1 What's the Bosch part number for the MAF without the plastic tunnel?

Euro Car Parts are taking the p*** at £200 for the tunnel version.

2 Would you ever buy a non-Bosch copy?

I remember somebody saying on rr.net that one from a Saab of some description fitted and worked. No idea on the part number or how well it worked though.

Can't tell you the part number, but if needed, you should get a genuine Bosch. Gems does not seem
to mind pattern parts, but Thor will generally run like crap with a copy.
Be aware that there are a LOT of counterfeit Chinese Bosch parts floating around.
A genuine part will have a holographic sticker on the box with a unique code number.
Take that code number to the Bosch parts checker.
https://protect.bosch.com/
Enter the code, and see if you got a good one! Just having the sticker is not enough.......
They are counterfeiting those as well!
Yes, they are indeed stupid expensive!
Happy hunting.

Thanks everyone. The hologram thing is a great tip, but I normally buy from reputable outlets. Your comments have put me off eBay!

Bosch F 00C 2G2 029

Rare as rocking horse poop and obscenely expensive.

Dear All,
Mine is spewing gallons of sooty black watery exhaust. My LPG diagnostics shows both lambda sensors (one brand new) sitting resolutely at 5 volts (GEMS engine). I've suspected the MAF and cleaned it and the filter but still the same. the car will run with the MAF disconnected but much worse and richer.
So Q1)
am I right to suspect the MAF, its labelled a Lucas part.
I've read the various MAF/problems/testing/cleaning threads but am still not sure,
Q2) what are my options for a replacement?
Thanks in advance.

The Zirconia sensors used on a GEMS work the opposite way round to the Titania sensors used on the Thor and most other cars, so 5V on a GEMS is lean with 0V being rich. That means it will be chucking more fuel in to try to get the voltage to come down. What diagnostics have you got? Anything that will show what airflow the MAF is reporting?

PC38 wrote:

My LPG diagnostics shows both lambda sensors (one brand new) sitting resolutely at 5 volts (GEMS engine).

I don't know who fitted your LPG system but is the LPG ECU even wired to the lambdas? If they're not connected you might get a reading of 5V from LPG software anyway.

Dear All,
I realise I should have put this in the electrikery section.
I did the installation and the LPG ecu is wired into the Lambda sensors so what it sees is what the RR ECU sees. In the past when doing other things and tuning the LPG system i've seen the lambdas working correctly in the same software, oscillating from 0-5 and back etc. So I know the diagnostic is seeing the real reading.

PC38 wrote:

I realise I should have put this in the electrikery section.

But then again, it's fuelling so that can leak....

Do you have an OBD reader that can show live values? If you do, check the lambda sensor and MAF outputs as it is, then disconnect the lambda sensors from the LPG system and see if it is the same. It may be that the LPG ECU is supplying a bias voltage.

I drove my GEMS for months with the MAF unplugged. Ran fine, and fuelling was more or less normal. A bit flat perhaps but certainly nothing untoward.

So yours not running properly with it unplugged suggests something else might well be going on...

With my bad MAF connected, it would often massively overfuel at startup and either chuck clouds of black smoke or not even start at all.

I ended up building a converter to use a MAF from an Audi TT, which has been in for a few months and seems to be working well enough.

when my MAF died it would not run for any reason. if the ecu picks up that it has a bad MAF it will automatically shut down when rpm is over 500 rpm, i could make it keep running if i pumped the throttle heaps but it would smoke out the shed in seconds . to determine that it was the maf i made up a lead that i could prod with the multimeter to get a proper reading from it . if you do this be careful , if you put power to the wrong spot you will burn out the ecu

mad-as wrote:

i could make it keep running if i pumped the throttle heaps but it would smoke out the shed in seconds

I bought a spares or repairs project P38 that was exactly the same. After pumping the throttle constantly, once running I could get it to run reasonably well. The pattern MAF sensors will usually work pretty well but if checked with an OBD reader, the airflow readings will be incorrect.

Its strange that they seem to act differently...

With mine, with the bad MAF connected up, it would start then immediately die. If you tried to keep it running with throttle it would produce clouds of black smoke and then typically still die a few seconds later.

However if you unplugged the MAF, then some portion of the time it would also start and immediately die, however if you gave it just the right amount of throttle it would stumble then run fine. A lot of the time it would just fire up and run normally.

I drove mine around all winter with the MAF unplugged, sorta forgot about it TBH, and you wouldnt have known for the most part. Then one day, wife drove it to work and it was utter crap. Stalling, stumbling, jolting, basically undriveable. I dont know why it changed. I plugged the faulty MAF back in and it started perfectly and drove home fine. That was the kick i needed to finish the converter though, and with the converter and Audi MAF installed its been spot on ever since.

PC38 wrote:

I realise I should have put this in the electrikery section.

Dear All,
Well if its of any interest the eventual outcome was that the earth to the MAF via connector C531 on terminal 3 the red and black wire was not grounding, as soon as I wired up an alternative route to 12v negative she again ran beautifully. I did not bother to try to find out where the ground was (not).