Is there some kind of problem with the DSM ECU?
Is there some kind of problem with the DSM ECU? |
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Several 1G owners have found that the electrolytic capacitors in their ECUs leak after roughly seven years. This problem is not limited to DSMs, engine computers or even the automobile world - many types of equipment suffer from similar problems, as electrolytic capacitors are commonly used in electronic equipment.
Excessive leakage can cause very troublesome damage to the printed circuit board (PCB) inside the ECU. This is very difficult to fix unless you have access to professional soldering equipment and tools. For those that do, they will find the repair difficulty on a par with any typical conformally-coated through-hole PCB repair.
For more details see the "How to Replace the Capacitors in a 1G ECU" page, from our friends at Technomotive.
Andreas Santoso offered to provide the required replacement capacitors for $1 plus a SASE. He later changed this to $2. See the archives for details. This offer is old and is likely out of date, but others may make the parts available.
As a special note for 1999 owners, the 1999 ECU may have had some type of build problem involving the throttle position sensor and the ECU. The single owner that reported the problem apparantly had it fixed under warranty. As a bonus, the replacement ECU was EPROM-based. No other owners have reported any problems, so this was likely to be an isolated case.
The Last Word: Still need caps? Try here.
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Why should I get 105 degree rated capacitors for my ECU? |
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Several manufacturers of electrolytic capacitors have confirmed that 105 degree capacitors will last roughly twice as long in any given application as 85 degree rated capacitors. This holds true even if the capacitors are not operated anywhere near their rated temperatures. (Note that capacitors are invariably rated in degrees Celcius, not Farenheit.)
The difference in longevity is directly related to the temperature ratings of the device because 105 degree capacitors must be of much better construction in order to survive at that high a temperature. The highly robust design requirements naturally lead to a longer-lived part. 105 degree capacitors can also survive higher ripple currents, a prime suspect in the premature failures of the factory DSM ECU capacitors.
It must also be noted that each different capacitor series from each different manufacturer usually has a different rated lifespan. Those who have the means should attempt to procure high-temperature, high-reliability capacitors when repairing their ECU.
For those who cannot procure 105 degree rated capacitors, 85 degree capacitors will work. They will simply wear out faster. Those who can practice cap replacement as part of a routine maintenance schedule will certainly be able to utilize 85 degree caps will virtually zero risk of ECU damage.
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No. No, no, no. Period.
The Last Word: Nyuk nyuk nyuk... good one, Todd.
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Read the FAQ page at Technomotive.
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This works - kind of. Read this post by Todd Day (of Technomotive) for the results. Technomotive recommends that only 1990 ECUs be used in 1990 cars, and that only 1991-1994 ECUs be used in the later cars.
However, you can make the switch, if you want to. Mike Hamilton has a FAQ on installing a 1991-1994 ECU in a 1990 DSM. This may be an option for people who have difficulty finding a 1990 ECU - they are becoming increasingly rare.
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Those few that have tried it have not reported any significant side effects from interchanging ABS and non-ABS ECUs and cars. However, several of them had already disabled the ABS systems.
The engine ECU does control the ABS on the DSM cars. It is not known for certain if a non-ABS ECU has the ABS circuitry installed at all. As in the case with knock sensor circuitry, different ECU models (in that case, turbo and non-turbo) might be the same ECU without certain parts.
In theory, an ABS ECU should work on a non-ABS car just fine. However, there is a strong possibility that the ABS ECU might "see" the lack of ABS equipment and cause the ABS light to turn on, because the ECU tests the ABS system on each startup.
Also in theory, a non-ABS ECU should work on an ABS car. In this case the ABS system might not work since the ECU may not have the circuitry necessary to operate it. If it did work, warning lights indicating an ABS malfunction might not work as intended.
As always, YMMV. There are few examples of DSMers trying this swap.
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Unfortunately, electrical schematics for the ECU are not available from any known source. No one has seen fit to release such documentation from within Mitsubishi, and the ECU is too complex to be easily traced out by hobbyists. If someone does have such diagrams, they are keeping them a secret.
