Hello.

I've done some modifications to my A4 1.8T.
Its an 98 AEB and I have some questions about the motronic handling when MAF gets maxed out...

Ive changed the MAF-housing to a 3" (76mm) ID one, instead of the OEM 60mm.
Im also running 440cc injectors (@4bar -> ~510cc)
Running rich on WOT, but thats ok!

But when Im running about 1.3bar (19psi) the ECU reads 5V -> 187grams.
Im planning on running about this pressure maybe 20-21psi max.

But how does the motronic handle when the MAF are maxed out? Injectors running max duty cycle? Is it retarding timing??

XR4ti, you seem to know much about these MAFs... Any idea/info for me?

BTW. Car is running great. 5-7k RPM pulls like mad. It MUST have 300+ ps I guess?
Corrected airflow would indicate around 350 also??

Thnx.

Jamez

once the MAF signal got above ~175g/s, and the injectors would drop a little towards redline.

As far as the ECU is concerned, it's not a bad thing, basically it goes a little richer than it should, just in case, and it's harder to fine-tune WOT A/F ratios with a maxed out MAF.

The Bosch MAFs have a bad rep for burning out when run maxed out, which is one of the reasons I got rid of it.

What chip and turbo are you running?

I am running a 3.5" maf housing with 800cc injectors and so far I have seen up to 185 g/s (dbw) when the car was running way too rich (10:1) but now I need to measure the readings with it running in the 12:1 - 11.5:1 range.

I'm running 1.6 bar of boost, a/f is constantly getting better. Idles stoich, and at WOT it's rich-from around 10.9:1 at 3000 rpm to 12.7 at 6500 rpm. I've got an answer for the low rpm richness too. Cruising at 80 mph/6th gear/3100 rpm is around a 14:1 a/f and EGT's are around 780c.

Been working with X4rtic some recently, trading "notes"

My MAF gets to max around 4500-4700 rpms, but injector pulse maxing out seems more related to throttle.

In a straight acceleration in 3rd gear, the relation between the MAF & injector pulse max out about the same time, around 4500 rpms. But if I'm in a higher gear, cruising at like 3000 rpm, & floor it, it almost instantly goes to max injector pulse, but the MAF doesn't max out for another 1000+ rpms(which at cruising speeds takes a few seconds). As X4rtic has suggested to me, it seems that the motronic is trying to base injector pulse based on it's calculation of VE in the engine(comparing the MAF/throttle signals to the O2 sensors/AIT/knock/etc.

I've used the Apex'i AFC to alter the MAF signal to the ECU, there's another device (P1s?) that some of the others are using, locally on VWs too. I think to get a better MAF result would be to go with the 3.5" MAF housing, which would up the max point in my situation, probably to the mid-5000 rpm range. I can't complain though, my car's running strong, & I just swapped in those new plugs X4rtic recommended. Reading the old ones (only 5000 miles) showed rich & hot, but equally important, was that they were all even.

..a custom welded pulse-manifold. wrapped.
And a GT25 (gt28r) turbo..

And the chip is a mtm stage 2 chip that supposedly was 210hp with the K03 at 1.3bar...

Went out tonight and tried some more. Runs better now. Running at about 1.2bar. This is FUN :)

have to drive it to get into open cycle for it to run properly.

Ran it with a G-tech meter today.
Runnig problerly without drawing timing it did 291whp.
but as soon it started pulling back timing it did around 230-240...
Also, after some in gear runs it fouled the plugs so bad they didnt ignite too good. Got some afterburners in my exhaust :D
Alot of fuel, obviously.

I am not running a FPR, so I guess I could try getting one, or atleast trying one from the older s4. They are 3.8bar. think this would work better...?

I do not have a EGT gauge, but I dont think I need it when I have a wideband...
still havent really logged anything with my vagcom or the wideband. Have to get some curves to make an idea on how I am really running...

Guess the readings at WOT/open cycle would indicate if I can take off some fuelpressure.

