General Air filter

[NebulaStilo]

Hi guys.

So as some may remember me. I have a 1.6 stilo and it had a cone filter(straight replacement) no induction kits. Car was pulling sluggish and hesitation in acceleration as time went by after having fitted this cone because of a cracked box.

CEL on with downstream o2 sensor which shouldn't affect performance AND there is no CAT. Previous owner done decat.downstream o2 is completely dead,no values.p0141 is the code. O2 values and STFT are steady ish at idle but become very erratic when driving hence the hesitation.(before replacing cone with box)

I eventually got hold of a used box in good condition with the panel filter in.
I am going to replace the paper filter inside though.

I fitted it and drove the car. It started much easier and idles smoother.
She pulls still abit sluggish but seems to be getting better. Only took it for one test.

I want to know,does the ECU need to readjust(relearn) what's happening with the standard box coming from the cone filters high air flow?

Thanks

 

[Ralf S.]

So the standard airbox, which the factory spent thousands of Euro's developing and tuning to the particular requirements of the engine, works better than a piece of drain pipe with a gauze over the end of it? Strange!

Certainly good progress though.

As far as I know, the Stilo ECU doesn't "learn" its new status. Logically, there is nothing connected to it that tells it what airbox is in place. It has to rely on the signals from the MAF sensor (what's going in) and the lambada sensors (what's going out) to work out how much juice to give it.

If you had a cone filter all this time, you may have a dirty/oily MAF sensor. I remember (maybe) that you cleaned this (or fitted another one) but if you haven't, it's worth cleaning yours with a *very* small, soft bristle brush and some electrical contact cleaner. The sensor is usually a thin piece of wire so you need to treat it very carefully.

If you can get hold of a new Bosch MAF for not much moolah, then that will remove any doubt about the MAF altogether. Cheaper MAFs may not last and can cause different issues if they're not well calibrated (Chinese guy gluing it all together in a shed.. you take your chances with that one) but sometimes even a bad MAF is useful, since it might make a difference (better or worse) that proves whether the problem is the MAF and/or something else.

Anyways.. if the MAF is good, or as good as it can be, you need to change the lambda (or work out why it's not giving you the correct readings/variances.

The De-cat itself shouldn't make a difference to the hesitation problem so worry about that last. At the moment, it sounds like the fueling is all over the place, and if the injectors aren't knackered that's only the MAF and the lambdas.


Ralf S.

 

[NebulaStilo]

So the standard airbox, which the factory spent thousands of Euro's developing and tuning to the particular requirements of the engine, works better than a piece of drain pipe with a gauze over the end of it? Strange!

Certainly good progress though.

As far as I know, the Stilo ECU doesn't "learn" its new status. Logically, there is nothing connected to it that tells it what airbox is in place. It has to rely on the signals from the MAF sensor (what's going in) and the lambada sensors (what's going out) to work out how much juice to give it.

If you had a cone filter all this time, you may have a dirty/oily MAF sensor. I remember (maybe) that you cleaned this (or fitted another one) but if you haven't, it's worth cleaning yours with a *very* small, soft bristle brush and some electrical contact cleaner. The sensor is usually a thin piece of wire so you need to treat it very carefully.

If you can get hold of a new Bosch MAF for not much moolah, then that will remove any doubt about the MAF altogether. Cheaper MAFs may not last and can cause different issues if they're not well calibrated (Chinese guy gluing it all together in a shed.. you take your chances with that one) but sometimes even a bad MAF is useful, since it might make a difference (better or worse) that proves whether the problem is the MAF and/or something else.

Anyways.. if the MAF is good, or as good as it can be, you need to change the lambda (or work out why it's not giving you the correct readings/variances.

The De-cat itself shouldn't make a difference to the hesitation problem so worry about that last. At the moment, it sounds like the fueling is all over the place, and if the injectors aren't knackered that's only the MAF and the lambdas.


Ralf S.

I cleaned the MAP(no MAF on 1.6)
I mentioned (i think) that the new box (new to me at least )came with a air filter that's bit dirty. I cleaned it to use it time being until my new filter arrives.

