Car ECU, replace or repair

[Balaur]

Just some (not so relevant) comments:

There is a world of difference between the Engine Management Unit (EMS) or (improperly called) Engine Control Unit (ECU) or Powertrain Control Module (PCM) and other Electronic Control Units boxes.

The lesser ECUs will manage auxiliary functions such as ABS, safety features (locking, windows, engine immobilization), suspension (if active), entertainment units, etc.

As jucole attested, a dedicated and resourceful person can be able to repair, improve or even duplicate the ECU boxes.

However, I highly doubt that the core functionality of the EMS unit is easy to be tackled at hobbyist level. Not because of the complexity of the task, most EMS are just a processor (with rich input/output features) with its subsystems and adequate output drivers. The EMS reads sensor inputs and drive a lot of actuators according to some pre-programmed Look-Up Tables (Maps). The difficulty resides in the fact that it's impossible to do anything remotely useful if you don't have an understanding of the physics of the engine and the impact of your actions. It's just not feasible. You should have some ways to observe the engine behavior (problems, performance) and counter-measures to highly dangerous situations (engine knocking, blowing, catching fire, etc).

There are some "generic" or Aftermarket Engine Management Units, but these are the result of quite expert people working hard.

Cheers,
Dan

[0xdeadbeef]

Nope. It's vehicle wiring. What's inside ECU - is a well-kept secret. Never seen a full schematics, although there's nothing hi-tech.

Depends on what you call hightech and and what vendor/car you look at. But a state of the art ECU can be pretty sophisticated.

Some manufacturers even go so far that they order ICs with their's own markings. And instead of original IC name like NE555 you will get something weird like J25. Good luck seeking a datasheet.

Not just markings. ECU vendors use their own ASICs and the CPUs can be also variants that are not available on the free market (e.g. stripped down or advanced versions of generally available base versions).

As a side note: hints uttered here like disconnecting the battery for 24h hours are (most probably) pretty much pointless. There are only a few ECUs which use a RAM with permanent supply. Volatile data is usually stored in SRAM and lost within seconds after disconnecting the battery and after the capacitors discharged (which usually doesn't take very long). Nonvolatile data is stored in EEPROM (old school) or flash (typical nowadays) and therefore won't get lost by removing the battery. Besides when removing the battery there is alway a slight chance that the nonvolatile memory gets corrupted, so be careful with this and do it only some minutes after switching off ignition/accessory.

If a component is deactivated due to a stored fault this can usually be either cleared by a normal power off cycle (if it's just temporary) or only by means of an OBD2 device (if it's critical). No need to disconnect the battery.
Then again, when a critical component like the fan is deactivated due to a electrical fault, chances are that the engine will only run in some kind of limp home mode. But this is vendor specific of course.

Anyway I still would suspect that some temperature sensor is defective. Note that there might be multiple temperatures like oil temperature, coolant temperature, engine temperature, air temperature. The fan is usually controlled via the coolant temperature, but you never know what people come up with. Usually a defective sensor should be detected by the ECU and reported via OBD2. Then again, if it's weirdly floating or it's a dumb ECU, it might as well not recognize the sensor defect.

[Simon]

it remains a mystery. Will have a poke around with my diagnostics panel later when I'm hoe from my work course. Not sure what it can do though as it's only basic. I'm certainly not in limp home mode, engine is performing better than it ever has with record low fuel consumption. Have driven up to 70mph and high revs (4300 rpm) with no problems.

[aluck]

There is a world of difference between the Engine Management Unit (EMS) or (improperly called) Engine Control Unit (ECU)

Why do you consider it improper?

As jucole attested, a dedicated and resourceful person can be able to repair, improve or even duplicate the ECU boxes.

Repair? Sure. Did that, been there.  Sometimes it's damn hard to solder (check out so-called Chip-On-Board type), but I did that.

Improve? Doubt it.

Duplicate? Next to impossible in terms of equipment and man-hours.

[aluck]

Depends on what you call hightech and and what vendor/car you look at. But a state of the art ECU can be pretty sophisticated.

Usually it's just an 8-bit microcontroller running at 16/20 MHz, EEPROM, a couple of MOSFET arrays, and (maybe) ADC. No state-of-the-art fancy ICs, no FPGAs. BTW, never seen an ASIC inside. Did you?

[aluck]

Have driven up to 70mph and high revs (4300 rpm) with no problems.

So, does that mean that you problem with the fan is gone?

