Hello All,

I have a 2016 Fiat 500 with 35K miles...have been getting check engine light only at idle...a misfire on cylinder 2. Did compression test and cylinder is 100psi compared to 210psi on the other three.

Talked to Fiat service department about warranty but it just expired. He told me he has never heard on cylinder 2 going bad only after 36K miles...he said me and my mechanic is probable doing the compression test wrong. He indicated the fiat engine is very complicated and need to be test with their diagnostic computer...He told me to take it in before I do anything to the motor...

Is this guy trying to trick me to take it in and charge me service fee...or is he telling me the truth that we did the compression test wrong...

I have a feeling he will just charge me fee and tell me cylinder 2 is bad

iwannafish said:

Hello All,

I have a 2016 Fiat 500 with 35K miles...have been getting check engine light only at idle...a misfire on cylinder 2. Did compression test and cylinder is 100psi compared to 210psi on the other three.

Talked to Fiat service department about warranty but it just expired. He told me he has never heard on cylinder 2 going bad only after 36K miles...he said me and my mechanic is probable doing the compression test wrong. He indicated the fiat engine is very complicated and need to be test with their diagnostic computer...He told me to take it in before I do anything to the motor...

Is this guy trying to trick me to take it in and charge me service fee...or is he telling me the truth that we did the compression test wrong...

I have a feeling he will just charge me fee and tell me cylinder 2 is bad

Click to expand...

My mom's 5oo, had the same problem, but a cyl 3 misfire. Try replacing the spark plugs first. Also, swap coil 1 with coil 2, so if you replace the coil and it reads a cylinder misfire, you'll know that, that specific coil, has the be replaced. Hope this helps.

Who did the compression test?
do the test again to check, 1.2 engine? If the result is still confirmed it's either the gasket to outside, leaking plug, broken valve or piston rings, either way it's a garage job and head off, don't rule out the plugs or leads, our plug lead failed causing a miss fire but the compression needs checking

In USA I think this will be a 1.4 engine, might have some differences to UK spec vehicles.

We need to know the exact engine for best help. Is it designated 'multiair' or similar?
If the valves are operated conventionally a standard compression test will diagnose well. If valves are electrically operated, or hydraulically 'on demand' diagnosis gets more complicated.

John202020 said:

Who did the compression test?
do the test again to check, 1.2 engine? If the result is still confirmed it's either the gasket to outside, leaking plug, broken valve or piston rings, either way it's a garage job and head off, don't rule out the plugs or leads, our plug lead failed causing a miss fire but the compression needs checking

Click to expand...

Yes USA.. so 'different rules' apply


To O.P. iwannafish

Is it oil and watertight ?

'Cylinder 2 misfire' is NOT conclusive...


However

Google the videos of Fiat Multiair to gauge what you are attempting to work with

Charlie

portland_bill said:

In USA I think this will be a 1.4 engine, might have some differences to UK spec vehicles.

We need to know the exact engine for best help. Is it designated 'multiair' or similar?
If the valves are operated conventionally a standard compression test will diagnose well. If valves are electrically operated, or hydraulically 'on demand' diagnosis gets more complicated.

Click to expand...

Thanks all for responding, sorry for not being clear on my question...

The main question is should I trust the fiat service person and take the car in to redo the compression test to see if cylinder #2 is bad. Based on Bill's respond, its possible cause the compression test needs to be done properly with their diagnostic computer. IS this correct...

Some background info

2016 Fiat 500 1.4L
- replaced sparks
- replaced coils
- check fuel injector

mis-fire always on #2 but only if you let the car idle for 2-3 minutes....During regular driving, no mis-fire...

cyl #1 - 210 psi
cly #2 - 100 psi
cyl #3 - 210 psi
cul #4 - 210 psi

tested #2 four times and always 100 psi

Could a bad Fiat Multiair cause a bad result in a compression test....

