Supercharged Stg2 VR6 Stalling & Overfuelling when cold

[Guest]

When I fit it, I'll see if I can mount it horizontally somehow.

 

This is what I'm planning on doing, but haven't found the time yet.

 

Kev, what flexi hose did you use? Need to get myself some.... Have seen stuff in ehem...Halfords...ehem :oops: like the metal flexi hose you get with induction kits for cold air feeds. Would this do the trick? Purely for temporary use of course...

Although the only problem i really get is the car being unresponsive, and it's something i could probably live with, i'd prefer it if it was cured, so want to try running with a MAF..

 

I know Guy H runs his Vortech charged VR with the MAF connected and without the clamping diode, and has no problems.

 

My worry is what Kev mentioned earlier, where the MAF will reach it's airflow limit and just stall the car. I have read on a forum in the states that the stock MAF can only output a signal of 5V max, which isn't really any good for anything more than 8psi. Although i'm only running 8psi, it could still hit that limit.

Now i'm not entirely sure what function the clamping diode that Vortech supply in the kit is (i didn't get one with my kit, with the intention of it running no MAF), but i assume it clamps the signal from the MAF so it doesn't reach it's 5V limit, therefore fooling the ECU into thinking there is less airflow than there actually is? Someone correct me if im way off... :oops:

Either way, im not that keen on running one.

Running a bigger MAF, maybe from another car that runs higher boost as standard could be an option, surely?

 

Stevo

[antera309 0]

This guy on eBay sells flexi ducting by the metre:

http://cgi.ebay.co.uk/COLD-AIR-FEED-IND ... dZViewItem

 

The link is to the 80mm stuff. Are we sure it's 80mm?

 

He also sells Samco hoses.

 

My thought is to lenthen the distance between the MAF and the charger by running ducting behind the bumper. There's not a lot of space back there, but flexi ducting can be "squashed" into an oval shape to if required.

 

My enquiries on VWVortex have turned up the same suggestion - space out the MAF and the charger. So guess what I'm doing this weekend? LOL

 

My setup looks like the 'U' bend of a loo now

 

Do you have any pictures of your install, buttles? I would love to see what you did as regards rerouting the intake.

 

 

Steve, I've read a lot of posts about the MAF going outside of its operating limits on supercharged VRs at high boost - this is the hard limitation that cheesewire mentions and one of the main reasons why Vince chose to start disconnecting MAFs in the first place. But I'm still struggling to understand how this problem can affect the cars behaviour at idle, when it is flowing only slightly more air than a N/A engine would.

[Guest]

Cheers for the link, will have to get myself some... Will eventually get samcos when i decide what the best set up is...

 

Incidently, looking at your diagram, you have your crank breather venting back through the charger (as per the kit intends). Not sure if it will make any difference, but i have mine venting to atmosphere after the catch tank. Means less hot air going back into the charger....

[Kevin Bacon 5]

Aha, OBD1 doesn't like having the MAF hanging vertically. OBD2 doesn't care, you can put it anywhere, but OBD1 must have the MAF horizontal and sitting at the same angle it would in the engine bay - it's very fickle.

 

I would also vent to atmos as Steve says because when the MAF is directly under the charger intake, oil and water vapours from the crank vent hose drip onto the MAF wire, shorting it out and giving +12V down the red signal wire (instead of 1 to 5), which will over fuel the engine something chronic!!

 

I am 90% sure your idling is because of the MAF location and it could also be incombination with a dying MAF, which doesn't help N/A VR6s, let alone S/C'd ones. Where you've got it is too close to the charger's compressor wheel, hence turbulent air confuses the MAF. You may think the charger isn't doing anything at idle, but pull off the discharge pipe and there's LOADS of air coming out of that charger ;-)

 

Yep 80mm flex hose, the wired stuff. Make sure it's double layered if you can afford it as it's much tougher than the single layer stuff. You need to bend the flexi round at quite an acute angle to get the MAF horizontal, so precautions against abrasion holes should be taken into account too.

 

When mine was OBD1 and 8psi VF'd, doing that transformed the engine, and not just at idle. Give it a whirl and good luck!

