GregAmy

I just got myself into a '92 968. I've been doing all the maintenance on it (DIY'd the timing and balance belts) and now I'm looking into engine management.

I'm a decisive Micro/Megasquirt fan and am inquiring from DIYAutoTune if they can offer a PnP as they do for the 944. It's clear they don't have one but we're discussing it.

I would not be surprised if their 944S2 ECU woujld bolt up, though it may require some firmware if the wiring is different. One wrinkle, though, is the Variocam: that ECU would not know how to handle it.

So I need two things right now to move this idea forward:

- Is the Variocam in the 1992 968 binary (solenoid on or off) or it is actually variable (pulse-width modulation)? If the former, then any ECU should be able to manage it.
- Where can I get a copy of the service manual or wiring diagrams for the '92 968 to compare the pinouts to the 944 ECU? See attached.

Thanks!

Greg

Zirconocene

I put this together some time ago; sounds like what you're looking for:

https://docs.google.com/spreadsheets...it?usp=sharing

The workshop manual can be found via a Google search; I don't think that posting something here is looked on kindly. At any rate, there are a few sources available.

ETA: I had a bit of a think and believe that the VarioCam is a simple on/off function, not a PWM type activation. I say this because it's pressure driven, which would not (I don't believe) lend itself well to something like PWM control. I don't really know, however.

Cheers

GregAmy

Thanks! You're very confident on these pinouts?

I'm checking around, but I can't find anything that implies the Variocam on the '92 968 is variable; the implciation is that it's binary. The data is lean, though; all my searches are coming up with how to time the came when replacing the guides and such.

If so, then a Megasquirt 2 PlugNPlay will work. We'd just need to edit the firmware for the right pin connections (assuming they're different.)

If anyone has further info, I'd appreciate it.

Greg

Zirconocene

The pinouts are copied directly from the WSM; you can see the picture of the S2 pinout diagram. There wasn't anything similar for the 968, which is why there's only text. Let me see if I can I'll get a picture of where I got the information, and I'll update that file.

Cheers

Paul Waterloo

Is this Greg Amy from old audiworld/quattroworld days?


WSM: http://audipages.com/968/manual/

GregAmy

Yes sir! How'r ya doin' brother? Haven't talked to you in a dog's age!

I do miss that '91 200TQ, great car. I moved to a '00 S4 for 11 years, then a '11 GTI that I still daily-drive. Got back into racing in the early 00s (Nissan NX2000, Integra, Civic Si, Toyota MR2, Honda Fit, Miatas) which I still have fun with. I'm doing a lot of stewarding now, too. Picked up a '74 914 street car which I restomodded (paint, interior, warmed-over engine, Microsquirted the D-Jet system) which led to a '74 914 historics car project (it makes appearance 2-3 times a year).

Then I had this 968 dropped on me. Always liked the lineup, I had a 944 back in the 90s, and this was a car that a fellow racer bought to turn into a race car. Though the paint is a bit tired, he decided it was too nice to make into a race car and sold it to another buddy, who made me a killer deal on it. So here I am.

Not sure what my plans are for this car; I'm pretty much retired now so it could be a daily-driver to replace the GTI. Or may it'll be a nice-weather driver like the street 914 (which I still have). But in the process of doing the timing and balance belts I got a good look at the car and I think it's rife for a tunable upgrade to the Motronics controller, so I'm investigating it. If I can work with DIYAutotune to make it plug-in, then we can all have a good baseline for whatever tunes we want, and tunable via via laptop instead of having to rely on external tuners and plug-in chips.

We'll see.

I hope all is well with you! - GA

Paul Waterloo

Nice to hear from you Greg. I remember making audipages.com a long time ago so we would have a FAQ like what we had on the 91 200q, can't remember what the page was or who built it, but I did audipages.com a long time ago. It even has a BIRA page on it for the 97 A8!

