Electronic Control Unit. The vehicle computer which controls the functions of the engine based upon input from various sensors. The ECU adjusts different aspects of the engine. PCM, PCU, and ECM can all be considered synonyms.

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Honda Hornet engine stalls

I have a Honda Hornet (CB600F) PC41 from 2007. It's the first model with EFI. The bike has an error that we can detect by observing the blinking pattern of the FI light: 2 long and 9 short flashes. ...
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29 views

What voltage does the ECU need?

I am tracing the operation of the ECU. I want to supply it with current but what is the ECU voltage input that I should supply?
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How to reprogram an 86 corvette chip key to a new Electronic Control Unit

I just put a new Electronic Control Unit (ECU) in my '86 Corvette. My key seems to be giving the right code, as I get fuel to the rail and spark to the plugs, however, I don't get injector pulse, so ...
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248 views

Tapping into the on-board computer

I'm thinking of replacing my car's radio panel with a custom built Raspberry Pi device, something like this device. However, it's usefulness would be much larger, if I could get information from the ...
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56 views

Need urgent help - car cut out and instruments frozen and will not start

I have just broken down. I am safe. My car has suddenly cut out and my instruments are frozen. The car will turn over but it refuses to start. My fuel gauge is stuck as well. My engine is cold so I do ...
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752 views

Sharp cornering is turning my Service light on for a second

Citroen C4 2005, Petrol Very rarely I happen to turn without braking properly and my forward momentum is quite high. In these situations I can feel the strain on my front wheels being very high. What ...
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Overwhelming the Eng. management system, is there specific course of action to recover faster

Citroen C4 2005, Petrol, UK Yesterday I managed to overwhelm my car (for the second time I've been having it, first time was about half an year go). What happened was I was at a rather busy stop ...
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63 views

Multimeter Voltage doesn't match ECU Voltage

I was messing around with electrical loads on my 98 Mazda 626 GF 2L today and noticed that the voltage I was reading at the battery with my multimeter, didn't match the voltage the ECU was report via ...
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100 views

Bike currently running rich due to aftermarket exhaust, will adding an aftermarket air filter without any ecu work fix it

I have an MV Agusta Brutale 675 with a GPR Carbonox slip on installed. The air filter is stock and no work has been done on the ECU. My problem is: at this state it's running rich as one can smell un ...
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40 views

How do you compare two ECU maps

I want to update my ECU mapping on my motorcycle to the latest one supplied by the manufacturer, but I'd also like to see what changed before doing so. I downloaded what was on the bike ECU and also ...
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58 views

Ford Focus 1.4 ZETEC - possibly ECU problem?

I've a problem with a Ford Focus MK2 and looking for advice as I don't want to run into mad costs, here's a quick introduction on what happened: Battery went flat - as radio and lights were turn on ...
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102 views

Car stalls and won't restart, but disconnecting the battery fixes it?

2005 scion tc 5 speed. 106xxx Yesterday driving home car stalls out on the highway and power steering goes with it. Battery and oil light come on and won't restart immediately. Dash lights still ...
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111 views

Is there a way to use a PC as an ECU for testing CANBUS Sniffer devices?

Is there a way to connect CANBUS sniffer device to a PC (computer) with CAN-H and CAN-L pairs and test the sniffer device? I want to convert my PC to an ECU emulator, connect a CANBUS sniffer device'...
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49 views

Honda Civic Mk8 FK3 interfacing with ECU/body computer

I wanted to create a few improvements for a FK3 Civic, such as: - automatic door locking - automatic cornering lights For those, I need to be able to read few parameters from the car's computers: - ...
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509 views

How does the car's ECU detect a misfire?

I was wondering what the specific mechanism used by car ECU's to detect misfires is, or are if there is more than one method.
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Do I have an ECU problem?

My 2001 Cabrio only idles. I had a mass/air error code, however I changed this and had no luck. I swapped one from a running VW, the other VW ran normally, but mine didn't. I had the shop read ...
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52 views

PCM Bench Testing

1997 Ford F350, 7.3, 2 wheel drive. PCM part number F6TF-12A650-AYG. OK the question is how to diagnose the PCM without codes due to the battery being dead? I have it out of the truck and was hoping ...
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ECM vs. PCM vs. ECU?

