View Full Version : Warning Blitz filters are blowing air flow meter

6th June 2000, 18:39
I have sold over 30 Blitz SuS Power Induction kits and around the same amount of the K&N type.

Fact is that the Blitz IS causing the air flow meter to fail. We have had 8 failures so far.

RaceLogic the agents say they are not aware of this problem, but I am 100% sure that the Blitz is no good .......


Danny Fisher
6th June 2000, 19:56
Steven, speaking to one of the service people at a dealership the other day, these filters are causing this problem on a regular occurrence. So please people be aware this may be an issue....


6th June 2000, 20:59
Are these filters pre-oiled type? If so it is possible tiny particles can contaminate the HEATED air flow sensor. Talk to, or find Power Engineerings web site, they know of the problem. Having said all this I believe they actually sell the things so it could possibly be something else. Still, it may be worth checking?
Cheers - John.D

6th June 2000, 21:04
Power sold me one 2 weeks later my MAF failed they then charged me 200 to tell me that the MAF had gone.


Bob Rawle
6th June 2000, 22:38
The problem is not one of filtration but of incorrect fitting, if the filter assy is not SECURELY installed the the subsequent vibration will damage the MAF. I've done over 30000 miles with my Blitz with no issues at all.


7th June 2000, 07:06
Yes Bob and you know how my one was installed


7th June 2000, 08:17
Guys I can positively confirm that the Blitz SuS Power Stainless Steel Cone kit is blowing the MAF (air flow meter)

Please be warned this is not a hunch but a guaranteed problem.

7th June 2000, 11:55
As far as my memory serves me, some months ago it was the HKS that 'did all the damage' and Blitz was ' perfect and brilliant'. How come it is now Blitz's turn? Just out of boredom or what?

As Bob has kindly pointed out, none of these filters blow AFM sensors if they are a) properly fitted and not dancing all over the place with one instead of two support elements and b) if we assume that they do what they are supposed to, i.e. filter and stop particles of damaging and polluting nature entering further down the 'cavity'. And I can assure HKS does it and I have no reason to believe otherwise about Blitz.

So, Mad Maz, I believe you 300% that Blitz Induction 'kills' AFM sensors as much as HKS or any similar device. "As much as" meaning very few in comparison to a number of units in field use. Caution is always welcome, but if someone has experience of either of these products consistently causing damage then how come it has only now become apparent?

Perhaps those who suffered could come forward and help the rest of us before more damage is done.


Pete Croney
8th June 2000, 10:21
I'm convinced the problem IS one of filtration quality.

Bob has the earlier hot wire and these are more robust. Also, the earlier intake has a 90deg bend and the dust builds up on the outside of the bend. (See Pat Herborn's post on scoobynet)

The later hot film sensors are very fragile and much more sensitive. If the filter does not stop the fine particles then the AMS is getting sand blasted. Particularly as the later cars have a straight tract from the filter to the AMS.

The K&N cone filter has a much higher level of filtration (best in a recent Jap cone filter test) and this is why Madmaz's customers have been OK.

The filter is there for a reason!!

Now where is that first issue of Japanese Performance magazine http://bbs.22b.com/ubb/wink.gif

8th June 2000, 11:29
I have been running a blitz cone on my MY99 (weaker MAF) for some time now.

When I switched back to the standard ECU I had no problems (Link ECU does not use the MAF so a problem would not be apparent).

I had the unit that Saj took off his car (wifey didnt like the noise!).

I HAD to make an additional bracket up, the supplied bracket held it in place but I was extremely concerned about the vibration. With the additional bracket the cone is held in place with a firmness similar to the original airbox.

It is also very easy to fit the cone with the outer edge touching the inner wing. This would also cause vibration problems.

Can't remember when I had your filter Saj but since then I've done thousands of miles, trackday etc.

From where I'm sitting right now I can understand, even EXPECT problems due to the fitment issues.

I'm nipping out now to remove the thing and inspect the insides. I suspect also the fact that the UK is not as dusty as other places on the planet plays a part.

8th June 2000, 12:25
OK..had the thing off..pulled apart all the tubing as well for a thorough inspection.

