General Spark plug reading fiat stilo 1.6

[NebulaStilo]

Recap my issue:
Surge
Loss power
No CEL
Fuel economy not very good

Replaced all parts it could be.
I had a p0141 and bought new sensor(universal upstream it seems)so put upstream sensor to downstream and brand new sensor to upstream. Code went away.never returned. Still a surge. I unplug new sensor and she runs better,slight surge occasionally,fool ecu by swopping connectors that downstream is now up etc and still runs better so I moved upstream(brand new sensor) to downstream and vice versa(ie old upstream back where it was). Still run better with no codes also.
New O2 sensor was a sensor the ECU did not like.

Shes still bit down on power and surge more prevailent when engine under load or hard acceleration. But driving much better.low speed driving is easy now,no jerks etc.

I checked plugs and this is what they looked like.These are new plugs bought like 2 or 3 months ago
Since replacing parts and sensors that it could be ,I'm looking at compression now,especially after seeing these plugs.I think they being thrown dead with oil leaking into combustion chamber because she occasionally puffs out a ball of blue-ish smoke.
Have a family member who has a tester but hasn't used in ages so he needs to find it.waiting on him,obviously busy.

I priced parts for a engine overhaul since she is very high mileage so might as well do all internals while down there. Price knocked my sneakers off??#LottoTime

Please help me read these plugs and tell me if I'm wrong.
Tell me about the Throttle body update on ECU if that will work.

 

[Ralf S.]

Those don't look too shocking.

From left to right, #1 looks like it has a lot of deposits on the central insulation? That could be a low compression cylinder.

#4 looks a bit oily.. so you could have a valve stem oil leak on that cylinder. If you clean it up with WD40 or some other solvent, to get the oil off it.. and then go for a drive, does the car run okay? The surge could be that a cylinder isn't firing all the time.. just occasionally (hence the surge).


The middle two look pretty good.



Ralf S.

 

[NebulaStilo]

Those don't look too shocking.

From left to right, #1 looks like it has a lot of deposits on the central insulation? That could be a low compression cylinder.

#4 looks a bit oily.. so you could have a valve stem oil leak on that cylinder. If you clean it up with WD40 or some other solvent, to get the oil off it.. and then go for a drive, does the car run okay? The surge could be that a cylinder isn't firing all the time.. just occasionally (hence the surge).


The middle two look pretty good.



Ralf S.

Hi

I did clean them off,used some carb cleaner on a cloth then wipe off. Those deposits I got most off with piece of wire,not a brush,making sure not to damage the plugs.

At first she misfired bad on idle. I switched off and she idled back up no misfire. Surge still there.

When under load say up a hill,very very seldom will she make a 'clank' noise. When she does that she puffs out smoke.

Sounds like spark knock on my mother's mach1 golf but bit louder??
If it's spark knock then I would think its the ECU trying to adjust ignition timing along with AF ratios along with a low compression motor.

Please correct if I'm wrong.

Fyi the clank sound sounds close to driver side(right hand drive)ie the cylinder no1 plug came out of.they are in order as they are there 1 to 4

 

[Ralf S.]

The spark plugs aren't the cause of the problems then. They're usually fairly consistent and don't change behavior between the engine being switched off and then back on again.

If you hadn't had a load of grief with the airbox and lambda's, I'd say it sounded more like a fueling problem... but the spark plugs show the fueling is okay.

Deposits on the plugs could be a low compression so it'll be useful to get that tested.. but one cylinder on low compression (or even all four) wouldn't cause surging and good idle followed by bad idle. It would idle badly all the time and it would just be slow, not slow then fast.

I'm thinking the problem is in the ECU, since pinking means that the ignition or the mixture aren't correct. A weak mixture could be caused by an external problem (MAP, lambda etc.) but again, when you swap the sensors around, the car behaves more or less the same.

Did the previous guy try to re-program the ECU at all? If the lad fitted a cone filter he could have done other "mods" which are now causing problems. Did you way you had a spare virgin ECU? It would be good to find a way to confirm your ECU isn't flakey.