Could it be the dirty filter?
Does post CAT sensor affect fuel ratio?
Could my pre CAT sensor be dying?
My o2 pre cat values are all over only on acceleration. I don't get ANY sort of code for pre CAT.

Post CAT has absolutely no values.
Swopped sensor connections around and same heater fault but for bank1 sensor 1 came up telling me its the sensor itself. Not the Loom or ECU.

Thanks

 

[NebulaStilo]

So the standard airbox, which the factory spent thousands of Euro's developing and tuning to the particular requirements of the engine, works better than a piece of drain pipe with a gauze over the end of it? Strange!

Certainly good progress though.

As far as I know, the Stilo ECU doesn't "learn" its new status. Logically, there is nothing connected to it that tells it what airbox is in place. It has to rely on the signals from the MAF sensor (what's going in) and the lambada sensors (what's going out) to work out how much juice to give it.

If you had a cone filter all this time, you may have a dirty/oily MAF sensor. I remember (maybe) that you cleaned this (or fitted another one) but if you haven't, it's worth cleaning yours with a *very* small, soft bristle brush and some electrical contact cleaner. The sensor is usually a thin piece of wire so you need to treat it very carefully.

If you can get hold of a new Bosch MAF for not much moolah, then that will remove any doubt about the MAF altogether. Cheaper MAFs may not last and can cause different issues if they're not well calibrated (Chinese guy gluing it all together in a shed.. you take your chances with that one) but sometimes even a bad MAF is useful, since it might make a difference (better or worse) that proves whether the problem is the MAF and/or something else.

Anyways.. if the MAF is good, or as good as it can be, you need to change the lambda (or work out why it's not giving you the correct readings/variances.

The De-cat itself shouldn't make a difference to the hesitation problem so worry about that last. At the moment, it sounds like the fueling is all over the place, and if the injectors aren't knackered that's only the MAF and the lambdas.


Ralf S.

Hi Ralf.

Yesterday while the engine was idling,I removed oil cap to see the affect,it went up couple rpm and smoothed out idle.

This is pointing towards the old air filter I got with the 2nd hand air box.
She has hesitant acceleration like a unsmooth acceleration still but at higher rpm she smooths out. Starts much quicker. She doesn't turn over as long before she actually gets going when starting.

But definately goes much better. I enjoy driving her now?

But yeah need to replace air filter then surely she should be back to 100%
You cannot see through the filter when held up in the light.
And removing oil cap and she idled better,telling me she isn't getting enough air because of the clogged filter.
Am I correct?

I put the cap back on fyi??

 

[NebulaStilo]

I cleaned the MAP(no MAF on 1.6)
I mentioned (i think) that the new box (new to me at least )came with a air filter that's bit dirty. I cleaned it to use it time being until my new filter arrives.

Could it be the dirty filter?
Does post CAT sensor affect fuel ratio?
Could my pre CAT sensor be dying?
My o2 pre cat values are all over only on acceleration. I don't get ANY sort of code for pre CAT.

Post CAT has absolutely no values.
Swopped sensor connections around and same heater fault but for bank1 sensor 1 came up telling me its the sensor itself. Not the Loom or ECU.

Thanks

Hi Ralf,

Quik question,can a dirty or clogged air filter cause uneven acceleration?

She's got more power it seems but she doesn't pick up smoothly and as quickly. You can feel though that she wants to move but there's restriction. She got better after changing my filter setup back to standard. Im using the second hand panel filter given with the box until I get hold of some more cash to replace the filter?She's averaging about 7.5 to 8l/100km. Sometimes lower than average with no traffic and traffic lights.

The fact she pulls better even with uneven acceleration,says it's pointing towards air issue especially with erratic o2 readings when she accelerates.

I'm going to replace air filter and throw in some injector cleaner to clean out the injectors and valves etc. Already cleaned Throttle.

 

[Ralf S.]

Hi Ralf,

Quik question,can a dirty or clogged air filter cause uneven acceleration?

She's got more power it seems but she doesn't pick up smoothly and as quickly. You can feel though that she wants to move but there's restriction. She got better after changing my filter setup back to standard. Im using the second hand panel filter given with the box until I get hold of some more cash to replace the filter?She's averaging about 7.5 to 8l/100km. Sometimes lower than average with no traffic and traffic lights.

