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Author: Matthew A. Spynda (firstname.lastname@example.org)
BOSH MOTRONIC ECU DISASEMBLY GUIDE:
A bit about our BOSCH OBD1 ECU’s
Let me first start by saying that there is often a lot of speculation about our Hyundai ECU’s being “special”, limited, and almost impossible to work with. Hopefully I will educate you further into the facts about our ECU’s and they’re capabilities and dispel some of the myth or misinformation about the BOSCH MOTRONIC OBD1 ECU Used in our S-coupes, excels, accents, etc.
Many refer to our ECU as a “smart ECU” or a “learner” And this is true to a degree. Let me state that although our ECU’s eeprom set is custom tailored to our specific vehicles it is capable and DOES support MANY platforms. And may be found in VW, AUDI, PORSCHE, BMW, Etc. Our Hyundai ECU’s do NOT set up apart from the rest of the automotive world and were not designed “just for the special Hyundai people”. Only the program set on the EEPROM’s and resistors that take input from various sensors are changed in these units to tailor them to specific vehicles. Many VW, Porsche, and BMW tuners have “been there, done that” when it comes to hacking our ECU’s apart and starting from scratch, while the beloved Hyundai tuners are still scratching they’re heads thinking “what can we do with this?” and the answer is simple – Anything the Porsche, VW, Audi, or BMW tuners have done! Even Subaru's run these things!
Until the Hyundai tuners get a good footing in the world of they’re ECU’s a good place to start learning is from the guys that have been hacking into these boxes since the beginning; the euro tuners. They have forums, search buttons, and you have google too. Research is powerful, I am giving you clues. For example, if there is a software based interface for tuning any of the above listed car makers ECU's - It WILL tune ours!
As far as dispelling any misconceptions about the ECU’s bugs or learning capabilities let me make a few more statements that I believe to be 100% correct through good old fashioned research. The reason our ECU’s behave better after a reset when we have performance modifications is easy. The Bosch motronic ecu’s have a type of watchdog platform built into the system program. The watchdog’s job is to compare engine sensor readings to a set of acceptable parameters contained in the EEPROM program. The system was designed with a really intelligent idea in mind, unfortunately it’s not very tuner friendly as far as bolt-on are concerned. It was designed to compare and adjust as necessary; the operating parameters to compensate for good old fashioned engine wear and over time any increased emissions, etc.
A vacuum hose cracks? - The ecu works around the changes.
Leaky injector? – The ecu tries to work around that too.
Emissions too high? – The ecu tries to work around that.
Now it is easy to see from an emissions and reliability standpoint why this was brilliant. Now think about performance modifications and how they could possibly replicate those conditions and it’s easy to understand why it is a nightmare to tuners.
Try and advance your timing mechanically – The ecu tries to retard it to meet the parameters in the EEPROM.
Increase you fuel flow – The ecu tries to work around it to meet parameters.
Increase your air flow – With an exhaust without proper timing advancment, an excess of unspent fuel will water down your o2 sensor to the point of leaning out the A/F mixture. So guess what? Your ecu just tried to correct this.
Etc, etc, etc..
It is no great wonder, taking these things into consideration that resetting your ecu, therefore putting the ecu into start-from-scratch mode; will allow you to realize the performance gains of your bolt on parts. Unfortunately the one thing a reset won’t do is eliminate the set parameters in the watchdog system and eventually the ecu will compare and tune as necessary to meet the stock parameters once again (yes, I am sighing right along with you right now) Can anything be done? YES!
1: Custom tune the EEPROM in your ECU to include new operating parameters that take into consideration your performance modifications (hundreds)
2: Purchase and install an already tuned custom chip or chip set for your ecu. Most companies will consider your mods when mapping your custom chip. (hundreds)
3: Bypass the ECU and go stand alone management. (can we say thousands?)
4: Piggyback management? Possible, but as long as your Bosch motronic can see sensors and still has the hardwired ability to change anything; you’ll still be fighting with it. If you can isolate it’s ability to adjust timing and fuel and let your external unit do it, the monkey may be off your back. (hundreds)
5: Hack your ECU harness power feeds and make them ALL switched! (Possibly the cheapest way out) Therefore your ecu will be in start-from-scratch mode every time you start the car. (REAL cheap! But has it’s limitations)
The most common figure kicked about is 10% when it comes to watchdog threshold. The exact figure is unknown to me. If a parameter get’s 10% or more out of spec, the ecu tries to fix it. SO small mods could be done and small gains made before the “bosch police” step in. But do anything drastic and the ecu will put your system “under arrest” until the next reset.