BTW, I am running a dump valve.
Might be a better idea getting a plumback, right?
Think I'll get rid of my afterburners when switching to BPV again...
But I love a bit of rice ;)
Really turn heads...

Jamez.

and you should definitely be watching EGT's and many other signals from the engine. It's an insatiable addiction to get it running better. Make sure the wastegate gets plumbed back in prior to the pre-cat o2 sensor, too!

STA for the latest spark plug discussion, I think you'd benefit from the same plugs I just installed. My engine definitely seems to like them better than the OEMs.

to expensive NKG plugs. Colder than OEM.
Also tried some bosch FD5POR special platin plugs, also expensive, but they did not run as good.

I believe the atmosphere dumpvalve and rich mixture otherwise leads to my "afterburners"

some less fuel wont harm me I believe. I might even get some less drawback on timings as o2 wont run as rich...

BTW what wide band are you using?

If your car is pulling timing back during WOT then your not going to be able to lean it out since that will just cause the ecu to pull more timing. First off you need to see what the AFR is during WOT.

So the car wont pull timing if running rich?
Only when running lean?

I find it hard to believe its running lean @3.5k rpm. With a 3" MAF that should increase flow about 60% but 440cc's @ 4bar is a ~100% increase.

Ill do some logs both from the wideband and the vagcom as soon as I have some extra time...

@WOT when running from standstill, through gears, I keep a RPM that high that it never gets to pull timing... Runs well this way...

BTW. 291whp isnt too bad on a gt25 turbo, is it?
I believe this is a apr s3-turbo...

Jamez

But no BOV sound with those, right?

Also, I have it reloacated before the TB.

Jamez.

lemme see if I can find a pic. Well there's one on my stalker photo page.....



running a bpv setup over a bov will help you, definitely. It'll lessen the richness you have...<ul><li><a href="http://www.capitalaudi.com/gallery/album57">stalker page</a></li></ul>

I made a connection on the intake-side of the turbo already, just in case.

Well I got the oildamp connected there, but gonna get a catchcan or separator. Or my hoses gonna get filled with oil...

What kind of BPV are you using?
A bosch one?
Im thinking of trying a 710N mounted the "wrong way"...? If I rip a few diaphragms Ill consider something else...

found the Evo motorsport valve to be much better with a very high pitch sound when I let off.

I am running lean @ WOT and low rpm... about 16.5AFR at 3500rpm, so it pulls that much timing that boost drops. First it climbs to 1bar, then timing gets pulled so much it drops to 0.6bar... And it keeps wrong AFR all the way to the top with bad timings...
This have to be dangerous.
Well, at least exhaust gets hot this way, so probably detonation-danger...!

Also, at high rpm my problems are the other way. Running rich above 5k rpm.
Afterall, my chip is made for K03... Wouldnt expect perfect result...

So I went driving with my local tuner-guy. We are a few audi-freaks nearby, but mostly 2.2 5cyl turbo-guys, and some even worse stuff...
well, He thought I really should get it remapped. He could mapp it from scratch.
He has this emulator that he connects to the motronic and get a realtime tracing on where in the map car is, load and rpm-specific rows, and he just adds the right injection times realtime.
Then he finally burnes a chip for it.
I could make chips both for racefuel and standard if I want.
But I guess I should stay below 1.4bar boost and pumpgas too keep power below dangerous levels for my engine. Stock rods dont like 400hp++ :D
he got visual 3D timing maps... really great equipment.
He did a car a few weeks ago. In 2-3hours they had a perfect map. (An 1.8T with K24 turbo, estimated @~280 hp)

what do you think? remap ASAP :) :) :)

BTW. If AFR and timings are good, he said using an atmosphere dump would be no problem at all, but he thought maybe I would get faster response with a BPV when shifting??

Well, its bedtime for me on the other side of the atlantic :D

for a K03 chip that is tuned for loads from a stock maf housing.

Dumping the pressure gets you nothing but sound, just think of all that extra air your lossing that you could be making power with after you get back into it.

unless you've an A/F controller.

On overly rich condition can cause lean readings on the O2 sensor.

Do you have a VAG-COM? What are the fuel trims like?