An old timer's trick is to squirt a small quantity of engine oil into the bad cylinder (through the plug hole) and repeat the compression test. If it restores or partially restores compression, the problem is likely a broken piston ring; if it's the same, the problem is likely to be with the valve gear.

It's also worth checking the cooling system holds pressure; if it doesn't, then it may be a head gasket problem.

iwannafish said:

Could a bad Fiat Multiair cause a bad result in a compression test....

Click to expand...

Yes.
If the system is not allowing enough air into the cylinder, low compression pressures will result.

As described above, a standard compression test should be done first dry, then wet. After the initial test, a couple of squirts of oil are put into the cylinder and the test repeated. Issues with piston or rings will usually show as a higher reading as the oil helps seal. If no change is found, any loss of compression pressure probably lies with valves or gasket.

It is likely that the multiair system is not working as it should on that cylinder.

I'd be trying a cylinder leak test on this one. A bit like a compression test but much more definitive and should let you know for sure if the engine is mechanically sound - ie pistons, rings, bores, valves etc. So once you've done it you should know whether you've got a leaking valve, excessive blow past a piston etc. If it checks out Ok then you can start confidently looking for more obscure things like electrics or multiair problems. I don't even know if your engines are multiair?

The UK speciaist found that it is normally the gasket sealing the multiair unit that fails tather than the £700 multiair unit

He had a batch of multilayer gaskets made and it was a successful fix

My inderstanding is a problem within the multiair control is stopping the cylinder being 'sealed ' effectively ... probably through impaired valve control

haha... for a moment I had hope that the issue is with the multiair. did some research on multiair and its not a simple cheap device/module I can replace myself

called the dealship, its $3500 to fix the multiair and $5000 for the piston ring....yikes...this is austin, TX


Read one thread about how low oil pressure can cause low pressure on the cylinder...in my case, I had a bit too much oil....drained to normal level but misfire is still there....maybe I should change out oil filter also...

after that, I'm out of ideas and will probable take it to the dealership...only issue is the dealship is almost 2 hrs away...

thanks everyone for giving me advice how to determine if its the valve or piston issue. Either issue is way beyond what I can fix...

No point messing with oil and filter, this will not fix the issue.

Unless you heard or felt a significant issue at soome time, it is unlikely to be a piston or ring issue. This is most likely to be a valve not sealing, and as described above by Charlie (Varesecrazy) this could be a simple fix. Be careful that they don't just swap out the multiair unit because they do not understand how to diagnose it properly.

varesecrazy said:

The UK speciaist found that it is normally the gasket sealing the multiair unit that fails tather than the £700 multiair unit

He had a batch of multilayer gaskets made and it was a successful fix

My inderstanding is a problem within the multiair control is stopping the cylinder being 'sealed ' effectively ... probably through impaired valve control

Click to expand...

'morning Charlie. So this multiair problem prevents the valve from seating properly? (ie, holds it off it's seat) or is it that it's failing to open the valve when the engine runs at low speeds?

Hope you are well
regards
Jock

iwannafish said:

haha... for a moment I had hope that the issue is with the multiair.

called the dealship, its $3500 to fix the multiair and $5000 for the piston ring....yikes...this is austin, tx

after that, I'm out of ideas and will probable take it to the dealership...only issue is the dealship is almost 2 hrs away...

thanks everyone for giving me advice how to determine if its the valve or piston issue.

Click to expand...

Hi
A member on here bought a good used motor for 400 canadian dollars..

The one thing.. you CAN probably do yourself : there is a small metal screen that filters the oil within the engine

It sounds like the car hasnt been to a FIAT service in a while.. so check it


I will post a link


https://www.fiatforum.com/500x/456448-500x-1-4-multi-air-oil-change-2.html?456448=#post4313914

One note..
High oil level...


How?

If it has gained fluid.. and lost water (coolant) you may have a different issue

Pugglt Auld Jock said:

'morning Charlie. So this multiair problem prevents the valve from seating properly? (ie, holds it off it's seat) or is it that it's failing to open the valve when the engine runs at low speeds?

