Seicento not quite an owner

[Tuga2112]

yes, new guy here.. i dont "have" a seicento. but look after one from a family member. so im joining here as i need help with fixing it.

theres a small chance someone here already knows me. as im a rather active member of a different car's scene and have a outube channel with plenty of content on other cars.
but as fr as the sei. i dont really record the work on do on it.

so. yes., im new here, but been faffing about with petrol cars for 10 years, but all of them have japanese engines, so when it comes to Fiat, i am pretty clueless.

i guess this is not the right place to ask. but the issue im looking into is the car stalls when the throtle is applied, this seems to always happen when warm. but when cold its usually ok.
if anyone can point me in the right direction ill appreciate it. but for now ill be having a browse on the forums see if someone else has had the same issue before

and finally, heres a shameless plug to the videos i have on the sei on youtube.

 

[varesecrazy]

Hi

Tell us more, new plugs..
Scanned for errors.. Etc

Member @blu73 may well "know your work" , and the foibles of a Sei..

Nor for me I'm afraid ( I'm allergic..)

 

[Tuga2112]

Tell us more, new plugs..
Scanned for errors.. Etc

theres no CEL light on, and being the 0.9 SPI model cant connect an obd.
i have been pointed in a thread in here about someone who got a startrek software running to comunicate with the marelli ecu and get data, after a bit of digging i got the software and already ordered the cables for it (considerably more expensive than the lotus alternative ive setup, but cheaper than the toyota setup i am aware of)
as far as new parts... the car had a vacum leak a year ago and failed mot.. before finding the leak, i started swapping parts.. so the following are all "new" (as rougly a year old, and less than 600miles use) parts
plugs
leads
coils
O2 sensor
TPS
air filter
fuel filter
fuel tank
fuel pump is 3 years old, and confirmed running
MAP sensor
oil
oil filter
coolant

as far as the issue, i have ordered this moring both a replacement thermiostat (although i am pretty sure its good) as well as a CTS (which i confirmed the resistance changes with temperature, but im not sure its actually reading with the right figures)

as someone who is used to seeing parts priced for a celica gt4 and a lotus elan. i find it very easy to just buy replacemetns to keep on the shelf for the sei, as if its the wrong part, i know i have a good in the shelf and confirmed the issue is not this for a "small" sum

also, as someone used to work on a lotus... changing bits on the sei is generally speaking a trivial matter.. partially reason why i never joined the forum before as the car has been rather reliable, and very easy to work on on the rare ocasions it needs work

 

[blu73]

these are actually pretty easy to get codes from.. you need a vagcom cable and a fiat 3-pin to OBD2 adapter.
Then you can use IAW-Scan2 or the free version of MultiEcuScan to read and clear codes. cable/adapter both readily available on ebay etc for not much.

your running issue could be a few things but from running these I'd be inclined to try a new crank sensor - they tend to not give a light until they fail fail and usually work cold and the signal starts breaking up as they get warm. Same goes for coils, they can act up with heat as well. But crank sensors have always been a weak point on them even when they were not old cars and you can get one for about a 10er so can't hurt trying. Usually if you read codes and have a failing crank sensor it will have logged misfires but no actual faults unless it goes full open circuit at which point you get no fuel or spark at all.

 

[Tuga2112]

these are actually pretty easy to get codes from.. you need a vagcom cable and a fiat 3-pin to OBD2 adapter.
Then you can use IAW-Scan2 or the free version of MultiEcuScan to read and clear codes. cable/adapter both readily available on ebay etc for not much.

your running issue could be a few things but from running these I'd be inclined to try a new crank sensor - they tend to not give a light until they fail fail and usually work cold and the signal starts breaking up as they get warm. Same goes for coils, they can act up with heat as well. But crank sensors have always been a weak point on them even when they were not old cars and you can get one for about a 10er so can't hurt trying. Usually if you read codes and have a failing crank sensor it will have logged misfires but no actual faults unless it goes full open circuit at which point you get no fuel or spark at all.

I'll order a crankshaft sensor tonight. The cooks were swapped last year, so I'm going to assume they're fine,
Funny you mention the sensor, because the one there is actually one I've fitted a while ago (pre lockdown)
I'm going to give it a clean tomorrow morning and retest but buying a spare replacement regardless.