One small consolation may be that the ECU pinout is available in every shop manual. The first-generation ECU pinout is also shown here, courtesy of Dallace Marable.
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Some of the parts can be found at mail-order retail shops such as Digikey, Newark Electronics and Allied Electronics. Please note that these shops cannot help you identify parts inside the ECU. If you require such assistance, try a local electronics parts store.
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You can't get code for the ECU, unless you can download it yourself. There are several people and businesses who have downloaded and disassembled the ECU code for the various different DSM cars, but they have not made the source code public.
While this might seem like an unfair thing to do, it is important to realize that some of these individuals spent years figuring out the DSM ECU, which is based on a proprietary microcontroller not generally available to the public. They had to figure out not only how to access the program code, but how to decipher it into instructions, and how the instructions operated the engine - all without any kind of documentation or support from anyone. This amount of effort is not to be taken lightly.
Also, many people have either built this specialized knowledge into a business, or was operating on the DSM ECU as part of a business venture. Private individuals are understandably reluctant to share their hard-earned work for nothing, and employees have legal and ethical responsibilities to their employers to not divulge trade secrets. Either way, they have little incentive to give away the information.
It is important to realize that this is very much like any business operates - on the strength of specialized and/or restricted information that they have gained through hard work. There is nothing stopping anyone from following in their footsteps, if they are willing to invest the necessary time (and money) . Most people would rather do other things, of course, which provides a foundation for commerce.
For a more personal viewpoint, please read Todd Day's comments on the subject - he is the 'talon mgr'.
The Last Word: DSM code may be available from various websites or vendors. At least, the people I know didn't have a lot of problem getting it.
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The engine control unit (ECU) only does the engine - there is a separate transmission control unit (TCU) that operates the automatic transmission. The ECU and TCU do not talk to each other. The TCU gets information regarding throttle position, RPM, etc. by sharing the same sensors used by the ECU.
On 2Gs, the TCU may communicate an error code at the ECU, so the "Check Engine" indicator will light, but that seems to be all. Apparantly, the ECU and TCU do not communicate in any other way.
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An EPROM is an electrically programmable read-only memory, or a type of computer memory that can be programmed only once, but read an unlimited number of times. EPROM ECUs have such a memory IC installed in them. This memory holds the program code that controls the ECU behavior. The EPROM is a separate chip from the microcontroller (computer chip) that actually runs the program. This makes it easy to change the ECU programming, since only the EPROM need be replaced, and EPROMs and their associated programming tools are relatively common.
The alternative, a non-EPROM ECU, does not have an EPROM. Instead, the program is stored inside the microcontroller itself (technically, in embedded EPROM memory that is part of the microcontroller). This makes it hard to change the ECU programming, because the microcontroller needs to be replaced. These are difficult to get, and require special programming tools that are equally difficult to find.
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You would already know this (hint, hint) if you had used the FAQ Locator. Read Todd Day's EPROM check webpage.
One fact that is not mentioned on this page is how to quickly check ECUs *after 1990* for an EPROM. There is a label on the top of the ECU (not the sides). If this label has an "E" in the lower right-hand corner, you have an EPROM. If it has an "M" or "T" in that corner, you do not have an EPROM. 1990 owners have to open the ECU to find out, as there are both EPROM and non-EPROM 1990 ECUs. This tip is also on this page from the developers of the DSMlink.
Galant VR-4 owners, again, have an edge - owing to the low production volume of that model, GVR4s are almost guaranteed to have an EPROM.
The Last Word: Hey, not ALL 1990s have EPROMs. Can't you read?
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These are all listed on the Club DSM Error Code Readers page.
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The 1G ECU codes can be found at Brad Bauer's Diagnostic Engine Codes & Procedures page, and also in this post from the archives. You can also read your shop manual.
The Last Word: OK, so Brad's site is gone. What do you want me to do about it?
