Jerky on 1st and 2nd when cruising

[Milnoc]

Hello all, I'm having an interesting problem with my 2015 Fiat 500 Abarth with manual transmission. It has 81,700 km and I'm the second owner.

The car can be a bit jerky at 1st and 2nd gear when I'm cruising at about 2,000 to 3,000 RPM. It's at its worst on 1st gear. It isn't overly dramatic, but it's definitely noticeable.

It ISN'T jerky when I'm accelerating or slowing down! And it isn't jerky once I reach 3rd gear.

This has been an ongoing problem with the car, but I'm now wondering if it's getting worse especially since I don't recall noticing this happening on 2nd gear, at least not too often to care.

I was thinking the clutch and throwout bearing since they're the usual suspects, but everything seems to be fine with that. I haven't experienced any clutch slippage at all or heard any weird noises. I do need to clean and lubricate the sideways lever since the shifter won't center on its own.

Aside from that issue, the rest of the car seems to be working fine. Tires at the right pressure, no CELs, fluids are good, added Redline MT-LV transmission fluid last July which works wonders in the winter. Note that the jerkiness was happening before the transmission fluid change, so I don't think that's the issue either.

Any ideas? Is it possible to inspect the clutch without dropping the transmission?

Thanks!

[doverosx]

Is this with Sport mode on?

[map]

That's an interesting problem. Doverosx, why are you thinking sports mode on?

I am not sure exactly what you mean by jerky but I assume you mean small pulses. Off the top of my head I can think of a couple things. First, are there any codes (have them scanned)? In other brands I've seen, the engine can surge when not under load, which might explain 1st and now 2nd gear.

Next, I've had one car where a CV was going out (binding) and caused some jerking, exagerated when turning. 3rd could possibly be the dual mass flywheel, if a spring is broken. That might also cause an increase in engine "tapping" at idle. Those are just guesses.

[Milnoc]

This is happening in regular mode. It does get a bit worse in sport mode. It does feel like small pulses, but the engine is running smoothly when it happens.

I've scanned for codes not long ago. The only pending code was B11FA, which is the internal humidity sensor next to the rearview mirror.

The only thing I know about turns is that it seems okay. However, either the clutch is engaged or I'm accelerating, so I wouldn't feel anything.

It's due for an oil change which I do at a DIY garage on a lift. I'll inspect the CV axles, wishbone, and clutch if I can access it with a boroscope.

Keep the guesses coming!

One more thing. I doubt it's the bearings. Along with no strange noises, I put my hand on the hubs after my commute and found no wild temperature variation. I'll double-check them during my inspection.

One other thing I'll try: engaging cruise control at a low speed. What if it were the accelerator pedal?

[Fiat500USA]

I don't know if this is what you are experiencing but Abarths are known to have a jerky/surging power delivery. It is like steps in the power curve while accelerating using light to medium throttle. It is very noticeable and we've had a few threads on it tagged: Surging

If it is while steady speed driving, typically that is a lean condition. You may also have to look at boost control components.

I'll take a look at my car when I go to work later and see what it does cruising at 3000 rpm in 2nd gear. I generally don't drive like that, so I'll give it a shot.

[Fiat500USA]

Also, make sure you check the oil and if the oil is dirty you could have running issues. My friend bought a 500 from a guy who thought the engine was blown. It just needed oil. The shop the previous owner went to didn't check the oil and proclaimed the engine bad. It was just low on oil. Long interval oil changes are not good on modern cars

[Milnoc]

Oil levels are checked at almost every fill-up. However, it's due to be changed now (8,000 km). In fact, I was planning to change it today after work if the DIY Garage has an opening.

The engine tuning is still stock. I'll monitor the fuel mixtures to see if there's anything weird going on. It's possible nothing's wrong and the car simply prefers to be driven a bit hard.

[doverosx]

That's an interesting problem. Doverosx, why are you thinking sports mode on?

I am not sure exactly what you mean by jerky but I assume you mean small pulses. Off the top of my head I can think of a couple things. First, are there any codes (have them scanned)? In other brands I've seen, the engine can surge when not under load, which might explain 1st and now 2nd gear.

Next, I've had one car where a CV was going out (binding) and caused some jerking, exaggerated when turning. 3rd could possibly be the dual mass flywheel, if a spring is broken. That might also cause an increase in engine "tapping" at idle. Those are just guesses.

The throttle mapping from the factory isn't the smoothest for the first 25% in non-sport and first 50% in sport mode. There is a "crawl" mode that is enabled at low speeds and the transition between crawl/take-off/cruise may not be very smooth - I'm hedging my bets on normal ;-).

[Milnoc]

I'll find out this Sunday morning (only opening left this weekend).

Will I have to soften the mapping like I softened the suspension?

[HotEars]

I don't know if this is what you are experiencing but Abarths are known to have a jerky/surging power delivery. It is like steps in the power curve while accelerating using light to medium throttle. It is very noticeable and we've had a few threads on it tagged: Surging

Exactly, this is completely normal and a characteristic of the Abarth, it's got this jerky acceleration that feels like an animal that just wanted to pounce.

Cool but annoying at slow speeds and parking lots.