Hope you are well
regards
Jock

Click to expand...

Hi Jock

Im fine thanks.. hope the same with you and yours


Multiair is complex..and then some..

It relies on oil pressure to even be 'enabled'

It has control over cam timing
And injection.. up to 7 pulses per piston stroke

( Jag are using it in their modern petrol engines.. as its a legitimate emission cutter)

In a conventional engine the variables are telatively confined...

But here there are many variables...

Electronic control being a big one

varesecrazy said:

Hi Jock

Im fine thanks.. hope the same with you and yours


Multiair is complex..and then some..

It relies on oil pressure to even be 'enabled'

It has control over cam timing
And injection.. up to 7 pulses per piston stroke

( Jag are using it in their modern petrol engines.. as its a legitimate emission cutter)

In a conventional engine the variables are telatively confined...

But here there are many variables...

Electronic control being a big one

Click to expand...

Thanks for the kind wishes.

I've read quite a bit about Multiair and I think I understand how it is supposed to work. Here's a video I found which describes it:

https://www.youtube.com/watch?v=5IrPcmMHqHE

What I don't know about is what goes wrong with them apart from having read somewhere about a chap who was having trouble with the pumping elements (held in by a big nut) coming loose and wrecking the casting in the process. The cost of sorting that must have been pretty eye watering!

During my you tube search I came upon this very interesting video about the Honda Vtec but it also discusses many of the simpler aspects of valve/piston operation so might be of interest to those browsing this thread who are not so technically inclined. The video is a bit gimmicky and very "American" so apologies but it explains things quite clearly I thought?:

https://www.youtube.com/watch?v=-R0LvgywiWk&t=14s

Then there is Honda's clever (I think it's clever anyway) I-Vtec valve train which is not particularly performance orientated (like the Vtec is) but concentrates instead on using the same technology to reduce pumping losses and give economy with power.

https://www.youtube.com/watch?v=Px0_6-Btx3Y

I still harbour a longing for a civic estate with this engine. I wondered about the reliability of those locking pins but several specialists have now told me they are not a problem. I also dislike the "flappy" control on the dual length inlet manifold as I've seen problems with this idea on other makes of car and I wondered if the throttle body butterfly spindle and it's controlling stepper motor might suffer wear but again I can't find any evidence that there are any problems with these. I've now driven one twice and like it very much.

Hope you enjoy
Jock

varesecrazy said:

Hi
A member on here bought a good used motor for 400 canadian dollars..

The one thing.. you CAN probably do yourself : there is a small metal screen that filters the oil within the engine

It sounds like the car hasnt been to a FIAT service in a while.. so check it


I will post a link

One note..
High oil level...


How?

If it has gained fluid.. and lost water (coolant) you may have a different issue

Click to expand...

I read about this during my research on Multiair. Thanks for the encourage, I will try to replace it before I take it in...since I have a lot of time right now and I have a spare car, I want to try to debug as much possible before I take it in...

on a positive note, I found a local mechanic that says he has experience fixing fiats. I might take it to him first and stress to look at the multiair gasket as the main issue.


haha, the high oil level was me putting too much oil in and forgetting to drain it before I put everything back.

kudos to everyone for posting links so I can understand more about this...I'm as green as they come, but I'm capable of learning

glad 2020 is over, what a year

finally took the car to the Chrysler dealership (fiat too far away). this is their findings:

1) smoked tested intake manifold and no leaks found

- is this comparable to the leak down test?

2) Using boroscope with cutl 2 at BDC inspected and found scoring on cylinder wall and piston damaged

- if piston is damaged, shouldn't it misfire all the time vs. only at idle....when I'm driving it, the car runs fine


Just want to hear yall thoughts before I take it in to get a new engine...they are quoting $11K, yikes

just curoius, can you even get a boroscope down to the cylinder wall without removing the head and multiair section