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The 2G ECU codes can be found at the 2G NT page, and also at the Avenger/Sebring Owners Group homepage. You can also read your shop manual.
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Here's what Todd Day of Technomotive has to say on the matter:
"As far as I can tell, there are only three ways that you can see a CHECK ENGINE light, but then not be able to clock out the code.
1) The ECU for some reason loses power or otherwise crashes and does a hard reset while driving. The CHECK ENGINE light comes on for five seconds because the ECU always turns it on for five seconds as a bulb test when power is first applied.
2) The ECU flags a legitimate error. After you turn off your engine, a Mitsu shop tech sneaks into your car with a MUTII scan tool and clears the codes while you are not looking. (1991-94 only)
3) The ECU flags a legitimate error. You turn the key to ACC or OFF, wait for the relay to go *CLICK* after seven seconds. The fuse that runs your radio memory and footlights and ECU BACKUP MEMORY is burnt out and your ECU loses its mind. You turn the key to ON to clock out the codes, but everything is gone.
If you have a case of #3, try turning the key to ACC to kill the engine, but immediately bring it back to ON. This will keep the main power supply to the ECU going, and you should be able to clock the codes."
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No. Or, at least, not directly. The operation of the BCS has virtually nothing to do with intake pressure. The only method of doing this is to disconnect the BCS and wire it to a customized boost controller. Theoretically, it could be done by by reprogramming the ECU, but the new ECU would also have to accept inputs from an additional intake pressure sensor. To date, nobody has created such an ECU modification.
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Yes. Mario Pennycooke has done something like this with his 'Poor Man's Profec'. Lots of variations exist.
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A datalogger is a device that monitors and records information for you. Dataloggers are often used on racing vehicles, to provide the tuners with better information from which to base tuning decisions.
Although there are several dataloggers available for DSMs, most people who refer to a 'datalogger' mean the TMO datalogger from Technomotive, although some might be referring to the Pocketlogger or DSMlink. These extremely useful devices recieve and interpret a continuous stream of information from the DSM ECU, allowing a 'sneak peek' into the 'thinking' of the car.
These products operate using proprietary software and hardware to collect, interpret, analyze and display the ECU information. To do a similar job, a device would have to know the format of the information output by the DSM ECU.
Specific information concerning DSM ECUs and their output format is not in the public domain and might only be found by deciphering the DSM ECU code. Advanced tuners have agreed that the 1G DSM uses the ALDL (Assembly Line Data Link) interface similar to many General Motors cars. For more information on ALDL, see this answer in this FAQ.
2G vehicles use the OBD-II system, which is not compatible with ALDL. The OBD-II system was adopted as an industry standard on later model cars. However, the OBD system is slower and has less information available as compared to the proprietary solutions.
It is possible to create a datalogger to monitor the same information that commercial datalogging systems provide. However, to create a comprehensive standalone system capable of matching the TMO logger, Pocketlogger or DSMlink in capability is a formidable task for most people. The job has recently been simplified as freeware datalogging software and ready-made cables have become available.
Those interested in the details of DSM datalogging may find the Pocketlogger FAQ and Technomotive's Datalogger 101 guide helpful.
The Last Word: TMO is long gone, but you can still buy Pocketloggers. At least until all the serial-port Palm units die - there doesn't seem to be a ALDL-to-USB device available (yet?).
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TMO is the conventional contraction and website address for Technomotive, the first company to ever produce effective, customized chips for DSMs and to manufacture a DSM datalogger. A TMO ECU is an ECU that has been modified with one of the TMO upgrade chips. The TMO datalogger is a laptop-based data acquisition and recording device for DSMs. For more details, visit their website.
The Last Word: TMO stopped selling chips a long time ago. Anyone who claims to be selling their stuff under license is a big fat liar.
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A Pocketlogger is a datalogger that runs on the Palm computing platform. Aside from operating on a Palm and not a laptop, it is substantially similar to the TMO datalogger described above. More information can be found at the Digital Tuning web site.