[SeanB]

Post some photos of the engine, with the water piping shown.

[Simon]

Have driven up to 70mph and high revs (4300 rpm) with no problems.

So, does that mean that you problem with the fan is gone?

No not that I'm aware of but just saying that the engine is running fine so doubt the ECU is in limp home mode, engine couldn't be running better. But as far as I know the ECU won't cut the fan in.

[Simon]

Post some photos of the engine, with the water piping shown.

not easy at the moment, what am I looking for ? it's a cheap two pass radiator with plastic tanks and a rather thin core (I've seen air con condensers that thin lol). There are no sensors on the radiator or on the pipework close by, maybe further back I grant you but no sign of them on the diagrams and the fan is definitely activated by the ecu as we did it manually.

[SeanB]

Normally next to the engine. The locally made vehicles are sufficiently different to the UK ones ( same kent derived indian made engine but modified for the ambient high temps and altitude changes) that the build is totally different. Not the radiator but the engine bay, looking to the back and down, from the sides and from the back looking down.

[aluck]

No not that I'm aware of but just saying that the engine is running fine so doubt the ECU is in limp home mode

If there is no C.E. light, it's definitely not in a limp home.

Still waiting for your measurements for fixin' ya car then.

[Simon]

No not that I'm aware of but just saying that the engine is running fine so doubt the ECU is in limp home mode

If there is no C.E. light, it's definitely not in a limp home.

Still waiting for your measurements for fixin' ya car then.

hopefully this weekend, I don't think the hotel I'm staying at will appreciate me taking my carto bits in their yard or overstaying my welcome 

[0xdeadbeef]

Depends on what you call hightech and and what vendor/car you look at. But a state of the art ECU can be pretty sophisticated.

Usually it's just an 8-bit microcontroller running at 16/20 MHz, EEPROM, a couple of MOSFET arrays, and (maybe) ADC. No state-of-the-art fancy ICs, no FPGAs. BTW, never seen an ASIC inside. Did you?

Even >13 years ago my very first ECU project had a 32bit CPU. The low end stuff was done with 16bit Controllers until a few years ago, but nowadays it's all 32bit, even in the very small three cylinder engines. On the high end side, there's e.g. a 256MHz CPU with nearly 500 pins (BGA) and the next step is dual core. Plenty of ASICs as well of course. More than 10 in one of the bigger projects. Never ever saw an 8bit main CPU - not even in a JetSki or snowmobile. Only as secondary.

[aluck]

Never ever saw an 8bit main CPU - not even in a JetSki or snowmobile. Only as secondary.

As far as I can remember, all pre-2000 Audi/VW ECUs used some variants of 80C51. You are right - more recent ones use 16-bit. But never seen BGA or 32-bit. Can you give an example?

[Balaur]

There is a world of difference between the Engine Management Unit (EMS) or (improperly called) Engine Control Unit (ECU)

Why do you consider it improper?

Because (at least in my experience), the ECU name is usually reserved to (lesser) Electronic Control Units, while the Engine box should be always called EMS or PCM.

As jucole attested, a dedicated and resourceful person can be able to repair, improve or even duplicate the ECU boxes.

Repair? Sure. Did that, been there.  Sometimes it's damn hard to solder (check out so-called Chip-On-Board type), but I did that.

Improve? Doubt it.

Duplicate? Next to impossible in terms of equipment and man-hours.

Exactly my point. I was talking in this context about the (lesser) ECU boxes, while acknowledging in the next paragraph the difficulty of working with EMS boxes.

Never ever saw an 8bit main CPU - not even in a JetSki or snowmobile. Only as secondary.

As far as I can remember, all pre-2000 Audi/VW ECUs used some variants of 80C51. You are right - more recent ones use 16-bit. But never seen BGA or 32-bit. Can you give an example?

There are several ARM-based products from Samsung. There are automotive chips, in the sense that there are very well equipped with serial and parallel I/Os, watchdogs, counters, DACs, ADCs, PWM, whatever makes sense in the automotive I guess.
A few examples are the following:
- ARM7TDMI-based: a few S3F4A*** such as S3F4A1HR, S3F4A2FR, etc
- Cortex-M3: S3FMA1U, S3FMA1G

The ARM core (and its wonderful JTAG bus) makes the chip instantly familiar to a lot of programmers (software and hardware).  You just need to concentrate on the extended I/O features to make them do whatever you want.

