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MAF/Airflow sensor values on 2.3 petrol MK2

Started by brianh, May 03, 2022, 04:52:09 PM

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Evening All!

Does anyone here know what value you should be seeing on the MAF on a 2.3 petrol engine 2001 Galaxy. I can view the value, graph the value, but no idea what the actual value at a given RPM (ideally idle) should actually be.

Did initally suspect a vacuum leak, but can't locate one anywhere, so just trying to rule out an underreading MAF sensor now.

I've tried looking on TIS but haven't found anything there unfortnately.

Not sure what the readings should be however I wonder if one option would be to take one off a friend's Galaxy and see how it runs when they're switched over

Alternatively maybe one of the petrol owning Galaxy people on here could take a reading from their own motor vehicle for comparison purposes

I would do it myself for you Brian but I have the diesel engine

The Galaxy - one of the best motor cars money can buy. Whether you're a boy racer, a busy mum, a plumber or simply an old granny poodling around the shops, the Galaxy has everything you could ever need from a motor car.
I drive a Seat Alhambra 1.9Tdi which has 115bhp and an automatic gearbox.

I am happy to help you with all your questions. I am not a qualified mechanic but seem to be better at fixing my car than even the most experienced garages.

I have lots of friends here and very much enjoy talking with you all. Always remember, a motor car is a serious tool and should be treated with respect. Put your safety first, always.

THat would be an option, but I don't know anyone else who still has a Galaxy to borrow it from!

If someone could read theirs at idle that would be helpful. I'm trying to source a replacement otherwise to see if I can rule it out.

It does run even worse when unplugged, but then I think I've found that to be the case when the MAF is working correctly on the petrol ones anyway, unlike the diesels.

Calling all petrol Galaxy drivers! Attention, Attwntion!

My friend Brian needs some data about air flow readings at idle. Please can you take some readings and report back.

Thank you!!
I drive a Seat Alhambra 1.9Tdi which has 115bhp and an automatic gearbox.

I am happy to help you with all your questions. I am not a qualified mechanic but seem to be better at fixing my car than even the most experienced garages.

I have lots of friends here and very much enjoy talking with you all. Always remember, a motor car is a serious tool and should be treated with respect. Put your safety first, always.

Can anyone help poor Brian out with this please

He is always so helpful and helps other people with their motor car problems

Maybe one of you has a 2.3 petrol model and can help him out

Thank You In Advance
I drive a Seat Alhambra 1.9Tdi which has 115bhp and an automatic gearbox.

I am happy to help you with all your questions. I am not a qualified mechanic but seem to be better at fixing my car than even the most experienced garages.

I have lots of friends here and very much enjoy talking with you all. Always remember, a motor car is a serious tool and should be treated with respect. Put your safety first, always.

Done a smoke test now and can't find any sign of a leak, so its looking like a MAF is on the cards. I'd suspect very few are still running the 2.3 petrol on here, most of those still here appear to be diesel powered. I know when I was looking round to see what was available most of the petrol ones available for sale were the 2.8 rather than the 2.3

Hey I had a look on my 2.3 mk1 now with still the original MAF. Just after startup when the idle is still a bit over 1000rpm I read around 5.0 g/s and 1.14V
I own a MK1 1999 2.3 DOHC Ghia & 2003 1.9TDI Trend.

Thank you Orbis!!!!

I wonder how this compares to the figures you are betting Brian?

So many kind and helpful people here
I drive a Seat Alhambra 1.9Tdi which has 115bhp and an automatic gearbox.

I am happy to help you with all your questions. I am not a qualified mechanic but seem to be better at fixing my car than even the most experienced garages.

I have lots of friends here and very much enjoy talking with you all. Always remember, a motor car is a serious tool and should be treated with respect. Put your safety first, always.

Thanks Orbis, that gives me a good indication that both of the ones I've got are likely broken, i'm seeing values of 2.2 at idle, not checked the voltage though, will have a look at that. I've ruled out vacuum lead via a smoke test now, so fairly sure its dodgy MAF i'm looking at now.

If not done yet, you can try cleaning the sensor. It is a very tiny delicate wire however, it can break easily. I think isopropyl alcohol is fine to use, but google is your friend.
I own a MK1 1999 2.3 DOHC Ghia & 2003 1.9TDI Trend.

I think there are sprays you can spray through the MAF to help clean it too
I drive a Seat Alhambra 1.9Tdi which has 115bhp and an automatic gearbox.

I am happy to help you with all your questions. I am not a qualified mechanic but seem to be better at fixing my car than even the most experienced garages.

