Midrange hesitation with Scivision chips

[JarmoL]

Hi all,

I managed to buy a Scivision 1.0 bar chipset from ebay for my 944 turboS. I installed the chips along with a new 3.0 bar fpr. I haven't shimmed the wastegate yet. Car starts and idles and drives ok except between 3000-4000 rpm where it's hesitating. (what's the better word for that) I have checked all the vacuum connections I can reach and they all seem to be ok. Also the car ran ok with previous chipset so there really shouldn't be any problem with the car itself. I also checked that the FQS is set all the way to counter clockwise, I suppose that's the stock setting.
So:
is that normal behaviour for these chips?
will the wastegate shims cure the symptoms?

The previous chipset in the car was apparently not original also as the stickers on them were handwritten: DME HR2 2.7 1.1 and KLR HR 1.1. There was also a restriction in the banjo bolt which I removed while trying the Scivision chips. Does anyone happen to know anything about these HR chips? Car drives ok with these but the low end torque and response isn't that great.

All help and advice is greatly appreciated, it seems that I am out of official support from the chip manufacturer as I bought the stuff second hand.

Jarmo

 

[Fen]

I think you're missing two things; the SciVision chips are intended to be used with the SciVision MAF. Now the story with that part is that it is a direct AFM replacement and doesn't need chips (the purpose of the chips to be to increase the boost), so you should actually be OK to use it on that basis.

The second thing your missing is some means of controlling the boost. The chips are 1.0bar in that they provide the correct(ish) fuel for a 944 Turbo with a K26/8 turbo running 1.0bar above atmospheric boost (standard being 0.82bar above atmospheric). The chips only alter the fuel and possibly the overboost protection, but they cannot set the boost and you are missing a second piece of hardware in the shape of an AccuBoost, ReliaBoost or Boost Enhancer. Basically they are all subtly different flavours of a valve with some degree of adjustment that sits in the line between the banjo bolt and the cycling valve and their function is to prevent the boost signal reaching the cycling valve and wastegate until it reaches a level that can be adjusted by a knob.

Currently I think you are probably running rich everywhere as you have the fuel to suit an extra 0.18bar of boost without the boost (and therefore air) to go with it, hence the stumbling. If you sort out some boost control you should be OK if the SciVision MAF is as direct a replacement as it's supposed to be for the original flap type AFM.

Shame the manufacturer couldn't at least have taken the time to tell you that rather than leave you high and dry.

Shimming the wastegate can only be a move in the right direction, but I can't see it having anywhere near enough effect. I think you should take the chips out until you get a boost controller sorted out, ideally replacing the poor standard wastegate and removing the cycling valve in favour of a dual port wastegate of some sort with at least a manual boost controller knob.

 

[AndrewS]

Hi Jarmo,

You purchased the SciVision chips from eBay? If purchased from eBay - are you certain you have the genuine article?

Secondly, the SciVision chips are designed for installation in a standard car. You need to have the cyling valve operational and you may need wastegate shims (which I believe you have ordered). You can also use an inline boost controller to raise the overall boost - but if you have a weak wastegate, the shims are a better bet (just harder to fit).

I would like to ask Fen how the "manufacturer couldn't at least have taken the time to tell you that rather than leave you high and dry" when they were purchased without guidance from eBay? SciVision do not sell direct and the chips were purchased from eBay.

Used correctly, the SciVision chipset is very effective on both an AFM or MAF equipped car up to 1.0bar boost. A 3.0bar FPR is also recommended for this software.

Regards,
Andrew

 

[Fen]

Someone's a bit over-sensitive today! Are you the manufacturer, Andrew? No. Ergo it has sod all to do with you, but personally I have no time for companies that think they can wash their hands of responsibility for their products just because the current owner didn't buy them new.

If my advice on the boost control was wrong then I will modify it thus: At 15+ years old the 944 Turbo's boost control system is poor at best and chips are utter rubbish if they are designed to maintain increased boost using purely the cycling valve and KLR computer as they can't even maintain standard boost properly after all this time. Before anyone tries to tell you different they might like to consider whether their first foray into Porsche aftermarket parts was with a product to address exactly that deficiency on the standard car running standard boost.

