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Discussion Starter · #1 ·
I have a 159 with the 1750 TBi engine, but I have two problems with it.

1) Look on this video: 1750 TBi - YouTube . When I start my Alfa in the morning, it starts up nicely, but after several seconds, the engine speed drops significantly or eventualy stops completely. After I start it again, there is no problem and the engine is running without any drop. It seems that colder weather makes it worse - when it's freezing in winter, the engine usualy stops completely. And again, when I start the engine for a second or third time, it runs nicely even when freezing. And of course, it doesn't happen every time, sometimes there is just a small variation of idle speed several seconds after the startup.

2) When I run in low engine speeds (say 1500-2000rpm) and I press the accelerator, sometimes I hear a loud clicking mechanical noise from somewhere under the bonnet and the turbo pressure stays at 0.6 bar and won't riase even when the accelerator is all the way down. I can stay like this for whatever long time and nothing happens, turbo at 0.6bar and of course, my Alfa doesn't accelerate. The only cure is to release the accelerator and then press it again. After this, all is running as it should. Sometimes, the clicking sound is periodical with a period about 1 second, when the engine is shaking as the turbo pressure periodicaly goes from 0.6 to 1.2 bar. Again, releasing the accelerator cures the problem. This happens only at low engine speeds, say under 2000rpm.

I already was in Alfa service and they...just upgraded software in ECU :rolleyes:. The diagnostics showed an occasional problem with a knock sensor on cylinders 3 and 4 (error code P0330), so they cleared the error. Then I was in another service, which changed spark plugs (original NGK), but they told me that the 1750 TBi engine has no fuel filter, so they couldn't change it. Is this true?

There is no warning light on the dashboard.

Do you have any advice what should I check next?

Thanks,
Petr
 

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Is there really no fuel filter?

My mate picked up a new Moto Guzzi LM1 from the factory years ago -- they had no experience of anything other than open bellmouth carbs and couldn't conceive that a bike heading for Australia would need air filters.
 

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I had something similar. The throttle pedal needing to be released again before it would accelerate. It also had the knock sensor fault recorded in the ECU.

But in the end it was a fuel pressure fault. Once the pump was changed it was cured.
 

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Discussion Starter · #5 ·
I had something similar. The throttle pedal needing to be released again before it would accelerate. It also had the knock sensor fault recorded in the ECU.

But in the end it was a fuel pressure fault. Once the pump was changed it was cured.
Thanks! Did your problems happen only at low engine speed (say below 2000rpm)?

Have you also had any problems with idle after starting?
 

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Discussion Starter · #7 ·
Great, at least somebody has a) the same engine, which alone is a curiosity :rolleyes: and b) has similar problem.

Is there also some fuel pressure regulator or is it only the pump that might be responsible for proper fuel pressure?
 

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I've just returned from a 2700 mile round trip to Western France during which mine tried to kill me :eek: several times due to a fault almost exactly like #2 described by the OP.

Overtaking when you're sitting on the wrong side is difficult enough without the car throwing its toys out of the pram when you do attempt a manoeuvre, leaving you facing oncoming traffic with what feels like the power output of a moped at your disposal, :mad: . With mine it always occurred when the revs were between 2.5 and 3k, but it didn't happen with any sort of pattern making it impossible to predict. It might do it several times in quick succession then not at all for a few hundred miles then maybe once or twice before another lapse and so on, :confused: . Even winding it up first didn't guarantee success - you could push it all the way to 5.5-6k in one gear, change up and then have it unwilling to pull beyond 3k. The feeling was exactly the same as when you hit the rev-limiter, except at half the revs, and as described above the only 'cure' was to lift off then go back on the throttle, exactly as you have to do if you trigger the rev-limiter. A couple of times when it chucked it, I had the windows open and you could clearly hear a loud but short hiss of escaping air, suggesting the turbo dump valve had blown-off.

Coming up the A1 on Wednesday, around Harrogate, the engine management light came on accompanied by the "Have Engine Checked" message but, bizarrely, for the next 70 miles or so it was running better than it had for weeks - that was right up to the point where it went into 'limp' mode resulting in us completing the final 120 miles home at a maximum of 45mph, :rant: . I stopped several times to try and clear it (battery disconnect, the works) to no avail. Thursday morning, when I first fired it up the check engine message came up for a few seconds then disappeared along with the EML, :rolleyes: . It has not reappeared and the engine seems to be running 100% so I don't know if the dealer will be able to identify anything when it goes in next week.

Thinking back, it had been running a little bit 'off song' for a week or two prior to our departure, with an occasional hesitancy apparent when pulling away from low revs, but not enough to make me take it in for investigation. I knew that it would be due its 42k service upon our return so would have it checked then. Having since gone head to head with a juggernaut on a couple of occasions, boy do I wish now I'd taken it straight to the doctor then.
 

