Tech Corner: SAAB Trionic and Ionization Sensing

The Short History of Saab Trionic

When it comes to engine part management, there are several ways to cook the goose.  When the IC engine was first produced, several huge hurdles had to be overcome just to get it running right.  The science behind using venturi currents to feed fuel based on airflow (how carburetor parts works) was a huge breakthrough, and is still used today as a simple and effective device to control how an engine works.  As time progressed, we realized that the more control we had, the better our engines would run.  The biggest hurdle to overcome was how to provide the best performance, without allowing the air/fuel mixture from pre-detonating, or knocking.

A big moment happened when Saab parts like the knock sensors began to be installed on Saab engines.  However far from sentient, this allowed our Saab to know when the timing is too far advanced past top dead center and pre-detonation is occurring before the spark plugs go off.  The computer could use this data to retard timing, reigning in the performance but with it, damaging pinging.

How Ionization Sensing Works in Saab Engines

When engineers realized they could go further, the gears at SAAB were turning.  As early as the mid 80’s, the technology that Saab Trionic is built on was being developed, a system that wins the engine management 1-up game handily.  Here’s why:

Saab Trionic PartsThe knock sensor cannot tell what cylinder is knocking.  When it registers a knock, it signals to retard timing and the entire engine is affected. Because of the way consumer grade engines work, no two combustion cycles will be the same.  The Saab performance part for Saab engine management, the Trionic does things fundamentally differently.  In combination with a critical component called a Direct Ignition Cassette (oh, you’ve heard of it?), the computer is able to very precisely control everything that is going on with each individual cylinder and Saab engine parts such as the spark plugs.  The critical difference from a knock sensor is the system’s ability to detect the ionization in each cylinder and relay that info back to the computer individually.

To do this, the computer uses the DIC to send a signal between the Saab electrical parts such as the spark plug electrodes to measure the electrical resistance of the air in between.  Depending on how well the flame envelope is burned, and what is left over after the main combustion, the computer can deduce a lot.  It’s like the DIC is telling the ECU “On the sensing phase of that last firing in cylinder number 3, I got 734.2 ohms, and on this one I got 729.8 ohms” Then the ECU can return with, “I’d prefer a range in the 600s, for the next combustion I will retard timing by .5 deg, let’s see where that gets us”*.

This happens many times a second, for almost the entire time the engine is running.  This way, no matter what quality or octane fuel you use, no matter the altitude, humidity, or temperature of air…. the system will always be able to dial in exactly the turbo pressure, spark timing, and fuel injection timing.

The only time that this active timing doesn’t take place is when you just start the engine.  Upon initial startup on a Trionic engine, all Saab engine parts, including the spark plugs are firing at the same time, using a much older process called “wasted spark“.  That just means on cylinders that aren’t combusting (exhaust stroke), the spark is ‘wasted’.  During this phase, Saab Trionic is getting its bearings.  Soon after, the process switches to sequential ignition and the process above starts.  The most intricate Saab parts; the fuel injection system and turbo pressure are also controlled with this information, hence TRIonic, but that is a discussion for later.  Additionally, when the engine is shut off, the Saab engine management computer sends a hefty dose of high powered spark across all the plugs for a second or two in Trionic 5 cars.  This cleans the Saabs electric current systems plugs to prepare for the next cold start.

Differences between Saab Trionic 5, Trionic 7, and Trionic 8 Engines

Saab Trionic 8 Parts

In Trionic 8 cars, the Ionization module is moved out of its predecessor’s DIC and into a separate unit

Trionic 5 engines like Saab’s use a MAP (Manifold Absolute Pressure) sensor to assume approximate airflow, and feature a RED direct ignition cassette.  Trionic 7 cars switched over to use a MAF (Mass Air Flow sensor), and feature a Saab performance part, the BLACK ignition cassette.  If you are wondering if the DIC’s are interchangeable, think again.

This argument comes up, as they basically do the same thing and the prices are different.  However, make no assumptions; Saab parts like the coils are different, the inductance is different, the knock (ion) sensing is calibrated differently, and they use completely different charge and discharge circuits.  These are different families of technology, when shopping get the one that fits your car.

On Trionic 8 cars, which include the new gen Saabs 03+ 9-3 and 2010+ 9-5 cars, the ionization sensing is moved into its own unit.  These cars feature individual Saab ignition coils and a separate ionization module that control the process of retrieving and sending ionization data.

Lately, most new cars are coming with this type of ionization sensing hardware, due to its effectiveness.

Troubleshooting Saab Engine Ionization

When cars and Saabs alike cannot detect proper ionization, or is getting false readings, it will cause your engine and all the engine parts to run poorly, have bad fuel mileage, and throw engine codes.  These codes will typically signal misfires, and often come back with errors related to car parts including the cam sensor or knock sensors.  Of course, these cars do not have cam sensors or knock sensors, the ionization takes care of all of this.  That’s when you must look at your ignition system.

  • Start with spark plugs, because if they are in bad condition it’s hard for the ionization module to understand what’s going on.
  • If that doesn’t fix it, you may want to look at combustion system car parts like the ignition coils next (or DIC).
  • On Trionic 8 cars, if you’ve replaced all ignition parts like the spark plugs and coils and are still having these engine codes, the ionization module will be a likely candidate.

