2.4 JTDm won't start

[Alfa-mad]

I can't start the Alfa Romeo 159 2.4 JTDm.

The battery voltage is fine, and when I put the key in I hear the fuel pump prime and I also see the glow plug symbol light up and even when I try to get it jump started, it will turn over once then lose power. The power recovers very quickly but just won't turn over.

So I can be reasonably sure its not a power issue as the voltages are fine and its able to turn over.

However, I noticed from time to time that I had the warning 'DPF is blocked' or something like that come up a few times and whenever that has come up, the car has been a bit shaky on start, so I think the DPF being clogged up a good deal is contributing to the non-start.

Also, my oil needs changing and, it has been very cold lately so combined with those things, I think they are all making it hard to start.

So if old oil, cold temps and clogged DPF make it hard to start, how am I going to get this thing started? Considering it won't even with a jumpstart?

Would unbolting the DPF to allow unobstructed airflow help? Any ideas welcome!

[Craig_m67]

How old is the battery?
Get it load tested and/or try swapping in another to test.

[Alfa-mad]

How old is the battery?
Get it load tested and/or try swapping in another to test.

Yeah I thought of that afterwards, as I realized the battery is at least 3 years old that I know of and probably not in great condition, even though the indicator window is still showing green (warranty for 30 months on it that has passed). But from memory the green indicator isn't as bright as it was.

I might just buy a new battery anyway, all things considered. But I'll take the old battery in and get it load tested at the same time just to be sure.

[poohbah]

At 3 years, its almost definitely done its dash. Battery in our 2019 Subaru is lucky to make 2 years (had two replaced under warranty already) - it's all the extra draw needed for multiple ECUs and electronics. Giulias and Stelvios also have a reputation for issues resulting from premature battery failure, so lots of folks go for an upgraded non-factory replacement as the one that comes from factory is just not up to it,

[Alfa-mad]

Yeah I'm thinking I won't get the standard battery 750CCA but go for the ultra 900CCA just to be sure.

After I do the badly needed oil change, that should make a difference to starting as well, especially in this cold. I'll also make sure I change the oil again in maybe 2000-3000km so I can really flush out as much gunk as possible.

I'm actually well overdue to have the water pump changed, the timing belt done, the tensioner and more importantly, I have to clean out that damn intake manifold. I had the intake pipe off and noticed quite a thick layer of gunk. Plus the car can get jerky around the 2000rpm area when the swirl flaps actuate so it definitely needs cleaning out.

Ideally I want to get the EGR blanked off completely and do the ECU tune for it, but I still want to keep the swirl flaps.

Gonna be a big job to do in my garage but I'm up for a challenge.

[bazzbazz]

Getting jerky at 2000 rpm is usually a failing EGR Valve, not the swirl flaps.

Let me guess, most noticeable at around 60 km/h, maybe up a very slight incline, with very light throttle applied, sound familiar?

[Alfa-mad]

Getting jerky at 2000 rpm is usually a failing EGR Valve, not the swirl flaps.

Let me guess, most noticeable at around 60 km/h, maybe up a very slight incline, with very light throttle applied, sound familiar?

Can you explain how a failing EGR valve would cause those symptoms?

[bazzbazz]

If the valve is not sealing fully, "Fluttering" or opening at the incorrect time it allows hot exhaust gasses into the intake manifold at the incorrect moment, resulting in surging and/or lost manifold pressure/engine power.

I have had several clients with 159s exhibiting these symptoms and all have been resolved with either replacing the EGR valve or these days I just blank it off and map it out of the ECU.

If you do have leaking swirl flaps it won't help much either, easy to detect with applying soapy water along the top bushes of the swirl flaps and looking for
bubbles.

[Alfa-mad]

So it's because the system is expecting the intake air to have a certain amount of exhaust gas mixed in and when it doesn't get that, it throws the air/fuel mixture values out which results in uneven power delivery?

If I blank off the EGR in the meantime before getting the ECU remap, the car will still run ok right, just not as good as it could be?

I'll definitely be getting the EGR delete and remap, don't want to deal with any of the issues related to that anymore like the gunked up intake etc.

[bazzbazz]

Car will run just fine, you will just get a engine warning light till it's mapped out.

[Alfa-mad]

Battery replaced, starts immediately. The old battery voltage was fine (12.58V) and its condition window was still showing as Green but clearly the condition wasn't actually good at all, as it couldn't provide the Amps necessary to crank the engine.

I tested the alternator output and it's functioning as expected so the battery was simply old.

[poohbah]

Good result. I have a vague recollection reading somewhere that you really need well over 12v (eg +13v) to start a car, but maybe I'm imagining that.

[Gerardf]

12.5V is low for a car battery. Should be in the 13s. I wouldn't block off the EGR either.

[bazzbazz]

A fully charged lead acid battery normally sits at around 12.6v, unfortunately as Alfa-Mad has found out it's only an indicator and not a true measure of a battery's condition.

And just why wouldn't you block off the EGR valve, do tell?

The only reason EGR valves are fitted is to meet emission standards, other than that they are completely detrimental to the engines operation/function/longevity.