Scan readings

[Mr2paul]

Hi all and hope we are still coping.
My question is, are my readings ok or a cause for concern ?
Engine seems to run hot and abit fumey, tho not the correct term I no.
As you no it is economical and of no running issue. The code has not returned as yet, was 0420 or o240 but catalyst based. As you no she had a good run hence my last post so maybe she needed a good burn out of all the crap?? . Anyway, do you think she will pass mot given the readings as they stand ? Tick over only so maybe not correct but I seek advise from the gurus here, and I no who you are. No issues but that does not mean all is ok. Hell the amount of attention she gets is crazy so when I go back diesel someone will get a sweet car

[Ardent]

My 2p.
I mention the easy bits.
Tricky to say in an idling state.
Revs look high. Not warmed up?
The STFT. Anything below 5% is generally not worth worrying about.

A dongle and torque pro work well, so you can record some real time data. Very good to see the short and long fuel trims. They reveal a lot.

[shnazzle]

My 2p.
I mention the easy bits.
Tricky to say in an idling state.
Revs look high. Not warmed up?
The STFT. Anything below 5% is generally not worth worrying about.

A dongle and torque pro work well, so you can record some real time data. Very good to see the short and long fuel trims. They reveal a lot.

It's the combined fuel trims you do need to look at

STFT can be 0 but if LTFT is 15,it just means it has set a new baseline and its doing very well managing that. Fuel trims above look excessive. 

It seems to be dumping a fair bit of fuel in. Which could account for higher rpm.

Two options;
there's unmetered air coming in. Air leak after MAF.
The o2 sensors are reading lean because of an air leak in manifold, cat flexis, etc.

It's unlikely to be one o2 sensor, as both banks seem to be almost equally lean.

First port of call would be MAF and check all the clamps around the air pipe between throttle body and MAF.

I'm guessing as well that if you give a bit of gas, LTFT decreases?

[Ardent]

@shnazzle

I was basing my comments on the readings were taken at tick over.
Which I took to mean, standing idling warming up tick over.

I did not say it, but was thinking the same as your last line.
Mine does that. LTFT look less than ideal. Then once I move away, they drop to where I'm happy.

@Mr2paul
Warming up, or, cooling down idle?

[shnazzle]

My guess would be warm idle.
Spark advance is 14deg,which is what it should be.
MAF is 2.86g/s,which is correct for normal idle.
TPS is 12.5,which is the normal closed position.
And it's in fuel mode 2 clearly so it is warm. And IAT is 32,which,with an ambient temp of around 10 would mean a decent amount of heat soak. 

But it's loading fuel in, which (as per STFT) it seems to be happy with.

To answer the question ; it MIGHT pass MOT. But I'd say it's unlikely. Have a clean of that MAF and check the pipes. Don't reset the ECU and have a look at the fuel trims. Post back

[Mr2paul]

Thanks guys. I appreciate your comments and will read them through many times I'm sure.it was warming up as you stated so sorry for the lack of info there. I think I'll go back to the std air box after testing again just to compare the values. Is there anything else I need to be looking at ?. Thanks again.

[shnazzle]

Thanks guys. I appreciate your comments and will read them through many times I'm sure.it was warming up as you stated so sorry for the lack of info there. I think I'll go back to the std air box after testing again just to compare the values. Is there anything else I need to be looking at ?. Thanks again.

I'm sorry, I didn't pick up on the aftermarket intake.

That'll explains it.

Mine's the same on an aftermarket. Shove a stock in, reset ECU and MOT should be fine. Although it does bring into question the post-cat sensor now. Or the cat itself.

Put a bottle of cat cleaner through, if you have time an oil change, an Italian tune-up. Should be fine

[mr2garageswindon]

Take it to your local MOT centre and ask them to do emissions test on it as they would for MOT is the best idea then you will know for sure and the results could help pin point any issues.
They might charge you a tenner or something but more than likely do it for free.. like I do although I'm a bit far away to help I think.
Jon.

