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[Albatross]

I've just had a long chat with a chap from a specialist garage that deals with this sort of thing here in Bedford.

He says that he thinks:

• It is unlikely to be a fuel pressure issue
• More likely a MAF issue
• The exhaust change will not be a cause
• The secondary sensors definitley do NOT affect trim, but only measure the pre-cat efficiency.

As far as he is concerned I need to bring the car down to him and leave it with him for the day to scan it. He wants to check the MAF sensor voltage and the grams per hour rate of the air flow too.

He's quoted me £50 for the initial scanning etc.


I had another chat with a mobile engine tuning chap and the first thing he said was have you checked the fuel pressure?

Any thoughts? (Kevin et al.)

Do you think that it is worthwhile to start to go down the road of investing in the 1st garage's time and investigations?

[feeutfo]

another maf refrance. I would try cleaning the maf first. Then if it persists see your man.
Give maf a good spray with carb cleaner. Easy job. Dont physicaly touch the internals with anything solid. Like a brush, rag or finger. Good chance itll break.

[Albatross]

Is the MAF the big metal block that bolts onto the front of the plenum?

If so I cleaned out the "MAF block" when I did the breathers whilst JamesV6CDX was doing the cam-belt and water pump.

I did touch stuff, but only with carb-cleaner, fingers and kitchen roll. I'm pretty sure I didn't break anything.

The breather, plenum and that metal block with the butterfly valves were like new when I (James) put it all back together.

[feeutfo]

no thats the throttle body. Maf is up stream of there. Iirc, look at air box. The maf i think is next in line. Its black plastic with electrical plug.

Ps, might be worth checking all the jubilee clips are tight on the air intakes/bag pipes. Makes sure there are no air leaks/splits cracks in the plastics.

[Albatross]

But any air leaks that could possibly be related if they are there at all would be downstream of the MAF sensor wouldn't they?

Otherwise the MAF sensor would be "aware" of the additional air going through it.

[feeutfo]

But any air leaks that could possibly be related if they are there at all would be downstream of the MAF sensor wouldn't they?

Otherwise the MAF sensor would be "aware" of the additional air going through it.

Yep. Air leak. Proper term, unmetered air.

[Albatross]

Is there a picture around of an engine bay with MAF sensor and related bits highlighted?

Even a picture of the MAF sensor itself would be useful. I've looked through the maintenance section.

[Kevin Wood]

Is there a picture around of an engine bay with MAF sensor and related bits highlighted?

Even a picture of the MAF sensor itself would be useful. I've looked through the maintenance section.

MAF sensor is just below the elbow that leads from the lid of the air cleaner box. Yours is reading exactly the same as mine at idle. Not so sure further up the rev range but might eb worth a try giving it a clean. If that doesn't work, investigate the fuel system a bit further I reckon.

Kevin

[Albatross]

Cheers Kevin. Given the reports on the garage vs. the mobile tuning mechanic what do you reckon?

Is it six and two three's or do you reckon the mobile man is more on the nail having gone straight to the fuel system?

[Kevin Wood]

Cheers Kevin. Given the reports on the garage vs. the mobile tuning mechanic what do you reckon?

Well, they both have hunches based on what they've seen before. The question is: will either of them go through a logical sequence of eliminating the possibilities or will they start replacing expensive parts based on hunches?

Is it six and two three's or do you reckon the mobile man is more on the nail having gone straight to the fuel system?

They both have identified possible issues which need to be investigated. We know MAF failures are rare on an Omega, and I've looked through your datalog again tonight side by side with a log from my car and I reckon the MAF signal looks OK. I might be wrong because I haven't compared logs from the same route, speed, driver, etc. but it's certainly not dead.

I think my money is still on something in the fuel supply - low pressure or poor delivery from the pump.

Keivn

[feeutfo]

hop helps  

[Albatross]

Cheers Kevin. Given the reports on the garage vs. the mobile tuning mechanic what do you reckon?

Well, they both have hunches based on what they've seen before. The question is: will either of them go through a logical sequence of eliminating the possibilities or will they start replacing expensive parts based on hunches?

Is it six and two three's or do you reckon the mobile man is more on the nail having gone straight to the fuel system?

