Hello guys,

I have problem with my 98 skoda octavia, 1.8 20v naturally aspirated, engine code AGN.

I simply cannot start engine while air mass sensor is plugged on! If i disconnect air mass sensor, engine can be started straight away???

I have checked continuity on 5 wires between air mass sensor plug and ecu connector. They are all ok, none of the wires are broken and they dont short to any other wires in between them. I have also checked earth points, cleaned them and put them back, but no improvements.

I have fitted new airmass sensor and and there were no improvements, HOWEVER i have noticed following:

If i only plug electrical connector to air mass sensor without attaching it to the air filter intake paipes engine will run, BUT if i blow litlle bit of the air inside air mass sensor engine starts to die. If i stop with blowing engine will continue to run OK!

I have only discovered this while i was dealing with imobiliser issue on the same vehicle?

Imobiliser issue is still present, but i am just wondering if this imobiliser issue is somehow part of above problem?

Thanks for reading

Kind regards

Sounds like the MAF is knackered and giving a duff reading, which is why the engine will run with it unplugged as it'll run a default setting for the MAF signal.

Hi

I have fitted new air mass meter already, but it made no improvements still cannot start engine with air mass sensor pluged on, once plug is disconected engine dies straight away?

Regards

sorry

i meant once plug is disconnected engine starts straight away

thanks

Did the connector look OK when you unclipped it? No cracks or shorts?

Hi

I have fitted new air mass meter already, but it made no improvements still cannot start engine with air mass sensor pluged on, once plug is disconected engine dies straight away?

Regards

Is it a genuine one? Aftermarket ones can be very unreliable on the 1.8t's.

Hi all again,

The connector attaches to airmass meter ok without any problems, however litlle security plastic clip is broken. The plug defenetelly makes sufficient contact as faults can be deleted and wont came back on, but at this stage as air mass sensor is connected i am unable to start engine. As soon as air aitmass sensor is connected i simply cannot start the engine.

Part that i used in not brand new but is is original SEAT TOLEDO one, that comes from the same engine AGN. Also both part numbers are the same.

Regards

Are you continuity testing the new one also?

Some sensors are damaged by doing such a test

have you checked all the earth wires by the battery box sometimes these get corroded and will cause airflow meter running problems

Hello guys,

Thanks for all your advice

Yes, before i began testing wires for continuity i have disconnected air mass sensor and both connectors on the ecu. There are no broken wires and there are no short in between all 5 wires.

I have cleaned all earth points on the bulkhead and gear box, but i have noticed where battery is there are two small earth wires, they looked quiete rusty and this will be the job in the morning ( as felicia 16V suggested). I have just finished working on this car and its almost midnight. Had enought for tonight.

Will keep you updated with progress, BUT in the mean time if anyone have any further suggestions plese let us know.

Kind regards

Hello guys,

I have spent quite a lot of time today sorting out the bad earth connection around the battery try, all round connectors replaced with new ones and also soldered just make make sure there is a sufficient connection, but gess what????? problem still present.

Istill cannot start the engine with air mass sensor connected.

It has started to drive me mad.

Any furher suggestions??

Regards

have you had any diagnostics done on the car/do you have vagcom

Hi

Yes i have done lot of diagnostics myself, but obviously im not good enought so sort it out. Have been through wiring diagram several times, and everything appears to be ok according to the diagram.

I do have VAGcom, but cannot pin down the problem.

Regards

Paste here the full Vagcom log

with the engine running and the airflow connected but not in the airstream can you post up what the measuring blocks are reading the airflow as,

then maybe see what they change to when you place it into the airstream (may need to log for that i guess as it stalls) it may give us an idea, also see if you can find the lambda reading too (30/34 i think)

so the air mass meter is a 2nd hand one? maybe this is also faulty, knowing how often these go down i wouldnt advise buying 2nd hand

Ok guys,

I will try to log readings while engine running without airmass sensor connected and the readings when engine dies out. Hopefully this might leave some trace to follow.

The second airmass sensor that i used as a DONER PART was working ok and still works ok on the other vehicle, so really this air mass sensor defenetelly worksok.

Ps. Do i just copy and past reading from vag-com or is there diffrent way of attaching this reading?

Kind regards

copy/past is the easiest. or you could use the screen shot and upload it as a pic (press the button marked prt scrn this takes a snapshot of everything displayed on the screen at the time of pressing, then past into word pad or similar)

hello guys,

i have managed to overcome imobliser issue, but issue with air mass sensor still present. I have following reading:

If i go to engine and maesure value block, channel 2, field 4 air mass-with air mass sensor disconnected and engine running it dispays approximatelly 5.13air mass grams/second. However, if i quickly plug on and plug off connector readings drops down to 1.37 grans/second.

Now, if i go channel 4, fields 3 and 4 air mass- readings are 00, no matter if engine runs on not.

have look at log file

Wednesday,20,January,2010,22:29:15:62365

VCDS Version: Release 908.1

Data version: 20091018

Address 01: Engine (06A 906 018 DJ)

22:28:20 Group 002

800 /min RPM

2.55 ms Time

4.03 ms Time

4.65 g/s Mass Flow

What do you think?

Can you do a log of block two and drive the car as they are just idle readings

Need too se what its doing through the revs

Morning all,

Yes i will log the readings for the field two during the driving and will come back to you guys

Thanks

hello guys

this is the log of air mass reading in chanel 2,3 and 5. I was traveling atapproximatelly 26mph. Reading in chanel 2 field 4 does flactuate on idle but hardly moves from 5 gram/seconds while driving.

Thursday,21,January,2010,19:46:04:62365

VCDS Version: Release 908.1

Data version: 20091018

Address 01: Engine (06A 906 018 DJ)

19:44:38 Group 002

800 /min RPM

2.70 ms Time

4.29 ms Time

5.00 g/s Mass Flow

19:44:38 Group 003

800 /min RPM

12.530 V Voltage

69.0°C Temperature

19.5°C Temperature

19:44:38 Group 005

810 /min RPM

810 /min RPM

10.2 % Lambda

5.00 g/s Mass Flow

If air mass sensor isn't connected how come the reading in channel 2, field 4 is changing?

Regards

so is that with the sensor plugged in? and connected to the pipework so the engine is sucking thru it or just plugged in?

have you checked for the correct voltage at the sensor plug?

hi

i did drove my car while i took log

Regards

I will take another snap shot while driving tommrow

Regards