Ralf S.

 

[NebulaStilo]

The spark plugs aren't the cause of the problems then. They're usually fairly consistent and don't change behavior between the engine being switched off and then back on again.

If you hadn't had a load of grief with the airbox and lambda's, I'd say it sounded more like a fueling problem... but the spark plugs show the fueling is okay.

Deposits on the plugs could be a low compression so it'll be useful to get that tested.. but one cylinder on low compression (or even all four) wouldn't cause surging and good idle followed by bad idle. It would idle badly all the time and it would just be slow, not slow then fast.

I'm thinking the problem is in the ECU, since pinking means that the ignition or the mixture aren't correct. A weak mixture could be caused by an external problem (MAP, lambda etc.) but again, when you swap the sensors around, the car behaves more or less the same.

Did the previous guy try to re-program the ECU at all? If the lad fitted a cone filter he could have done other "mods" which are now causing problems. Did you way you had a spare virgin ECU? It would be good to find a way to confirm your ECU isn't flakey.


Ralf S.

Standard air box.
Car was bought from dealer so no clue about owner history.

When I put the new lambda I bought on upstream or on upstream role then she really behaves badly and misfires at round 2000rpm.
Then when putting old upstream sensor which I put on downstream when replacing with brand new sensor,she behaves much better. Still a very slight surge and low on power but better than before.

When she reaches 4000 the power comes and she moves. But times she is sluggish all way through revs.

Then at idle she idles rough generally. Even if its sort of smoooth it's still low ish. Times it like she wanna switch off but ECU corrects her.

The surge is only on acceleration.like a boat rocking. Thats with brand new o2 on upstream. With old upstream back in its original place,upstream,she doesn't surge that much. Like you must really concentrate to feel.at heavy engine load or hard acceleration the surge is evident. But always is the low power clear. Its clear she is down on power. I struggled yesterday to run away from a normal Toyota van which I could normally run away from.

When she very low on power then blue smoke comes out.

Brand new sensor is sitting on downstream. No CEL.
Maybe try running her with downstream unplugged, completely removing brand new sensor from attributing to fuel mix. Maybe she still throwing AFR off slightly?

When plugs was out,I took a light and looked down the hole,saw top of piston and just see black oil buildup. That sticky stuff.

Maybe a ECU update and remap?

 

[NebulaStilo]

Also I'm doing a oil change as part of normal maintenance.

Is engine flush good for old high mileage engine like mine? I'm scared it will remove sludge that is actually protecting engine seals etc.

Is this true because that's what they say few places on the net

 

[NebulaStilo]

The spark plugs aren't the cause of the problems then. They're usually fairly consistent and don't change behavior between the engine being switched off and then back on again.

If you hadn't had a load of grief with the airbox and lambda's, I'd say it sounded more like a fueling problem... but the spark plugs show the fueling is okay.

Deposits on the plugs could be a low compression so it'll be useful to get that tested.. but one cylinder on low compression (or even all four) wouldn't cause surging and good idle followed by bad idle. It would idle badly all the time and it would just be slow, not slow then fast.

I'm thinking the problem is in the ECU, since pinking means that the ignition or the mixture aren't correct. A weak mixture could be caused by an external problem (MAP, lambda etc.) but again, when you swap the sensors around, the car behaves more or less the same.

Did the previous guy try to re-program the ECU at all? If the lad fitted a cone filter he could have done other "mods" which are now causing problems. Did you way you had a spare virgin ECU? It would be good to find a way to confirm your ECU isn't flakey.


Ralf S.

Hi
Done a oil change today. Oil and filter. Put some restore in. It says it reseals worn rings and stops oil from burning. Take it she must still run through the engine.

Anyway,she had a very rough idle on my trip to fetch my other half at work. Idle ok at times,but times she was really bad like she drop to 200rpm.

If you floor her she smokes a clear smoke. If you drive normal,say accelerate then coast then accelerate at normal speeds,she smokes blue smoke. Sometimes at idle too. When you driving and you take foot off pedal engaged in a gear then she would backfire a little then foot again on gas then she smokes blue.