I have lots of friends here and very much enjoy talking with you all. Always remember, a motor car is a serious tool and should be treated with respect. Put your safety first, always.

I've tried a can of carb cleaner on it and its made no difference at all, looked fairly clean though. I've ordered a replacement now, hopefully that will sort it!

Fingers crossed 🤞
I drive a Seat Alhambra 1.9Tdi which has 115bhp and an automatic gearbox.

I am happy to help you with all your questions. I am not a qualified mechanic but seem to be better at fixing my car than even the most experienced garages.

I have lots of friends here and very much enjoy talking with you all. Always remember, a motor car is a serious tool and should be treated with respect. Put your safety first, always.

Hi Brian what are the symptoms to your problem or have I missed it somewhere?
2016 Vauxhall Insignia Elite Nav in White 2.0CDTI Manual.
2009 Kia Sedona GS In Black 2.9CRDI 183PS. 5 Speed Manual WAV.
2003 MK2 Galaxy Ghia In Solid Black 1.9 TDI 115PS. 5 Speed Automatic.
Upgraded Eberspaecher booster heater to independent heating with 7 day timer.

With VCDS lite (full version) need a code clearing or want to scan for faults in the north kent area, PM me. All for a pint of Strongbow.

Fuel trims at idle stuck at +25%, stalling at idle and logging system too lean messages. On both fuels. Got the new MAF arrived yesterday, its on the list of jobs to do tomorrow so hoping that sees an improvement! If you have any suggestions I'd be interested, though I know very few petrol MK2 owners still on here (or if they are on here, they are very quiet!)

I know you said you couldn't find any air/vac leaks but did you look at the PCV valve it's quite well hidden and has a short rubber elbow that perishes.
2016 Vauxhall Insignia Elite Nav in White 2.0CDTI Manual.
2009 Kia Sedona GS In Black 2.9CRDI 183PS. 5 Speed Manual WAV.
2003 MK2 Galaxy Ghia In Solid Black 1.9 TDI 115PS. 5 Speed Automatic.
Upgraded Eberspaecher booster heater to independent heating with 7 day timer.

With VCDS lite (full version) need a code clearing or want to scan for faults in the north kent area, PM me. All for a pint of Strongbow.

Looked at it, can't see any sign of leakage there even with the smoke tester, I've got to do an oil change in the next week, so if the MAF doesn't fix it, that will be the next place to look now as I will be under there anyway.

May 13, 2022, 11:40:41 PM #17 Last Edit: May 13, 2022, 11:44:48 PM by SirDavidAlhambra
Only takes 20 seconds to change the MAF and if it's covered in dirt then the car would under measure air intake causing the fuel trim to go positive to compensate for excess unexpected air. Those things do wear out after a while

There's only two logical possibilities here, fuel restriction is unlikely so then we're talking about unmetered air getting in and there's not many ways that can happen.

So I reckon the MAF's likely to be your problem squire

If that hasn't sorted it, then have you checked the o2 sensor readings after the cat
I drive a Seat Alhambra 1.9Tdi which has 115bhp and an automatic gearbox.

I am happy to help you with all your questions. I am not a qualified mechanic but seem to be better at fixing my car than even the most experienced garages.

I have lots of friends here and very much enjoy talking with you all. Always remember, a motor car is a serious tool and should be treated with respect. Put your safety first, always.

Quote from: SirDavidAlhambra on May 13, 2022, 11:40:41 PMOnly takes 20 seconds to change the MAF and if it's covered in dirt then the car would under measure air intake causing the fuel trim to go positive to compensate for excess unexpected air. Those things do wear out after a while

There's only two logical possibilities here, fuel restriction is unlikely so then we're talking about unmetered air getting in and there's not many ways that can happen.

So I reckon the MAF's likely to be your problem squire

If that hasn't sorted it, then have you checked the o2 sensor readings after the cat

As of now, the MAF doesn't seem to have made any difference, Unmetered air shouldn't be an issue as the smoke test didn't show anything up. Suspecting the pcv valve pipe I've given it a spraying with carb cleaner today to see if it made any difference and nothing has happened, so I'm fairly sure thats also ok.

O2 readings look fine - the pre-cat sensor voltage flips back and forth as it should, its now had another sensor installed (as the wiring from the one on there originally was damaged somehow, though was doing the same thing anyway). The one after the cat doesn't appear to be problematic as far as I can tell, though it doesn't do a lot (I know they are a different type of sensor, and don't mirror the front sensor, but need to look at what exactly is expected) though if its not working that should result in catalyst efficiency messages I think, not system too lean messages, which would be down to the sensor before the cat, not after.

