Many thanks WB/DTS, couldn't stand going back to the hairdryer sound of a standard STi

I always warm my car through before opening it up, always let it cool down (C600 turbo timer), an interim Mobil 15/50 Motorsport + filter change and never run it on anything less than super unleaded, mostly Optimax.

Apart from squealing brakes my car has been 100% reliable

 

BTW, mine's now running the PPP sports cat downpipe with TSL two piece centre and Firestorm backbox, sounds very loud and is going well - it's definitely got quicker in the two months since the PPP was fitted.

Also drive mine hard but with mechanical sympathy, and it has been 100% reliable

[Edited by Dave T-S - 12/24/2002 8:59:00 AM]

 

Dave,

TSL Firestorm backbox eh? A little rash, my boy. What will the neighbours say (ooerr missus)?

I saw the very first production one of these at TSL and was there when Trouser fired it up on his express (as was). Subtle is not a word that springs to mind in describing the aural sensations that hit your pinkies...

Hope you and Mrs TS have a good one over the festive period.

WB

 

WB
Put it this way....the people opposite have moved their daughter's bedroom from the front to the back of their house

Oh, and last Friday I took the day off, they missed their 06:30 alarm call (me going out) and overslept

Both true

Best wishes to you too over Christmas and New Year

 

Blimey....

So the prodrive guru claims no gains over all the "competitors" products ....

Now that makes me question ANY filters anyone attempts to sell me....

LOL Mike Wood - what a beautiful one liner!!!

Jza

PS My PPP chip had to be replaced within 3 weeks of it being fitted 'cause it was faulty

 

Hi Pete, guys

Hope all are well after the c-mass and new year thing

On the subject of filters I think the point Mike is making is based on the fact that in all FHI's testing they did not aprove the filtration of any aftermarket filters. There was also an issue with oiling.

Note: "filtration"

There is no issue with the flow ability of various aftermarket filters, the issue is filtration (and also oil)

I would also comment on some of the things John B has been posting, testing has shown that what he is saying is correct. Changes to the intake system can give power BUT on those we have looked at so far - the increase has come from running leaner, NOT from the SuperHyperMegaSpecialFlowPower thing thats been fitted...

Cheers all

Simon

 

Thanks for the input Simon.

Andy

 

Clearly running with a filter that allows more air flow onto a fixed fuel map will run a car leaner and give more power, if the filter that allows more air flow is then compensated for in the fuel maps you will return to the status quo re mixture but still get more power, more fuel and air in equals more power out. The comments about leaning apply to a non remapped car of course. Oil particles of any sort if allowed to detach from the filter will always get into the maf element however its shaped due to the fact that the element must have air flowing over it to work, the hot film is heated to 167 deg C and is then kept at that aginst a varying airflow according to engine load which then derives the output the ecu see's (compensation factors applied). Its a known fact that changing induction can and will screw up the maf callibration to varying degrees, a panel filter will normally not do that so, as Simon has mentioned, we are left with contamination issues only. Have a good look at the compressor blade edges of a turbo thats been used with a course filtering aftermarket induction, looks as though its been shot blasted. With any oiled filter the trick is to only have the minimal oil content necessary in the filter, once the initial evaporation has taken place then no more should release. A paper filter should not cause contamination issues but will normally be more restrictive by nature. (solution fit a damn great big one)

Have to say that the use of EcuTek software for remapping has revealed a number of issues relating to maf behaviour that were only "guessed at" before, since coming across the gross effect of one certain induction I've been experimenting merrily with differing filters to cross check maf effects, also with differing inlet tract lengths etc, its truly significant the difference that a seemingly small change to induction can make on maf behaviour. That said most cars are fueled rich enough to stand it, back to the lean and mean syndrome, its only when the wrong combination is applied that engines go pop.

Whatever mods anyone does it is always essential to get the car checked out for fueling/detonation to make sure no issues are going to occur. BTW the main cause of MY99-00 maf failure is vibration not contamination but, as Mike W has mentioned a maf can fail progressively and gradually produce a lower and lower output leaning the engine all the time. In the ultimate this will lead to problems. Anyone with an aftermarket ecu using the speed/density principle would not have these problems as the maf is not used.

 

Bob seems to be talking sense here. I do not see how improved flow can cause leaning off if the ECU has 'somewhere to go' with its fuel map. My knowledge of ECU mapping is limited, but surely there is a broad enough working range within the fuel map to compensate for spiking etc? Can anybody confirm this please?

 

Simon & Bob,

Happy new year to you guys and thanks for your input. I thought everyone had lost interest in this thread, glad to see its sprung back again.

Taking Simon's points I guess we have to go with FHI's significant R&D on the car and their decision to use paper rather than oiled filters I assume because they had a concern re contamination issues re oiled based filters.

What I can't understand is why use a MAF in the first place when you can use an ECU that does not need to "worry" about air flow. Can anyone throw any light on FHI's thinking on this?

Does anyone know whether verifying the health status of the MAF forms a part of any of the servicing break points for the STi7?

Ta.
WB

 

Which is a good question really... MAP based fuelling does (in theory) not fully cater for changes in air density, but I guess you can get very close with temperature compensation ?

Breathing mods (i.e. decat exhaust) usually are OK (given the right fuel) on the CG8 because the MAF based system allows the ECU to compensate, I guess with a MAP based system that would be a no-no. But I can't imagine aftermarket exhausts are FHI's first worry.