[Mr2paul]

Hi all. Iv put the air box back in and all seems well. Please note, it has an unknown maf sensor ( which I thought I may as well test ) , an old genuine air filter ( blew it out with compressor gun ) and no pipe to intake from the duct.
Readings have all changed and tick over has dropped 200rpm. Please take a look to see if the change is for the better. Many thanks.

[shnazzle]

Very informative way of showing the impact of an uncalibrated aftermarket intake though, so thanks for that.

I had much the same measurements,oddly. 12-15%. Although I believe mine was negative.

Fingers crossed for your MOT

[Carolyn]

I just took out a 'hurricane' inlet and reinstated the standard air box ducting in Scotte's (ex Stewart@borough) TF.

Luckily, I had all the bits in stock.

I've yet to fire her up, as I'm awaiting new plugs.

A word of advice: if you must install a different intake, don't throw the original away.

[Ardent]

Post #10

That requires some sort of double thumbs up.
Sounds blindly obvious. But sage words.

Rather lends itself to the oft conclusion here. Stock is best.

[Dev]

There is a way to get genuine positive fuel trims where the ECU can add additional fuel for more power by using a calibrated aftermarket intake. They sell this for other cars but not ours. If you are able to free up the exhaust and other things then the intake could be a bottleneck where it can take advantage of making a little performance.
Unfortunately aftermarket intakes get a bad reputation from the available choices and the kind of filters that use oil that damage the MAF sensor.

 Aftermarket parts can be all over the map but there are some genuine ones that do actually what they claim but because of the bad ones they tend to get lumped in as being all bad. 

 

[Mr2paul]

Thanks to all. I thought it was important to show the differences of a std air box compared with a "power filter", interesting result tbh. Car drives fine same as usual but even on tick over the rpm goes down. Fuel trims are better, maf is better so all in all. Don't change to a power filter . Stock is good for the car. I could have gone on not more detail with sensor readings at load but you get my point here. This is a point well documented but not proven so it came down to here say n not fact. I've now got all the readings and have proven without doubt the facts. Std is best unless you want to fool the mot or ecu. I'm happy again now. Bit less noise also for my commute to work.
Happy days.
I can't see what more I can do, no codes, cataclean done a while ago, oil change 1k ago, as said, she is well cared for 🤗🤗🤗

[shnazzle]

Thanks to all. I thought it was important to show the differences of a std air box compared with a "power filter", interesting result tbh. Car drives fine same as usual but even on tick over the rpm goes down. Fuel trims are better, maf is better so all in all. Don't change to a power filter . Stock is good for the car. I could have gone on not more detail with sensor readings at load but you get my point here. This is a point well documented but not proven so it came down to here say n not fact. I've now got all the readings and have proven without doubt the facts. Std is best unless you want to fool the mot or ecu. I'm happy again now. Bit less noise also for my commute to work.
Happy days.
I can't see what more I can do, no codes, cataclean done a while ago, oil change 1k ago, as said, she is well cared for 🤗🤗🤗

That pretty much sums it up. I've been through the same cycle.

Sure you CAN put different things on that "massage" the MAF signal into shape but I got to a point of asking myself why.
If anything I noticed better response and power when I switched back to stock.

Let us know how MOT goes.

[1979scotte]

Thanks to all. I thought it was important to show the differences of a std air box compared with a "power filter", interesting result tbh. Car drives fine same as usual but even on tick over the rpm goes down. Fuel trims are better, maf is better so all in all. Don't change to a power filter . Stock is good for the car. I could have gone on not more detail with sensor readings at load but you get my point here. This is a point well documented but not proven so it came down to here say n not fact. I've now got all the readings and have proven without doubt the facts. Std is best unless you want to fool the mot or ecu. I'm happy again now. Bit less noise also for my commute to work.
Happy days.
I can't see what more I can do, no codes, cataclean done a while ago, oil change 1k ago, as said, she is well cared for 🤗🤗🤗

That pretty much sums it up. I've been through the same cycle.

Sure you CAN put different things on that "massage" the MAF signal into shape but I got to a point of asking myself why.
If anything I noticed better response and power when I switched back to stock.

Let us know how MOT goes.

Unless you're going for a stand alone ecu I honestly think NA tuning is pointless.