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I have recently become a proud owner of a GTV Cup no 138. I have spent a small fortune on having Cambelt, front and rear suspension, driveshaft etc etc sorted but have had ongoing problems with 'hitting brick wall' type issues when accelerating. I thought I had cracked it when I discovered a numpty had put a 2.0 air filter in my 3.0 airbox - something I understand can kill mafs quickly. I replaced air filter with correct version but when taking top off one of the studs broke due to rust. I therefore cannot be sure it is as airtight as it could be on that part of the airbox lid. I replaced the maf sensor part with one I had from my old 166 3.0 (I know it is the wrong part number) but this seemed to work for a short while. I have also been careful not giving it too many revs when warming up. Unfortunately I think i gave it too many revs (not redline though) when cold yesterday and it hit the brick wall. It then did it a few more times yesterday around the 4-4.5k rev range. I will try to unplug maf to see if this helps tomorrow. When the brick wall feeling happens it does flash up warning lights for an instant but these disappear and revs pick up again. I have plugged in to fiatecuscan today but no fault codes apart from transponder key not being recognised sometimes.


Why do I seem to be killing mafs? Are they that sensitive? Would a new airbox be sensible?

Sorry to waffle on but I really want to get this sorted as I am starting to enjoy this car - similar feeling I had with my fiat coupe - never had it with my rx8 though.
 
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There is always, always why a MAF fails, no moving parts to wear out, so down to contamination.... The problem is: Where is the contamination coming from?
A common Alfa fault is all the standard airbox lids are:
1, Prone to cracking on the retaining bolt lugs causing lift of the lid on one side slightly but enough to let in by-passed, unfiltered air. Repair or replace lid
2, Bad practice of not cleaning out the airbox after changing the filter, leaving dirt, dust and contaminants at the bottom ready to suck up the induction tube. Give it a clean out with a vaccuum, although, too little too late now!
3, Leaks in the induction tube all the way up to the convoluted rubber induction pipe: Check all the pipe work by sealing the ends with rubber goves/ rubber bands and dunk test it in a bath to check for leaks anywhere
4, Back pressure blow back from the crank case breather pipe can cause oil vapours and droplets to run down the pipe to the MAF when engine is turned off. Fit a cheap, small oil catch tank in between if it's obvious that oil has been dropping down onto the metal gauze of the MAF body:thumbs:

One last thing: Don't automatically assume that your MAF is totally goosed.... Clean it first (plenty of advice an tutorials on how to do this) and could save you a fortune!... Could also be your MAF multiplug too so clean and check the security of the connection!
 

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Discussion Starter #4
Thank you for your reply. Very informative. There have been posts on here stating that over revving can destroy mafs. I can't see how though?? No fuel passes over them? The pipes etc do seem clear of oil from breather pipe but I will check again today when I take it apart again.
 

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Make sure to establish the MAF is faulty... run the car with it unplugged (ignore the dash light) and the jerkyness will improve if it's faulty.

There are other problems that cause the same symptoms (holes in the inlet, hoses not connected etc), so you could be chasing your tail.
 

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Discussion Starter #6
Just unplugged it and she is warming up now. Discovered there is a gap in air box lid due to bolt shearing off so assume rush of unfiltered air under revs knack wring maf. Just off for a blast now.
 

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Discussion Starter #7
Just got back from blast. The only jerk was the one driving it. Pulled like a train in upper rev range. Kept it around the 4 - 5k and no brick walls. Sounds like I need an airtight air box now! Autolusso to the rescue hopefully.
 

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Discussion Starter #8
Update!

Got the air box out. Managed to cut and drill the stud out and replace with nice shiny new nut and bolt to seal lid up nicely. Happy days. Then I tried to put the air box back - could I get it to sit on the housing properly? Could I ****. Tried until it went dark then got fed up. Is there a knack to getting the air boxes back on? Please help!!
 
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Yeah there is: On a 156 anyway, but a GTV , not sure
The bracket itself is easy enough to do with the bolts as long as the two plastic locator pegs fit into position at the bottom of the airbox itself. Thats wher the problem occurs! You think they are located correctly but they never are:rolleyes:

They fit into two rubber bushes.
Jack up the front end of the car and get it onto axle stands
(bottom engine undertray removed)
The trick is to lubricate the rubber bushes with grease or WD40 etc and get a helper to push it down with force while you are under the car and guide the pegs back into the bushes. Once done, attach the outer intake hose from the inner wing into the airbox and hen simply secure the bolts to the airbox bracket in front of the battery tray
Re-attach the engine undertray, Job done
Replace the airbox lid and re-attach all the induction/maf body etc:thumbs:
Allow 30 minutes total with help;)

Forgot to mention that most owners d.i.y repair the airbox lid in position without actually removing the airbox for that very reason, sorry.
 

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I'd never heard of a MAF before i joined this site, seems alot of owners having bad luck with this problem, Grahameo seems to have hit the nail on the head though.I'll be checking my airfilter box.
 

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Managed to get it refitted. Took the housing out and fitted the box and housing as one. Quite easy that way. Fixed the lid of the airbox by drilling out sheared bolt and fitting new nut and bolt. All nice and tight but used duct tape to create a nice tight seal. Early indications are promising. No hesitation or brick walls ... So far!
 
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Do straight induction pipes have any detrimental effect on a MAF as on my v6 Graham?
To be honest mate I havent really heard of such an effect... Look at it logically... The air is circling upwards from the filter in a natural vortex motion.... All the nooks and cranny's on the old resonator type induction pipe do is to slow it down a little on one side to cause a plume of air.... Imagine if it was smoke and you could see it, it would look like a big surfer's wave as it comes past these deliberate gaps thus what is called the lamina flow effect... Its mainly down to sound reduction but has little effect as far as slowing down the airflow to the throttle body...
When a throttle body is actually open fully, it is sucking the air in faster, not simply flowing it through...