 

[Guest]

ORIGINAL: Fen

I think you're missing two things; the SciVision chips are intended to be used with the SciVision MAF. Now the story with that part is that it is a direct AFM replacement and doesn't need chips (the purpose of the chips to be to increase the boost), so you should actually be OK to use it on that basis.

I'm thinking of binning my Scivision MAF kit that I bought from ProMax a fw months ago and getting hold of a proper AFM. Since I fitted it I'm getting about 20 MPG and it runs so rich from cold that the car runs like a dog until it's warmed up. Once it's warmed up, it's still down on power, because the plugs get choked up.

I suspect that the "direct replacement" applies to certain models, so it might be ok on a Turbo, where you want it to run a bit richer for safety. It seems to be a bit OTT on my S.

I considered taking the car to a rolling road and getting it checked out, but I think they'll just say the same thing that I've found out on the non rolling road. It isn't fuelling correctly for my car.

James

 

[AndrewS]

Hi Fen,

No not at all oversensitive. I have seen crude copies of ProMAX and SciVision chips sold on eBay with incorrect checksums that will somehow still work (i.e car will start and run).

Would Microsoft support a pirated copy of Windows? What about a copied DVD that jumps and skips in a DVD player?

As a SciVision authorised Dealer, ProMAX Motorsport support SciVision product. It's imprtant to establish whether it is the genuine article so we don't go chasing a problem that isn't there in the original software.

As for your statement about the chips being "utter rubbish". I assume you have tested a set and can say this with authority? If so, perhaps you could explain whats wrong with them?

The factory boost control system works fine. With the age of the car, it may not be operating at peak efficiency and this is usually as a result of a poor wastegate. The electronics controlling the wastegate air pressure signal compensate for this to a large extent. This problem can be easilly addressed with properly designed wastegate shims.

Regards,
Andrew

 

[JarmoL]

Hi there,

The chips I bought seem to be similar like the ones at the http://www.transaxle-motorsport.de/tms/doc/prdChips/sd.php?RT=/tms&DN=prdChips. Of course I have no idea if the seller or somebody else have copied or hacked the chips somehow. But anyway the stickers look like the official ones. If I understand correctly these SHOULD have the ability to raise the boost without any additional devices. I suppose there isn't much chance to have these checked for originality??
I guess I'll try to figure out if the CV in my car is operational. At least it has all the vacuum lines and electrical connectors intact.
At the time when I bought these chips I thought my car had original chips in it.
(stupid me!) If I had known it has been chipped already I guess I wouldn't have bought these at all. Oh well.. But of course now that I have them I'd like to know if there might be any improvement for low and midrange torque.
And yes, I ordered the shims from you Andrew. I figured out I'll need them anyway as I'll be using aftermarket chips in future too. Hopefully you have them shipped soon.

I'd also like to mention that I am not upset that I am not having any official support from the chip manufacturer. (whether is it scivision or transaxle-motorsport or what ever) I bought the stuff second hand so this is to be expected.

Jarmo

 

[AndrewS]

Hi Jarmo,

How are you?

If your car has any other mods, the SciVision chips may not be suitable for your car (i.e. if you run a DPW or run different injectors). To get the most from them you will need a 3.0 bar FPR, the wastegate shims and also make sure your cycling valve is operating correctly. Also make sure your intake system can hold 1.0 bar of pressure and that your bypass valve is not leaking. Check all intake hoses - especially round the intercooler.

The SciVision chips are a nice safe upgrade for a standard car and utilise the boost control system to improve turbo spool up and also increase the maximum boost from .75 to 1.0 bar.

If you need assistance, please let me know at andrew@promaxmotorsport.com

Have a good day!

Regards,
Andrew

 

[AndrewS]

I'm thinking of binning my Scivision MAF kit that I bought from ProMax a fw months ago and getting hold of a proper AFM. Since I fitted it I'm getting about 20 MPG and it runs so rich from cold that the car runs like a dog until it's warmed up. Once it's warmed up, it's still down on power, because the plugs get choked up.

I suspect that the "direct replacement" applies to certain models, so it might be ok on a Turbo, where you want it to run a bit richer for safety. It seems to be a bit OTT on my S.

