold.

[Pugglt Auld Jock]

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

View attachment 461948

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

View attachment 461950

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

Thanks koalar. I think the point is that, because a voltmeter requires no current passing to register a reading (the plumber's analogy that it's measuring pressure not flow helps to understand) then all it would need to achieve a battery voltage reading in this case is a pathway. Or, to put it another way, the thinnest of wires acting as an earth or a poor/dirty/loose earth connection will show battery voltage on the meter but when the starter, or any other heavy load, is drawing current the poor connection/thin wire (ie shredded earth cable due to corrosion/damage) will act as a high resistance and drop the voltage. I think quite unlikely to be the culprit in this case but, as so easily and quickly checked, why not?

 

[PacoJones]

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

At 3k rpm and stationary, STFT is roughly -20 and LTFT roughly +20

 

[koalar]

At 3k rpm and stationary, STFT is roughly -20 and LTFT roughly +20

Mmmm

Confusing

At 3K STFT negative will start to drive the LTFT down, eventually the LTFT would end up being close to 0

I forgot did we get round to checking for an air leak by blocking the top of the throttle body

Faulty evap solenoid can cause similar readings, which is pretty easy to eliminate, pull blue pipe off and block the end

 

[PacoJones]

Yes, I blocked the throttle body with my hand previously and the vacuum seems good and the engine stalls in quick succession.

Faulty evap solenoid can cause similar readings, which is pretty easy to eliminate, pull blue pipe off and block the end

I've detached this from the inlet manifold with the car idling and there's no change when I detach it, nor when I block the pipe leading into the throttle body sorry, inlet manifold. There's no noticeable vacuum when I block the pipe, is this how it should be?

Thanks.

 

[koalar]

Yes, I blocked the throttle body with my hand previously and the vacuum seems good and the engine stalls in quick succession.


I've detached this from the inlet manifold with the car idling and there's no change when I detach it, nor when I block the pipe leading into the throttle body. There's no noticeable vacuum when I block the pipe, is this how it should be?

Thanks.

Yes, that is how it should be

There should be no vacuum at idle with the pipe disconnect and it's electrical connector still on

Can be hard to detect, I wet my finger and tap it on the end you shouldn't feel any pull at all

Assume this is the case put it back and let's move on

Let's go back to basics

Disconnect the large black breather from the cam cover take it for a drive, to clear any oil out of the inlet, let it idle and see what the fuel trims and inlet manifold pressure are, does it improve

It's not far off I'd expect the fuel trims to be within 15% of the default values, which they are if the revs are raised


The plugs aren't dark, so it looks to me like the O2 are probably reporting correctly, it's more like the ambient, coolant or pressure isn't quite right so it picking the wrong values


You could disconnect for a few seconds and reconnect the battery battery to clear any adaptive settings

 

[PacoJones]

After a good 20 min run with the large black breather disconnected and the car idling, the fuel trims look like the attached video.

Inlet manifold pressure in the same state is 290mbar

 

[PacoJones]

In case it helps, the attached video was taken on a flat stretch of dual carriageway maintaining 3k rpm in 4th, so about 60 mph. Just thought it might be useful to see the fuel trims under load.

 

[koalar]

Cool fuel trims at idle look much better

Within a few percent of 0%

Dose point towards the oil covered MAP as the only problem

Could be intermittent, do the car feel better to drive with the pipe disconnect or is it too early to tell

 

[PacoJones]

The car is actually driving fine at the moment, so too early to tell. When it next starts being difficult, I will disconnect the large breather and try again.

However, with the large breather disconnected, there are strong oil/petrol vapurs in the car (probably to be expected?) and I also notice that in that short time where the hose was disconnected I have seen oily residue appear on the throttle body exterior where it was pointing (below the pipe it normally connects to).

Is there a simple fix to stop the MAP oiling up?

Thanks.

 

[koalar]

It shouldn't oil up

Plenty of vacuum in the inlet to draw any gasses back in and burn off

It's not generally a problem for the first 10 years of the cars life

By far the most common cause is a leaking pipe, if the breathe pipe or air box to throttle body isn't a reasonably good seal, the gasses linger, condense out and dribble down into the inlet manifold

It's quite common to find the clamps missing

There are other causes

Excessive blow by gasses
Leaking head gasket
Water in oil
Coolant in oil
Oil past it service life
Wrong oil
Wrong tappet clearance
Wrong oil level

Some of which a catch can would help.

There is a service bulletin on this I will dig it out

 

[koalar]

Here you go

Home Page

aftersales.fiat.com

 

[Pugglt Auld Jock]

Here you go

Home Page

aftersales.fiat.com

Thanks for that koalar. You know how hopeless I am with computers? Can you tell me how I can save this on a windows laptop?

 

[MrMagoo]

It does appear that you have excessive blow-by causing your MAF to foul up with oil.
What oil are you using? It it needs a semi-synthetic oil; I use 10w-40.

 

[jrkitching]

Can you tell me how I can save this on a windows laptop?

