CIS-E to Motronic



The CIS-E Motronic system from a 1990 - 1992 2L 16v Golf/Jetta/Passat is an upgrade to the CIS-E engine management system fitted to the Scirocco 16v. Modifications must be made naturally, but when you decide you want to wring the last tiny bit out of your motor this is a logical step. Don't expect supercharger like performance improvements, under most operating conditions and RPM ranges CIS-E is at least 90% of the performance of a Motronic system (when the CIS-E system is properly tuned and a fuel enrichment device is being used). If this is what you were really after (getting the best from your motor), then make everything as perfect as possible and use new parts where it makes sense. Like just about every other 16v performance enhancement, it can get rather expensive. You should be handy with a VOM, and be able to interpret Bentley wiring diagrams to do this conversion. I take no responsiblity if you blow something up. :-)

Parts list necessary for conversion:

2L 16v block required, as the 1.8L block does not have the proper mounting point for the second knock sensor that Motronic uses.
Motronic brain box, must begin with the part number 8A0 if you want to chip it, and you will as that's the major reason for converting to Motronic isn't it?
Motronic wiring harness, Golf / Jetta harnesses are easier to work then the Passat.
Motronic idle stabilizer valve; it's a two wire unit vs the CIS-E three wire, it's also larger.
Motronic fuel distributor, entire top of the air box. Includes DPR & air flow sensor plate potentiometer. Warning: the procedure for checking the Motronic pontentiometer is not correct in the Bentley.
Motronic coil power stage, coil optional as the CIS-E coil can be used "inside" the Motronic power stage.
Fourth plug wire sensor; helps computer respond to knock / ping.
Motronic injectors; the injector pin circumference is larger then the CIS-E units, more flow?)
Two knock sensors, they are the same as the late model CIS-E units.


Other Parts:

I would not even consider the swap unless everything was perfect, and I could rely on the parts I'm using. What's the point otherwise? To that end, I would replace, get new, or renew:

Three wire O2 sensor
Two knock sensors
Distributor / Hall sender if yours is leaking oil.
Plug wires & spark plugs (Bosch copper triples or NGK triples work well).
CIS-E fuel line to Motronic fuel injector convertors, more on these below.
Cork gasket for between the fuel distributor and the air box.
Viton injector o rings and seals, lower injector seats and seals.
Fuel injectors should be cleaned and balanced. I have used C&C Fuel Injection service with success.


Notes:

Speed sensors are optional, and are not required for a working conversion.
Evaporation, charcoal canister valve control wiring harnesses can be cut out of the Motronic engine wiring harness.
The Motronic engine harness plugs directly into & works with the CIS-E distributor / Hall sender, coolent temperature sensor, fifth injector, and O2 sensor.
Pull back the rubber weather protection boots on all the wiring harness connections, replace all the connections showing cracked / open wires. Personally, I found at least 3 which required replacement.
Many people will tell that the fuel injection system must be moved to the passenger side, but this is no longer the case. The only reason this PITA move had to be done was to accomodate the Motronic fuel lines and injectors. The Motronic injectors are threaded differently then the CIS-E injectors. However, Mike Potter at Virtual World Parts found a place that makes a beautiful brass converter which allows the CIS-E fuel lines to attach to Motronic style injectors. Problem solved. Fuel lines and fuel distributor stays on drivers side where it belongs on a A1.

Here's a picture of a converter.

Use new knock sensors and upgrade the Motronic wiring harness with gold connector pins. The new knock sensors will already have gold pins in their respective wiring pigtail harnesses.
Various parts of the Motronic wiring harness will have to be shortened as the Scirocco engine bay layout is a bit different, especially when you leave the fuel distributor on the drivers side. Be sure to solder and properly shrink tube all connections.
All but two connections for grafting the Motronic harness into the Scirocco are already in the engine bay, and it's arguably all but one. Here are my notes for my conversion, based on a wiring harness from a 1990-1991 Jetta GLI:

Motronic CIS-E Color Connector Color Connector Red / White G1/8 Red / White (R/Y) E14 (Fuel pumps) Red / Yellow G1/3 Red / Yellow D13 Red Y/4 Red (30) (+ direct) BRown / Red G1/6 D22 Black / White G2/4 Black D2 Black & Black / Yellow G1/4 Black D23 Green F/9 & G1/12 Red / Black D26
The connectors named in the chart is the fuse box ID code for that wiring trace. I recommend working with a Bentley manual for your doner vehicle and your Scirocco 16v. It's important you actually understand what you are doing so you can service it at a later date. Motronic Wiring Harness

Motronic CIS-E
Color Connector Color Connector
Red / White	G1/8	Red / White (R/Y)	E14 (Fuel pumps)
Red / Yellow	G1/3	Red / Yellow	D13
Red	Y/4	Red	(30) (+ direct)
BRown / Red	G1/6		D22
Black / White	G2/4	Black	D2
Black & Black / Yellow	G1/4	Black	D23
Green	F/9 & G1/12	Red / Black	D26

The CIS-E ground point behind the throttlebody at the back corner of the intake manifold can be utilized for all Motronic grounding needs as long as this point is good and clean. Check ohm reading between this point and negative pole of battery, a reading of < 5 ohms is good.
The Motronic wiring harness can be carefully bent to the desired shape and angles by warming the wiring bundle with a heat gun. It will fit through the same hole as the CIS-E bundle, and it will bend in the opposite direction. The Golf / Jetta harness wants to bend the wrong way. The wiring harness must point towards the drivers side Scirocco style mounting location.

Engine Bay Brain box

The Motronic fuel distributor fits on top of the CIS-E air box with no problems, be sure to use most of the CIS-E lines & fittings from your old CIS-E fuel distributor. Note that the CIS-E air flow sensor plate potentiometer points to the side, while the Motronic one points forwards. This will interfere slightly with the battery and may eventually cause wire separation within the connector.


Motronic Fuel Distributor

Using the Motronic Fuel Pressure Regulator *Important Update* After running with the CIS-E fuel pressure regulator for a while, I realized that the Motronic injectors were designed to operate at a slightly higher fuel pressure. Switching to the Motronic FPR cured an off throttle harsh transition I was having. However, the Motronic FPR is not a direct bolt on when it comes to using it in the Scirocco in the same way the CIS-E unit was.

The FPR is the black canister with the 'vacuum' line coming off the top. The picture to the left here is a shot of the CIS-E style FPR with the fuel lines attached. The problem using the Motronic FPR in place of the CIS-E unit in a Motronic conversion comes with plumbing one of the fuel lines for the Motronic fuel pressure regulator.

The CIS-E FPR uses a banjo style fitting for one of the lines as seen on the left. The Motronic style FPR uses a fitting at the place where the arrow is pointing to in the picture of the CIS-E type FPR which is exactly like the CIS-E & Motronic fuel return line fitting. The fuel return line fitting in this picture is pointing straight up in the air at the upper right hand corner. There are a couple of different ways to solve this problem.

I had a small section of rubber fuel return line with the correct fitting. I had a spare CIS-E style fitting designed to run between the fuel distributor fitting and the FPR. I shortened the CIS-E double banjo fitting hose a bit, and cut off end which was supposed to go into the CIS-E FPR. The picture at the left is the spare CIS-E double banjo hose, with a slit already cut into the end being replaced. This type of fuel line are a two layer affair, with a tough abrasive resistant outer skin, and a hard plastic inner sleeve. For the proper Motronic fitting, I cut the fitting out of the spare rubber fuel return line, more details above.

Using some light machine oil to lubricate the return line fitting where it would slide back into the plastic sleeve of the CIS-E line, and using a heat gun to warm the hose and fitting, I pressed the return line fitting into the old CIS-E hose. It is a very tight fit and there has been no issues with fuel leaking during operation. The inner plastic softens slightly during the heat process, and seems to shrink back over the barbed fitting while cooling. Do not take chances with these modifications, and if you are not comfortable, or lack the necessary skills to make these modifications you should not attempt them. That said, I do not take any responsibility for any damage you might cause.

Here is the finished Motronic FPR installed with the modified fuel line. The line runs between the two numbered arrows, with the fitting numbered '1' in the picture being the modified one.

If you have any specific questions, you can contact me at brett@netacc.net

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