[antera309 0]

New MAF & 80mm flexi-ducting ordered. Hacksaw at the ready!

 

I can't thank you all enough for your advice - I let you know how I get on. :)

[buttles 0]

Antera309, sorry no pictures at the moment. Just to say it's fairly natural how the filter and MAF sit. Filter and maf attached, the filter points fowards into the bumper area. The MAF is now directly under the inlet to the charger. This is where the flexi tubing comes in. Route it down, back then down and foward to attach to the exit of the MAF. I used some poly foam wrapped in bodge tape to make a support against the crossmember mount which is just above the MAF. If you have stiff front mount then the rubbing shouldn't be too much of an issue. The wheel arch front panel has a moulding on it which I had to cut off to stop cutting into the tubing. They say a picture is worth................... :wink:

[Kevin Bacon 5]

Good man, keep us posted 8)

 

Yes Steve, you're right..... the purpose of the MAF clamp was to limit the voltage to 5V, or 4.8 to be precise, as 5V is the absolute limit of the ECU. When the ECU sees 5V (at 4000rpm WOT usually), it doesn't understand how that much air can be entering the engine against modest injector duty cycles, so it shuts the injectors off.....nice! Not all engines did that for some reason though, but both my AG OBD1 and OBD2 did.

 

The cure is to either raise the MAF table limit so that the ECU doesn't throw a wobbler when it sees 5V, or fit a larger MAF housing and corresponding MAF table remap. Going from a 3" MAF (stock) to a 4" MAF doubles the air flow and therefore the ECU will never see 5V.

 

Only snag is you can't get 4" MAF housings for OBD1, but surprise surprise, you can for OBD2! So a certain amount of ripping the OBD1 MAF apart and splicing into a bit of 4" drainpipe is required. Works well. Providing Vince can remap the MAF tables to suit.

 

But this whole shutting the injectors down is the main pitfall of OE ECUs. Standalones can be told exactly what to do and won't try and get all clever on you and do a Microsoft and take over your engine.....and crash it :-)

[antera309 0]

I've noticed that you can get 4" Billet MAF housings for OBD2...

http://www.bahnbrenner.com/media/php/ca ... p?pid=1900

 

C2 Motorsports do them as well, and I'm sure I read somewhere that they have developed an OBD1 version. I've emailed them for confirmation...

http://www.c2motorsports.net

[corradovr6sc 0]

Antera309, here's a pic of my maf on my old Corrado. I think the problem on a golf is lack of room to position it horizontally.

[antera309 0]

Antera309, here's a pic of my maf on my old Corrado. I think the problem on a golf is lack of room to position it horizontally.

 

Quite right, the Golf III does not have such a large overhang ahead of the front wheels as a Corrado does. I think the answer is going to lie in taking it across the front of the car. I have a (very thin) fibreglass front bumper on mine with no internal supports or foglight housings, which should help. :)

[Guest]

I'm glad this thread has started. In the past 2 days i've got all the info i've been searching for, for the last few months!!

Nice one guys, and thanks!!! Will also let you know how i get on when i can be arsed to get the bumper off!! Need to repair my MAF plug as well...

[KADVR6 0]

i think we would have all been pleased, if the money given to stealth for the re-map worked in the first place. if you bought a TV for example, for £412, and it was only showing in black and white. would you not take it back and get ya money back?? instead of tring to fix it yourself.

[buttles 0]

ER? The way I understand it is Vince didn't produce the Kit. He took a big risk in taking on the mess that ensued. Those that bought the VF kit after reading Kev's lengthy missiv should have been very sure about what they were embarking on. I for one was prepared for a few problems. VF should be your first port of call if things didn't go according to plan.

[antera309 0]

I agree that responsibility ultimately has to lie somewhere, but I'm not sure it's with Stealth. In the US, the VF-E kits are supplied with a direct-replacement GIAC chip, pre-mapped for the setup. Custom remapping is not required unless the engine has other significant mods (such as a Schrick manifold, water injection or aftermarket cams). LOTS of cars in the US are running VF-E stage 2 with the bundled GIAC chip with no problems whatsoever.