Does turbo spin long between shifts in your case...

Just ordered a bosch 710N to try... Got it for only 45$ brand new... Worth a try isnt it :D

and the size hose that fits to the BPV and intake tube.

is much longer.
Long hoses gives much more resistance than small.

Also, the small short one is ment for the K03 working at 0.5bar boost...

A big BB turbo flows alot more air!!

Agreed with John, if you had an air/fuel controller, you could manipulate the fuel curve somewhat. Although, I have one, and it still goes wide open injector pulse way too early. I think the best answer is a change in programming, and you might also want to look into an adjustable fpr if you haven't already.

Agreed with Mike, a bov is only good for intimidation. BPV is much more functional, and draws less attention(sometimes that's better!). Plus, letting air out of the metered system will only make it harder to tune properly(BOV or open wastegate dump tube).

I think your biggest problem though is that you have a K03 program in your ecu. it's freaking out &amp; pulling boost &amp; timing in the hopes of achieving it's programed/learned parameters, which are all out of wack from a big turbo/gas pump sized fuel injectors, and a MAF that's 2x as big. What do you have controlling boost, the N75 valve? I'd recommend some kind of mbc. You're gonna want a program that'll let you run up to 1.3 bar of boost, for starters, to tune it.

You seem to have a setup much like mine. And Its working out pretty well for you?

I have to decide wheter to tune my car now, with the injectors I have (440s?) and the 3" maf, or if I should run larger MAF and larger injectors...

As far as timing and AFR is ok while MAF is maxed out, it shouldnt be a problem,
but what consearn me more right now is if I can deliver enough fuel for around 4000rpm?

You seem to keep a rich condition for midrevs.
But injectors run at MAX even at 3000rpm in high gears. This is what I see also. Max is 21.68ms right? seem to be on my vagcom atleast.
I dont know if this will be enough fuel in the 3-4500rpm range??

What are AFR on in your case when MAF and injectorpulse max out? @about 4500rpm?

Do you have full boost at, say 3400rpm? In high gears at this rpm, do you get enough fuel?

Since Im running stock internals I might just tune it as far as I can with this MAF-housing and injectors, and rather try to be satisfied.
Like you say, a 3.5" MAF-housing or a custom 3.25" would probably been perfect...

BTW. Im not really 100% sure what my injectors are. I was told they were 440cc, but later I was told that the guy who sold them wasnt really sure. He said they were APR injectors that came with a stage 3, and that they probably were TT225 injectors that were modified? Seems about right?

<a href="http://forums.audiworld.com/performance/msgs/63378.phtml">I wrote this while you posted yours</a>

When I have this great possibilities to remap an AF-controller is not the way to go for me!

And as far as BOV goes Ive ordered a 710N now so Im going back to BPV.
With it mounted before the TB its easy to put in a BOV if wanted, but the truth is Im really not sure anymore that I want that much attension. Im already "famous" in the city, much because of this and some nice flames from the exhaust... :p

The K03 program have to go!!

And I am using a MBC. But I think its making fusses on me, but Im not really sure since pulling timing also drops boost.
Anyways, It never closes the WG fully, so I just ordered a profec B spec1 from japan. 260$ shipped. It'll probably give much better spool... :)

I do not have an adjustable FPR. But I probably should get either that or bigger injectors. Read my other post...

if you have DBW, then it's a lot more.

440s are probably maxed out by 350HP, at least for nonDBW, DBW seem to be able to run more power.

but when you get the right stuff, it'll chew up that rubber diaphragm &amp; spit it out the tailpipe ;-)

Sorry, I'm a busy guy. Don't have as much time to surf the forums as I'd like.

and I believe it was Mike that's pointed it out before......

Due to the fact that it's connected to the intake side of the turbo, there's vacuum present in the pipe. So, when the bpv opens, in addition to the charged air in the pressure side looking for a place to go, there's vacuum present to pull it through! Make sense?

