Good Day at Stealth

[jaysVR6 2]

Well, FINALLY I have now got my car running properly, after a rediculus drive to Stealth which usually takes 2 hours and in fact took me 4!

For those of you who don't know much about my car, I had the engine rebuilt and rebored to 2.9 with forged pistons 6 months ago. Then a friends charger came up for sale for mates rates and I couldn't resist! I went straight to Stealth for a (MAFLESS this bit is important) remap and the car only managed 200bhp!!! Vince told me that the timing was out and to go and see the guy who built it!! (I was not happy!!)

After the MAP my car was running like a bag of nails, hesitant, no power and dumping neat fuel out the exhaust.

After quite a bit of expense and faffing about I was told and shown by the guy who built it that there was no way on earth the timing was out! But was asked why the MAF was unplugged and I explained, on re-connecting my car intantly gained more power.

So after talking to Vince I finally managed to get my car back into Stealth yesterday. The whole problem boils down to no MAF and standard injectors. Because I'm running a Z charger which only produces 6.5psi there is no real need for big injectors but the standard ones need to be turned up to 94% for full throttle position so you can get away with it.

The problem seems to boil down to injector pulse. With Standard injectors pulsing at 94% and no MAF the ECU wonders why the hell the injectors are giving the engine so much fuel, with no air flow (as because the MAF is unplugged it thinks there is hardly any air coming into the engine) and backs off the fueling. But with big injectors they pulse alot slower so the ECU is happy and all goes well! So, I now have had my car mapped with the MAF on the car and the drive is great, smooth and progressive.

I only have the 2.9 rebore and the Z charger and the car is making 260bhp. I have been told that I'll see another 10-15bhp with a decent exhaust (as I only have a standard exhaust with a different back box.) and aquamist to bring the charge temp down.

So all in all, I'm quite pleased. But a word of warning to all that are charging with standard injectors. Some cars are ok with standard injectors and no MAF and some aren't. There is also an ECU glitch which is why Vince did MAFless remaps that he has had to iron out in mine, that I wont go into detail over. Lets just say fueling and airflow on charged VRs seems to be really quite difficult and you have to give Vince credit for having the balls and knowledge to do things the way he is.

A happy bunny

[IbiVR 0]

There is no need to run a vr without a maf, and a mafless map will never run properly. we map our cars standard ecu up to 25-30 psi (so far) with maf, and it runs like stock.

I dont see the problem, and i dont see how anyone can map a car without a load input and expect it to run properly.

Glad its sorted now though, and not a bad result!

You may want to think about injectors though - fueling can become a bit unreliable over about 80% injector duty, so if your running 94 you should use bigger ones really.

Tom.

[cadguy77 0]

There is no need to run a vr without a maf' date=' and a mafless map will never run properly. we map our cars standard ecu up to 25-30 psi (so far) with maf, and it runs like stock.

I dont see the problem, and i dont see how anyone can map a car without a load input and expect it to run properly.

Glad its sorted now though.

[/quote']

Who and where maps your setups m8?

[The_0ne 0]

Im not a tuner or anything but ive always been shocked to hear that vince maps with the maf disconnected.

Just shouts cowboy to me

[IbiVR 0]

Who and where maps your setups m8?

We do.

[cadguy77 0]

Who and where maps your setups m8?

We do.

Is your service open to the public, or open to members of the forum at least?

If so what's the damage on the pocket for a session?

[IbiVR 0]

No not at the moment. We will be supplying the code with the turbo kits as and when we offer them, but we dont really work on other peoples cars as its only a part time business at the mo.