They both have identified possible issues which need to be investigated. We know MAF failures are rare on an Omega, and I've looked through your datalog again tonight side by side with a log from my car and I reckon the MAF signal looks OK. I might be wrong because I haven't compared logs from the same route, speed, driver, etc. but it's certainly not dead.

I think my money is still on something in the fuel supply - low pressure or poor delivery from the pump.

Kevin

Thanks as ever...

Is the "log" you talk about something that can be posted as meaningful information? Can mine and yours be posted? I'd really like to have them to show to whoever is going to look at this.

I plan on summarising this thread and having it all ready and printed out for their benefit as I think it will help focus their investigations and save me a little money. It will also help me to look a little less clueless and be able to hold my ground on the process and not let them take the mickey.

hope helps  

A lot, thanks also Chris

[Kevin Wood]

Interesting development on this today. Had a look at
Kieran's 2.6 for a gearbox and climate update and he mentioned that there had been some codes that he'd had problems getting rid of. Our old friends 0170 & 0173.

No obvious air leaks anywhere but fuel trim up to 24% on both banks.

To cut a long story short we eventually swapped his and my MAF sensors and the problem went away. The faulty MAF was reading only about 30/31 kg/h @ a fast idle (about 2400 RPM). The good MAF was reading 46/47.

Tried cleaning the faulty MAF to no avail anthough we didn't have a security bit to remove the element.

Don't suppose you can get your car to a Tech 2 / ELM reader and see what the MAF reads at 2400 RPM?

Kevin

[Albatross]

Interesting development on this today. Had a look at
Kieran's 2.6 for a gearbox and climate update and he mentioned that there had been some codes that he'd had problems getting rid of. Our old friends 0170 & 0173.

No obvious air leaks anywhere but fuel trim up to 24% on both banks.

To cut a long story short we eventually swapped his and my MAF sensors and the problem went away. The faulty MAF was reading only about 30/31 kg/h @ a fast idle (about 2400 RPM). The good MAF was reading 46/47.

Tried cleaning the faulty MAF to no avail anthough we didn't have a security bit to remove the element.

Don't suppose you can get your car to a Tech 2 / ELM reader and see what the MAF reads at 2400 RPM?

Kevin

That is a very, very interesting development. Thanks Kevin.

I can get my car to a reader, but they're going to charge me £50 for the privelige!

Now I know this, I am probably going to see when TB is about to nip over to Brackley for a quick read.

Where can I get the "security bit" you refer to? Do you think that it is worthwhile doing this cleaning of the element?

How much is a new MAF sensor? I may just bugger it and buy / fit a new one as I could spend as much diagnosing as fixing here.

I'm tempted to buy a new MAF sensor tomorrow 1st thing, fit it, get the codes cleared, get the secondary O2 sensors moved back to behind the main cats and drive it to Leicestershire this week to see what happens.

[feeutfo]

Interesting development on this today. Had a look at
Kieran's 2.6 for a gearbox and climate update and he mentioned that there had been some codes that he'd had problems getting rid of. Our old friends 0170 & 0173.

No obvious air leaks anywhere but fuel trim up to 24% on both banks.

To cut a long story short we eventually swapped his and my MAF sensors and the problem went away. The faulty MAF was reading only about 30/31 kg/h @ a fast idle (about 2400 RPM). The good MAF was reading 46/47.

Tried cleaning the faulty MAF to no avail anthough we didn't have a security bit to remove the element.

Don't suppose you can get your car to a Tech 2 / ELM reader and see what the MAF reads at 2400 RPM?

Kevin

That is a very, very interesting development. Thanks Kevin.

I can get my car to a reader, but they're going to charge me £50 for the privelige!

Now I know this, I am probably going to see when TB is about to nip over to Brackley for a quick read.

Where can I get the "security bit" you refer to? Do you think that it is worthwhile doing this cleaning of the element?

How much is a new MAF sensor? I may just bugger it and buy / fit a new one as I could spend as much diagnosing as fixing here.

I'm tempted to buy a new MAF sensor tomorrow 1st thing, fit it, get the codes cleared, get the secondary O2 sensors moved back to behind the main cats and drive it to Leicestershire this week to see what happens.

iirc the "securaty bits" are torx bits with a hole in the end to get the air box/cleaner lid off etc, Halfords at a guess? Worth a clean first, Mafs aint cheap.