The fact she pulls better even with uneven acceleration,says it's pointing towards air issue especially with erratic o2 readings when she accelerates.

I'm going to replace air filter and throw in some injector cleaner to clean out the injectors and valves etc. Already cleaned Throttle.

A dirty filter doesn't tend to cause *uneven* acceleration - it just restricts how much air can get sucked in and if the filter is very dirty that will make the car feel down on power... but the acceleration would be mostly consistent.

Cars tend to want to a rich mixture when they accelerate, which a dirty air filter actually helps... but the emissions control "sensible" software will be trying to lean it off as soon as it can, so it's fighting the engine trying to make power. That might be making the fueling a bit variable but since the airflow through the filter is consistent (it will be just "not enough") then I doubt you would notice hesitation.

It still sounds like the brains are confused how much fuel to use. Your consumption is 29-31mpg, in the old money which is not a disaster but I'd guess it ought to be around 36-38mpg (6~ 6.5 l/100km) so it's not quite right (in case you couldn't tell).

The lambda sensors need to be sorted out though. They are the main agents that control fueling and you say there are fluctuating or no signals from any of them. If they're not working the engine will be using a default fuel map, which along with a dirty filter would give you the symptoms you have.

Try the old analogue "lambda test" (before diagnostics software was invented to confuse everyone). Accelerate the car in second gear (it's smoother than first) slowly, from 1000-3000 rpm. Be consistent (don't move your foot on the gas pedal) and note what the car does when it passes through 1600-1800rpm. If it hesitates then picks up after 2000rpm then that's a poor lambda transition... so your problem will definitely be in one or both of the sensors.


Ralf S.

 

[NebulaStilo]

A dirty filter doesn't tend to cause *uneven* acceleration - it just restricts how much air can get sucked in and if the filter is very dirty that will make the car feel down on power... but the acceleration would be mostly consistent.

Cars tend to want to a rich mixture when they accelerate, which a dirty air filter actually helps... but the emissions control "sensible" software will be trying to lean it off as soon as it can, so it's fighting the engine trying to make power. That might be making the fueling a bit variable but since the airflow through the filter is consistent (it will be just "not enough") then I doubt you would notice hesitation.

It still sounds like the brains are confused how much fuel to use. Your consumption is 29-31mpg, in the old money which is not a disaster but I'd guess it ought to be around 36-38mpg (6~ 6.5 l/100km) so it's not quite right (in case you couldn't tell).

The lambda sensors need to be sorted out though. They are the main agents that control fueling and you say there are fluctuating or no signals from any of them. If they're not working the engine will be using a default fuel map, which along with a dirty filter would give you the symptoms you have.

Try the old analogue "lambda test" (before diagnostics software was invented to confuse everyone). Accelerate the car in second gear (it's smoother than first) slowly, from 1000-3000 rpm. Be consistent (don't move your foot on the gas pedal) and note what the car does when it passes through 1600-1800rpm. If it hesitates then picks up after 2000rpm then that's a poor lambda transition... so your problem will definitely be in one or both of the sensors.


Ralf S.

Hi.

That sounds hurting to the wallet??
Sensors are so expensive here but I'll need to save up. I will replace both sensors.
Ive noticed its abit heavier on fuel.
Her erratic readings are from sensor 1. No reading at all from sensor 2.

At times especially in higher gears or if you floor her from 1st then she's pretty good.

I get mixed info about post CAT sensors. Do they actually help with fuel trim?

Thank you

 

[NebulaStilo]

A dirty filter doesn't tend to cause *uneven* acceleration - it just restricts how much air can get sucked in and if the filter is very dirty that will make the car feel down on power... but the acceleration would be mostly consistent.

Cars tend to want to a rich mixture when they accelerate, which a dirty air filter actually helps... but the emissions control "sensible" software will be trying to lean it off as soon as it can, so it's fighting the engine trying to make power. That might be making the fueling a bit variable but since the airflow through the filter is consistent (it will be just "not enough") then I doubt you would notice hesitation.