I hope this was easy to understand, as it is a complicated process, but the ability of these engines to run well and adapt instantly and correctly to changing conditions rely on you for regular parts maintenance.  Never go too long on Saab performance parts like spark plugs, make sure your PCV system isn’t burning off too much oil, and make sure you use Saab dielectric grease whenever you change plugs in order to get the clearest possible ionization signal for the computer to work with!

*All data made up for sake of explanation, I couldn’t find specifics, but if you have a good source I’d be interested to know.

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9 thoughts on “Tech Corner: SAAB Trionic and Ionization Sensing
  1. Paul

    Excellent article!

    Having replaced 3 failed Direct Ignition Cartridges in my ’99 93 (one of which lasted less than 500 miles) and searched many sources online, I can say that this is the clearest and most informative tutorial I’ve ever come across on Saab ignition.

    My only added advice would be that if your high mileage car uses Trionic 5 or 7, to carry a spare DIC in the trunk – especially if you’re running on an aftermarket one which seem to be far less reliable than the (much more expensive) genuine Saab ones. It’s a 10 min simple job to swap out a bad DIC with hand tools you likely already have in the car…

  2. Rick

    I would like to find/read the listed thesis but cannot locate ISBN 91-7291-7067.
    Did find Chalmer’s University of Technology.
    Seems the early TRIONIC was far superior to the later systems when GM decided to cheapen it.

  3. mark B

    Hi, first of all thank you for the tutorial it is very informative and pretty clear,my problem is,I have a 06 SAAB 9 5 sedan with the 2.3 Turbo motor,had lots os problems with the ignition,charging system,replaced the alternator,battery and a slew ofother parts,if parked for more than 5 hours the battery would die,I went on some SAAB forum and learned that some times if not allways the ignition switch won’t :pop up” when the key removed the system won’t go to sleep and would drain the battery in the matter of hours!
    I cleaned the ignition switch and that solved it!
    What remains is the fact that the lights (all lights) are flashing at ideling speed,the Hi-Beam wont engage at all ,any sugestions ?
    Your comments areapreciated !
    P.S> sorry I don’t mean to hijack this conversation,just looking for help since SAAB is no more and the SAAB mechanics in Las Vegas are none existing !

    Thank you !

    • Adam Goral

      Glad you figured out the problem with the ignition switch, but sorry to hear you are still having electrical gremlins. Most typically, problems of this type are attributed to rusty or otherwise compromised ground wires. The ground completes the electrical loop to ensure everything runs smoothly, and if they aren’t well connected then you will see things like parasitic battery drain, strange light behavior etc. The threat of rust is probably lessened living in a desert environment like Las Vegas. Make sure you can spot all the major cables that attach to the car body or frame and look for cables or wires that may have been rubbing, to make sure the insulation hasn’t been worn off or dryrotted, causing a short. If you are having specific issues with the lights in particular, then you can narrow the hunt down to that specific area, to check the grounds, relays (and relay connections) and wires of those particular devices. Not an easy task but well worth it.

      • William

        Mark, I assume that you’ve found your problem by now, but just in case you haven’t:
        I think Adam’s advice is exactly right. I rebuilt the engine in my wife’s Saab 9-5 and there were two small ground wires hidden close to the thermostat housing that I missed during reassembly. I had all the flashing lights on the dash also.
        The only high beam issue I had was operator error. Since the lights automatically come on at startup, I would forget to turn the light switch to the on position. Then the high beam lights would not stay on.

  4. A most interesting article about the Saab trionic system! I have a 2002 Saab 9-3 Viggen there seem to be many assumptions people have expressed in many forums about the functioning of the system, in particular, the function of the spark plugs and how they could affect it. the dic’s are notoriously unreliable albeit a chap in Australia says he has made one that will never fail! when I wrote a post about using a different spark plug, a veritable firestorm of hate and vitriol was unleashed( including that a non- oem plug would fry the DIC! hmmm mayhaps but mine has been fine for 15 years ! ) well in some sites there’s no rules about civility! Hence, there is frequently none! I’m still researching the issue! I like to think that a sparkplug that was theoretically and actually better at firing off the Fuel/Air mixture would be superlative and compatible ! this article does nothing to refute that supposition!

    • Harry

      Having had 2 9000’s with Trionic 5, I am always mystified by tales of the un-reliability of the DIC’s. I have never had a failure, and both cars are high mileage – 225K and 150K respectively. As far as Trionic 5 is concerned, tech manuals say the use of R (Resistive) spark plugs are essential – else early DIC failure will result.

  5. Robert Ho

    This is a great and timely article. I have an 2003 9-3 linear which is throwing misfire codes. I’ve already replaced the ignition coils (Proparts) and plugs (Bosch), and my mechanic used BG44 to clean out the fuel system. I still get codes on/off. What do you think it is? Replace DIC? Or first try NGK platinum plugs? I suspect that is the first thing to do is use the spec plugs.

    • Adam Goral

      Yes for one thing ALWAYS use the correct spark plugs for your car, which ones exactly did you install? The Bosch FR6KPP33X will work in that car, but we do recommend the NGK BKR6EIX. The Bosch plugs shouldn’t cause misfires though your problem is probably elsewhere. Your Saab doesn’t have a DIC, it has individual coils that you have already purchased. The article you are commenting on states: “On Trionic 8 cars, if you’ve replaced all ignition parts like the spark plugs and coils and are still having these engine codes, the ionization module will be a likely candidate.“. We have this part on our website. Other possible options, as mentioned in response to the other comment you made in the 9-3 common problems blog post you should also look for air leaks in the intake system and vacuum leaks which are prime candidates for misfires.

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