Engine Control Module Powertrain Control Module Engine Control Unit Reading about them online, they seem to be the same thing, computers. So what are the spcific difference between them? Is the other ...
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109 views

Could a modern car be modded enough to work without ECUs?

With enough time and skill sets, could a modern car be modded enough to work without microprocessors? Having machining skills and a fitted workshop, without buying a new motor block or transmission. ...
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406 views

Keep Alive Memory (KAM)

What is "Keep Alive Memory" (KAM) and how is it different from RAM? From what I read over the internet, it is kept alive even after the ignition is OFF, but isn't that what a ROM is supposed to do?
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Peculiar Interior Lighting Issue

Recently a friend of mine was driving a VW Fox (not new, I'm not sure what year but it was certainly 5+ years old) home in the dark with the lights on. Strangely, after a minute or two of driving all ...
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88 views

Response to 2001 Toyota Carolla vvt code 1349: what should I do?

I got a vvt 1349 code on my 2001 Toyota Carolla. I have noticed a sharp decrease in fuel economy. Some people have reported that the oil control valve may be causing the issue. The oil control valve ...
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161 views

What is the cost/benefit for reprogramming an ECU for a non-enthusiast?

As I've been learning more about cars, I keep hearing about how manufacturers are conservative with ECU settings. For someone who isn't into racing, but would like a bit better performance out of his ...
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Mazda 3 2011 1.6 Lts Gasoline - ECU

I was wondering if its possible for a Mazda 3 2011 AT car to function without ECU? The reason I am asking is When I start the engine, the CheckEngineLight doesnot come at all When I took my car for ...
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1k views

LTFT and STFT values are off and don't make sense

Car is a 2015 BMW M5 and it has an aftermarket CAI and a catback (slip on) exhaust. No other performance mods or tunes. About 6-7 months ago, I bought a Kiwi OBD-II reader, simply out of curiosity ...
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73 views

2009 Aprilia RSV1000 - Piggy Back ECU, Should I get one?

I have an Aprilia Tuono, 2009. It seems to run lean after putting an Akrapovic exhaust on it. It makes exhaust popping sounds on deceleration. My boyfriend said I need a power commander on it to ...
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83 views

How do I pull error codes from my Kawasaki motorcycle?

I have an FI light on my Kawasaki motorcycle that is 2002 or newer. How do I get the error codes so I can troubleshoot it?
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164 views

Determining active gear from OBD2 for Ford Fiesta

I am trying to to write an app which advises the driver to change gears and do some other driving quality assessments. For this purpose I need to determine the RPM and currently active gear in a ...
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98 views

Letting Off Gas Forces Open Loop

I noticed something that seems a bit strange to me. Many times when I let off the gas the ECU drops out of closed loop into open loop for about a second. You can see on the graph that this happens ...
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Fuel Economy Gauge Modification

I have a little digital screen in my dash that re-evaluates my average fuel consumption (L/100km) every thirty seconds. How can I modify this to increase the reporting frequency? Preferably, at least ...
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151 views

How is barometric pressure related to emissions testing?

In the VW emissions cheating scandal, news reports say the following: According to the EPA, "the position of the steering wheel, vehicle speed, the duration of the engine's operation, and barometric ...
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269 views

ECU replacing procedures

In a Renault Laguna 1.6 2003 , the ECU got damaged physically (the connector went off ) so i have to replace it with another one ( used ECU ) , I've read that I will need to disable the Immobilizer ...
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Chiptuning for a car with DPF (Diesel Particulate Filter) is a bad idea?

