TD5 MAF Stuffed?

[Rok_Dr]

Hi All

I have been having a very occasional bout of sluggishness when I first start off in my 2003 D2a. After about 10-20 seconds it disappears and all is fine. Only occurs once a week or so and only when starting from cold. Inter-cooler hoses and fuel regulator have recently been replaced.

I got a Nancom recently and decided to plug it and see what I could find.

Anyway long story short there were no engine faults logged, but went for a drive and the Airflow failed to budge from a reading of 4.3. So I let everything cool down, removed the MAF and gave it a good cleaning with contact cleaner, let it dry and reinstalled. Did another test run and still a flat line reading of 4.3. Nanocom log for the first run is attached for those who are interested.

Searching the forum it appears I should be getting about 50ish at idle up to a max of 500ish. So would I be correct is saying I'm up for a new MAF sensor or should I be looking a bit deeper?:(

Cheers

Steve

[Tombie]

Check your fuse, and the wire running to the MAF...

Slunnie knows exactly which fuse it is...

Even an out of range MAF should be reading something...

Anyone nearby you know - try their MAF :cool:

[goingbush]

well bugger me,
i didnt know you could save a log like that on the nanocom.
very handy. how do you do it ?

[Rok_Dr]

Thanks tombie

I did check the fuse (no 2 under the bonnet) and wiring looks ok, anything in particular I should be looking for there? I also gave the connector a clean, before plugging in again.

Goingbush I don't have the nanocom powered up so from memory.... at the bottom of the instrument read out screen towards the right side is a blue disk icon. Tap that and it goes to a file screen. Tap in a file name hit ok and ok again and logging starts. Tap the same icon again to stop logging and the nanocom will give an alert that the logging has stopped. You need to have an SD card inserted though. Plug the Sd card into your computer and you can open the file in excel. Note it is not a true csv file as it uses semicolons instead of comas as a delimiter but you can easily spread break it up into columns by selecting the data and using the text to columns command.

Cheers

Steve

[JC Rover]

I ran the Nanocom on the defender TD5 with MAF unplugged by accident. The Nanocom read air flow constantly as 4.0.

Strange, it also ran a lot better. The MAF had been reading low. I will try cleaning it, and then perhaps replace it.

JC

[tailslide]

Hi Steve,

I have a spare MAF that you are welcome to try. It is from my V8 but IIRC they are the same on the TD5.

We met a few weeks ago at LifeStyle 4x4 and I'm not too far from there. I'm also home all next week resting my shoulder...

Cheers
Ron

[Rok_Dr]

Thanks Ron, the offer is much appreciated. Yep I remember you and your tidy silver/grey d2 :)

I just had a quick check on the Russian Microcat site and unfortunately the td5 and v8 MAF sensors have different part numbers and in the schematics look different as well. So it probably won't help in conclusively diagnosing the problem.

Good luck with the shoulder. I'm hoping to get away to Mt Jackson on the weekend with the club. Thankfully the sensor problem isn't a show stopper, and the car is running well.

JC thanks for your observation. I'll try running it unplugged and see if my readings change.


Cheers

Steve

[Franz]

Hi Steve,

I have a spare MAF that you are welcome to try. It is from my V8 but IIRC they are the same on the TD5.

We met a few weeks ago at LifeStyle 4x4 and I'm not too far from there. I'm also home all next week resting my shoulder...

Cheers
Ron
Are they the same? I was under the impression that the V8 has a different MAF. They are also cheaper than the Td5 MAF.

[OffTrack]

Note it is not a true csv file as it uses semicolons instead of comas as a delimiter but you can easily spread break it up into columns by selecting the data and using the text to columns command.


Talk about doing the hard way. :D

In excel use Import > CSV File rather than open.

The import wizard allows you to select semicolons as the delimiter.