I'm starting to suspect an inlet valve may not be sealing properly, so compression test will be the next thing to try unless anything else is suggested.

Post cat sensor is purely for monitoring cat efficiency nothing else. If that's knackered all you will get is the cat efficiency error as you quite rightly say.

Ok we have to help Brian fix this guys

O2 sensors sound fine, MAF isn't the cause

Does the LTFT change when u raise the revs or put the engine under load?

Any exhaust air leak before the o2 sensors?

Anything to suggest low fuel pressure?

Could you put a bottle of redex through in case something's a bit clogged?


Calling all engine experts: what should Brian check next please??? Thank you
I drive a Seat Alhambra 1.9Tdi which has 115bhp and an automatic gearbox.

I am happy to help you with all your questions. I am not a qualified mechanic but seem to be better at fixing my car than even the most experienced garages.

I have lots of friends here and very much enjoy talking with you all. Always remember, a motor car is a serious tool and should be treated with respect. Put your safety first, always.

Quote from: johnnyroper on May 14, 2022, 08:45:28 PMPost cat sensor is purely for monitoring cat efficiency nothing else. If that's knackered all you will get is the cat efficiency error as you quite rightly say.

Agreed, pre cat one does affect fuel mix tho I think because it gives feedback about whether the stochimetric ratio is correct. I first became an expert on cat converters when fixing my Ford Focus. Older cars just didn't have this problem
I drive a Seat Alhambra 1.9Tdi which has 115bhp and an automatic gearbox.

I am happy to help you with all your questions. I am not a qualified mechanic but seem to be better at fixing my car than even the most experienced garages.

I have lots of friends here and very much enjoy talking with you all. Always remember, a motor car is a serious tool and should be treated with respect. Put your safety first, always.

Did you check the idle air control valve?
I own a MK1 1999 2.3 DOHC Ghia & 2003 1.9TDI Trend.

Quote from: SirDavidAlhambra on May 14, 2022, 08:52:00 PMAgreed, pre cat one does affect fuel mix tho I think because it gives feedback about whether the stochimetric ratio is correct. I first became an expert on cat converters when fixing my Ford Focus. Older cars just didn't have this problem

No, but older cars had plenty of more annoying problems and were generally more unreliable at the same time, as well as far less efficient.

Quote from: Orbis on May 14, 2022, 10:14:01 PMDid you check the idle air control valve?

I've tried cleaning it, but its rather limited what you can actually do with it as it doesn't seem to come apart? Though anything going through the IAC should also be going through the MAF as well so not causing an issue there as far as I can see? If you have a way of checking it please share and will give it a go?

Quote from: SirDavidAlhambra on May 14, 2022, 08:49:55 PMOk we have to help Brian fix this guys

O2 sensors sound fine, MAF isn't the cause

Does the LTFT change when u raise the revs or put the engine under load?

Any exhaust air leak before the o2 sensors?

Anything to suggest low fuel pressure?

Could you put a bottle of redex through in case something's a bit clogged?


Calling all engine experts: what should Brian check next please??? Thank you


Can pretty much discount any issue with the fuel injectors as both fuels show the issue (the LPG ones are seperate to the petrol ones). Its got a newish downpipe as the original one rotted away at the bottom joint a few months ago and blew the gasket out, no sign of any air leak I can see there.

Yes the LTFT drops as the revs are increased. The odd thing is, the STFT is all over the place, sometimes negative, sometimes slightly positive, other times its going up to +25% at idle, which usually ends up with a stall or a stutter and then keeps running. That will typically be after around 30 seconds of running.

Will have to give a compression test on it and see what that shows up. I've got the tools to do it so makes sense to check that next.

You're right, it shouldn't affect the MAF reading. And indeed, the IAC can't easily be taken apart.

A few other late night thoughts:
Is the intake air temperature sensor working correct? Can you monitor it's value?

Was also thinking about checking the condition of the spark plugs and also checking the gaps. And the coil pack ( I assume you have the later coil pack model, one for 4 cylinders).

Looking forward to the results of the compression test.
I own a MK1 1999 2.3 DOHC Ghia & 2003 1.9TDI Trend.

Quote from: brianh on May 15, 2022, 12:13:44 AMYes the LTFT drops as the revs are increased. The odd thing is, the STFT is all over the place, sometimes negative, sometimes slightly positive, other times its going up to +25% at idle, which usually ends up with a stall or a stutter and then keeps running. That will typically be after around 30 seconds of running.

This is a big clue I think.