[6potmkII 0]

mines booked in at stealth next week. i would much rather prefere for vince to map it with the maf tbh, as said above, without it, the ecu wont know how much air is being brought in, so it may run without it plugged in and may even create good power, but imo will run lumpy etc...

but good result jay glad its sorted

[Dubsingh 0]

so what are we saying coz when i rang and spoke to vince about mafless map the fisrt thing he pointed out to me was i would need bigger injectors....now im unsure if i should go for the mafless map...

the other dilema i have is my maf is inbetween the charer and throttle body as supose to between charger intake and filter.....

whats better

1) maf between charger outlet and throttle intake

2) maf between charger inlet and filter?

iv got the z engineering kit but i cnt get hold of the buggers ho have taken over them since they went bust.. i need to get a belt and some other goodies to try and up the power

any advice is welcome

[J5KE F 0]

I have had a mafless setup in my 2wd vr with no problems at all. I even feel a tad defensive towards vince being called a cowboy as the problem with the maf doesnt mean vince just did away with it to make it easier for him. He actually spent over 12 hrs straight with no food stops to try and sort it, he tried everything but the MAF was majorly conflicting with the Lambda and vice versa, causing the fueling to fluctuate irraticaly.

He asked me to keep an eye on it, and even called me a few times over the next few weeks to see if i needed to bring it back, and still i had no problems.

There are two people who i trust to mess about on vr's and they are Vince and Tim from the Phirm.

I HAVE BIG INJECTORS AND UPRATED FUEL PUMP!

[matth76 1]

I may be wrong but I'm pretty sure the maf is good up to a certain limit. When the air flow gets too big the maf is actually a limiting factor as it can't correctly sense the amount of air flow, and should be removed and the car remapped properly without it (obviously along with other necessay supporting mods). Big power Jap cars often tend to be mapped without the maf as it cannot correctly gage the amount of air flow over a certain limit. On lower powered cars where the air flow is a lot lower the maf is required. Vince is one of the best around in the country. I would trust his judgement over anyone else, when it comes to mapping a vr.

[IbiVR 0]

Maf should not be removed. Its limited in the ecu by a clamp. Thats all. with the correct mods in the code and to the maf its good for 28psi.

The jap cars your on about remove the maf and replace it with a map sensor.

You have 3D maps in the code. RPM versus Load = Fuel or ignition. Remove the load and it all gets confused. There are maps that look at TPS in this situation, but its all guesswork.

This is fine in some conditions, but then your compensation maps wont work properly, temp, batt voltage etcetetc.

If you want to run it and it works for you great, but your missing out on what the standard ecu can do for you.

Tom.

[aad 0]

jay glad your vr is running right .I think though that these z s/c spool up pretty quick imo.I also run standard injecters.

dubsingh.

I have always run my maf between s/c and the throttle body never been

a problem.

[badboyV6 4]

Jay - chuffed your motors running properly - lucky barsteward!!! :-)

Tome really interesting what you have to say though as a mechanic friend of mine who does a lot of VW motorsport cars (i trust his judgement) has said exactly the same thing.

[wayne_1@tiscali.co.uk 27]

i looked at your charger dubsingh on your rally and u have a vortech v1 not a z enginnering unless u have changed your charger since alley palley show if u have changed ive got a no for z enginnering for all parts

[binliner 0]

Vince told me that the timing was out and to go and see the guy who built it!! (I was not happy!!)

He seems to have a habit of blaming problem on someone else setting up the timing wrong!

[jaysVR6 2]

Vince told me that the timing was out and to go and see the guy who built it!! (I was not happy!!)

He seems to have a habit of blaming problem on someone else setting up the timing wrong!

It was bizarre. One of Vince's final comments was 'I guess we'll never know if the timing was out will we?!!'

I thought, why say that? I saw the engine taken to bits in front of me and was shown how it was set up! I know exactly how he must of felt though. A whole extra 5 hours of rolling road and remaping and not getting a penny for it, I would be so annoyed if it was me!

But the guy deserves his credit and I appreciate all his hard work.

The problem with running with the MAF on a charged car is something to do with the Voltage, I can't really remember what he said but the car had a really nasty misfire under load at around 3,500-4,000rpm and on viewing the graph as soon as this happened the graph dropped slightly and never really recovered, as the ECU basically shit itself. So Vince changed the MAF map somehow and managed to irradicate it, but VAG COM still shows a 'MAF short to ground' and he said that mine was has been the only car that he's managed to get around it on. But the ECU is still seeing the problem but you cannot feel it now.