The words "clean" and "whistle" spring to mind. There was more dust/oily gunk in the tubing when I removed the original subaru filter and airbox.

Quick rinse out and blow-dry http://bbs.22b.com/ubb/wink.gif

One thing I noticed when reassembling it is that it is pretty easy to fit the thing at an angle which might introduce an air leak.

I wonder also, how many people have retained the mesh that sits inside the tubing directly in front of the MAF ?

So, on the evidence presented to me I'll be sticking with it.

9th June 2000, 16:49

So you'll finally be selling K&N's soon then? http://bbs.22b.com/ubb/wink.gif


10th June 2000, 20:31
Lee, i have got the Blitz and Bob R fitted it with no additional modified brackets and no apparent vibration issues. Ok, ive been too lazy to take it off and check if for south london dirt (which is the hardest durt anywhere!) and Pat appears to have had a dodgy filter which can happen to any manufacturer.

How do you know when the MAF fails?


11th June 2000, 04:01
Lee, how come you removed the Link?

21st June 2000, 17:28
Anyone got a spare braket handy as I'm not a DIY person and have one of them Blitz filters which Bob Rawle kindly refitted for me - although 2 brackets is much better than the one bracket - they only supply one bracket.

22nd June 2000, 17:49
marcus..i removed the link for a brief period of time as the board had a minor fault (lighting the check engine light) - although this made no difference to the operation of it i still sent it back and had it fixed.

sunil..i guess with the link fitted you'll never know if the MAF has gone..dunno whether this is good/bad or indifferent.

all..i was under the impression that the blitz WAS now supplied with 2 brackets ? In any event, if BobR has fitted it for you I am sure he will have done it well since he is well aware of the vibration issues.

23rd June 2000, 14:23
My blitz cone came with two brackets, one for a legacy, one for an impreza... so there is only one bracket holding it into my car at the mo, the impreza bracket. I didn't have any MAF problems with my blitz.


24th June 2000, 20:43
erm, my blitz came with 2 brackets, a set of handcuffs, a french maids outfit and a bottle of baby oil.

I havent had any problems either

27th June 2000, 04:56
Finally something that I can contribute to .. http://bbs.22b.com/ubb/biggrin.gif

The master of the dead MAF.. I'm on my 5th or is 4th.. http://bbs.22b.com/ubb/confused.gif

Ok my car is Impreza 2.5 RS with Garret t3/4 and Spearco intercooler. MY99 with hot film MAF, they are actually made by Bosch..

I had an cone filter AIRINX. result dead MAF.

Thought was vibration so strapped the filter to the inside of the fender (wing) result Dead MAF x2

Went back to the stock intake ahead of the MAF.. Result dead MAF

The Hot film MAFs simply cannot handle the extra air flow.

It is NOT vibration that is the problem nor filtration from the work that we have done dissecting MAFS and examining them under the microscope. The problem seems to simply be increased air flow

Mate of mine as MY98 with same Turbo kit but with the Hot Wire MAF.. Result Never had a problem..

Now thinking about replacement ECU http://bbs.22b.com/ubb/frown.gif

Oh this has happened with a variety of cone style filters.


27th June 2000, 18:21
so, on that basis it can be argued that Blitz cone FLOWS MORE AIR than any other!! http://bbs.22b.com/ubb/smile.gif

There ya go - the most efficient induction filter ladies and gentlemen!

28th June 2000, 07:00
That was a little "dangerous leap to a conclusion" http://bbs.22b.com/ubb/biggrin.gif

I haven't tried the Blitz filter but the problem persists regardless of using a cone filter or the stock air box ahead of the MAF.

Car still goes like "stuff off a shovel" though http://bbs.22b.com/ubb/biggrin.gif

<BLOCKQUOTE>quote:</font><HR>How do you know when the MAF fails?

When mine have started to go I get a slight hestitation between 3500 and 4000 rpm which over a week or two gets worse until the car eventually dies.. At least by disconnecting the SFC the car drops back into "limp home" mode.

Now have MAF fitment down to 7.5 minutes http://bbs.22b.com/ubb/rolleyes.gif


[This message has been edited by rsquire (edited 28 June 2000).]