It still sounds like the brains are confused how much fuel to use. Your consumption is 29-31mpg, in the old money which is not a disaster but I'd guess it ought to be around 36-38mpg (6~ 6.5 l/100km) so it's not quite right (in case you couldn't tell).

The lambda sensors need to be sorted out though. They are the main agents that control fueling and you say there are fluctuating or no signals from any of them. If they're not working the engine will be using a default fuel map, which along with a dirty filter would give you the symptoms you have.

Try the old analogue "lambda test" (before diagnostics software was invented to confuse everyone). Accelerate the car in second gear (it's smoother than first) slowly, from 1000-3000 rpm. Be consistent (don't move your foot on the gas pedal) and note what the car does when it passes through 1600-1800rpm. If it hesitates then picks up after 2000rpm then that's a poor lambda transition... so your problem will definitely be in one or both of the sensors.


Ralf S.

Hi.

Did I mention she idles few hundred rpm more when oil cap was removed?.
What does that mean?

 

[NebulaStilo]

A dirty filter doesn't tend to cause *uneven* acceleration - it just restricts how much air can get sucked in and if the filter is very dirty that will make the car feel down on power... but the acceleration would be mostly consistent.

Cars tend to want to a rich mixture when they accelerate, which a dirty air filter actually helps... but the emissions control "sensible" software will be trying to lean it off as soon as it can, so it's fighting the engine trying to make power. That might be making the fueling a bit variable but since the airflow through the filter is consistent (it will be just "not enough") then I doubt you would notice hesitation.

It still sounds like the brains are confused how much fuel to use. Your consumption is 29-31mpg, in the old money which is not a disaster but I'd guess it ought to be around 36-38mpg (6~ 6.5 l/100km) so it's not quite right (in case you couldn't tell).

The lambda sensors need to be sorted out though. They are the main agents that control fueling and you say there are fluctuating or no signals from any of them. If they're not working the engine will be using a default fuel map, which along with a dirty filter would give you the symptoms you have.

Try the old analogue "lambda test" (before diagnostics software was invented to confuse everyone). Accelerate the car in second gear (it's smoother than first) slowly, from 1000-3000 rpm. Be consistent (don't move your foot on the gas pedal) and note what the car does when it passes through 1600-1800rpm. If it hesitates then picks up after 2000rpm then that's a poor lambda transition... so your problem will definitely be in one or both of the sensors.


Ralf S.

Hi Ralf.

So I tried that o2 test and in 2nd from 1000 rpm it done a hesitation. So not smooth from about 1200 rpm. She goes then like she slows down acceleration then accelerates then slows down. As if you pumping the accelerator slowly. She does this smoothly not jerky. Its not as noticeable or bad at 3000. If you floor her from 1st or 2nd,especially 2nd she goes and accelerates better and not so much 'hesitation'. Before I replaced the box I didn't get good acceleration at all. So im making progress?? whats your verdict along with fact that she idles few rpm higher when oil cap is removed?

Thanks

 

[Ralf S.]

If the car hesitates as the revs increase through 1800-2000rpm, then the lambda sensor is probably the culprit. If you're not getting any signals or an erratic signal, then that is suggesting the same thing.

You could try to diagnose the sensor using a volt meter, to see what readings it's sending but I don't know what the reading should be or how it changes. I read somewhere on the forum that the reading changes from 0 to <something> (1.5?) volts or the other way round, if the sensor is working correctly. A check that is independent from the OBD errors would be more reliable - sometimes the OBD can interpret errors and give you misleading results.

But if it was me - limited electrical knowledge - I'd just change the sensor, albeit it costs money and might not make any difference.

If you have two sensors, you can try swapping the connectors over to see if one sensor works in both locations, or if both sensors only work in one location... that would prove whether the problem is the sensor or the wiring to it. But it's more likely that one or both sensors have failed, rather than wiring/fusebox/connections (especially since you're in a dry climate).

The engine idles better/faster without an oil cap because there's a huge vent to the atmosphere without the cap on. As the pistons down, they pressurize the crankcase (they're basically pumping the air inside the engine downwards, into the sump). Some of the pressure equalizes by being sucked up behind the pistons that are going up... but some of it also vents through the crankcase breather (the pipe runs from the rocker cover to the air intake).