If you want to make life even easier got to td5 map suite (http://luca72.xoom.it/td5mapsuiteweb/downloads.html)
and grab a copy of Graphic Viewer CSV (at the bottom of the page).

http://www.aulro.com/afvb/attachments/technical-chatter/51482d1348450760-td5-maf-stuffed-graphicviewer.jpg

[tailslide]

Are they the same? I was under the impression that the V8 has a different MAF. They are also cheaper than the Td5 MAF.
Hi Franz,

You are correct, they are indeed different. The V8 MAF has a 5 pin connection and the TD5 appears to only have a 3 pin connection. I was under the impression that they were the same after looking under the bonnet of a few TD5s but sadly not to be. Sorry for the miss info...:(

Cheers
Ron

[Rok_Dr]

Aggh you are so correct Offtrack. I use your method for txt files but for CSV I have fallen into the habit of double clicking, call it brain fade ... ;)

I've also played with the graphic viewer program. Quite neat and easy to use. A few more bells and whistles would be nice but then it is free and robust so one can't complain.

Cheers

Steve

[Rok_Dr]

Hi all

Well after a couple of day's letting the problem sit and a bit more googling I've has another dig around the engine bay.

First check was unplugging the MAF. Nanocom reading was now a flatline 4.0 just as you observed JC.

Following Tombie's advice I also has a good look at the wiring loom running across the front of the engine. Well the conduit cover passing over the air cond compressor was pretty crumbly and falling apart but from the water temp sensor to the ecu looked fine. Removed all the crud conduit (it just fell apart in my hands!) and had a look at the actual wiring. I saw nothing untoward, no brittle insulation or abrasion. Whacked on some new conduit and then started the car. Still a flat line! Wriggled the wiring to see if that made a difference but no change.

I then decided to check the resistances across the pins of the MAF meter reasoning that this checks the MAF only, while the nanocom reading is a calculated figure from the electrons passing through a lot of wiring circuits. Pins 1-2 were right on at 16.75k ohms, but there was infinite resistance across both pins 2-3 and pins 1-3, ie no circuit.

So my conclusion is that the MAF is dud. This is very much a learning exercise for me (but an enjoyable one ;)) so I ask the question of more learned members, should I be checking anything else and is there anything in the above I have misinterpreted, before I hit the visa card?

Cheers

Steve

[gavinwibrow]

Hi all

Well after a couple of day's letting the problem sit and a bit more googling I've has another dig around the engine bay.

First check was unplugging the MAF. Nanocom reading was now a flatline 4.0 just as you observed JC.

Following Tombie's advice I also has a good look at the wiring loom running across the front of the engine. Well the conduit cover passing over the air cond compressor was pretty crumbly and falling apart but from the water temp sensor to the ecu looked fine. Removed all the crud conduit (it just fell apart in my hands!) and had a look at the actual wiring. I saw nothing untoward, no brittle insulation or abrasion. Whacked on some new conduit and then started the car. Still a flat line! Wriggled the wiring to see if that made a difference but no change.

I then decided to check the resistances across the pins of the MAF meter reasoning that this checks the MAF only, while the nanocom reading is a calculated figure from the electrons passing through a lot of wiring circuits. Pins 1-2 were right on at 16.75k ohms, but there was infinite resistance across both pins 2-3 and pins 1-3, ie no circuit.

So my conclusion is that the MAF is dud. This is very much a learning exercise for me (but an enjoyable one ;)) so I ask the question of more learned members, should I be checking anything else and is there anything in the above I have misinterpreted, before I hit the visa card?

Cheers

Steve
Steve, I have a spare MAF you are welcome to use as a test if you are not too far away.

[Mark Adams]

It really does sound like the MAF is dead. This is very very common, and shows in the fixed air consumption. Strangely they never do put up a fault code for this failure.

The MAF is mainly used to caclulate when to operate the EGR valve, and when the MAF dies it operates at the wrong time which leads to the stumbling when you try to pull off.

[roverv8]

It really does sound like the MAF is dead.

The MAF is mainly used to caclulate when to operate the EGR valve, and when the MAF dies it operates at the wrong time which leads to the stumbling when you try to pull off.

So if you blank your EGR, what else does the MAF do?

[justinc]

Auto trans shift points are partially referrenced from it, as is engine loads etc and it works in conjunction with ambient air sensor for a density/ volume calculation of incoming air.

