Trionic 5 (T5) Conversion: What you need
One of the first T5 Conversions I did in 2012
A major component in decision-making is trying to give something a sense of value. Is something worth our time, money, and mental energy. When many heard of this Trionic 5 conversion, the natural skeptical response is, "What are they talking about and why do I want to spend more money on this car that doesn't seem to run right in the first place? OR "My car runs perfectly fine the way it is, I don't want a freakin' race car!". All are perfectly normal adult responses. Maybe you've seen some internet yahoos go on and on about how much better the car drives/starts/idles/boosts or that their engine harness isn't crumbling anymore. Who knows, but the first step to making the right decision for you is getting the details about what is involved.
The case for Trionic 5
Before diving into what you need, I’ll briefly explain why you might want it in the first place. There are a few major reasons besides just being part of the cool factor (it’s super cool).
Availability of parts & Simplicity
Improved engine response
Flexibility
Diagnostics
So let’s break that down a bit
Availability of Parts & Simplicity
Although relatively robust, any analog electronics components from the ‘80s are going to have some natural decay as well as just standard wear on mechanical components. Critical parts like the LH-Jetronic air mass meter (AMM) or the ignition distributors are becoming increasingly difficult to find with quality rebuilt components. The heavy lifting with Trionic 5 is the DI Cassette which is still at this point made available new and was used on new SAABs up until 2009. The “Tri” in Trionic stands for the three subsystems that one computer has full control over; Fuel, Ignition, and boost. Consolidating these separate control units into one, not only is functionally superior but it reduces the number of components required.
Improved response
The majority of the performance gains with T5 are due to full control over the engine’s ignition timing. The standard distributor uses a mechanical advance and retard system that has a very limited window of control. The compromise is that to achieve even standard boost levels and performance, the off-boost timing is set to a less-than-optimal spot so that it falls within that window under full load. This equates to sluggish engine response, more turbo lag, and worse off-boost performance. Trionic does not have any mechanical limitations and has full control over ignition timing to off both off-boost and on-boost peak performance. Even with a completely stock engine, the drivability gains are transformative and simply make the car nicer to drive without even a consideration of maximum horsepower levels. There is also a basic generational advancement in the technology that translates into more a stable idle, better efficiency, and greater engine protection that is not even possible with the original systems.
Flexibility
The last key with Trionic 5 and why it works so well as a retrofit is that it has been completely reverse-engineered so that it is essentially a standalone engine management system. The base tuning is fairly flexible on most engines and can accommodate a fair amount of modification before retuning is necessary. However, if you want to go wild with different components, retuning the system for optimal performance can be done. Advanced tuning features are available including integrating engine logging and feedback while maintaining the factory engine safety protocols that keep everything in check.
Diagnostics
Trionic 5 can run the OBDII standard interface that was required of all US cars in 1996. A $20 code reader will be able to communicate with the ECU and report any engine codes. More advanced tools can show live data and sensor information without needing a hook a laptop up or do any additional configuration. This a huge step forward for the early LH 2.2 systems which cannot even store engine codes. So if you do have a problem down the line, it should be easily diagnosable. Every harness I make has an integrated OBDII port standard as well as the updated ECU software enabled.
So What do I need?
Conversion Wire Harness
Red DI Cassette
T5 ECM (Any ‘94-99 SAAB Turbo), set up for a classic 900
Crank Position Sensor Trigger w/ sensor kit
4x Bosch Red Top (431) NG900T, 94+ 9000 Injectors (OE # 9132449)
Coolant Temp Sensor (OE# 9357021)
Air Temp Sensor (OE# 8859886)
Intercooler Pipe modified for Air Temp Sensor mount
Throttle Position Sensor (OE# 8857195)
Throttle Position Sensor Adapter , 2.1 900 or 9000 Throttle Body
Throttle Body O-rings ( OE #7506264 and 7521875)
3.0bar Fuel Pressure Regulator (From 2.1L Bosch #028016706 or 7486921 with adapter hose)
MAP Sensor (OE# 9132374)
Vacuum Line (3.5mm line of your choosing)
Vacuum "T" fitting
T7 Boost Control Valve (OE#55557331)
Air Idle Control Valve (2 pin 89+ 900 Turbo Bosch #0280140516)
Oxygen Sensor (Stock 3-wire works fine)
4x NGK BCPR7ES Spark Plugs Gapped .039-.041”
Distributor Oil Plug (OE# 9135211)
Ok, so that is the bullet-point list, but I'll go deeper into each item as some need a little more explanation.
I also sell a COMPLETE T5 KIT so you don't have to worry yourself with part numbers or forgetting something, this is as turn-key as it gets.