During idle when the throttle plate is closed, the vacuum in the intake manifold is high and very little air flow is entering the engine, so even a small amount of un-metered air will have an effect on fuel trim. This forces the PCM to react to the lean condition with positive valued fuel trim readings. The fuel trims will return to almost normal during cruise and wide-open throttle when the throttle plate is open and there is little vacuum in the intake but lots of air flow into the engine. The small amount of un-metered air creating an idle vacuum leak is hidden or masked when the engine's airflow increases, so the effect on fuel trim is less evident.

I wonder if the diaphragm in the PCV oil separator assembly has ruptured, allowing full manifold vacuum to enter the engine.
I drive a Seat Alhambra 1.9Tdi which has 115bhp and an automatic gearbox.

I am happy to help you with all your questions. I am not a qualified mechanic but seem to be better at fixing my car than even the most experienced garages.

I have lots of friends here and very much enjoy talking with you all. Always remember, a motor car is a serious tool and should be treated with respect. Put your safety first, always.

Quote from: Orbis on May 15, 2022, 12:54:55 AMYou're right, it shouldn't affect the MAF reading. And indeed, the IAC can't easily be taken apart.

A few other late night thoughts:
Is the intake air temperature sensor working correct? Can you monitor it's value?

Was also thinking about checking the condition of the spark plugs and also checking the gaps. And the coil pack ( I assume you have the later coil pack model, one for 4 cylinders).

Looking forward to the results of the compression test.

Don't know on the intake temp, will check think I can monitor that. Though think it's part of the MAF anyway so should be OK unless there's a wiring issue.

It's the coil pack with 4 leads running back to a single block mounted on the end if the engine, rather than the pair mounted on the end, not sure if that qualifies as later? Plugs have been changed recently with NGK ones so that should be OK. Might put my spark plug tester on it to see what's going on with coil pack though don't think its an issue with ignition as it runs fine and just dies suddenly, not running lumpy beforehand or anything.


I can't do compression test before next weekend, some of the other bits I can tackle though.

As far as vacuum is concerned, the vacuum reading looks stable, and reads around -24 at idle, can't remember what measurement value that's in without checking now.

Intake air temp showing 17c-21c when checked today, which agrees with the dashboard air temp reading of 17.5c so think we can say thats ok.

Gap wise, the plugs are iridium so not adjustable. I forgot to pickup the spark plug testers I meant to collect earlier, so will try for that tomorrow instead.

Could it be that PCV valve
I drive a Seat Alhambra 1.9Tdi which has 115bhp and an automatic gearbox.

I am happy to help you with all your questions. I am not a qualified mechanic but seem to be better at fixing my car than even the most experienced garages.

I have lots of friends here and very much enjoy talking with you all. Always remember, a motor car is a serious tool and should be treated with respect. Put your safety first, always.

Quote from: SirDavidAlhambra on May 15, 2022, 05:25:40 PMCould it be that PCV valve

Any suggestions on how to test it? Theres pressure when either the oil filler cap or the breather tube at the other end of the rocker cover are removed with the engine running, doesn't look like theres any external leaks as it doesn't change with squirting carb cleaner around the area of the pipe from underneath, I don't know of any other way to test it for failure short of removing it?

Tbh I wouldn't even test it, I would just swap it over if you think it might be at fault.

It sounds like it may well be stuck open

One test would be to take it off and shake it, listening for a rattle... if you don't hear a rattle, it's probably stuck. But it's worth changing these things from time to time in any event

Here's hoping we get that lovely Galaxy of yours back on the road very soon
I drive a Seat Alhambra 1.9Tdi which has 115bhp and an automatic gearbox.

I am happy to help you with all your questions. I am not a qualified mechanic but seem to be better at fixing my car than even the most experienced garages.

I have lots of friends here and very much enjoy talking with you all. Always remember, a motor car is a serious tool and should be treated with respect. Put your safety first, always.

Trouble is, if its the bit I think you mean, its a right pain to access as its buried under the exhaust manifold.

Will give the spark plugs a test and compression test before going down that route I think!

This was the post I done a few years back but there seems a problem with knowledge base photo's, I have spoke to Mark about this.

https://www.bigcarclub.com/ford-galaxy-common-faults-and-problems/engine-cutting-out-when-cold/
2016 Vauxhall Insignia Elite Nav in White 2.0CDTI Manual.
2009 Kia Sedona GS In Black 2.9CRDI 183PS. 5 Speed Manual WAV.
2003 MK2 Galaxy Ghia In Solid Black 1.9 TDI 115PS. 5 Speed Automatic.
Upgraded Eberspaecher booster heater to independent heating with 7 day timer.

With VCDS lite (full version) need a code clearing or want to scan for faults in the north kent area, PM me. All for a pint of Strongbow.