JC

[PAT303]

JC the Td5 I've got here runs better with the MAF dis-connected,it blows black smoke so I'm thinking it's gone to the default setting?. Pat

[Rok_Dr]

Hi All

Well the old sensor was dead. Bought a new sensor (Siemens), fitted it last night and now I'm getting readings on the nanocom as per normal, mid 50's at idle etc, etc. On the test drive the car felt subtlety different. Less lag at takeoff and it revs out more cleanly and less strangled at high RPM. It may be my imagination but the auto shifts seem a bit crisper as well. I'll be interested to see how my fuel economy goes now......

So the outcomes for me were:

1. A flat line reading in the 4-4.5 range indicates a dead sensor (at least in my case).

2. It is well worth checking the wiring back to the ECU, if only to replace the conduit cover before the heat destroys the wiring insulation and also check for any other damage.

3. While it helped I didn't find the resistance testing to be particularly reliable. Both the dead and new sensors showed 16.7kOhm across pins 1-2. New sensor showed mid 20's mOhms across the other pins which is a bit lower than other posts have noted. Interestingly a test of the dead sensor after a hour or so driving in traffic showed very low approx 1.8mOhm values across pins 2-3 and 1-3, which leads me to suspect a fracture in the sensor's circuitry somewhere that causes an open circuit when cold. All I can say is that high values across pins 1-3 and 2-3 good, very low or no values bad. I certainly wouldn't be using them to predict % life left etc.

Anyway thanks one and all for your help with my problem. Its amazing what you can do with modern electronic diagnostics and my nanocom is now well on the way to paying for itself :)

Cheers

Steve

[OffTrack]

I think the good measurements mturri has posted are too high. There are now three reports of brand new or known good mafs measuring around 20Mohm so you'd have to assume this is normal rather than "dodgy" as mturri suggested.

[Bradtot]

Hi All

Well the old sensor was dead. Bought a new sensor (Siemens), fitted it last night and now I'm getting readings on the nanocom as per normal, mid 50's at idle etc, etc. On the test drive the car felt subtlety different. Less lag at takeoff and it revs out more cleanly and less strangled at high RPM. It may be my imagination but the auto shifts seem a bit crisper as well. I'll be interested to see how my fuel economy goes now......

So the outcomes for me were:

1. A flat line reading in the 4-4.5 range indicates a dead sensor (at least in my case).

2. It is well worth checking the wiring back to the ECU, if only to replace the conduit cover before the heat destroys the wiring insulation and also check for any other damage.

3. While it helped I didn't find the resistance testing to be particularly reliable. Both the dead and new sensors showed 16.7kOhm across pins 1-2. New sensor showed mid 20's mOhms across the other pins which is a bit lower than other posts have noted. Interestingly a test of the dead sensor after a hour or so driving in traffic showed very low approx 1.8mOhm values across pins 2-3 and 1-3, which leads me to suspect a fracture in the sensor's circuitry somewhere that causes an open circuit when cold. All I can say is that high values across pins 1-3 and 2-3 good, very low or no values bad. I certainly wouldn't be using them to predict % life left etc.

Anyway thanks one and all for your help with my problem. Its amazing what you can do with modern electronic diagnostics and my nanocom is now well on the way to paying for itself :)

Cheers

Steve

So does this mean you coming to Mt Jackson with us tomorrow? Hope so!!...LOL

[Rok_Dr]

Yes indeed cu @ the lakes 10.30:)

[turps]

Thought I would post here as I think mine is not 100%. I thought I would disconnect it to see what happens. As I have been having some very poor auto gear changes since having the auto rebuilt. Also driving up Mt Hotham the other night I had to use low range.
Power feels better and there is slightly less lag. But the best bit is the auto seems to sft better. It's still crap but better.

The down side of this power is the EGT go thru the roof. I am assuming my ems2 with egt is setup correctly. And just resuming cruise from 60km/h to get back to 100. With get in excess of 750c.
So unless you can monitor temps. I would be cautious on using all the extra power.
I am going to attempt to clean my MAF tomorrow. But also search for a replacement.

[Rok_Dr]

Hi turps,

CRC do an maf cleaner now, but contact cleaner also works well. Make sure the MAF is cold before cleaning otherwise you could fracture the wire. Also ensure it is throughly dry before reassembling.