As far as reading codes, it's good to know there's more than one piece of software for that, I will look into those as well

 

[blu73]

IAW Scan2: home

Multiecuscan - Diagnostics software for Italian cars

 

[Tuga2112]

I Have sucessfully connected the computer to the car and got readings.
theres no trouble codes registered.
also changed the coolant temperature sensor as well as the cam angle sensor.
car is still dying when i put the foot down when its warm.
seems that running cold will be just fine
i have also taken the throtle body apart to check if there was anythign clogged, but no signs of any trouble.
im wondering if i shoudl swap the spark plugs ? the thing is. the ones currently there are only 1 year old and have less than 300 miles. so it seems rather unlikely they would be a problem.

im running out of ideas of what could be wrong with this car. starting to wonder if i should be checking the cilinders for compression but i dont see how that could be an issue only when putting the foot down warm. as i would assume if theres an issue with compression warm, the idle would also suffer.

i have a replacement thermostat. im wondering if a thermostat stuck close may cause the ECU to decide to cut off when the foot is down because the coolant is too hot maybe ? HOWEVER my underrstanding is that
1 - thermostats are designed to fail open
2 - a closed thermostat woudl keep the radiator coolant cold, and i can feel a hot hose coming out of the radiator at the top

 

[blu73]

the ecu is way more simple and not clever than you give it credit for, there is no limp mode or anything like that.

The thermostat is a mechanical device, it can fail in any position, open, closed or anywhere in-between - but the ecu has no idea what the stat is doing, only the coolant temp. the coolant flows from the head, through the stat once open, in the top of rad and out the bottom. So in correct operation the top rad hose should stay mostly cool until the stat opens then suddenly get warm - thats a bodge test of it anyway. It shouldnt slowly warmup with the engine temp, that would indicate its stuck open (there is a small hole so water can always flow so it will creep up slowly but there should be a moment when the stat cracks open and it suddenly warms up.

categorically though, the stat is not related to the issue unless the issue is caused by overheating which doesnt sound like the car does... compression test can't hurt none, you can check the plugs at same time - might give you a good indication of whats going looking at the plugs, if its running rich, if ones massively different to the others etc.

 

[vexorg]

When you say dying when you put the foot and the engine is hot, do you mean from idle, or just a lack of power when already moving?

The thermostat should be easy enough to know if it's roughly right by feeling the heat in the radiator.

Does the software report the coolant temp from the ecu?

When it dies, does it misfire or just bog down.
Does that car have a single coil, or coil pack, or coil per plug?

 

[Tuga2112]

the ecu is way more simple and not clever than you give it credit for, there is no limp mode or anything like that.

The thermostat is a mechanical device, it can fail in any position, open, closed or anywhere in-between - but the ecu has no idea what the stat is doing, only the coolant temp. the coolant flows from the head, through the stat once open, in the top of rad and out the bottom. So in correct operation the top rad hose should stay mostly cool until the stat opens then suddenly get warm - thats a bodge test of it anyway. It shouldnt slowly warmup with the engine temp, that would indicate its stuck open (there is a small hole so water can always flow so it will creep up slowly but there should be a moment when the stat cracks open and it suddenly warms up.

categorically though, the stat is not related to the issue unless the issue is caused by overheating which doesnt sound like the car does... compression test can't hurt none, you can check the plugs at same time - might give you a good indication of whats going looking at the plugs, if its running rich, if ones massively different to the others etc.

from that description, i am pretty confident the thermostat is fine.

i did take the plugs out and i think it was overfueling on 2 but to be honest i im not familiar enough with what their meant to look like to be sure.

When you say dying when you put the foot and the engine is hot, do you mean from idle, or just a lack of power when already moving?

The thermostat should be easy enough to know if it's roughly right by feeling the heat in the radiator.

Does the software report the coolant temp from the ecu?

When it dies, does it misfire or just bog down.
Does that car have a single coil, or coil pack, or coil per plug?

When you say dying when you put the foot and the engine is hot, do you mean from idle, or just a lack of power when already moving?

both, it completely shuts off. both when moving or at the ramp.

Does the software report the coolant temp from the ecu?

yes, it does and seems within what i woudl expect. gone up from 60 to 82 in the run. which is not surprising because when i plugged it the engine already had ran earlier and the coolant should have been warm to start.

When it dies, does it misfire or just bog down.

just bog down, theres no signs of misfire that i can hear

Does that car have a single coil, or coil pack, or coil per plug?

2 coil packs. with 2 plugs attached to each pack both packs are new, as well as the leads. and the plugs are only 1 year old with less than 300 miles

 

[blu73]

my money is still on crank sensor, did you get one?

 

[Tuga2112]

yes

cam angle sensor

i meant crank angle. sensor.
the one that you reach from the drivers side wheelarch.