CIS-E To CIS-Motronic Conversion
Keith,
How's your summer coming along, and the progress with Project 16V Cabriolet? I just thought I would forward this update regarding the conversion of my 2.0L 16V Rabbit Convertible from CIS-E to CIS-Motronic. The swap has worked (thanks largely to a Techtonics EPROM...), and I definitely feel a performance boost especially at part throttle. The car seems to leap from corners in 2nd and 3rd gear now, where before I had a bit of lag while the motor came on cam & the CIS-E enrichment module kicked in.
In case you know of anyone else interested in the same conversion, below are the details of the swap.
Talk to you soon!
Eric
Want to get a bit of a fatter power band from your 1.8L 16V motor? Currently those of us with CIS-E 16Vs are stuck with fuel enrichment modules as the only means to improve performance using the factory management system, beyond the usual bolt-ons like cams, headers and the like. We are the forgotten stepsons, no high-end goodies like turbos and superchargers for us without replacing the factory ECUs or adding patchwork micro-fuelers. Well, I wanted a digital ECU and it's ability to be chip-modified in MY 16V motor, and with a little research and a little work it's now been done. Is there a performance boost to be had with just the management system upgrade? Not in itself, but with the installation of an aftermarket EPROM designed for my specific application I have realized not only the boost at the top-end from full throttle enrichment (similar to CIS-E power module) and better ignition advance, but improvements at part throttle as well. The ability to adjust the fuel AND ignition curves allows the tuner to provide power across the RPM band, rather than just at wide open throttle --something you can feel around town instead of only at the racetrack. Not to mention that an aggressive tuner like Garrett Lim can create custom chips using a chassis dyno to wring every last HP from your current motor's setup. And when it's time to strap on the turbo or supercharger, there are tuners who cater to the CIS-Motronic 16V crowd - no more "sorry, we don't do CIS-E". Depending on how you obtain the required components and how good you are with a multitester, the upgrade should be in the $500.00 - $1,000.00 range. I spent about $600.00 on the parts, but that included a couple trips to the dealer (OUCH), so you should profit from my experience and ask (or scrounge) for those little items from the junkyard.
CIS-E to CIS-Motronic 16V Conversion, Required Components (Best to have from same donor car, '89 - '92 2.0L 16V G/J, '90 - '95 2.0L 16V Passat):
Tips:
I started with my 1984 Rabbit Convertible that has a 2.0L 16V CIS-E motor. I started with a good used CIS-Motronic ECU and harness from a '91 16V Passat, but any '8A0' ECU should work (avoid ECU's with part number 893 907 404 E 7 F - these early models have soldered chips so why bother?).
For A1 16V conversions the adaptation of the harness is similar to the CIS to CIS-E conversion. If you keep your stock instrument cluster (recommended!) you can eliminate much of the harness connectors, or if you're feeling 'saucy' you can adapt the later style instruments to your A1 car (laborious as it requires installing some of the later model's vehicle wiring harness...). Using a shop manual for the year/model of the donor car, find the wiring diagram for the engine management controls & identify the connectors. FYI - The L-Shaped plug for the CIS-Motronic ECU uses the pin numbers referenced in the Bentley guide's wiring diagrams (no diagram for the connector itself - thanks!! I guess they assume we all have the 'special' VW Diag tool...). Once you have everything labeled you should be able to add the later model components & plug it in. This job should be similar for 16V Sciroccos and easier for A2 CIS-E 16Vs, so let me know!
Depending on the year/model of your 'host' vehicle, the list of connections that DON'T match should be something like...
EGR Temp Sensor - lose it and pray the CIS-E emission system will suffice. As the same CIS-Motronic harness was used for non CA Emissions vehicles the system should function without it. This was the consensus opinion, along with 'don't cut the connector - just in case'. A2 16Vs may include this sensor.
Charcoal Canister Solenoid Valve (CCSV)/ Charcoal Filter Solenoid Valve (CFSV) - filters the evaporative gas tank emissions, required for '90 ('89?) up vehicles. May also regulate fuel system pressure though I'm not sure - seems to just control fuel vapor venting. This system can't be retrofitted to the A1 cars without the late model fuel tank with expansion unit, breather valve and gravity valve. Likely also the rear-mounted fuel pump and filter assembly are required for the tank lines and fittings to work, I just didn't get that far into it. The Charcoal Filter is fed fuel vapor from the gas tank via a line from the gravity valve, yet another 'retrofit' problem. As the control unit SENDS signals to the solenoids, the idea is to leave the connectors loose and cross the fingers. It may be possible to 'loop-back' the connectors to prevent fault code buildup, but as the CIS-Motronic system is not OBD the system should not go into limp-home mode. At least in theory... If you have any ideas as to how to loop the signals, please forward them along. I'm getting no ideas from the shop manuals! A2 16Vs may have these components, so pass the info along if and when it's been tried.
The following items were required to finish the upgrade, as I started with only the ECU and engine management harness:
CIS-Motronic Coil - REQUIRED! The harness connection from the coil is an important feed-back and control system for the CIS-Motronic setup. The ECU reads knock signals from the two sensors, and based on this information can retard or advance timing on a cylinder-by-cylinder basis. Very cool, especially if you have access to 100 octane!
CIS-Motronic Ignition Timing Connector (AKA Impulse Sender) - REQUIRED! This inductive sensor slips over the number four spark plug wire and feeds timing data to the ECU. As stated above, this allows the knock system to determine which cylinder requires attention, based on the signals from the two knock sensors. The fun part was drilling the 7mm sensor to fit over 8mm plug wires (I have Nology Hot Wires), not to mention CAREFULLY removing the distributor-cap boot to fit the sensor onto the wire. Hot Wires have a carbon core, and are sensitive to over-flexing. But they separate with a counter-clockwise twist at the boot end of the wire, and don't forget the lube! If you have standard wires it's much easier (no drilling...).
CIS-Motronic Idle Stabilizer Valve - Required? The CIS-E ISV uses a three-wire connector for a two-wire circuit, but the CIS-Motronic unit uses a smaller two-wire connector. It may be possible to splice the earlier style connector onto the harness and thus use the CIS-E ISV, but I elected to obtain the CIS-Motronic model. In my experience, the less you cut into a harness the better!
CIS-Motronic Airflow Meter assembly (with Fuel Distributor, Pressure Differential Regulator, Potentiometer (AKA Aiflow Meter Position Sensor)) - REQUIRED! At the very least the Potentiometer is needed, as the CIS-E unit sent VERY WRONG signals to the Motronic ECU (fuel cutout at full throttle - very bad!). The FD and PDR have different part numbers, as well, so the whole airflow meter 'assembly' (bolts to the top of the airbox) from a '91 Passat was used. This was the final step, once this was in place the car fired right up and ran great. There is limited clearance at the battery side of the airbox for the later style Potentiometer connector, so if anyone comes up with a fancy angled connector (or a plan to relocate the battery...trunk??) let me know. This should not be a problem for A2 16V cars, as they have the passenger-side airbox and thus plenty of room. FYI before this last problem was dealt with the car ran with the CIS-E Potentiometer disconnected! Not very well when cold, but enough for me to make the June 6th driving school at Sears Point!
You will save yourself lots of trouble by finding a donor car for the swap, or at least getting the complete shopping list filled from the same junkyard car - and why not go 2.0L at the same time? Just as an idea, the hot-tip hotrod 16V setup is the later 2.0L block with early 1.8L 16V head, as the 2.0L US 16V heads have smaller intake ports to help low-end torque (hurts top-end power, though...). So find a wrecked 16V Passat in the junkyard and GET BUSY!
