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Discussion Starter #1
Got an Alfa 159 about 4 months ago. Up until this point I've changed the following: rear springs, one front suspension arm, 2 bushings, a thermostat, a dpf, a temperature sensor on the dpf, hand brake cable. I currently have no error codes and the car runs fine. Cleaned MAP and MAF, known for a fact EGR is off, remapped and blanked, also swirl valves are blocked in the off position. I decided to map the car to the original software and have the EGR back on. I'm happy with the car for now, with the exception of one thing: I cannot believe it is so lazy with low down revs. It's been the same with the EGR off, before. If i exit a roundabout in second at 1100 rpm or so, i grow old until revs pick up until 1500-1600 and turbo kicks in. If I am slowed down by traffic in front of me to again, about 1 to 1.2k rpm in 2nd, it takes ages to regain speed until turbo kicks in at about 1500 rpm. Same with taking sharp corners in which you have to slow down. Is the problem the swirl flaps removal? I'm thinking of getting a new inlet manifold with fresh swirl valves next. Also, I seem to be getting close to a DPF regeneration, since it says it's about 90% clogged. Is it normal that the car at this stage doesnt boost fully? It boosts only to about .8 to 1 bar and is more sluggish recently. I know it's not a vacuum leak since: a) it's only been this way the past few days, it doesnt smoke nor whistle or make any strange noises and b) the boost works well for the first minute or so when starting the engine, be it cold or warm.
 

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First off what manifold is fitted as plastic ones can’t be blocked in off position they need removing. In fact I would strongly advise getting rid as they kill the engine when ingested.
On to the fault I would say either vanes are sticking,n75 on slam panel not working correctly,vac hose issue or it has taken in some swirl flaps damaging the exhaust wheel in turbo.
 

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Discussion Starter #3 (Edited)
First off what manifold is fitted as plastic ones can’t be blocked in off position they need removing. In fact I would strongly advise getting rid as they kill the engine when ingested.
On to the fault I would say either vanes are sticking,n75 on slam panel not working correctly,vac hose issue or it has taken in some swirl flaps damaging the exhaust wheel in turbo.
It has the alloy inlet manifold. Regarding the low down power, isn't the turbo effective from about 1400rpm onwards? The turbo itself has been recently taken apart for checking and was fine, plus, the car works fine when regened, I had this happen before. Before a regen it is sluggish and doesnt fully boost. How lazy should the alfa be in the low rpm range? Could it be in my head? I just can't seem to get around traffic as i would wish.
 

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So manifold is the safer one then, have you any leaks around the swirls as that can cause issues.
It is a heavy car and I found mine to be a bit lethargic but not as bad as you describe yours is like,plus you say it’s ok when first started so there’s clearly a problem.

have you plugged diagnostics on to see if any faults logged?
 

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Discussion Starter #5
So manifold is the safer one then, have you any leaks around the swirls as that can cause issues.
It is a heavy car and I found mine to be a bit lethargic but not as bad as you describe yours is like,plus you say it’s ok when first started so there’s clearly a problem.

have you plugged diagnostics on to see if any faults logged?
No faults logged, swirl flaps are blocked, no leaks around them. So it should behave the same way all throughout the "driving range" of the dpf? As in same power first kilometer after regen as the last kilometer before a regen lets say?
 

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Discussion Starter #6
So manifold is the safer one then, have you any leaks around the swirls as that can cause issues.
It is a heavy car and I found mine to be a bit lethargic but not as bad as you describe yours is like,plus you say it’s ok when first started so there’s clearly a problem.

have you plugged diagnostics on to see if any faults logged?
One more question. Whenever i downshift i try to rev match as it's both easier on the transmission and more comfortable for the people in the car. But it's really hard to? It revs pretty slow and it's hard to bring the revs up fast enough for a nice rev match downshift. Is this just because of the nature of diesel engines?
 

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Have you cleaned the TMAP sensor? Also check the injector wiring plugs. I had to replace mine as the insulation had degraded


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Discussion Starter #8
Have you cleaned the TMAP sensor? Also check the injector wiring plugs. I had to replace mine as the insulation had degraded


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Yes i have, the map sensor was clean, just a bit of oil on it nothing much. The wiring also seems fine on the outside, and the idle is not rough. Injector values are also fine.
 

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0,8 boost is not right, regardless if pre or post regen. Lower boost is acceptable when regen is active (you can tell that by enormous inst.fuel consumption).
If there are no leaks and MAP is healthy - turbo vanes are sticking or faulty n75 valve (vacuum turbo actuator).

It does not rev as fast as Honda VTECs, but I have no troubles rev-matching on the downshifts - both in slow/comfy and sporty driving modes.

Try disconnecting MAF sensor and take her for a spin (car will run from default map from MAP sensor readings). If it gets better - your MAF is faulty/incorrect model.
 

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Discussion Starter #10
0,8 boost is not right, regardless if pre or post regen. Lower boost is acceptable when regen is active (you can tell that by enormous inst.fuel consumption).
If there are no leaks and MAP is healthy - turbo vanes are sticking or faulty n75 valve (vacuum turbo actuator).