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I have experience in car and motorcycle maintenance dating back to schooldays when we rebuilt a MG TF (admittedly not to concours standard) but a scream when we got it going and received a severe reprimand for doughnuts on the cricket pitch (followed by congratulations on actually getting it back together and running).
I have rebuilt 100's of motorcycles, including my daily used 20 yr old Ducati, but at some point you realise someone can do something faster and better (albeit at a cost) than you. Hence modern engine diagnostics for example (well beyonf FECUScan) I hand it over to guys I can trust; and they can remedy it rapidly. I think that is where you are. Find a good indie who can do it and pay him - you'll appreciate the outcome and you give the small business guy who knows his Alfa beans good ongoing business!

I know of a few locally I can trust for specfic jobs, Petry I think you need to find one cos its a long drive to Yorkshire!"!
 

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Discussion Starter · #11 ·
I've just returned from a 2700 mile round trip to Western France during which mine tried to kill me :eek: several times due to a fault almost exactly like #2 described by the OP.
Could you please let us know what was the problem after you make the diagnostics? It seems that several TBi Alfas have a similar problem.
 

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Happened to me once as well. also during overtaking. Did not come back since 2k km, and no faults in computer memory... will be interested to see what may be of problem, cause my warranty runs out in Oct.
 

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I'd follow up on fuel pressure. Mine happened to last long enough for the dealer to get the diagnostics connected to show the low pressure.
 

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Update : there is no update - yet! :(. In typical Alfa fashion, the car made me out to be a liar as no error codes were found during the diagnostic check, :confused:. It has been performing perfectly for the few days since it's visit to the dealer but then on a 10 mile run today, the no power halfway through an overtake heart-stopper reared its ugly head again - not once, but 4 times, :eek: :mad: , and now it's gone all lumpy at idle too with the tacho needle flickering noticeably by about 100-150rpm or so. Oh well, back to the 'surgery' it goes, :cry:.
 

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Sometimes when cold starting the engine the revs can flicker with 100-150 rpms for a couple of secs but that can't be abnormal, can it?
 

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Update : there is no update - yet! :(. In typical Alfa fashion, the car made me out to be a liar as no error codes were found during the diagnostic check, :confused:. It has been performing perfectly for the few days since it's visit to the dealer but then on a 10 mile run today, the no power halfway through an overtake heart-stopper reared its ugly head again - not once, but 4 times, :eek: :mad: , and now it's gone all lumpy at idle too with the tacho needle flickering noticeably by about 100-150rpm or so. Oh well, back to the 'surgery' it goes, :cry:.
Exactly like mine. It will be the fuel pump.
 

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OK, so I'm just back from another visit to the dealer and this time they were able to retrieve 5 fault codes, all relating in one way or another to the Lambda Sensor. Apparently there is a known issue with the wiring (there has been a Technical Bulletin issued), and a loom modification will be carried-out next week once they get the relevant parts in.

The last couple of weeks, whilst it has been running relatively OK, the fuel consumption has gone through the floor. The readout has optimistically been suggesting an overall average figure of 21.7mpg (which is bad enough, :mad:) but in reality (brim to brim) it has been 19.2, :eek: (even my old V6 was way better than that), with the instantaneous readout getting down below 3 on full throttle. I got my good lady to take it out and give it a thrash with me following in the 'G' and it was chucking out a lot (and I mean a LOT) of black smoke under acceleration, so hopefully this relates back to the Lambda fault and I'll see a major improvement after next week. I was averaging 33+ before so it would be nice to get back closer to that figure, :rolleyes:.

I'll keep you posted of any developments.
 

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Update.

The modified wiring loom to the Lambda sensor was fitted on Wednesday. Since then I've covered about 300 miles with absolutely no hint of any lack of power, loss of throttle response or hesitancy of any sort. In fact, if anything, it now has some added 'urgency' under full throttle and the latest brim-to-brim measurement has returned 32.3mpg so it looks like normal service has been resumed, :thumbs: :D.
 

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Update.

The modified wiring loom to the Lambda sensor was fitted on Wednesday. Since then I've covered about 300 miles with absolutely no hint of any lack of power, loss of throttle response or hesitancy of any sort. In fact, if anything, it now has some added 'urgency' under full throttle and the latest brim-to-brim measurement has returned 32.3mpg so it looks like normal service has been resumed, :thumbs: :D.
Could I ask you to PLEASE get me the part number for the correct wiring loom? My car has the same problem with the same poor fuel economy! :( I've even lost a turbo already but the dealer doesn;t get any fault on the car!:confused:
 
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