[Baliszoft]

Never ever saw an 8bit main CPU - not even in a JetSki or snowmobile. Only as secondary.

As far as I can remember, all pre-2000 Audi/VW ECUs used some variants of 80C51. You are right - more recent ones use 16-bit. But never seen BGA or 32-bit. Can you give an example?

Yes. Dont forget about the siemens c166/167 on 16mhz either. They also used two of these in conjunction for six cylinder engines.

[0xdeadbeef]

Never ever saw an 8bit main CPU - not even in a JetSki or snowmobile. Only as secondary.

As far as I can remember, all pre-2000 Audi/VW ECUs used some variants of 80C51. You are right - more recent ones use 16-bit. But never seen BGA or 32-bit. Can you give an example?

Most if not All ECUs from BMW, Audi, Porsche etc. in the last ~10 years used e.g. TriCore CPUs (TC17xx) from Infineon or Oak/eSys CPUs from Motorola/Freescale. Even before that, the Hitachi SH7055 was used here and there. In the last few years, also a lot of VW/Skoda/Seat ECUs use 32bit ECUs (mostly TriCore, some eSys). Modern GM ECUs use large FSL eSys CPUs as Viper, Copperhead, Mamba and Cobra. At least the larger ones of these CPUs are BGA.

[aluck]

Most if not All ECUs from BMW, Audi, Porsche etc. in the last ~10 years used e.g. TriCore CPUs (TC17xx) from Infineon or Oak/eSys CPUs from Motorola/Freescale. Even before that, the Hitachi SH7055 was used here and there. In the last few years, also a lot of VW/Skoda/Seat ECUs use 32bit ECUs (mostly TriCore, some eSys). Modern GM ECUs use large FSL eSys CPUs as Viper, Copperhead, Mamba and Cobra. At least the larger ones of these CPUs are BGA.

Nice! Do you fix or make those?

[_Sin]

Here's a picture of the internals of an Audi Q5 ECU:



I guess it'll be common across the range.

[0xdeadbeef]

Nice! Do you fix or make those?

I work for one of the biggest suppliers, so we develop ECUs (HW and SW).

[jucole]

I work for one of the biggest suppliers, so we develop ECUs (HW and SW).

cool stuff!! - just out of interest how much input protection is there from the sensors etc on early thru to today's ECUs (HW and SW),? are they easy to mess up?

[0xdeadbeef]

ECUs are supposed to be more or less idiot-proof. Stuff like reverse polarity, loss of ground and applying battery voltage or ground to every pin without damage is to be expected even for low end stuff.
Depending on the level of protection that a customer requires, there might be also ESD protection for CAN etc.
However a normal input pin is usually only protected by serial resistor and (CPU internal) clamping diode.
Outputs are usually provided by specific ASICs (e.g. fully integrated H-bridge or highside/lowside drivers) which implement full diagnosis (at least open load, short circuit to ground, short circuit to battery) and self protection.
Anyway, I don't think the protection strategies changed that much during the last decade. Just the diagnostic capabilities increased a bit due to stricter requirements.
On SW side, you can expect that there is very detailed diagnosis available inside the ECU (e.g. also stuck/inplausible values for sensors) and with modern ECUs,
the number and detail level of diagnosis reported to external testers has increased quite a bit. But of course, it will be alway a condensed and simplified version of the information available internally.

[vl400]

Never ever saw an 8bit main CPU - not even in a JetSki or snowmobile. Only as secondary.

GM used 8 bit for many many years, in Oz we had a HC11 variant based ECU and PCM until changing to a Bosch in 2004 on the locally built V6, the same car but with a V8 went to a 32bit 68k Delphi PCM in 2000 after running the same HC11 prior. We first got them in 1988 using a secondary ASIC. From 1994 it controlled engine and trans but on different hardware. It was all US developed hardware and firmware with aussie engineers doing the engine calibration here. Its a simple processor with well written assembly so has been a hacker and DIY users dream, we have added all sorts of stuff to the code.

[Simon]

is there any chance that ignition interference can cause issues, the mechanic said he has had some in the past. Not sure if he was referring to ignition wrecking other stuff or the ignition drivers breaking due to the ignition hardware driven. I think for cheapness most stuff is all in one ecu on my car.

[aluck]

is there any chance that ignition interference can cause issues

Never saw one. Read about some issues with Ford Mustang's, whose camshaft position sensor had problems due to EMI.