Due to the nature of this watchdog system I cannot see how “resetting your ecu and driving like a madman for 30 minutes” would be anything but a misconception. The logic of the system leads me to believe that until hard-core proof is presented it is false. If anything a hard drive will at best force the ecu to fine-tune the system under the most intense operating conditions, which will result in more accurate emissions elimination during easy driving. So if your worried you won’t pass a smog test, go reset your ecu, drive like hell for 3 days and pull it into the lot of the inspection station. The emissions should be about as clean as they are gonna get. Else, I cannot take into consideration the design of the system, weighed against the simple fact that no car company designs an ECU with performance in mind; and still honestly believe that this ecu will allow you to remap it to your driving habits with a simple reset and a speeding ticket. The reason a reset helps is simply because as mentioned before, your ecu is starting from scratch and has not tuned out your mods yet. It is an emissions device, and always will be. That’s why ECU’s were introduced into vehicles in the first place. After you drive it around for a while smiling about your new HP gains, your ecu will eventually tune out your newfound HP so gradually that you won’t even notice you lost it until you reset again.
It is just one giant circle. You need to break the cycle.
I will now go into a D.I.Y I wrote myself to help you open up your Bosch motronic ECU and have a look around at things, or even install a custom chipset. Or if you like you can just stare this tuner-hating beast dead in it’s core. Understand that your bosch ecu does not tailor itself to your needs. It tailors your vehicle operations to the needs of a little german engineer locked in a cold white room staring at charts of specific vehicles and they’re emissions layouts, specs, etc. They are severly underpaid, overstressed, AND maybe even undersexed! You are at HIS/HER mercy until you take control. Modify it, work around it, or get rid of it! Either way you go; Use this information as a correct building block to understanding your ECU’s as opposed to just kicking around speculation and misconceptions. I put a lot of time and thought into this, and would like it put to good use. This is one of many contributions I am making to the Hyundai tuners. You are encouraged to share your knowledge as well but only if it is factual.
“If we do not share what we know, we will know nothing” – Wrote that myself
Please refer to www.hmaservice.com
to locate and remove your ECU.
Please! Before you interject on this thread with your own ideas, be prepared to back them up!
UNLOCKING YOUR MAGICAL BOSCH MOTRONIC OBD1 ECU:
Once you have removed your ecu, place it on a clean, sturdy work surface with plenty of light and prepare the following tools.
T-10 torx screwdriver
T-20 torx screwdriver
Mini flathead screwdriver
#2 flathead screwdriver
Needle nose pliers (just in case)
Anti-static wrist grounding device (radio shack, like 2 bucks)
Chip extractor (only if you plan to remove your EEPROM(S) radio shack, cheap!)
Below you will see the Bosch motronic ecu in all of its tuner-hating glory. Stare it right in the face and know that it’s either you or her (we call it “her” because of the similarity of the opposition to the boys playing with they’re cars – no disrespect to the female tuners out there, we love you =). And as long as you are taking shit from her your bolts-on’s may not see the light of day after only a few days of driving; which makes our bolt-on’s an even less attractive investment the buying a barrel of stones or even going to the nudie-bar. Let’s see here, 650 bucks for an exhaust your going to enjoy for a few days, or 650 bucks for a few hours in the Champaign room at silky’s? I don’t know about you, but living up 10HP for a few days compared to a few hours in the Champaign room at silky’s just doesn’t compare at all. But if I can live up that 10HP forever it beats a few cheap broads…. in a dirty room….. bathing you in Champaign…. and licking it off of you…. any day of the week and twice on Sundays. Well…. Sorta... maybe… anyway! back to the subject at hand! (How many of you are running out the door with a fist full of one’s right now?)
If you look at the little picture below you will notice some important information. Learn it, it means something. You will also note on turbocharged vehicles there is a vacuum reference port. Until I can find more factual information on exactly how much responsibility this has in the system, I will not speculate on it. Facts are welcome here, but only facts please. I can say it runs into a barametric pressure sensor on the main board inside the ecu.