The pressure in the crankcases and the air moving around from high pressure (under the falling pistons) to low pressure (the rising pistons) causes resistance, which makes the engine work a bit. With less resistance (the oil cap being removed) the engine can breathe more freely and so runs slightly faster.

You need to vent to the air intake (rather than the atmosphere) to preserve emissions... although a lot of the modifiers when they fit a cone filter etc. just vent the crankcase to atmosphere, through a tiny gauze/cone filter on the end of the breather pipe. It works.. but it's a bit anti-social.


Ralf S.

 

[NebulaStilo]

If the car hesitates as the revs increase through 1800-2000rpm, then the lambda sensor is probably the culprit. If you're not getting any signals or an erratic signal, then that is suggesting the same thing.

You could try to diagnose the sensor using a volt meter, to see what readings it's sending but I don't know what the reading should be or how it changes. I read somewhere on the forum that the reading changes from 0 to <something> (1.5?) volts or the other way round, if the sensor is working correctly. A check that is independent from the OBD errors would be more reliable - sometimes the OBD can interpret errors and give you misleading results.

But if it was me - limited electrical knowledge - I'd just change the sensor, albeit it costs money and might not make any difference.

If you have two sensors, you can try swapping the connectors over to see if one sensor works in both locations, or if both sensors only work in one location... that would prove whether the problem is the sensor or the wiring to it. But it's more likely that one or both sensors have failed, rather than wiring/fusebox/connections (especially since you're in a dry climate).

The engine idles better/faster without an oil cap because there's a huge vent to the atmosphere without the cap on. As the pistons down, they pressurize the crankcase (they're basically pumping the air inside the engine downwards, into the sump). Some of the pressure equalizes by being sucked up behind the pistons that are going up... but some of it also vents through the crankcase breather (the pipe runs from the rocker cover to the air intake).

The pressure in the crankcases and the air moving around from high pressure (under the falling pistons) to low pressure (the rising pistons) causes resistance, which makes the engine work a bit. With less resistance (the oil cap being removed) the engine can breathe more freely and so runs slightly faster.

You need to vent to the air intake (rather than the atmosphere) to preserve emissions... although a lot of the modifiers when they fit a cone filter etc. just vent the crankcase to atmosphere, through a tiny gauze/cone filter on the end of the breather pipe. It works.. but it's a bit anti-social.


Ralf S.

Hi Ralf.
What you saying makes sense yeah.

After what you said about the lambda test,I noticed around about 2000 especially she hesitates. Above 2000 more around 3000 she runs better.

I swopped the sensor connectors around already. P0141. The code came back as upstream heater circuit malfunction. And no downstream fault meaning the downstream sensor itself is a culprit too with the CEL. Ie the code moved to the position I put the connector into(from down stream to upstream. ) so it is not a circuit issue.
I'm going to have to replace both sensors anyway so yeah.

I did also notice that if you floor from 1st while rolling say in traffic(tried this as I turned into my road)she was rolling on her own in gear. So driving on idle basically then I decided to floor her flat foot and see how she reacts. She took like a split second to react but you notice that late reaction. She didn't react to Wide open throttle immediately. When she reacted she picked up pretty good but not as good as what I know as normal.
I read that o2 sensor upstream can be bad without a code. This is especially the case when the sensor has become lazy or bias and slow to voltage changes (changes in AFR). This makes sense to me and could be my case.

Am I right?


Off the topic, I'm giving advice to a guy who has a Hyundai Who's 1.1. Car doesn't matter,he complains at high speeds on highways it jerks.at traffic lights it will stall. And can feel she doesn't pull like she used to. CEL on and came back with map sensor fault. After paying so many people for diagnostics and fighting with them(hence can't tell me the exact code because they wont tell him after he told them off).
He had map replaced with 2nd hand one and drove better for a week then same issue. I recommended a brand new MAP sensor rather. Could a MAP cause stalling etc?
Just a Q on the side thanks Ralf S

 

[Ralf S.]

Hi Ralf.
What you saying makes sense yeah.

After what you said about the lambda test,I noticed around about 2000 especially she hesitates. Above 2000 more around 3000 she runs better.