Perhaps the MAF allows finer resolution when not on boost ? And thus would help towards emission tests etc... Bob ?

 

Theo I put some stuff in my earlier reply bottom Page 2:

"The benefits of a MAF though are GENERALLY more tolerance to breathing mods if you don't make the sensor misread, better emissions and part throttle behaviour, and in SOME cases far more consistent fuelling in different temperatures."

 

No not really, the resolution in the factory maps is not that much better than a lot of aftermarket ecu's, a map based system with a good closed loop running stoich is every bit as good on emmisions given that to pass these days you should have a cat !! or I can set a car up to pass (and have done) running purely off fixed map values, again using a cat.

Without a good closed loop system a maf based ecu is still just running fixed values. MY99-00 Sti Jecs ecu's go open loop at less than zero boost (or vac) so the mapping has to be "right" as you are cruising on fixed map values. Its my view that these ecu's also go closed loop when the engine is far too cold which leads to the cold engine hesitation that is sometimes complained about.

Subaru do use a speed density system, some of the USA models have it in place of the maf based one.

In real terms the maf just provides a part of the equation to allow the engine load to be registered in the ecu, so the map is still a set of numbers that are then picked on by the ecu. The main difference in measuring (or representing is a better word) airflow is that you could have a small throttle opening and say high boost of 1.4 bar then a large throttle opening at say 0.5 bar and both "could " pick then same map point, this is why throttle position is factored in as well otherwise you could end up picking a point that was not compatable timing wise with both conditions. thats not the end of the story as there are several other compensation factors used in addition (battery volts, coolant temp etc)

The main thing to remember is that maf is not infallible and can be "made" to misread and therefore misdirect the ecu into running from the wrong part of the map, in some cases I have seen up to 30% wrong !! That not only affects fueling but timing as well.

Its relatively straightforward to pick this up from a deltadash log, if this is happening and the log has been made with the right version then you can analyse and pick the load points in the map against other known cars of similar mod state, also the log gives you a flavour of what the fueling is doing from the oxy sensor. (lets not debate that here please)

 

John,

We were both posting at the same time so I missed your point re MAF benefits. It is worrying though that something as important as this (the MAF) is seemingly so fragile, with potentially catastrophic consequencies.

I know you are more concerned with det but....

 

If the MAF is gradually failing are the symptoms just the car leaning out? If so, would an AFR give you an indication that somethings wrong?

Stefan

 

There is more to emissions than MOTs for the OEMs though, which is a very basic emissions test. Bosch in their Automotive Handbook do state something along the lines that part throttle and transients are easier to pass under legislative barriers using MAF than speed density. However, Bosch do tend to do more MAF systems so maybe they are biased, and a lot of us rip out the cats I suppose that is not entirely relevant I doubt any car I have done would pass Euro 5 but thankfully I don't work within OEM constraints

Interesting that my narrowband lambda sensor shows 0.92V at the same AFR as a friend's showing 0.83V Both are about 11.2:1 AFR on wideband. Both are entirely out of expected range in opposite directions.

Yes Ozzy, an AFR would help you, but with caveats - on my car by the time it showed lean it would be much leaner than expected! It is getting to know what is normal on your car if you have gauges.

Also MAFs are much more reliable if you don't mess around with the inlet, so from the OEMs point of view they are still often the choice. However, some Subarus and worse I gather some VAG MAFs are pretty notorious.

[Edited by john banks - 1/6/2003 11:47:32 PM]

 

Could anyone quickly explain the difference between wide and narrow band lambda?

 

Wideband is designed typically to show a range from 10-20:1. Narrowband is designed to show only 14.7:1, and that is all it is good at.

 

Can just the MAF sensor be bought for the UK and does anyone know the part number?

 

btt

 

Andy,

I think there was a separate thread on MAF part no's a little while back. Use search to see what you get.

WB

 

Changes in flow properties can lead to MAF misreads. These can be large and cause the wrong areas of the map to be read. Since this usually results in advanced ignition AND lean fuelling this can be bad news. The benefits of a MAF though are GENERALLY more tolerance to breathing mods if you don't make the sensor misread, better emissions and part throttle behaviour, and in SOME cases far more consistent fuelling in different temperatures.

To put it another way, if you are navigating on the side of a mountain and get your bearing 10 degrees out and your position 100m offset one way you could fall off.

Overboost scenarios - a standard map should allow for contingencies, but if you fit a decat to a setup with borderline wastegate flow you can get horrendous boost spikes and boost creep. Some STi7 ECUs clearly do not cope with this and the car dets. In contrast a UK 99/00 for example could take a 20 PSI boost spike with a decat and not det.

Maybe the newer ECUs are more clever, but the timing is also more dynamic and aggressive, if that solution does not work it can fall over big time.

[Edited by john banks - 1/6/2003 10:38:42 PM]

 

If you do modify the filtration, would an AFR and Knocklink warn you of potential problems or would things have gone a bit Pete Tong before you could do anything about it. That is, will these monitors tell you your cars just gone pop?

Stefan

[Edited by ozzy - 1/6/2003 11:27:53 PM]

 

Yeah, but isn't your car strung tighter than a Mother Superiors knicker elastic?

If we're talking a MY99/00 with a de-cat and just an ITG, would it be just as extreme? or is it to specific to individual cars to know?

Stefan

[Edited by ozzy - 1/6/2003 11:51:42 PM]