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A DSMlink is a tuning and datalogging product for the 2G DSM. Not just another OBD-II datalogger, DSMlink includes a new ECU chip that allows the factory ECU to effectively communicate. DSMlink now has both laptop and Palm clients.
Additionally, it allows the DSMlink laptop to re-program the ECU "on-the-fly" to a certain extent, giving the operator additional flexibility by allowing changes to the onboard ECU fuel and timing maps. This feature is not currently available for any 1G product, although the DSMlinks developers have a 1G version in mind.
The DSMlink is limited by the fact that it only works on 1995 ECUs, because 1995 ECUs are the only models that can come with an EPROM memory installed. Owners of 1996 and up cars will have to obtain a 1995 EPROM ECU to use DSMlink.
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ALDL is an acronym for Assembly Line Data Link. It is a one-wire interface used to connect the engine control unit (ECU) to diagnostic computer systems for diagnosis and troubleshooting.
1G DSMs use a version of the ALDL interface. All 1G dataloggers are designed to connect to the interface and interpret the information. 2G vehicles do not use ALDL, they use OBD-II (see below).
DSM enthusiasts did not recognize the ALDL interface for what it was until fairly recently. Because of this the GM hobbyists have much more information available on how ALDL works. There may be differences between the GM ALDL format and the DSM ALDL format since ALDL is not a formalized standard. For more information on ALDL, see these links:
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OBD is an acronym for "On Board Diagnostics". OBD-I was version 1, OBD-II is version 2.
It is an industry-standard method of communicating with the onboard engine computer. It was created so that ECUs from different manufacturers would have a standardized communication protocol instead of several different proprietary versions.
Sometimes pre-OBD cars (such as 1G DSMs) are referred to as OBD-I cars. This is not accurate, since they use the ALDL interface. 1995 cars might be OBD-I rather than OBD-II, but since most OBD tools support both I and II the difference is usually not important.
There are actually three different possible interfaces within the OBD-II standard: PMW, ISO, and PMZ. [So much for standardization....] All 2G DSM's use the ISO version of the interface, so any diagnostic equipment used must also support the ISO version of OBD-II.
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"Fuel trim" in the ECU is the ECU's method of tuning individual cars.
In theory, the ECU reads the amount of air entering the engine via the mass airflow sensor (MAS) in the air intake. It will then add the proper amount of fuel through the injectors, ensuring a good burn, low emissions, etc.
However, while that works in theory, it rarely does in practice. MAS sensors vary, even when calibrated, even if only due to age. Injectors become clogged, fuel and turbo pressures can vary, parts wear or are replaced.
The way to compensate for the individual car-to-car variations is through fuel trim. By checking the oxygen sensor, the ECU can "check" if the amount of fuel it added was too high or too low. It will then add or subtract fuel in small increments depending on what it "sees". It "remembers" these adjustments and averages them over a period of time, resulting in a "trim" factor. The fuel trim is constantly applied and adjusted.
There are three fuel trims on DSMs: low, medium and high. These refer to the mass of air entering the engine, and only roughly correspond to RPM ranges. Low applies mostly to idle (750-1000 RPM), high in the 3000-4000 region, and middle in between.
Users of Super-AFC and similar units usually try to adjust their AFCs so the fuel trims are near 100%. This is mostly to provide a baseline of settings for future tuning - it means the AFC settings are "fooling" the ECU into "thinking" the car is still stock (or near stock). It also allows the ECU a lot of range to adjust the fuel trims as necessary.
Fuel trims have no effect at open loop (high RPM or hard accelleration). In this situation the ECU is ignoring the oxygen sensor and there is nothing to trim. Datalogger owners will see their fuel trim "stick" at 100% in open-loop situations.
Those interested in the details of DSM datalogging may find the Pocketlogger FAQ and Technomotive's Datalogger 101 guide.
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Maintained by Sean Costall. Changes and suggestions are welcomed! If you have any information on the answers to any of these questions or wish additional questions, please mail me.
This page is an extension of Club DSM .