[FishWick 21]

Junking the MAF loses you a lot of the map, especially in the part throttle fine metering, so you lose throttle response. Tom is right in saying you need larger injectors and a larger MAF, but bigger MAFs aren't the easiest of things to map for smooth part throttle response. We tried a MAP sensor on OBD2 in my car, but a 2 bar one didn't work. Went into full throttle map too quickly. We think a 1 bar N/A map sensor might work but the one Vince had was duff, so we couldn't tell....but running mafless and a safe map is a good way to get round some issues for some people, but it's not ideal!

[antera309 3]

so what are we saying coz when i rang and spoke to vince about mafless map the fisrt thing he pointed out to me was i would need bigger injectors....now im unsure if i should go for the mafless map...

the other dilema i have is my maf is inbetween the charer and throttle body as supose to between charger intake and filter.....

whats better

1) maf between charger outlet and throttle intake

2) maf between charger inlet and filter?

iv got the z engineering kit but i cnt get hold of the buggers ho have taken over them since they went bust.. i need to get a belt and some other goodies to try and up the power

any advice is welcome

Vince was unable to get my car running acceptably without the MAF and I have the Stage 2 VF-E kit (8Psi) with the redtop injectors. I got exactly the same problems as Jays - over 40BHP down on power, overfuelling, rough idle and stalling. Interestingly enough, Vince blamed valve timing in my case too.

I don't think injector type & size has anything to do with it. Some ECUs can handle Stealth's custom MAF-less setup and some can't. After his experiences with my car and others Vince is coming round to the thinking that there are more ECU types don't work with the MAF-ess setup than those that do....

Once the MAF was reconnected, Vince was able to get it running OK, but there are some drawbacks to retaining the MAF - hot air from the charger gets recirculated by the recirc valve and blasted onto the MAF wires when you come off the throttle. This causes the MAF to tell the ECU that the engine is under greater load and the fuelling is increased, causing an unwanted surge. Well, that's the theory. In practice, we found that my car didn't do this, so maybe the problem has been worked around in the design of the ductwork on the kit I have.

At any rate, you would definitely want the MAF BEFORE the charger, as the heat of the compressed air coming out of the charger would throw the MAF reading big time if it was located after the charger, although this might be something that could be worked around in the software as long as the MAF remained within its operating limits.

[mk3anni 0]

Or run a dump valve.

[cadguy77 0]

steve, is your MAF before or after the s/c? I would of thought being before the s/c would be the ideal location!

[6potmkII 0]

see how would you do this with the zr2 charger on a mk2!!!!

[VR6BOY 2]

I have to defend vince too he mapped my vr6 stg2 vortech and dumped the airflow meter and runs like a dream totally spot on btw its OBD2

[antera309 3]

Jay, I am so sorry. I mistakenly deleted your last post. I meant to click the "Quote" button but must have clicked delete by mistake.

Buddy, when did you find this out? I had my original MAP done back at the begining of May, that's when he told me the timing was out.

I\ll be rather annoyed if he had exactly the same problem with you before me.

My remap was done last week, Jay, waaay after yours was done.

So I guess I should be the one that is annoyed. Which I was, at the time. I've calmed down now.

I still ended up 13BHP short of the expected 280BHP (not that I'm disappointed with 267BHP!!!) and Vince was very concerned about the amount of ignition advance he had to program in just to get it to perform at the top end at full throttle. Valve timing (and its effect on the Cam Position Sensor, which drives the injection timing) was once again cited as the reason.

Once my new daily driver arrives, the gearbox is gonna come off so I can see for myself whether the chains are set up correctly or not. If they are, then I'm going to have to find out what the real problem is, out of curiousity alone.

At the end of the day, Vince is an experienced professional and if he wasn't confident doing these charger remaps, then he wouldn't do them. But I think the differences between the different revisions of the OBD1 VR6 ECU may have taken him a bit by surprise.

What is your ECU code then, Jays?. My ECU is an 021 906 258 AF

mk3anni, yes, I can't see any reason why an atmospheric dump valve couldn't be used on s/c VR6s that exhibit the surge problem.

[FishWick 21]

Not a good idea as it's metered air being dumped off, the ECU won't be too happy. If you're not running a MAF, then by all means an at atmospheric DV is fine.