I considered taking the car to a rolling road and getting it checked out, but I think they'll just say the same thing that I've found out on the non rolling road. It isn't fuelling correctly for my car.

James

Hi James,

I have sent you a private email - but if you had a problem - why did you not get in touch first? I wasn't aware of this at all.

Your MAF should be working fine - there are many out there on the 944S2 and 944S models now. Are you certain you don't have other issues? Is your ISV working correctly?

There are basic tests that can be carried out and also checks for MAF wire contamination. Can you get the car to the workshop for investigation? Have you tried substituting your old AFM? The workshop can supply you with a test AFM if required.

Regards,
Andrew

 

[944Turbo]

I hope the shims were not too expensive. I found stainless washers were fine and allowed better fine tuning than the guru shims, I set the wastegate using a foot pump (Search for wastegate wellbeing) and found I needed longer bolts. Dont go too far and stop the wastegate from pening though.
Tony

 

[AndrewS]

Hi Tony,

The shims are deisgned specifically for the job - we don't use the GURU items. Shims can be seen on the website.

Regards,
Andrew

 

[944Turbo]

And what is the advantage of these shims over washers?

Washers can be inserted opening pressure checked and more installed as required. longer bolts can be installed and more washers put in. cheap simple and effective. I maybe missing something but I dont see the advantage of the plate type.

PS I searched google for promax motorsport and got this http://www.promax-motorsport.com/new_page_1.htm
Are you branching out?

 

[AndrewS]

ORIGINAL: 944Turbo

And what is the advantage of these shims over washers?

Washers can be inserted opening pressure checked and more installed as required. longer bolts can be installed and more washers put in. cheap simple and effective. I maybe missing something but I dont see the advantage of the plate type.

Hi Tony,

The plate type spreads the load saving distortion of the wastegate.

Regards,
Andrew

 

[944Turbo]

But in this thread http://www.porscheclubgbforum.com/tm.asp?m=33373&mpage=1&key=shims&#33373 you can see the wastegate flange isnt flat it curves up and away from the mounting face. (Paul did you use smaller bolts with nuts rather than longer bolts in ths standard orientation?) so provided you use the same size washers and the same amount in each side I dont see a porblem (and didnt experience one) I guess the Rolls Royce solution would be one of your shim plates spaced up with washers (between it and the main body of the wastegate) to get the opening pressure you require,
Tony

 

[Fen]

Andrew I'm not being drawn into another argument with you simply because you chose to wade into a conversation that mentioned neither yourself nor the company you give the impession you run.

 

[JarmoL]

Oh well..

Is this rennlist or what??
I checked the CV according the instructions given in the factory manual and it seems to be ok. So not much to do then, I'll try again after I get the wastegate shimmed.
Anyway I installed the old chips and banjo bolt restriction back along with the 2.5 bar fpr and the car runs ok now. Original boost gauge goes all the way to the 2.0 bar line and holds there until about 5500 rpm and then falls back a little. Maybe I should get the car dynoed to see that I am not running lean.. On the other hand it has survived very hot trackday activity as it is so I guess it's not that bad.

Thanks,

Jarmo

 

[eastendr]

The HR chips would be the Huntley Racing (USA) chips and they were originally shipped with the banjo restrictor. If they're giving the boost indication you suggest, I'd say the car was fundementally healthy. The boost guage on my turbo was nowhere as inaccurate as many would have you believe - checked against several calibrated cources. However saying that, I've only tested two 944 Turbo boost guages against known calibration.

I think the issue of the chip checksum is a bit of a red herring as the change of a single bit will change the checksum. There are a lot of different chips around that may just have a single bit changed (for example) in the rev limit byte to change it by as little as 40RPM. No difference at all in the real world, but a change is a change and copyright is nulled. That's why there are so many chips on the market. In may cases the difference may be over £200 for an otherwise identical chip.

If I were to modify a version of the (for example) GURU chipset (itself a copy of another) by changing a single bit, it would have a different checksum. I could then sell these chip sets on ebay for cost (£5 - I have a LARGE number of blanks I bought for 944 turbo when I was developing my maps) without a problem.

Thats the up's and down's of using 1970's EPROM technology !