Conversion Wire Harness
Ok so I'm biased here, but a custom-built new wire harness specifically for the classic 900 T5 conversion is what I bring to the table. Over a decade ago, I began on this T5 journey modifying stock 9000/NG900 wire harnesses to adapt them to fit the classic 900. This required tearing down the old harness, wiping off all the nasty grime and grease that accumulates inside the old tape, and splicing each wire about ~24" out so that I could run it to the stock location. You find lots of crumbling insulation and broken connectors and there is still a significant amount of rewiring required. Many components are not in the same orientation between the classic and new generation models and the T5 main engine harness does not include the relays or boost control wiring as the original harnesses do.
Yes, there are some people who skip this step and drill a big hole right through their firewall or mount the ECM somewhere else in the engine compartment, but I like having a really clean install that was as good, if not better, than the original. This was quite a tiring exercise and ended up finding all sorts of broken/brittle connectors or suspect connections that I'd have to fix along the way. Later on, I decided to see if I could try to track down all of the components as new and just buy colored wire to start fresh. The first new replacement T5 conversion harness was born and I never looked back. Now, If you enjoy pouring over wiring diagrams, I won't stop you from building or modifying your own harness (heck I'll probably even help you if have questions), but the one I offer today is my 5th revision to make the best c900 Trionic 5 Conversion Harness possible. All NEW components, OBDII Diagnostics, and plug-and-play compatibility.
Red DI Cassette
This is the heart of Trionic 5, don't buy aftermarket, ever. Should you buy new ones? Old DIs work just fine but don't expect them to last forever. Date codes can be read on the SAAB sticker on the bottom of the DI next to the connector. It’s a 4-digit code above the "SAAB" logo that is the year of manufacture followed by the week of the manufacturer. In other words, 1605 would be 2016, the 5th week of February. Can I use the black one? Can you? Yes, Should you? Not really. Although somewhat backward compatible, the Black DI cassette (stock on Trionic 7 cars) has some different calibrations and uses AC vs DC spark, which may not work optimally with the T5 brain. If you're in a pinch, sure, but use the red one!
T5 ECM
Trionic 5.5 (the .5 is important!) ECMs actually come in two flavors with some subtle differences in hardware. Rather than bore you with the details, I will just say that the OBDII versions which came on MY97+ SAAB turbo models are preferred and the most compatible. If you can only scrounge one up from a 94-96, no big deal, but just know what you have. My foreshadowing about the .5 being important is all due to the fact that there was also a 1993-only Trionic 5.2, that shares a similar worldview to 5.5, but that is about it. 94-99 turbo cars (and even the 9000 non-turbos!) all had Trionic 5.5. So once you have a unit, it still needs to be programmed to run on a c900 correctly. Some of them have VSS (Vehicle Security System) enabled, some are set up for 2.3L motors, and all will not give you a correct speed calculation based on your speed signal (if you have one), so you'll likely be set up for base boost. For all these reasons, (and more) your T5 ECM should be tuned specifically for the c900, and your car’s own setup or modifications. The B202 in the c900 does have different flow characteristics than the B204 engines so although they are similar enough to run the car, you'll find some lean/rich areas as well as some sub-optimal performance.
CPS Kit
Another topic of slight contention is how to get the crank position signal. This sensor is missing from the stock Jetronic system, it gets around this by using batch fire. Instead of injecting fuel for each cylinder, once per combustion cycle, it blindly squirts fuel into multiple cylinders each rotation. The factory Trionic cars use a "toothed" (reluctor) wheel bolted right to the crank inside the block. That isn’t really going to work for easy conversion. The modified flywheel option is my go-to because it allowed the most straightforward installation and has very few disadvantages. The flywheel can only be mounted one way and is bolted directly to the crank making it perfect for accurately referencing the crank angle. Another option is to bolt something to the crank pulley side, but being “in-backwards” make for tight quarters for making adjustments needed to get the sensor and trigger wheel lined up perfectly. Due to lack of space, usually, the A/C pulley is sacrificed which is a non-starter for many. Most alternatives I’ve seen also make belt changes challenging and general “front” engine service requires removing the setup completely. The biggest challenge is maintaining accuracy as the smaller diameter of the pulley wheel has a much larger margin of error. When the stock sensor is mounted into the block and fixed to the crankshaft, this isn't much of a concern. However, the reluctor being mounted from the crank to the pulley, to an adapter, allows for concentricity and alignment errors. This is why they can't just bolt right on, they need to be tweaked until the proper timing is set. Trionic is fairly tolerant of some of these misalignments, so you may not even know your timing is off, but even a degree or two can make a huge difference in performance.