I swopped the sensor connectors around already. P0141. The code came back as upstream heater circuit malfunction. And no downstream fault meaning the downstream sensor itself is a culprit too with the CEL. Ie the code moved to the position I put the connector into(from down stream to upstream. ) so it is not a circuit issue.
I'm going to have to replace both sensors anyway so yeah.

I did also notice that if you floor from 1st while rolling say in traffic(tried this as I turned into my road)she was rolling on her own in gear. So driving on idle basically then I decided to floor her flat foot and see how she reacts. She took like a split second to react but you notice that late reaction. She didn't react to Wide open throttle immediately. When she reacted she picked up pretty good but not as good as what I know as normal.
I read that o2 sensor upstream can be bad without a code. This is especially the case when the sensor has become lazy or bias and slow to voltage changes (changes in AFR). This makes sense to me and could be my case.

Am I right?


Off the topic, I'm giving advice to a guy who has a Hyundai Who's 1.1. Car doesn't matter,he complains at high speeds on highways it jerks.at traffic lights it will stall. And can feel she doesn't pull like she used to. CEL on and came back with map sensor fault. After paying so many people for diagnostics and fighting with them(hence can't tell me the exact code because they wont tell him after he told them off).
He had map replaced with 2nd hand one and drove better for a week then same issue. I recommended a brand new MAP sensor rather. Could a MAP cause stalling etc?
Just a Q on the side thanks Ralf S

Yes, I'd say so. If you have a lazy or failed sensor (or its wiring) then the results you would get will be inconsistent and will cause fueling issues. The sensor uses a very small voltage variation to send a signal to the ECU, so even a slight failure.. or a perfect sensor but slightly corroded/dirty connections will cause a problem.


The second question could be the MAP sensor, especially since changing it seemed to improve things for a while. I'm not sure if the car has an Idle Control Valve but stalling could be caused by that too... but the Idle Control just tends to make the car not idle and a bit jerky to pick up, rather than affecting how it runs once it's moving.

So, yes, try a different (ideally new and ideally original equipment) MAP first... but while he's fitting it, it's also worth cleaning out any other sensors fitted to the TB or the intake.


Ralf S.

 

[NebulaStilo]

Yes, I'd say so. If you have a lazy or failed sensor (or its wiring) then the results you would get will be inconsistent and will cause fueling issues. The sensor uses a very small voltage variation to send a signal to the ECU, so even a slight failure.. or a perfect sensor but slightly corroded/dirty connections will cause a problem.


The second question could be the MAP sensor, especially since changing it seemed to improve things for a while. I'm not sure if the car has an Idle Control Valve but stalling could be caused by that too... but the Idle Control just tends to make the car not idle and a bit jerky to pick up, rather than affecting how it runs once it's moving.

So, yes, try a different (ideally new and ideally original equipment) MAP first... but while he's fitting it, it's also worth cleaning out any other sensors fitted to the TB or the intake.


Ralf S.

Thanks Ralf.

Today I tried that again. Stepped on her pedal flat foot and she almost like under revved during hesitation then she went ahead and took off. She goes better at higher speeds but at lower acceleration she's hesitant.

 

[NebulaStilo]

Yes, I'd say so. If you have a lazy or failed sensor (or its wiring) then the results you would get will be inconsistent and will cause fueling issues. The sensor uses a very small voltage variation to send a signal to the ECU, so even a slight failure.. or a perfect sensor but slightly corroded/dirty connections will cause a problem.


The second question could be the MAP sensor, especially since changing it seemed to improve things for a while. I'm not sure if the car has an Idle Control Valve but stalling could be caused by that too... but the Idle Control just tends to make the car not idle and a bit jerky to pick up, rather than affecting how it runs once it's moving.

So, yes, try a different (ideally new and ideally original equipment) MAP first... but while he's fitting it, it's also worth cleaning out any other sensors fitted to the TB or the intake.


Ralf S.

Hi Ralf.
I noticed something also,at 1800rpm approx if you keep it steady at 1800 in 2nd gear while driving then she jerks ahead until you accelerate more then smoothens out.

Is that also 02 related?

 

[Ralf S.]