Like I said when flooring at higher rpm smoke is clear.

Sometimes she's sluggish other time she goes better. Times she starts off sluggish and then surge of power normally around 3000 or 4000.

She won't rev passed around 5500. Sound like she not breathing properly. She will rev through the other gears and just stop at that same mark. When I do take her there then white smoke she emmits.

She's blowing some air when I open oil filler cap. Like you can see the air,don't know if its steam or what but you can see it blow slightly out the filler cap when removed

Im thinking valve seals?
I read this about bad valve seals
ENGINE BRAKING TEST
Engine braking is when other ways besides external braking are used to slow down your vehicle within an engine. When you have a bad valve seal, the oil that collects at the front cover of the head will end up burning when you push on the accelerator after coasting for a while. This is apparent especially when going downhill and again will be indicated by the excessive smoke that leaves the tailpipe. The oil here burns longer than in normal cases.

This happens to me.

 

[Ralf S.]

Yes.. smoke on the over-run is usually a sign of leaking valve stem seals. You may have knackered rings instead or too but generally those produce smoke at higher revs.

Valve stem seal leakage would have to be pretty bad to interfere with the combustion process.. but if oil is getting sucked in, then the exhaust gas coming out will appear "rich" to the lambda sensors, so your car will have a problem working out what mixture to inject. It could be running too lean but still thinking it's too rich.

If you can see an oily piston crown, then that would qualify as "pretty bad". If you can, try to do a compression test to check the rings and/or get an endoscope to have a look at the valve stems (they should all be grey/brown and dry like the spark plugs) then that will help you to be sure that there's a leaking valve (or valves).

It's a head off job to replace the valve stem seals... and if you go that trouble/expense it's a no brainer/no huge extra cost to replace ALL the valve stem seals and re-seat the valves, while they're out.

You need to do a compression test though, since once the head is off, if you have also diagnosed that you have knackered rings too, then now's the best time to replace them. If you unbolt the big-end caps you can push the pistons out one at a time, without disturbing the crank. This might all be more aggro' and expense than you wanted/or the car is worth however (head off means a new cam-belt and water pump already).


Compression test it and see what the valve stems are like first, while you psyche yourself up for the next stage.. If you remove the rocker cover only, you may be able to see the valve stems (dunno if the 1.6 has hydraulic lifters, which would be in the way). Bits of rubber hanging off the top of the valve, or lumps missing out of the collar would be an instant clue.

Ralf S.

 

[NebulaStilo]

Yes.. smoke on the over-run is usually a sign of leaking valve stem seals. You may have knackered rings instead or too but generally those produce smoke at higher revs.

Valve stem seal leakage would have to be pretty bad to interfere with the combustion process.. but if oil is getting sucked in, then the exhaust gas coming out will appear "rich" to the lambda sensors, so your car will have a problem working out what mixture to inject. It could be running too lean but still thinking it's too rich.

If you can see an oily piston crown, then that would qualify as "pretty bad". If you can, try to do a compression test to check the rings and/or get an endoscope to have a look at the valve stems (they should all be grey/brown and dry like the spark plugs) then that will help you to be sure that there's a leaking valve (or valves).

It's a head off job to replace the valve stem seals... and if you go that trouble/expense it's a no brainer/no huge extra cost to replace ALL the valve stem seals and re-seat the valves, while they're out.

You need to do a compression test though, since once the head is off, if you have also diagnosed that you have knackered rings too, then now's the best time to replace them. If you unbolt the big-end caps you can push the pistons out one at a time, without disturbing the crank. This might all be more aggro' and expense than you wanted/or the car is worth however (head off means a new cam-belt and water pump already).


Compression test it and see what the valve stems are like first, while you psyche yourself up for the next stage.. If you remove the rocker cover only, you may be able to see the valve stems (dunno if the 1.6 has hydraulic lifters, which would be in the way). Bits of rubber hanging off the top of the valve, or lumps missing out of the collar would be an instant clue.