Fuel Injectors
The path of least resistance is to use the standard T5 injectors and a 3.0 bar regulator since the software mapping is already set up to use these components. The question is often asked, why can't I use the standard 900 Turbo injectors? The reason is that the stock classic 900 injectors are sized @ 21lb/hr whereas T5 injectors are sized at 33lb/hr. The reason why they are so much larger is that Trionic 5 will inject fuel only once per combustion cycle. The Bosch Jetronic system has no idea where it is in the combustion cycle (no CPS), so it will inject smaller amounts multiple times in multiple cylinders. The end result is a similar amount of fuel but just done more efficiently with T5. The stock injectors I found to be good for about 260whp (300 crank). After that, they can't keep up, and larger injectors should be fitted. This for most is plenty so no reason to change. I will also mention there are alternative, modern injectors that could offer some additional benefits, but again, the software would need to be recalibrated to take full advantage of this.
Coolant Temp Sensor
When I build my harnesses I retain the stock connector for the coolant temp sensor. If you have your own modified harness from a T5 car there is a good chance it has a different style of connector. Just make sure you match the sensor to the plug you have. Also, note with the square-style connector, there are a few oddball 9000 coolant temp sensors on TCS cars, you want the ones that are blue, not white or black.
Air Temp Sensor
The same info applies to the air temp sensor as the coolant temp sensor above regarding the connectors. It should be added that there is no air temp sensor in the Bosch Jetronic system because it uses a MAF (Mass Airflow Sensor) to read incoming air mass. T5 uses the combination of a MAP (Manifold Absolute Pressure) & Air Temp to calculate air mass. These two sensors are most critical for accurate fuel calculations. To fit these I prefer to have them installed into the intercooler pipe before the throttle body just as the 9000 has. This isolates the sensor from having its temperature affected by engine heat soak. More importantly, it keeps it out of the turbulent zone of the throttle body which can physically destroy the sensor. Since there are two versions of intercooler piping, cast aluminum (85-88) and aluminum tubing (89+) installation varies. The cast aluminum pipes are thick enough to be drilled and tapped, whereas the aluminum tubing should have a bung welded to it. The sensor is an M10x1.25 thread. Remember, oil also collects in these pipes, so it is best not to mount the sensor on the bottom.
Throttle Position Sensor
The throttle position sensor is a fairly straightforward swap with a couple of options. T5 uses the same sensor that was used on the 2.1L 900, so if you have the parts cache, you can simply swap the throttle body. Make sure to replace the o-rings behind the throttle body as well as the coolant passage o-ring behind the sensor while you have it out. It is also a good idea to epoxy the brass fittings in place as they are not used to seeing positive boost pressure and commonly blow out. The second option is to use the MCS TPS Adapter. The adapter allows you to use the T5 sensor on the stock throttle body. It's also recommended to change your throttle body o-rings (while you're in there).
MAP Sensor
You need this. Max resolution for this sensor is 1.5 bar above sea level (~22psi boost) If you plan to exceed 20psi often, you should consider a 3bar sensor, but that is a different article. The sensor should be mounted with as short and rigid a hose as possible with a thick sidewall to prevent ballooning. Ideally, it should have a dedicated hose right from the manifold and not be shared with other components.
T7/8 Boost Control Valve
The boost control valve from Trionic 7 (or 8) cars offers more reliable performance at a cheaper cost. I make all of my wire harnesses and c900 ECM tunes set up for the T8 BPC so no other modifications need to be made.
Spark Plugs
NGK BCP*R*7ES-11. The -11 means they are pre-gapped to 1.1mm. If you get them without the dash, they should be re-gapped to the proper spec which is 0.9-1.1mm (.035-.041in). Spark plugs are exteremly important for Trionic to function properly, so it is best to stick with the book.
Oxygen Sensor
Replace your o2 Sensor if you don't know how old it is. The o2 sensor constantly monitors & adjusts your air-fuel mixture to get the best economy and efficiency, so it is vital that it functions well. Within Trionic 5, it is confusing because some sensors have three wires and some have four, meanwhile the stock c900 sensor has three wires, but two connectors. The truth is that all the (LH & T5) sensors are all functionally the same with different connection styles. I make my T5 conversion harness with the stock connector in mind, but any of them will work. There is a difference between the three and four wire sensors , which has to do more with wiring configuration than anything else. Again, the sensors are the same, but the four wire uses an "extra" ground wire to run directly from the ECM where as the three-wire is just grounded to the chassis through the exhaust system. Four-wire systems are a little more robust, but the three-wire work just fine as long as the sensor contact surfaces are in good shape.
Distributor Oil Plug
One of the benefits of the conversion is all of the components that get consolidated. The distributor is one parts that when removed, makes you feel good. But in its place there are a couple options. SAAB at first used a nice spun aluminum block off plate held in with the factory distributor retainer, but later changed this to simple rubber coated steel plug. The rubber coated plugs tend to leak after a while, so a small amount of sealant around them before installing will help...at least for a little while.