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Dear community, I hope you can help me with my question/problem.

I've recently bought an Alfa Romeo 159 TBi with 90k kilometres in it. Sparks, engine oil, air, oil filter, timing belt replaced. Also cylinder head gasket, valve rocket sealing was replaced (previous owner replaced oil only 2 times at 35k and 70k - what a shame).

Since I did not drive any other TBis, I have no clue that the thing I'm experiencing is normal or not, so some advice/help would be appreciated:
I can reproduce my issue most easily in 2nd gear, when I'm pushing the throttle approx. half way down from RPM 1000. What I'm experiencing is the engine is twitching a couple of times between 1000 and 2000 RPM - with constant throttle. It feels like a turbo lag, but it does not appear once, but like 2-3-4 times between 1000-2000 RPM. The engine is smooth above 2000 RPM in any gears.
Engine behaves absolutely normally in any other scenarios: idle is smooth, consumption is normal.

Thanks,
Tamas
 

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Hi Tamas,

I don't know if it is your case, but for me (2.2 jts) it was doing the same until I cleaned the throttle, and after that feels like a completely different car at low revs. The problem is the air intake for low revs is quite small, so if the throttle is opened just a little the air intake does not suffice because of the dirt.
Also you may want to check the whole air intake to make sure it doesn't have any leaks.

Best,
Liviu.
 

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I would have walked away from a car that tried to run a turbo on the same oil for 35,000 miles.
Yes I know... I was an idiot. I've checked literally everything on the car, asked them to lift it up, so I can check the bottom, measured the paint thickness with a measurer, asked the owner how was it serviced and he said it was regularly serviced, the only and single (and probably most important thing) I didn't do is to check that retarded service book, only after I bought it :)
Lesson learned. However there was a compression test made afterwards and the engine still produces the factory results.
 

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But what about the turbo?
My alfa mechanic buddy checked that too, he said he saw a lot of turbos and by moving the axle of the turbo he can feel with his finger the "state" of the turbo and he said it's fine. Of course this is not a precise measurement :) But I believed him that it's fine. And the twitching is not super bad, as a passenger I might would not notice it immediately. But as a driver, who knows and feels how do you press the throttle, you feel that the engine does not pull smooth.

Let me explain it a bit differently: imagine that you have a super sensitive throttle pedal, where the engine immediately reacts on the pedal movement. And now imagine that while you are accelerating (holding the pedal let's say half way down), you press a little bit more on the pedal or release it a little bit, so the acceleration varies just a little bit. This is what I feel, but of course without changing the pedal state.
 

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My alfa mechanic buddy checked that too, he said he saw a lot of turbos and by moving the axle of the turbo he can feel with his finger the "state" of the turbo and he said it's fine. Of course this is not a precise measurement :) But I believed him that it's fine. And the twitching is not super bad, as a passenger I might would not notice it immediately. But as a driver, who knows and feels how do you press the throttle, you feel that the engine does not pull smooth.

Let me explain it a bit differently: imagine that you have a super sensitive throttle pedal, where the engine immediately reacts on the pedal movement. And now imagine that while you are accelerating (holding the pedal let's say half way down), you press a little bit more on the pedal or release it a little bit, so the acceleration varies just a little bit. This is what I feel, but of course without changing the pedal state.
Hi Ktamas,

My 1.9 JTDM does this too. Could be an EGR issue (assuming this engine has one) or as LSDIMA suggested something along the throttle body/air intake. It does always seem like a dive into a rabbit hole when trying to diagnose haha. Do you get strange noises when this happens?
 

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Hi Ktamas,

My 1.9 JTDM does this too. Could be an EGR issue (assuming this engine has one) or as LSDIMA suggested something along the throttle body/air intake. It does always seem like a dive into a rabbit hole when trying to diagnose haha. Do you get strange noises when this happens?
No strange noice or anything like that.
Is that possible that I also feel the switch of the variable valve timing? As far as I know it's around 2000 rpm with the 200hp TBi.

Thanks for the suggestions, next time I will have a look at the throttle first of all.
 

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What's the fuel economy like? If it's not a slightly dirty throttle body (the first place I'd check) then it could be the lambda sensor is on the way out. Around 1300rpm the lambda heater switches off.

I wouldn't worry about the service history now.. 35,000kms is about 20,000 and a lot of cars now only need a service every 18,000 miles (30k) so it's not a disaster (or at least too late to change anything). And if you use km's then chances are you're in a warm climate so the oil will have warmed through more often than if you lived in the UK. It would have helped.

Change the oil every 10,000km for a while, so the new oil can gradually remove any residues left behind.


Ralf S.
 

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What's the fuel economy like? If it's not a slightly dirty throttle body (the first place I'd check) then it could be the lambda sensor is on the way out. Around 1300rpm the lambda heater switches off.

I wouldn't worry about the service history now.. 35,000kms is about 20,000 and a lot of cars now only need a service every 18,000 miles (30k) so it's not a disaster (or at least too late to change anything). And if you use km's then chances are you're in a warm climate so the oil will have warmed through more often than if you lived in the UK. It would have helped.

Change the oil every 10,000km for a while, so the new oil can gradually remove any residues left behind.


Ralf S.
Thanks Ralf and all others the answers and help! Very appreciated.

I use the car in Switzerland (and was used here as well before).
What I did regarding the oil is that I've changed right after I bought it, and after 1500 kms too. So the engine is more or less "washed" I hope. I'm planning to change oil every 10k km until I own the car. It will thank it on a long run. Prevention is better than cure.

I think fuel consumption is ok: last 400 km: (~10% in city; ~20% highway 120km/h; 70% highway 80-100km/h) and the average is 8.6 l/100km at the moment. And this includes dynamic accelerations (with warm engine only).
 

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Thanks Ralf and all others the answers and help! Very appreciated.

I use the car in Switzerland (and was used here as well before).
What I did regarding the oil is that I've changed right after I bought it, and after 1500 kms too. So the engine is more or less "washed" I hope. I'm planning to change oil every 10k km until I own the car. It will thank it on a long run. Prevention is better than cure.

I think fuel consumption is ok: last 400 km: (~10% in city; ~20% highway 120km/h; 70% highway 80-100km/h) and the average is 8.6 l/100km at the moment. And this includes dynamic accelerations (with warm engine only).
You could use something like an oil system cleaner. I personally tried this one ( https://www.wynns.eu/product/oil-system-cleaner/ ) and I'm pretty happy with it, enigne sound improved also, though before I would recommend to remove the engine head cover and check for any oil residues ( I had the same problem with oil changed at 25k by one of the previous owners ). In my case was a thin layer of (red'ish) oil residue.

Liviu.
 
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