During my shifts, I go slow, for a couple reasons. It's better for the trans, and if I shift quick, the fuel trim goes rich &amp; stutters. I can do a nice calm shift, and get into it when I let the clutch out there's boost right away. I'd contemplated installing the bpv in reverse, but haven't tried it yet.

=)

unless you retune the chip for the different load readings the larger maf housing will cause.

What does your injectors look like, since APR uses 440's for the ndbw and the 225TT (360-380cc) for the dbw.

=)

black and blue, and a bit too short, so I had to use a special gasket to get them tight...

Of course I am going to tune!
But I maybe thought going with even bigger MAF before I do might be a good idea. So I dont have to retune twice if I find that MAF/injectors arent bigenough in the first place...
But still, I dont know if I want that much power with my stock rods :p

driven with OEM BPV for 3years chipped, K03 and 1.35bar pressure.
The 710N are supposed to be stronger than my old OEM...

"but when you get the right stuff, it'll chew up that rubber diaphragm &amp; spit it out the tailpipe ;-) "

If diaphragm crack, its no danger for it flying into my compressorwheel, is it? It'll just crack and not hold boost, rigt?

<img src="http://pictureposter.audiworld.com/40674/k03log.jpg">

What are the injection on times...
This are a run with my old K03 setup...

It also pulls timing way down as you go up in rpms since the IAT's are also climbing. New Software is going to change all that allowing for much more air flow since you will make more adv timing and hold boost much longer.

When the bosch valve goes it will just rip and flap while it just lets the air out of the bpv.

so it looks higher with the vag.

when you go larger you will start having issues of getting the air to flow exactly straight during vacuum.

If the injecors are skinny then it sounds like they are the 225TT set which were used for the dbw because the injectors needed to sit deeper into the runner. You can always just go to the bosch green top which will work well for the ndbw.

so that other tuners cannon read and "copy" the chip or something?
I dont know...
It couldnt be the second column that are the injector times? Those numbers seem to have propotions with the MAF-readings also...
Could be injector on times per revolution??
That would actually make really good sense with calculations...! Well that is if injectors inject twice each cycle (each two revolutions)
And the fact that it can supposedly reach 16ms also applies then...

Well this guy here at ES-tuning probably gets things fixed... He have tuned several engines to 500hp++

And I see how the 710N will get more beating because of the new turbo delivering MUCH more air, so that when TB closes the pressure on the BPV would get much higher than with the K03...
But mounting it after the intercooler should really help much! Much denser air/less flow.

Well Ive bought one, 45$ , so Ill testfit it soon, and try till it blows. if it does. Maybe it dont :D
If not I'll get a piston one. When mounted before the TB I'll get it changed in a minute :)

Jamez.

Maybe the European ECU has the ability for more injector on-time? Or possibly MTM has found a work around.

now Im not sure if I am lean on midrevs afterall. I though that was strange, cause I should really be rather overly rich all the way!

The fueltrim at idle, block 000,8 is pending 120-145... a bit rich... (128 is no trim, right?)

haha ;)

just kidding :-O

then it doesn't burn. If it doesn't burn, then some of the oxygen isn't used up, and the O2 sensor will report it as being lean.

I have a feeling normal O2 sensors are more susceptible to this than a Wideband O2 though.

...if they are from APR?? Could they be modified?
I believe they are.

either way, they should probably deliever enough fuel! (It sits 210cc (243@4bar) orginally in my car, and they deliever enough for 210hp)

the tt225 injectors at 4bar even unmodified should deliver 456cc (395cc@3bar)...

That have to be enough for my power...
I think my car is running overly rich too. We'll see when tuning.
Ill get it done within a few weeks.

If I need more fuel I'll raise fuelpressure..

jamez

Also just looked over my last log and I hit 228.67 g/s in 2nd gear at 6400 rpms which is 4 times as much air compared to the 59 g/s I am moving at 4000 rpms. Now to just figure out the max reading for this maf sensor in the 3.5" housing.

That would be a few stallions...

I did put a 710N in there to try...<ul><li><a href="http://forums.audiworld.com/performance/msgs/63519.phtml">post with pics...</a></li></ul>