One option is to take a screen grab, which allows you to select a part of what's showing on the display and save it as an image file. This is useful in all sorts of situations when you want a permanent record of something you're looking at on screen.

Hold down, simultaneously, the windows key, the shift key, and the S key. Then use the cursor to select what you want to copy. You can then save this as an image file, print it, or do anything else you can do with an image.

Have a play with this - it's pretty intuitive.

 

[koalar]

Screen grab
Book mark
Copy hyperlink into a txt file
Or the print command then save as a pdf

I use all these options, depends what I am doing at the time

Download this file might help

Whoops had to change the page size otherwise the bottom gets cut off

Corrected pdf is now below

 

[Pugglt Auld Jock]

Screen grab
Book mark
Copy hyperlink into a txt file
Or the print command then save as a pdf

I use all these options, depends what I am doing at the time

Download this file might help

Whoops had to change the page size otherwise the bottom gets cut off

Corrected pdf is now below

Thanks koalar, I clicked on it and it's in my downloads file now so I can call it up any time I want now.

Screen grab, book mark, Copy hyperlink into txt file or the print command and then save as a pdf? Haven't a clue, might as well be Martian to me. I've heard of screen grab but never done one and don't know how. Book mark? Hyperlink? ( something Captain Kirk would do? and saving a print command to pdf. I know what a pdf is and I've got some saved in my downloads but haven't a clue what you mean here. I'm afraid I'm just not up with this sort of stuff.

I only downloaded your file because you're a known poster on here so thought I'd trust you. Otherwise I wouldn't normally download anything.

 

[koalar]

How you go about it depends on what operating system and or browser you are using

I am on android phone at the moment

And chrome browser

I can go through it step by step but it only of any use if you have the same system

 

[Pugglt Auld Jock]

How you go about it depends on what operating system and or browser you are using

I am on android phone at the moment

And chrome browser

I can go through it step by step but it only of any use if you have the same system

Very kind of you to offer thanks. However I'm pretty slow on the uptake these days and "computery stuff" just doesn't seem to "meld" easily with my brain. I've found in the past that I'll probably need someone sitting beside me to answer the multitude of questions I always seem to end up asking. I laso seem to forget it all again unless it's something I'm doing repeatedly. I'll just muddle along as I am but thank you, your offer of help was very kind and much appreciated.

 

[PacoJones]

What oil are you using? It it needs a semi-synthetic oil; I use 10w-40.

It's got 5w-40, not sure if synth or semi-synth. Would a heavier oil help reduce blow-by? Maybe worth using 10w-50 next time?

I run 10w-60 on my Forester STi, but it has a built motor and it was getting through a lot of oil with the usual 5w-40

 

[Pugglt Auld Jock]

How you go about it depends on what operating system and or browser you are using

I am on android phone at the moment

And chrome browser

I can go through it step by step but it only of any use if you have the same system

I'm beside myself with self satisfaction. For many years now I've use my Panasonic Lumix camera to take photos, transfer them to my laptop - and NAS if it's something I really don't want to loose. For years my laptop (Win 10) has automatically saved these to my Pictures file when I ask it to download an image from the camera. However, a few weeks ago, after a big updating download, it started downloading these images to "Photos", a completely different appearing screen which I'd never seen before, and they weren't then turning up in my Pictures files so I couldn't select an image to attach to a post I was making on the forum. The way in which I have access to the NAS also seems to have changed subtly? Anyway, last night, with Mrs J watching Eastenders and other "stuff" I have no interest in, I got stuck into understanding what the computer is doing.

While clearing out his house, I've found a picture of my old Hillman Imp estate, taken by my deceased brother probably about 40 years ago - judging by the juvenile conifers in the foreground which subsequently grew to such a height I had to take them down entirely due to neighbourly complaints. I want to take a copy of it and store it on the laptop (and NAS if I can find out how to transfer it there!) So I used the camera to take an image of the photo and told the computer to import it. As expected, The "Photos" screen came up so I started looking around on it to see if there was any way I could influence what it's doing with the image. Geronimo! there's a wee "thingy" on the screen top right which ia labeled Import. I clicked on it and it opened a big box mid screen which displays the image from the camera and lets me choose to shunt it into my Pictures files. So I did this - backed out to the desktop and went back into the Pictures files and, Bingo, there it is in exactly the place it would have automatically gone to before the big update changed everything.

I do wish they'd stop doing this. Although this time it was quite a dramatic change, almost every time it does a larger update it changes how stuff interacts like this and, for a simpleton like me, it makes things very difficult!

Anyway, here's the picture. Can't have been long after I finished refurbishing the old girl as it was obviously taken just after I'd resprayed her and the respray was the last thing I did to her before putting her back on the road. Wish I now looked like I did in that picture, hardly recognize myself.

Hmm. Wonder what I'm fiddling with in my hands?

I feel I should apologize for deviating from the thread's subject but it, kind of, tied in with what koalar was advising me about earlier. - grovel.