NOTE: For the added piece of mind and safety we use the anti-static ground strap when working on sensitive electronics. Strap it to your wrist and find a suitable earth ground to clip the other end to. DO NOT go an try and plug it into your you wall outlet! If you get it wrong your done for! Any pipes, conduit, etc that are metal and running into a stone wall etc all function as an earth ground. Do some head scratching with the guys from radio shack. I don’t know what you have in your home, so I can’t help you here. Before you start, get strapped to ground. Better safe then sorry.
Turn the ecu upside down. You should see tabs folded over the bottom that secure the top cover of the unit. I like to use the small screwdriver (shown) to start prying up the tabs enough to insert the #2 screwdriver (shown) and then lift them completely vertical. Be careful not to lose your grip and put the screwdriver tip through a finger or something.
With all of the tabs in vertical position move on to the screws. If you have 4 torx screws in a box formation, your ecu has on-board ignition controls and these screws function to bind the heat sinks for the ignition electronics to the chassis for heat dissipation. If you don’t have them thank sweet-n-sunny Jesus that there is one less thing you ecu has total domination over; and move on. If not, remove them using the torx t-20 screwdriver. Next move onto the two T-10 torx scres that fasten the base of the ECU’s PCB to the bottom of the chassis, you don’t need or want them in your way for this.
Turn the unit over and remove the top cover. Examine your project and note anything that could hang up while your separating the unit’s parts from one another. You will note on one side of the front connector there is a safety catch. As an example of things that could hang you up note that you will have to remove the board a certain way and angle to clear this.
Now gently flip it back over and notice the three nylon locking pins that run through both PCB’s and into the bottom of the chassis. In short, these need to go. There are plenty of pics there. Using your small screwdriver, find the slits on the sides of them and insert there. Pin the tip under the mushroom head of the nylon center and work it up and out. These can be a little nerve-racking, but you’ll get the hang of it.
Once they are out gently separate the bottom PCB from the chassis in the rear as shown. Note the ribbon cable connecting the top and bottom PCB’s.
Now that the PCB is separated from the lower chassis, you can massage it away from the chassis so that you now have just the sandwiched PCB’s to work with.
Next you want to separate the rear of the PCB’s from one another. Note the picture. Gentle pressure here should force the ball sockets apart. There will be two in back as shown, and one hidden behind the ribbon cable. Upwards pressure should take care of all of them. Don’t nervous, they will separate and they are supposed to make a snapping noise when they do.
Now the only thing that should be holding us back from total separation of the two PCB’s is the front edge connector. There are three rows of pins on this connector. The top pins are part of the top PCB (that’s P C BOARD) and the bottom two rows of pins are connected to the bottom PCB. The front edge connector has a small lip on it that locks this into place to keep it from separating. For the most part you just need to pull the rear of the top PCB upwards on a steep enough slope that the front edge connector lip will slip under the other lip that locks it into place. Once on a steep enough slope, push it rearwards and it should slip out of the connector. If it gives you a hard time do this while slipping the tip of your #2 screwdriver in-between the locking lips as shown. It’s had to describe but hopefully the pictures will tell a better story.
Once it is unlocked and moved out of the socket enough to clear, open that sucker up like a clamshell.
If you plan to remove your EEPROM(S) You should use a chip extractor (radio shack, couple bucks) and the below pics will explain removing the flimsy safety retainers.
On an interesting side note that sensor that reads the input from the external vacuum port is shown here. It is a Bosch 200Kpa sensor. This particular Bosch sensor is good for 2 bar of pressure!
You will also note while looking around that there are two eeproms. One is responsible for on set of instructions, the other has it’s own problems to worry about. It is your homework to find the difference.
Furthermore note the suspended resistors on the boards. They are that way because they are designed to be changed for specific applications. These are another targeted modification area; all you need to learn is what goes where and how to properly modify them. You can here modify signal intensities to the ECU. I will leave some homework for you to do here.
I hope you have enjoyed the read!
If HP.com needs a good product suggestion, contact a few reliable chippers and get remaps for our cars cheap. Work closely with the makers to ensure our watchdog systems are eliminated from the program, new maps are installed, and you would even offer chips maximized to specific combinations of your bolt on products. Until then, the cheapest mod is to prevent the ECU from memorizing your engines actions and watchdoging them. Wire all ECU power supply inputs to the SWITCHED ignition source. Route through www.hmaservice.com
for wiring schematics.
Good luck tuners!
[Edited by SupaCoupa on Nov 11, 2004 6:55 PM]