siverson914

Hi everyone,

I have a 1991 964 3.6 liter engine installed in my 914. Recently got it back on the road after a 914 restoration and complete engine rebuild by Andial (had leaky cylinders).

The engine is stock, except:
- 964 Euro RS cams
- Andial valve springs
- 914/6 1 3/4" headers
- no power steering pump, etc
- lightweight flywheel

The stock chip is clearly wrong for my setup. The car hunts at idle when the o2 sensor is plugged in, and sometimes stalls when falling from high RPMs.

Other than that, it will idle (using some care at low rpms) and runs and pulls very strong until 5200 rpm where it cuts out under full throttle. It feels exactly like hitting the rev limiter, and it's always exactly at 5200 rpm. This happens whether or not the o2 sensor is plugged in. If you accelerate at partial throttle, the car will pull all the way to redline.

I know the car needs to be dyno tuned and optimized, but is it ready for that now? Is my 5200 rpm cut off a symptom of just the wrong programming for the cams/etc (i.e. the motronic thinks things are too lean or something), or is something else wrong?

Any ideas or tips?

Thanks,
Steve

Adrian

Dear Steve,
Just for info, the 964RS cams are identical to the standard cams, in fact they are the standard cams except one has the spur gear removed. This spur gear drives the power steering pump.
I am only going to deal with your 5200 rpm problem. The rest of your problems are directly related to flywheel, transmission etc etc.
Are you using the standard air intake system?
The 964 uses a reasonance valve. This valve opens at around 5000 rpm and effectively lengthens the air intake. I would suspect that this valve is either not hooked up or is not opening correctly. It is controlled by the DME and is a vacuum and electrical system. Because it is engine load (engine rpm) related it may well be engine load mismatch of mapping. It may be opening too late causing the stumble. Just for info as well. Check the Wide Open Throttle microswitch is activating and the O2 sensor input is ignored when this microswitch is made. Again you may have a general engine set up problem.
Ciao,
Adrian
964C4

siverson914

Adrian, thanks for the input, I'll check the valve.

BTW, I've found your 964 book very useful, plus, it's quite an interesting read. Haven't made it through all of it, but good job.

-Steve

PCar SBA

Like Adrian said a little more information is required: You could also have an issue with no getting enough fuel (fuel filter, fuel pressure regulator) under WOT.

The stalling when coming off from high RPM's is because your flywheel is a lot lighter than stock. A modded chip will help here. The hunting is a wrongly adjusted AFM. It needs to be leaned out most of the times.


If you are looking for a better chip this might be of interest for you: http://sswl.di.com/~ingo/Chipping.htm

Arjan B.

I would take a d-tour and drive by at ANDIAL and ask. May be it is simple.

siverson914

Thought I'd just post and update since I got this problem solved a couple weeks ago. To make a long story short, everything was operating correctly, except the stock programming got very confused with the modified cams. Turns out they aren't RS cams as I had mentioned (which you're right, have the identical profile), but an "Andial Sport Cam" (their own profile).

Now the car is running with an Autothority chip and MAF sensor. Wow! It's nice to have 5200-7000 rpms, and I'm not sure if it's the programming or MAF, but the car is much easier to drive at low speed too. It used to be hard to modulate between 1k-2k rpms, now it's very smooth.

Vroooom!

-Steve