Been through mostly Audis including an 01 S8, 07 S8 (just sold it last year, was cherry, owned it about 10+ years), had a 968, 951 and 996 which I just love. Finishing building a house by myself in FL, just moved from Chicago permanently a few weeks ago. I have done at least 50% of the total work myself. I'm going on three years but it's time to move in soon. I actually got to my great little community because I owned a 73 Alfa Romeo spider and it had an electronic distributor, I met the guy who builds them, he is now my neighbor and turned me onto my property.

I still post on quattroworld, but now in the DIY forum, here is my latest post: https://forums.quattroworld.com/arch/msgs/78431.phtml

Good to hear from you Greg.

Paul

jsheiry

Greg, I believe the answer you are looking for is binary and the vario cam valve is controlled by 12V. A combination of oil temperature and engine speed determine what the DME sends to the module. Rather than me translating I have made a PDF out of the two pages you need.

Info starts at Page 1 Solenoid Valve for Camshaft Adjustment. Added second PDF the first one references for additional info on the VarioCam.

Really interested where this project goes. Thanks John

GregAmy

Excellent info, John, thank you.

Given this, I suggest that even if the Megasquirt firmware for the 944S2 does not support Variocam on its terminal (#23?), it would be a very easy solution to leverage one of the PnP's Programmable On/Off Outputs to set it up by rpm with a simple rewiring or crossover lead. I'd have to review the firmware to see if it can be held back until a specific engine oil temp is reached.

Am I reading this correctly that the Variocam is DISabled upon reaching 5500RPM? If so, why? This could be tougher to program in. But I'll investigate the software on that option, too.

I'll keep y'all posted on what I learn. - GA

jsheiry

I added an additional PDF that goes into a little more detail on the VarioCam and operation. Can't say I know why exactly why its switched off at 5500. Question perhaps for Michael Mount or Pete Fitzpatrick or Cliff Hudson.

jsheiry

Greg, I added the DME pinout for you to keep all this info in one thread.

GregAmy

Still looking for info on why Porsche decided to shut off Variocam at 5500. It would also be useful to find out why they tuned it to come in based on oil temperature. Can anyone direct me to someone who may know?

Reason I ask, working the Variocam the way will Porsche did it would require going with an MS3-based system, which offers PWM control. However, if we can manage the Variocam as a simple output based on RPM, with no subsequent 5500 RPM cut, then we can go with the MS2-based system, same as what they offer for the 944S2, and save about 25% on teh cost of the ECU ($830 vs $1150).

Thoughts appreciated. - GA

Ufnavy06

Interested in where this goes. Curious also how it would compare to the APR Dinan ECU. They figured it out in order to develop theirs.

GregAmy

I used to have close ties to APR (I did some driver coaching and data acq for their Koni Challenge race team) but I think it's a totally different ownership now. I'll inquire.

However, theirs is just a chip. It uses the same stock Motronic ECU and its internal controls, it just changes when and how it does that. Since it's the same ECU I'm very confident that they have not changed the Variocam management strategy.

On the other hand, the Megasquirt is a fully-tunable and -customizable whole-ECU replacement. It would plug into the factory harness but does things totally differently. It would allow (but not require) opportuinity for adding wideband (among other stuff), sequential or batch injection, sequential ignition or wasted spark, and potentially ditching the MAF thus converting the engine management system to speed density. And, any tuning changes can be done via USB cable so the ECU never has to be removed and reinstalled.

If you have no interest in being able to do that, then the APR tuned chips are the best answer. Leveraging the stock the Motronic ECU you have now but with maybe a bit more spark advance, a little fatter fuel mixture, probably at the expense of some fuel economy and emissions. You would have to R&R the ECU and crack it open to get to the chip for tuning changes (if desired). - GA

jsheiry

This chip discussed much on one of the FB forums for 968....not sure anyone has done more research and Dyno time with 968's than Pete from RSBarn. RSBarn is not around anymore as far as the commercial website but Pete still chimes in and seems to be building engines and selling chips as he had developed a stage 1 and stage 2 chip for the 968. I will throw him these questions about the 5500 cut off and the oil temp and see what he says. Michael Mount often chimes in on this forum and could have much to say on the subject.