Ralf S.

She is now not chowing oil. I threw in oil treatment when i done oil change.

Improved compression slightly. She runs better more often and when she runs better she has quite a pull.

Valve seals seems to be the issue because I read up and said exactly what you saying,smoke after put pedal after deceleration and not on high revs. She will coast on deceleration then when you accelerate again she smokes then clears up. Blue smoke. From pull away no smoke unless standing long in traffic light. When flooring her she smokes on high rpm but a clear smoke not blue.

They say it afffects performance because oil gets into combustion chamber fouling out the plugs. Especially long periods at traffic lights
Ive noticed when she idles rough at the light then she will smoke on pull away but that's not often. She will idle decent most of the time. Seems she hates traffic??

When I floor her she loves it and I take her to high rpm often to clear out and not allow oil to sit on the plug. Let it burn.

Because I floor her often she is driving better.especially on start ups straight after standing for long(ie clean plugs)??

I'm getting 8.1 l/100km at best lately. Sometimes 7.8 around there. Do alot of city driving though and with my flooring nature it's kind of understandable??heavy foot.

I'm happy that she getting better ie getting closer to the issue and that she not using alot of oil. I would top up like twice a week. I done a change on Saturday past and checked oil yesterday and today and its still on the mark I left her on Saturday. And oil has a slight black tint but more gold.

Shes a rare car to see and ive seen a few but people here who have the stilo are old or not fanatics. Plain looking stilo.

I love a sporty looking stilo in a dark colour with a nice rim.

Ive got a abarth badge on I got a headspin from a fiat 500 abarth driver???

Thanks for the advice.
Stay safe?

 

[NebulaStilo]

Yes.. smoke on the over-run is usually a sign of leaking valve stem seals. You may have knackered rings instead or too but generally those produce smoke at higher revs.

Valve stem seal leakage would have to be pretty bad to interfere with the combustion process.. but if oil is getting sucked in, then the exhaust gas coming out will appear "rich" to the lambda sensors, so your car will have a problem working out what mixture to inject. It could be running too lean but still thinking it's too rich.

If you can see an oily piston crown, then that would qualify as "pretty bad". If you can, try to do a compression test to check the rings and/or get an endoscope to have a look at the valve stems (they should all be grey/brown and dry like the spark plugs) then that will help you to be sure that there's a leaking valve (or valves).

It's a head off job to replace the valve stem seals... and if you go that trouble/expense it's a no brainer/no huge extra cost to replace ALL the valve stem seals and re-seat the valves, while they're out.

You need to do a compression test though, since once the head is off, if you have also diagnosed that you have knackered rings too, then now's the best time to replace them. If you unbolt the big-end caps you can push the pistons out one at a time, without disturbing the crank. This might all be more aggro' and expense than you wanted/or the car is worth however (head off means a new cam-belt and water pump already).


Compression test it and see what the valve stems are like first, while you psyche yourself up for the next stage.. If you remove the rocker cover only, you may be able to see the valve stems (dunno if the 1.6 has hydraulic lifters, which would be in the way). Bits of rubber hanging off the top of the valve, or lumps missing out of the collar would be an instant clue.

Ralf S.

I threw in oil additive on oil change that increases compression etc.

Now that seals are more likely to be the issue,I want to know can I throw another additive that rejuvinates seals in with the previous additive already in the oil?will it do any harm etc?

Thanks

 

[Ralf S.]

The additive that increases compression is probably just a viscosity enhancer, so it's not much different from using thicker oil (which is also probably cheaper).

If the oil is thicker, it won't squeeze past the oil ring on the piston so easily, so it helps prevent any blow by of the rings, hence the compression is improved.

If it makes the oil a bit thicker, it will also mean the oil is less likely to seep past the valve stem seals, if the valve stem seals are just "worn" or hardened.