28th June 2000, 17:10

For the benefit of our "younger" viewers... What's the SFC, and how would you disconnect it to get limp-home mode?


[This message has been edited by MorayMackenzie (edited 28 June 2000).]

28th June 2000, 18:37

The SFC is the simple fuel management computer..

Simply adds increased fuel at different rpm ranges. Mine sits in the glovebox and is wired into the ECU. By simply unplugging it the car drops back into limp home mode ie rev limit is 3500


[This message has been edited by rsquire (edited 28 June 2000).]

30th June 2000, 07:37
My experience with Blitz.

Mine came with two brackets, one for Impreza and one for Legacy, I fitted it with only the Impreza bracket and did notice a degree of movement of the filter. I had my spark plugs changed and noticed that everytime I started the car, the cone would slap against the wing (someone didn't refit the bracket properly, the cone was very loose).

I refitted using both the brackets supplied with the blitz (they are very easy to bend into shape, and I think I used one of the fixing positions on the wing that the original air box used). The cone is now 'fully floating' and is as solid as a rock. I live in an area where the roads are terrible and I run fairly stiff leda B settings. I have done over 8,000 miles with no problems at all.

I will remove the filter this weekend and inspect, but I'm sure that I will have no contamination at all.

All in all I couldn't be happier. (and the noise is awesome http://bbs.22b.com/ubb/biggrin.gif )



1st July 2000, 07:36

I was recommended by SouRob (from the other bbs) to come'over'ere and have a read about Blitz air induction....

I had one fitted last year on my 95MY WRX 5 door, on the strength of PE advice - Lex autocentres in Warwick fitted it (with a magnex back box) as they had a lot of experience with a local importers of scoobs - said it was very easy to fit with the impreza bracket - it doesn't seem to move around.

So - first thing I notice is a tremendous difference in throttle response, some more miles per gallon, nice noises...probably more hesitation at lower revs.

However - year later - starting in the morning is now different. It sometimes takes a few seconds for the engine to pick up to the normal revs (high when cold) -even stalls but starts straight away. Also - when the turbo cuts in around 2.5-3 - the push I get is quite large (almost taking my breath away if the car is warmed up and I at the lights...) - a bigger shove than a MY97 UK Prodrive which seems to be much smoother - is this 'cos of the inductor?

Recently had a 45k (with 30k fluids) service and the mechanic thought it was because the inductor was ''blowing' the engine/sparks - what the hell does that mean????

So - what should I check for ?- shall I get the mechanic to take it apart and check for what? shall I put the original air box back on and use K&N or put a piper cross in -or just leave it and forget I even read your comments about Blitz.....

Apart from that - this BBS is quite interesting...it seems more technical than the other...



2nd July 2000, 10:55
O.k. related question here.... (i'm thinking of getting a blitz Induction kit)

IF.... after fitment everything went to rat s*** how much is a new MaF and could i retro fit the wire type to a My00.



2nd July 2000, 13:08

I suspect you would have problems retro fitting a wire MAF to your car... the ECU is calibrated to work with a more sensitive hot film device, which will probably provide a different signal range to the ecu... hence you would likely have problems trying to run the older style sensor with the new ecu. Of course, Subaru use the new sensor to allow better mapping, which will go to pot if you fit the old sensor.

Of course, all this means it may be incompatible with intercooler scoop splitters to, so I will do the decent thing and offer to take your's off your hands if you swap MAF sensors... just to save you extra running problems, you understand. http://bbs.22b.com/ubb/smile.gif http://bbs.22b.com/ubb/wink.gif


3rd July 2000, 06:47
thanks for the replies

Back to the other bbs....


3rd July 2000, 12:33

Sorry for not answering your query sooner... I didn't know there was a 48hour time limit in which questions had to be answered, how very remiss of me! http://bbs.22b.com/ubb/eek.gif I assume you tried an archive search on both BBSs before asking these questions. http://bbs.22b.com/ubb/rolleyes.gif

Ok, assuming you actually read this, now you've gone "back to the other bbs"... here goes:

You wonder why your '95 gives more of a kick than the '97 with a PPP. IIRC, The '97 engine was the first of the newer style unit with revised inlet, twin ignition coils on top of the manifold, different turbo, revised ecu and mapping etc... in short, the 97 model engine is smoother and more refined than the older style unit... so you are right, the 97 should feel smoother than your 95.