Very likely. 1800rpm is right in the middle of the zone where the Lambda heater turns off.

Heat usually increases electrical resistance, so without it the signal may look like a sudden spike. Other than testing the outputs as the revs change, the easiest check (albeit it's speculative) is to stick a new sensor in there.


Ralf S.

 

[NebulaStilo]

Very likely. 1800rpm is right in the middle of the zone where the Lambda heater turns off.

Heat usually increases electrical resistance, so without it the signal may look like a sudden spike. Other than testing the outputs as the revs change, the easiest check (albeit it's speculative) is to stick a new sensor in there.


Ralf S.

That's my plan. Even if I must change the sensors one by one (due to funds),I'm going to replace upstream first because downstream shouldn't affect AFR.

Every time I put foot flat it pauses for a second then she pulls,in first gear.

 

[NebulaStilo]

Very likely. 1800rpm is right in the middle of the zone where the Lambda heater turns off.

Heat usually increases electrical resistance, so without it the signal may look like a sudden spike. Other than testing the outputs as the revs change, the easiest check (albeit it's speculative) is to stick a new sensor in there.


Ralf S.

Hi Ralf.
Could you give your take on this please? I clean it out often then after a while it starts to build up. The one small hose(not the one going to intake pipe) coming from or going to the intake manifold from the oil filler cap was bit blocked on the intake side.I forgot to post this. Done this a while back. Drives slightly better when i clean it or its just my imagination hahahaha

 

[NebulaStilo]

Very likely. 1800rpm is right in the middle of the zone where the Lambda heater turns off.

Heat usually increases electrical resistance, so without it the signal may look like a sudden spike. Other than testing the outputs as the revs change, the easiest check (albeit it's speculative) is to stick a new sensor in there.


Ralf S.

Hi Ralf hope you well

Took out my tablet to read values better(bigger screen)

Opened up TPS,O2 down and up stream,short term fuel and MAP psi.

I read that 5 psi is normal at idle. All of this is at idle. TPS is at 5% which is also normal as far as I know.

I attached a pic of the data captured. Check the fuel trim though. When you drive the car it shoots all over the place just like the o2 voltage.

 

[NebulaStilo]

Very likely. 1800rpm is right in the middle of the zone where the Lambda heater turns off.

Heat usually increases electrical resistance, so without it the signal may look like a sudden spike. Other than testing the outputs as the revs change, the easiest check (albeit it's speculative) is to stick a new sensor in there.


Ralf S.

Hi

Update on my stilo.
I replaced air filter panel as pre caution. Didn't expect it to improve performance issues as you said but replaced anyway.

I noticed lately my car cranks longer to start and hesitation on acceleration has increased.

At times she goes like the wind with no problem.
Mostly goes good at higher rpm.

Next step is lambda sensor 1 then sensor 2.

Removed lambda and was covered in soot. Is that normal,it's to me an indication of running rich(no rich codes)nor is it smoking. Only clear smoke at times on acceleration.

Lambda sensor 1 data shows that she jumps around alot and short term fuel trim jumps from -80 to +10 for e.g. also very erratic like sensor 1 values. Stays mostly in rich (negative fuel trim)

I clean out her pcv often(always find that white stuff in it as shown in pic above)

 

[culeanu]

Lambda sensor 1 data shows that she jumps around alot and short term fuel trim jumps from -80 to +10 for e.g. also very erratic like sensor 1 values. Stays mostly in rich (negative fuel trim)

I clean out her pcv often(always find that white stuff in it as shown in pic above)

Hi,
Found your thread when looking for a solution to my 1.2 8v punto 03.

If you don't mind, I hope the 2 info below could be useful for you:

- for a correct view of the ECU fueling compensation, you may want regarding LTFT+STFT. Firstly LTFT. I use to analyze my engine with the combination of graphs attached (1) - it's a demo, do not try to find a logic. Torque screens could be also prepared for this kind of investigate, but I prefer car scanner.

- before buying new(s) O2 sensor, you may want to read at least the second attached photo. It's a screen save from a youtoube video, which I found to be one of best synthesis of O2 diagnostic. Interesting, it could also answer to the 'white stuff' question (unfortunately).