I know that it is possible to disable DPF (Diesel Particulate Filter). I'm wondering how bad it could be to leave DPF (Diesel Particulate Filter) functioning and add a chip to a car?
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Where are ECUs and for which tasks are they used? [closed]

ECUs are "Electronic Control Units". I've heard that modern cards have about 30 - 70 ECUs, but I couldn't find good sources for that. Do you have (citable) sources for where ECUs in modern cars are, ...
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Dealer can't program new ECU for 2001 Mercury Cougar because of transmission type

I brought the original ECM in to order a replacement, put it in myself, and then towed the car to Ford. Now they are saying they can't program it because the computer is for a manual and my car is an ...
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163 views

Reprogramming a Magneti Marelli Microplex MED604C

Im interested in reprogramming a Magneti Marelli Microplex MED604C ecu for the ignition of a uno turbo, but I can't seem to find any documentation for this? I'm new to ecu remapping, and my ...
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Honda Civic 2000 DX, Check Engine Light Becomes On but Does Not Give OBD Code

On my Honda Civic DX 2000, the Check Engine Light (CEL) has been on for a while, so I brought the car to AutoZone to have the OBD code read, but I was told that no code is stored in the computer. ...
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1995 VM Jetta/Vento - ECU pinout for my car

I own a 95 Vento GL (Jetta for the american market), with an 1.8 8v, 90hp ADD model engine. The ECU for this model is marked with part number 037 906 021A. I have checked with VAG-COM software and it ...
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Why don't thermostats have a sensor?

One of the more common reasons of overheating is a stuck thermostat. One of the most common reasons for blown head gaskets is overheating. One of the most expensive vehicle repair procedures is head ...
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232 views

ECU Diagnostic Port cut off and Check Engine Light disabled

I bought a used 92 Integra ZXi recently. I had starting issues so I took it to a mechanic. He found that the check engine light is disabled and diagnostic port from the ECU has been cut off. A very ...
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158 views

Are there plug-n-play ECUs?

I was just curious if there is such a thing as aftermarket plug-n-play ECUs that are compatible with a vehicle (have all the features the OEM ECU does) but also have some extra ones, such as maybe ...
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488 views

Do I need to reprogram ECU when adding custom Air filter

I was thinking of replacing the air filter of a bike into a custom free flow filter. I understand that I have to mod the exhaust to free flow as well to accompany the increase in exhaust due to the ...
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335 views

A most intriguing cold-start misfire mystery

I'm trying to help a friend out with a CEL on his 2009 Merc GLK 280. Hooked it up to an OBD2 reader and retrieved a single code: P0300 - 'Random/Multiple Cylinder Misfire Detected', via the 'OBD ...
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521 views

Will vtec engage without a factory released VTEC ECU when swapping to VTEC engine?

I replaced my honda civic d15z4 engine with a d16A. Apparently, VTEC engages at 5500rpm on these engines. My car is still practically standard, I'm not sure if it does switch over, if it does, the ...
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'93 Cavalier ECU issue

I have an old cavalier that loses power to the ECU randomly. It can take many attempts to start again. I do not lose battery power to the lights or stereo. If I flick the keys to the on position ...
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2001 Toyota 4Runner - ECU Drive Cycle Reset

After changing sensors that were bad on a Toyota 4Runner an emmissions technician stated that the vehicle needed to be driven "for awhile" before the "drive cycle" would reset the ECU to the new ...
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442 views

2005 Toyota Avalon how to reactivate vehicle's ECU

2005 Toyota Avalon FOB stopped working, have a replacement. Now believe accidentally deactivated vehicle's ECU by turning ignition on/off 5 times during process of adding new FOB. So now, how can I ...
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Is it common for ECU's to maintain individual limit maps for each knock sensor?

Preamble I'm in the process of interpreting my BMW M5's ECU binary with the aid of some nifty scripting and rather informative forum posts. One of the things I've found is that there are knock limit ...
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32 views

Dash compatibility and the ECU

I have a Citroen C1 and it's a very basic model. It doesn't have a rev counter but I can add one because it has the cable and plug for it already exists, it's just not plugged into a rev counter. What ...
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230 views

How are fuel injectors controlled?

I took the fuel injectors off of a wrecked Volvo 850 GLT 1996. I was testing them to see if they still worked by simply supplying voltage to them, and they do. I noticed that when I increase or ...