The mechanic probably told you that he thought it may the be the induction charge blowing out the sparks... this points to the ignition system. Your would probably feel/hear this as missfires when driving at high boost conditions or when the engine ic cold.

One problem that can occur with the older cars engine at significant miles is that the ignition coilpacks can degrade and require replacement. Assuming the service included a new set of properly gapped plugs, maybe you could get the dealer to check the coilpacks. It may be worth checking when the fuel filter was last changed to... just for peace of mind.


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3rd July 2000, 22:58
http://bbs.22b.com/ubb/wink.gif moray....

cost of a new maf per chance ?


4th July 2000, 07:14
Hi Moray,

I new that coment would get a response :) - 47 hours is usually my limit though....

Thanks for the detailed reply - I'll get coilpacks checked.

Why does the smoother UK 97 engine have a slower turbo 'pick-up' than my late 95 WRX? Just the design of the turbo? I feel most of my driving benefits from a quicker pickup around the b roads where I live.

I'll give you 49 hours for this one...


4th July 2000, 12:59
It is largely the turbo and partially the mapping that makes for this old-school-turbo-kick... If you fit a link or _other_ (didn't use "better", what a diplomat!) replacement ecu, or, in fact, a unichip, you can have a lot of the unrefined turbo kick mapped out.

I know that Adam M used to like that turbo kick, he felt it was more fun that way... as I understand it, he has now mapped it out and is pretty happy with the results. http://bbs.22b.com/ubb/smile.gif

The actual turbo in your car is oversized for the standard road car (blame homologation rules for group A), but it is also a fairly old design or sleeve bearing unit rather than a more efficient roller bearing setup, so it will suffer more from lag. The later cars have better matched, more efficient turbos because the WRC rules meant you don't have to compromise your road car to make a competative rally car.

My car has been breathed on a little... the motec is mapped to the engine is even smoother than standard... The car feels smooth rather than fast... then you look at the scenery change and the speedo climb and you realise it isn't slow. http://bbs.22b.com/ubb/smile.gif

I prefer the driveability and predictability of a refined power delivery... the kind that keeps your passenger/s held into their seat/s until you change gear rather than the kind that gives a bit of a kick in the back and then trails off. If you are driving a car on the limits, a more predictable, refined power/torque delivery will make for a more tractable, safer, quicker drive.

Now go away and think about this... remember I don't have to answer your next question until Sunday evening! http://bbs.22b.com/ubb/wink.gif


Danny Fisher
4th July 2000, 21:55
Moray, who setup the Motec for you?


5th July 2000, 00:12
O.K. back to the Blitz question... I think I have found a quality answer to this.....

check out www.mkiv.com/techarticles/filters_test/ (http://www.mkiv.com/techarticles/filters_test/) for a copy of a Jap magazine test. Also while you are there go to the videos section and take a look at "Bryces dyno run" it is fantastic http://bbs.22b.com/ubb/smile.gif

5th July 2000, 06:44
Thanks Moray - I've had a scoob for over a year now and this is the first time someone has taken time to explain why my 95WRX has more of a 'kick' feel than newer models.

Last question - you say I have lag however my turbo comes in at 2.5-2.8k revs? Have a got the definition of lag correct here....

I'll give you till next week :)

Just looked at the Blitz link provided by Macca....wish I could read Japanese :)



Mr. Two
11th July 2000, 16:10
A little info for you on the AFM - as in this months Redline mag page 57, I quote:

'The latest model Impreza has changed part of it's AFM from a hot wire to a hot film system. This has lead to some problems. When fitting an uprated (or even replacing a standard) air filter, you can get specs of dirt on the film. The slightest particles stick to the film and cause it to burn out. The only cure is a new air flow sensor at over 200. This has only been picked up on the STI version 5 so far, but it's worth remebering , if you're fitting a new/performance filter, to make sure you keep everything as clean as possible.'

Has anybody had a problem who doesn't have a version 5, or have Subaru only made the mistake on the 5?