 

Here in the UK, the GIAC chips were not supplied with the kits and those I've spoken to on VWVortex find this very strange - why pay a tuner to do what VF-E have already done?

 

I don't know why the GIAC chips were not supplied with the 20-odd kits sold by NS Racing last year. According to VF-Engineering, the UK-spec AF and AG ECUs are supported, but maybe NSR know better - I dunno.

 

Having said that, a couple of people on the Vortex have reported stalling issues even with the GIAC chip, and have had to reroute their inlet pipework as described above in order to solve the problem.

 

Is anyone on here running a VF-E kit with the GIAC chip? If so, I'd be interested to hear about their experiences.

[Guest]

antera309, just wondered if you've had the chance to experiment with different MAF locations, and what the results were.

 

I finally bought some of that 80mm Flexi Hose, and had the bumper off yesterday, to try and figure out a way of mounting the MAF horizontally. There was no way i could mount the MAF directly to the air filter, so it looks like I'm gonna have to go for the set up shown, where there's a piece of hose between the filter and MAF. The MAF will sit directly under the chassis leg, right where the bumper bolts go back in. (could be a problem when refitting!)

I really couldn't see any other way, as there's alot less room under there than i thought..

 

The only thing i need is a MAF plug. Just wondered where the best place to source one would be? I guess it's a dealer only part....

 

Cheers

Steve

[RS VR6 0]

I agree that responsibility ultimately has to lie somewhere, but I'm not sure it's with Stealth. In the US, the VF-E kits are supplied with a direct-replacement GIAC chip, pre-mapped for the setup. Custom remapping is not required unless the engine has other significant mods (such as a Schrick manifold, water injection or aftermarket cams). LOTS of cars in the US are running VF-E stage 2 with the bundled GIAC chip with no problems whatsoever.

 

Here in the UK, the GIAC chips were not supplied with the kits and those I've spoken to on VWVortex find this very strange - why pay a tuner to do what VF-E have already done?

 

I don't know why the GIAC chips were not supplied with the 20-odd kits sold by NS Racing last year. According to VF-Engineering, the UK-spec AF and AG ECUs are supported, but maybe NSR know better - I dunno.

 

Having said that, a couple of people on the Vortex have reported stalling issues even with the GIAC chip, and have had to reroute their inlet pipework as described above in order to solve the problem.

 

Is anyone on here running a VF-E kit with the GIAC chip? If so, I'd be interested to hear about their experiences.

 

The kit is pointless without the software. You might as well just get the C2 kit...I think it may be cheaper. Has anybody tried asking on VF Unplugged about the chip not being in the UK kits? You can also try sending a PM on Vortex straight to VF.

 

I've been running the VF stage 2 since 2004. I've put roughly 40k on the kit...and I've had no SC related issues. The reliability has been rock solid. VF was having stalling issues a couple years ago, when you clutch in at a stop the car would stall. VF fixed the issue bt moving the MAF farther away from the inlet of the charger.

 

I've ran the car with and without the MAF clamp...for me it made no difference. I do have it connected just because VF recommended it.

[Kevin Bacon 5]

NSRacing stopped providing the GIAC software with UK kits because it doesn't work for us. If GIAC were serious about preserving their reputation and writing a good map for UK cars, they would have flown over and sorted it out. They didn't bother. US cars have EGR aswell as other tighter emission controls that we don't have and GIAC didn't pull these out of the code for UK cars. So what we ended up with was too much fuel, too much advance and one very spiky torque plot. No thanks GIAC, we'll develop our own code.

 

RE the MAF you are in california. We are here. Two completely different climates, so it's not worth comparing your car to ours. Hot air does not throw the MAF into the 5V wall like cold, thick UK winter air does.

 

ER? The way I understand it is Vince didn't produce the Kit. He took a big risk in taking on the mess that ensued. Those that bought the VF kit after reading Kev's lengthy missiv should have been very sure about what they were embarking on. I for one was prepared for a few problems. VF should be your first port of call if things didn't go according to plan.

 

Well said. Vince hasn't finished with the S/C maps yet, he just doesn't get a lot of time in on it as it's out of hours and unpaid development for him.....for our benefit.