It does not rev as fast as Honda VTECs, but I have no troubles rev-matching on the downshifts - both in slow/comfy and sporty driving modes.

Try disconnecting MAF sensor and take her for a spin (car will run from default map from MAP sensor readings). If it gets better - your MAF is faulty/incorrect model.
I'll start with the MAF, and then look into that n75 valve and turbo vanes situation. Thanks everyone!
 

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Overall, JTD(m)s are pretty rev-happy engines and are usable throughout the whole RPM range, unlike some other diesel engines, where after 3k RPM there is just noise without any additional power/acceleration.
I personally don't keep it below 1,3k rpm - it puts too much unneeded strain on the drivetrain when quick acceleration is suddenly needed.
1,5-2k is the sweet spot for normal city driving, in my opinion. Below that it sure is less responsive, and is not a traffic light race warrior at any given conditions.

There is enough torque right from tick-over in my 5-cyl variant, that you don't need any accelerator input really when starting from standstill.
Rolling into roundabout in 2nd at low rpm have not given me any troubles also - it will be slow at first, but will pick up pretty quickly, giving it some gas pedal input. I have not caused any traffic congestion so far because of 'lazy' low down power delivery.

Just familiarize yourself with the engine better and learn when to give it some gas or change down beforehand to overcome a turbo lag.
 

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Discussion Starter #12
Overall, JTD(m)s are pretty rev-happy engines and are usable throughout the whole RPM range, unlike some other diesel engines, where after 3k RPM there is just noise without any additional power/acceleration.
I personally don't keep it below 1,3k rpm - it puts too much unneeded strain on the drivetrain when quick acceleration is suddenly needed.
1,5-2k is the sweet spot for normal city driving, in my opinion. Below that it sure is less responsive, and is not a traffic light race warrior at any given conditions.

There is enough torque right from tick-over in my 5-cyl variant, that you don't need any accelerator input really when starting from standstill.
Rolling into roundabout in 2nd at low rpm have not given me any troubles also - it will be slow at first, but will pick up pretty quickly, giving it some gas pedal input. I have not caused any traffic congestion so far because of 'lazy' low down power delivery.

Just familiarize yourself with the engine better and learn when to give it some gas or change down beforehand to overcome a turbo lag.
In my case, car stalls if i let the clutch out without accelerating. It even almost stalls with moderate acceleration input since once the clutch is all let out the car sometimes jerks me because it gets under 900 rpm. I cant change down to first when im still rolling at a decent speed because of the harsh engine braking and also the feeling that the gear stick doesnt wish to go into 1st when still rolling with a decent speed (10km/h-ish?). I really rev the car hard, almost never go below 2k rpm (ofc when it's warmed up) but sometimes trafic or a roundabout or corner anything like that forces me to reduce speed and once slowed down it just doesnt want to get going until it gets to 1500 even 1600rpm. If i go up a hill in third at about 1400rpm because its in a corner, car will just slowly slow down until it baaarely makes it up the hill giving you the feel it will stall beforehand so i always get it into 2nd, but it just doesnt seem right.
 

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Discussion Starter #13
I'll start with the MAF, and then look into that n75 valve and turbo vanes situation. Thanks everyone!
Disconnected the MAF. No difference whatsoever. Pending fault codes p0111 and p0101 after disconnection, car boosts the same only so slighty revs faster when revving in neutral/ clutch depressed.
 

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Discussion Starter #15
can you read the pressure across the dpf?
I've only got a simple bluetooth obd2 scanner and am using torque pro, but i have not found a custom PID to work for dpf pressure or clogging. If anyone can help me with that, I could give you an answer right away but if not, i have to wait until i see my mechanic 😐
 

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I've only got a simple bluetooth obd2 scanner and am using torque pro, but i have not found a custom PID to work for dpf pressure or clogging. If anyone can help me with that, I could give you an answer right away but if not, i have to wait until i see my mechanic 😐
Try AlfaOBD (free/demo) for Android. Your OBD scanner may not work with other modules, but it should read engine ECU..in theory.
 

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Discussion Starter #17
Try AlfaOBD (free/demo) for Android. Your OBD scanner may not work with other modules, but it should read engine ECU..in theory.
Thanks. Will do. New symptoms have appeared: pretty thick white-blueish smoke on startup and acceleration for the first couple miles (didnt get smoke before) and a slight whistling noise from under the hood when lifting foot of the throttle. Didnt get it before.
 

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Discussion Starter #18
Try AlfaOBD (free/demo) for Android. Your OBD scanner may not work with other modules, but it should read engine ECU..in theory.
Well obd connects but alfaobd says that it cannot receive the iso code? When i try to read dpf clogging, differential pressure it says request not supported by control unit.
 

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Well, I don't remember if it showed that code because of inability of scanner to fully read the ECU, or because you have chosen incorrect ECU from the list.
You've picked the first option - Bosch diesel EDC16 CF4 1.9/2.4, correct?
 

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Discussion Starter #20
Well, I don't remember if it showed that code because of inability of scanner to fully read the ECU, or because you have chosen incorrect ECU from the list.
You've picked the first option - Bosch diesel EDC16 CF4 1.9/2.4, correct?
Yes i have.. also tried the others just for good measure
 
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