Hi everyone, has anyone experienced an uneven power delivery from the twinair engine, it's only under full load, I can hear and feel the turbo spooling up to full boost then backing off and coming in again, it does it quite quickly, it still goes ok, but it makes for an unpleasant acceleration. Thanks guys

Pashers said:

Hi everyone, has anyone experienced an uneven power delivery from the twinair engine, it's only under full load, I can hear and feel the turbo spooling up to full boost then backing off and coming in again, it does it quite quickly, it still goes ok, but it makes for an unpleasant acceleration. Thanks guys

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I wonder if it's an ignition problem, dodgy coil packs are not unknown

Mercky said:

I wonder if it's an ignition problem, dodgy coil packs are not unknown

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Hi there, it did cross my mind, although I would have thought it would present other issues, its fine in eco mode and when cruising on the motorway for example, but the issue only becomes aparent when you demand full power when accelerating hard ?

Are you sure that's not just how they are? Fiat/ Marelli have a slightly amusing name for the issue, but it escapes me. Some have reported better results on 98 octane, but I don't see a difference.

Happens at around 4-5k rpm.

Pashers said:

its fine in eco mode and when cruising on the motorway for example, but the issue only becomes apparent when you demand full power when accelerating hard

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Yes mine did the same thing, only apparent on hard acceleration - not in ECO mode - around the 3500 - 4000 RPM.

One coil pack replaced and all ok... luckily i had a spare on hand - easy 10min fix

UFI said:

Fiat/ Marelli have a slightly amusing name for the issue, but it escapes me.

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You mean "sobbing". Forum member The Twins described it as follows: Instead of vroooom you get v-v-v-vr-oo-oom hence the term 'sobbing'.

See: https://www.fiatforum.com/500/359475-warning-marelli-twinair-tuning-box-users-3.html?p=4033744

UFI said:

Are you sure that's not just how they are? Fiat/ Marelli have a slightly amusing name for the issue, but it escapes me. Some have reported better results on 98 octane, but I don't see a difference.

Happens at around 4-5k rpm.

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I have no idea, I wouldn't have thought do no, it's quite an obvious fluctuation, enough to make the passengers rock back and forth, a bit nauseating actually. You can hear the turbo pressure coming and going

AGH1965 said:

You mean "sobbing". Forum member The Twins described it as follows: Instead of vroooom you get v-v-v-vr-oo-oom hence the term 'sobbing'.

See: https://www.fiatforum.com/500/359475-warning-marelli-twinair-tuning-box-users-3.html?p=4033744

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So is it a problem or a quirk??

Cheers for the reply

Pashers, I don't know if your car really has this "sobbing" problem. That problem occurred when a Magneti Marelli tuning box was used on a TA. However, forum member UFI stated that his TA suffered from this problem without such a tuning box.

See: https://www.fiatforum.com/500/359475-warning-marelli-twinair-tuning-box-users-6.html?p=4039751

AGH1965 said:

Pashers, I don't know if your car really has this "sobbing" problem. That problem occurred when a Magneti Marelli tuning box was used on a TA. However, forum member UFI stated that his TA suffered from this problem without such a tuning box.

See: https://www.fiatforum.com/500/359475-warning-marelli-twinair-tuning-box-users-6.html?p=4039751

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Thanks for the reply. The car goes back to fiat main dealer on Monday so I guess we will see, it certainly doesn't feel right to me! I'll update you if i do get any answers! And once again, many thanks ??

Hi , I know it may not be the same engine as the old gt but I had a similar problem , under hard acceleration the turbo would boost up and then slow down , under normal driving it was ok , I found that a small vac pipe had come off from the turbo end , re attached it ad it's been fine since [emoji1303]

Just a thought could it be the waste gate on the turbo, if its only happening under max boost that would figure?

marcusgillies said:

Just a thought could it be the waste gate on the turbo, if its only happening under max boost that would figure?

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That's exactly what I think it is, fiat called today and said they couldn't replicate the issue (no idea why) and said there's no fault codes (I could have told them that)

I give our twinair 105 a fair poking sometimes and I've never noticed any throbbing. It certainly goes well once you get it between about 3000 and 5000 revs!

Fiat called today and can't fault the car, they can feel the pulsating but can't find a cause, wastegate and actuator on turbo are in good condition so that's my theory out the window lol

Pashers said:

Fiat called today and can't fault the car, they can feel the pulsating but can't find a cause, wastegate and actuator on turbo are in good condition so that's my theory out the window lol

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Perhaps they should ask Ed China...he seems to know all !!

Same issue on my 500 TA 2010, after several hard accelerations engine starts pulsating between 3000 and 4000 revs. Tryed to change coils, plugs, MAP, oil+filter (Selenia K) also brand new TA modul, issue still persists.

Any idea about root cause? Thanks

Is the turbo spooling/whistle sound on the twinair 105 very audible? I just bought a 500L with this engine and I can hear the turbo quite a lot. The power seems ok though.

I’ve never heard the turbo on my Twinair 105, but a turbo has very fine tolerances so I guess the tiniest difference can make a lot of difference to how much noise you get. You’ll need a few more opinions than mine to get a feel for this. Perhaps the sound deadening is better in a 500L muffling more of the bass tones and allowing through the higher frequency turbo whistle?