Additives that rejuvenate the seals work by chemically affecting the rubber.. usually making it swell up a bit, so that the seal becomes a tighter fit around what it's supposed to be sealing. I've never used them, so I don't know how good they are or how long th effect lasts, but if you're saving up to fix the problem properly, then they would be a good interim solution (if they work).

The rubber-expanding goo won't interfere with the oil viscosity additive since they're doing different things.

It'll be interesting to know how the seal improver stuff performs, out of curiosity.



Ralf S.

 

[NebulaStilo]

The additive that increases compression is probably just a viscosity enhancer, so it's not much different from using thicker oil (which is also probably cheaper).

If the oil is thicker, it won't squeeze past the oil ring on the piston so easily, so it helps prevent any blow by of the rings, hence the compression is improved.

If it makes the oil a bit thicker, it will also mean the oil is less likely to seep past the valve stem seals, if the valve stem seals are just "worn" or hardened.

Additives that rejuvenate the seals work by chemically affecting the rubber.. usually making it swell up a bit, so that the seal becomes a tighter fit around what it's supposed to be sealing. I've never used them, so I don't know how good they are or how long th effect lasts, but if you're saving up to fix the problem properly, then they would be a good interim solution (if they work).

The rubber-expanding goo won't interfere with the oil viscosity additive since they're doing different things.

It'll be interesting to know how the seal improver stuff performs, out of curiosity.



Ralf S.

Hi

The car was running better after oil change and adding additive. Still has a good pull at times. Think the plugs get fouled out by oil so a seal rejuvinator will be a good interim solution.

So it won't affect oil pressure etc and intefere with the already added additive?

Additives used:
Shield Stop smoke(yellow colour. Improves compression and stop burning of oil)

For valve seal treatment I'm looking at Wynns Engine diff and gearbox stop leak(rejuvinates seals)

 

[Ralf S.]

I don't think so. Viscosity enhancers thicken the oil because of the molecular chains they contain, whereas the oil treatment is designed to chemically interact with the rubber/neoprene seals.

Oil can range from mineral, to fully synthetic and each one of those will be chemically different, so the oil treatment should be formulated to not react with anything that can possible be found in engine oil. If the Wynn's brew says its safe to use with any oil, then that's a good bet.

But you might need to give the additive some time to work. It's one of those things that some people swear by while others say it's completely useless. I guess it depends on the nature of the oil leak people are hoping to reduce.. and whatever the seal/gasket material is made from in different cars.. not to mention how bad the leak is... but you probably need to give it a few days and a few hundred kms before you can be sure what it's done.


Ralf S.

 

[NebulaStilo]

I don't think so. Viscosity enhancers thicken the oil because of the molecular chains they contain, whereas the oil treatment is designed to chemically interact with the rubber/neoprene seals.

Oil can range from mineral, to fully synthetic and each one of those will be chemically different, so the oil treatment should be formulated to not react with anything that can possible be found in engine oil. If the Wynn's brew says its safe to use with any oil, then that's a good bet.

But you might need to give the additive some time to work. It's one of those things that some people swear by while others say it's completely useless. I guess it depends on the nature of the oil leak people are hoping to reduce.. and whatever the seal/gasket material is made from in different cars.. not to mention how bad the leak is... but you probably need to give it a few days and a few hundred kms before you can be sure what it's done.


Ralf S.

Hi

So just decided to remove plugs to see how they look after oil change and oil additive in. This is how they looked...


I'm going to get my hand on a bottle of valve seal rejuvinator.

Thanks

 

[NebulaStilo]

I don't think so. Viscosity enhancers thicken the oil because of the molecular chains they contain, whereas the oil treatment is designed to chemically interact with the rubber/neoprene seals.

Oil can range from mineral, to fully synthetic and each one of those will be chemically different, so the oil treatment should be formulated to not react with anything that can possible be found in engine oil. If the Wynn's brew says its safe to use with any oil, then that's a good bet.

But you might need to give the additive some time to work. It's one of those things that some people swear by while others say it's completely useless. I guess it depends on the nature of the oil leak people are hoping to reduce.. and whatever the seal/gasket material is made from in different cars.. not to mention how bad the leak is... but you probably need to give it a few days and a few hundred kms before you can be sure what it's done.