If you can get access to a nanocom or similar it will really help with the diagnosis, alternatively using a multimeter to check resistances across the pins will also give you an indicator as to whether it is stuffed or not. Otherwise you will be shooting in the dark and a MAF is not cheap!

That said from what you are describing there may well be other issues besides the MAF causing your problems.

Good luck

Steve

[OffTrack]

Thought I would post here as I think mine is not 100%. I thought I would disconnect it to see what happens. As I have been having some very poor auto gear changes since having the auto rebuilt. Also driving up Mt Hotham the other night I had to use low range.
Power feels better and there is slightly less lag. But the best bit is the auto seems to sft better. It's still crap but better.

The down side of this power is the EGT go thru the roof. I am assuming my ems2 with egt is setup correctly. And just resuming cruise from 60km/h to get back to 100. With get in excess of 750c.
So unless you can monitor temps. I would be cautious on using all the extra power.
I am going to attempt to clean my MAF tomorrow. But also search for a replacement.

If you haven't done so already, get someone to reset the adaptations in the Auto ECU. The primary purpose of the adaptations is compensate for wear in the transmission clutch packs so need to be reset when you replace or rebuild the auto. While it won't fix lack of power it should help with the auto shifts.

cheers
Paul

[turps]

Had the auto reset. Made no difference.
Also brought an aftermarket maf from the uk. Think I went a little to cheap. It has fixed the lag on take off. So back to normal there. But as soon as I use more than 50% throttle. I get a massive miss.
As soon as I disconnect. I no longer get the miss. So I don't believe it is an oil in the loom issue.
Anyone got any tips on where to buy a new one?
As I kinda need it fixed. So I can sort out my auto issues. So will most likely buy from someone in aust. As I would like delivery by Friday.

[justinc]

The miss is most likely an overboost situation, you really need to get a nanocom or similar, this could all be solved very quickly and at little cost to you with a diagnostic tool. (and with all our help of course:))

JC

[turps]

The miss is most likely an overboost situation, you really need to get a nanocom or similar, this could all be solved very quickly and at little cost to you with a diagnostic tool. (and with all our help of course:))

JC

Pretty sure not over boost (boost gauge not hooked up yet). As I have had the over boost thing before.

Yer I know I should get a nanocom or similar. Was going to buy one before Xmas. But until i get a chance to use it and enjoy it offroad, without the auto being a pig. it maybe for sale soon.

[Rok_Dr]

X2 Justin's comments regarding plugging in a nanocom or similar. It could save you a lot of time, frustration and $. I can't help feeling that you have another issue besides the MAF sensor, which an electronic diagnosis could well reveal.

Have a look at the first thread in the electronic diagnostics forum (members with diagnostic equipment). There may be a forum member near you with one who will be able to assist. Offtrack (Paul) updated the map of members recently and the link to the google map is on the second last page of the thread.

Good luck

Steve

[turps]

New maf. Drives nice. Romsey LR even checked the ecu for faults. And there was only one. And it was due to the auto.

[The Bullfrog]

Reading this has convinced me to check my MAF as my fuel consumption is very average (17-20L/100Km!!) and my EGT's are high (if i don't watch the gauge they can hit 1000degrees!!!!!) and i have to religiously watch the EGT gauge. Also of note is the standard ECU will push it up to 750, so not sure if that is normal for a standard ECU??

Is a 2000 disco td5 auto with bar work, susp lift, 31 inch tyres etc, D2a intercooler, mandrel bent exhaust and remapped NNN ECU.

Hawkeye connected and showed about 59 at idle.

Checked the resistance values and i got:
pins 1 and 2 = 16.85 k ohms
pins 1 and 3 / 2 and 3 = between 2.9 m ohms and 5.9 m ohms.

I know there is a general consenus that I shouldn't ditch it just by the resistance values, BUT, from what I have read through searches of posts, the second values are WAY out of whack..

Would I be correct in thinking those values are too far out and I should buy a new MAF???

Cheers

Troy

[nobbyclrk]

is a general consenus that I shouldn't ditch it just by the resistance values

Where are you getting these values from?