Now comes to your original query:
Logic dictates that:
Given where the MAF is situated in relation to the filter and then concurrently to the Induction pipe above, how can it be detrimental?
The air is flowing at the exact same speed rate and lamina flow manner over the MAF as it would with the standard resonator induction pipework... The only difference being once it has passed up the tube to the resonator gaps then and only then does it slow down somewhat....
With your more free flowing induction pipe it isn't slowing down so better throttle response at the defecit of noise abatement and a little less fuel economy

So... I can't see it having any effect on the MAF.

However if your oil breather runs into this modified tube which I assume doesn't, then it would be somewhat easier for oil vapours and droplets to find their way down to the maf body due its inner smootheness once the warm engine has been turned off... Hope this helps:thumbs:
 

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Perfect logic from Graham above.

Can confirm that oil from breather does dribble along the pipe, which is a concern (although I don't believe engine oil is harmful to MAF)

Must also add that practice has shown that if MAF placed too close too the inlet, the air pulses causes a really jumpy jerky throttle response... Not a problem if you keep the 90 bend tho.

Sent from my E10i
 

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To be honest mate I havent really heard of such an effect... Look at it logically... The air is circling upwards from the filter in a natural vortex motion.... All the nooks and cranny's on the old resonator type induction pipe do is to slow it down a little on one side to cause a plume of air.... Imagine if it was smoke and you could see it, it would look like a big surfer's wave as it comes past these deliberate gaps thus what is called the lamina flow effect... Its mainly down to sound reduction but has little effect as far as slowing down the airflow to the throttle body...
When a throttle body is actually open fully, it is sucking the air in faster, not simply flowing it through...

Now comes to your original query:
Logic dictates that:
Given where the MAF is situated in relation to the filter and then concurrently to the Induction pipe above, how can it be detrimental?
The air is flowing at the exact same speed rate and lamina flow manner over the MAF as it would with the standard resonator induction pipework... The only difference being once it has passed up the tube to the resonator gaps then and only then does it slow down somewhat....
With your more free flowing induction pipe it isn't slowing down so better throttle response at the defecit of noise abatement and a little less fuel economy

So... I can't see it having any effect on the MAF.

However if your oil breather runs into this modified tube which I assume doesn't, then it would be somewhat easier for oil vapours and droplets to find their way down to the maf body due its inner smootheness once the warm engine has been turned off... Hope this helps:thumbs:
Totally agree with you but I'm thinking of when the air is coming back the other way when the throttle body snaps shut and the air bounces back then as you say the resonators may soften the effect slightly...
 
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It doesn't snap shut mate or the engine would starve and stall immediately regardless of what revs you were doing... Its a dampening process that follows the track of the magnetic potentiometer ring qas per the flow rate demand on the ECU readings to engine revs at that moment so its more of a gradual closing although never fully closed, it hovers at around 5 to 8% open on idle:thumbs:

Clever stuff really, even more complicated on my Q-system as my throttle body is controlled by both ECU's, the engine and gearbox:rolleyes: Yet it some how works:D
 

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so time to have a good look around my airbox then to see if that has anything to do with maf failure. either that or I am just very unlucky...
 
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P0100 is "mass or volume air flow circuit malfunction" so yeah, it looks as though your MAF is contaminated

Stuff that you need to arm yourself with is:

Isopropyl alcohol spray (maplins) for cleaning the Maf sensor wires, DO NOT TOUCH THE WIRES AND RESISTOR, JUST SPRAY AND LET IT EVAPORATE good stuff, not as harsh as Carb cleaner and WILL NOT damage the wires, it WILL remove all the contamination.
Cotton buds (raid Penny's make up kit):lol:
Silicon lubricant spray (Halfords) for the rubber seals on the airbox lid etc. it will lubricate and slightly swell the rubber sealing ring back to original size giving a much better seal. It will also help the induction pipe rubber seal properly on the throttle body, I little spray wiill do you nicely.

Carb cleaner for the throttle body (any motor factor) DO NOT USE ON THE MAF, just on the throttle body butterfly only.

To remove the 5 pointed security screws on the MAF you can use a pair of long nosed pliers on the outer edge of the screw head. A bit of a chew on but will come out,they aren't in too tight. Once you have removed them, get replacement standard cross point screws from B&Q etc... Take the security screw for comparison of thread and length and speak to one of the wise jedi- like pensioners who work at B&Q, they will sort you out mate.:thumbs:

PLUSGAS (any motor factor) A godsend when it comes to siezed bolts and nuts from airboxes etc... much better than WD40 poop:rolleyes:

Glass cleaner (raid Penny's cleaning cupboard) for the angled mirror inside the MAF sensor
A vacuum cleaner (see Penny for where it lives) to give the airbox a good clean out and to give the airfilter a quick dust off

Now you are armed with the essential MAF and total induction cleaning kit (will last years BTW) you can tackle the job, no more than an hour total:thumbs:

How to:
Easy as pie : Fun starts @ 3000! Go to the tips section Alfa Romeo
Written by Jeff Porter no less and a God when it comes to technical know how and saving money on buying MAF's when they aren't needed:rolleyes:

When you put it all back together, dont forget to rub a little bit of silicon spray on the rubber sealing ring with your finger on the MAF to make sure it gets an air tight seal and use the isopropyl alcohol to clean the electrical contacts on the MAF (once refitted in) and on its multiplug to ensure a good electrical contact.
Get stuck? give me a holla and I will try and help as best I can mate ok:thumbs:
 
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