Ralf S.

These are the plugs

 

[Ralf S.]

Those aren't desperately bad...

There's obviously something (like oil) upsetting the combustion, since they've all got a black soot rim around the thread and a couple of the plugs have blackened centre electrode insulation... but the electrodes themselves seem to be keeping clean.

It'll be interesting to see what happens when you get the seal rejuvinator in there... sounds like your leak is exactly what the stuff is meant to make better... (I can't say "fix".. ).


Ralf S.

 

[NebulaStilo]

Those aren't desperately bad...

There's obviously something (like oil) upsetting the combustion, since they've all got a black soot rim around the thread and a couple of the plugs have blackened centre electrode insulation... but the electrodes themselves seem to be keeping clean.

It'll be interesting to see what happens when you get the seal rejuvinator in there... sounds like your leak is exactly what the stuff is meant to make better... (I can't say "fix".. ).


Ralf S.

Thanks.

I'll keep you posted.

Is it worth replacing MAP sensor? No codes for it though.

Ive noticed on startup with the old upstream back in its upstream place,she idles rough then kicks up a notch when she's cold or standing overnight. It done that before with that sensor.
On scan tool(torque light)it says o2 sensor heater:incomplete. It only says that on that cild start up in mornings. When car idle kicks up it changes from incomplete to complete.
What does that mean?

The brand I bought(new o2 sensor)my cousin bought the same brand in another sensor and had endless problems then bought original oem and never a issue. He said the brand is horse ****.

She runs good when standing long(say whole day outside work) then pulls great but when driving whole day around then she starts with surging.

Does the 1.6 have a inlet air temp sensor and a cold start valve or injector or sensor?

Thanks

 

[NebulaStilo]

Those aren't desperately bad...

There's obviously something (like oil) upsetting the combustion, since they've all got a black soot rim around the thread and a couple of the plugs have blackened centre electrode insulation... but the electrodes themselves seem to be keeping clean.

It'll be interesting to see what happens when you get the seal rejuvinator in there... sounds like your leak is exactly what the stuff is meant to make better... (I can't say "fix".. ).


Ralf S.

So i done a compression test

PSI around 210. One cylinder(cylinder 3),had just under 200.
Then i performed a wet test with oil in the cylinder on cylinder 3,the compression went up to 210.

Tommorow morning after i drive her and get to my destination,I'm going to do another dry test to see if she still shows high or lower than the rest.

Is 210 high or is it normal?

 

[jackwhoo]

Did you
Disable the injectors?
Remove all the spark plugs?
Do test on fully warm engine?
Have fully charged battery?
Hold throttle fully open during test?
Watch the gauge to see how the needle rose to maximum?
Google how to do a compression test and interpret results?

It would have been interesting if you had done a compression test before adding the magic formula to the engine oil and after the magic treatment. Then compare results.

 

[Ralf S.]

So i done a compression test

PSI around 210. One cylinder(cylinder 3),had just under 200.
Then i performed a wet test with oil in the cylinder on cylinder 3,the compression went up to 210.

Tommorow morning after i drive her and get to my destination,I'm going to do another dry test to see if she still shows high or lower than the rest.

Is 210 high or is it normal?

Your 1.6 has a compression ratio of 10.5:1 so I’d expect it to make around 150PSI. Was the engine hot and did you have all the spark plugs out, or just the cylinder you were testing?
You also need to hold the throttle fully open when you crank it.

The main thing though is that the readings were more or less identical and within 10% of each other. It’s not indicating any serious issue with the piston rings or valve seats, anyway.

The wet test was only a marginal improvement.. which normally suggests that the rings are okay and the lost psi are down to the valve seats or guides.. but the reading is so close to the dry test that even a tiny rings issue would read higher on a wet test.

If your valve guide seals are leaking then that doesn’t show up on the compression test, since that just measures how gas tight the cylinder is when the valves are closed. Not a bad result though.

Ralf S.