dsmyth

I am thinking on taking Ryan up on his offer to switch out my 95 intake,ecu and harness for his Varioram units ecu and harness. Does anyone know what i'm up against as far as

1, Im currently running without an sai pump and don't want light issues?
2. Will I have immobilizer issues ? do I need his immobilizer?
3, Any other issues /challanges to consider.

Help is appreciated. thanks Doug

Bill Verburg

Why?
If you want v-ram it's easy enough to add one to your existing setup, if you want to get rid of the immobilizer that is also easly done w/ your existing setup.

The Motronic DME v2.10.x used on '95 US and and all '94-98 RoW n/a 993s is easy to modify. the Motronic v5.2 used only on 993turbo and US '96-98 993 is a comparative nightmare

axl911

Agreed on all points /w Bill. If you want the varioram, just swap out the non-varioram to varioram. And update to the later harness if you still have the old one which has been recalled.

Don't need to swap out the DME. I've done the same thing and gained a TON of torque down low.

Challanges include:
- Getting the vacuum lines right for the varioram. This is a major headache if you get the C4 unit which doesn't have the brake booster vac lines.
- Getting the electrical wiring right to activate the vram. There is a diy on this, but you still gotta splice and dice wires.
- Getting a proper chip to control the vram. This is also documented in the diy.

rmag

Bill - Here's why he wants to swap: https://rennlist.com/forums/993-foru...-varioram.html. Basically I blew the motor in my '96 race car and am planning on backdating it. Since I run prepared class, I am allowed to tune the ECU, however, '96 ECU's cannot be. I offered an even swap of my Varioram, harness, and '96 ECU for anyone with a '95. So we just want to make sure we provide each other with all the necessary components to pull this off.

Bill Verburg

I certainly understand why you want to swap, what I don't understand is why anyone would take you up on the offer.

rmag

I'm new to this 993 stuff,(just got the race car in October), plus a driver, not a mechanic. I can understand for 993 track purposes why someone wouldn't want to swap (my predicament). But for a street 993, I see getting the varioram, correct ecu, and harness (so no splicing required) for no cost as a plus? Back to his original question, to make the swap work, what else should I provide (immobilizer, Fobs, etc)?

BTW, thanks for all the informative posts here. Having just ventured over to this section a few months ago, I've been reading many of them.

Bill Verburg

The problem w/ the US '96-99 88pin 5.2 Motronic is complexity and difficulty to modify or work w/.

The 55pin Motronic 2.2 is comparatively easy to work w/ and to modify.

want vram on a '95 US, no problem, bolt on the parts and swap a few wires at the connection pins, install an easily available chip, voila! you have a functioning vram.

the Motronic 5.2 does not have a user replaceable chip, the '96 version is particularly difficult to modify because it's twin chips set is not even flashable. The '97/98 version of 5.2 with single chip is at least flashable but a good set of microsoldering skills is necessary to R&R the chip so that it can be re-flashed.

The swap is probably doable but you will need the manifolds, both intake and exhaust exhaust, as the O2 arrangement is also different, the engine to DME harness, the DME. In addition the '95 airbag/DME interface is also different from the '96 up arrangement and there are probably other issues not even thought about.
here are the pinouts for the 2 systems, look through all the interfaces