Questions tagged [ecu]

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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22
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1answer
29k 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 ...
18
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3answers
18k 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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2answers
3k views

Why do we need make-specific cables to read car ECUs?

I find it bizarre that the automotive industry has standardized the use of the OBDII protocol, yet most cars require make-specific cables in order to access the complete set of diagnostics and ...
12
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2answers
623 views

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 ...
11
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3answers
5k 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 ...
10
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1answer
3k 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 ...
9
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1answer
2k 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 ...
9
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2answers
12k 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?
8
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2answers
30k views

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 ...
8
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3answers
9k views

Shouldn't my post-cat O2 sensors (lambda probes) be reporting varying numbers?

On my 2002 BMW E46 330Ci, I've been getting error codes 202 Lambda regulating limit Bank1 and 203 Lambda regulating limit Bank2. Here's the angry sensor readings from the INPA software: I understand ...
8
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1answer
428 views

Changing from two heated O2 sensors to a single O2 sensor

I'm going to be removing a Motorcraft 2150 carburetor in a 2.8L V6 and swapping it for a Ford CFI (and ECU) from a 3.8L V6. I've just recently pulled everything (ECU, throttle body, sensors, harnesses,...
8
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3answers
6k views

Can a check engine light reset itself when a scan tool is connected?

I have a Toyota RAV4 2002 4WD. I was driving to the car wash when suddenly the check engine light come on when I accelerated hard. After the wash, it still was on. I drove home, shut it off, turn it ...
8
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1answer
784 views

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 ...
7
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3answers
19k views

Cause of limp mode in Vauxhall Astra which ECU code is relevant?

The engine now runs ok when started cold, but if the weather is very hot or it's started when warm it goes into limp mode, whereby the orange spanner symbol comes on and max acceleration is only 1/3 ...
7
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1answer
3k 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'...
7
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1answer
16k 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?
7
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1answer
2k 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 ...
6
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3answers
1k 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 ...
6
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2answers
5k 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 ...
6
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2answers
2k views

Replace or Repair Mazda MPV 2000 faulty ECU?

I asked a question about troubleshooting ECU related short circuits. No more short circuits in the wiring harness, the only short left appears to be inside the ECU. This leaves me with a faulty ECU. ...
6
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1answer
4k 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 ...
6
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4answers
10k views

What voltage does the ECU need?

I am tracing the operation of the ECU. I want to supply it with power but what is the ECU voltage input that I should supply?
6
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2answers
947 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 ...
6
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1answer
205 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 ...
6
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2answers
1k views

Is a bad AFM (Air Flow Meter) a likely cause for fuel cut at high RPM and poor performance at low RPM?

Edit: I answered my own problem, the solution was the AFM (see full answer below). This question is for the same engine and the same car as in the following question: Likely cause of poor performance ...
5
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2answers
846 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 ...
5
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2answers
2k views

Cannot Access ABS-control-unit with ODB2-adapter

I have an ODB2-Bluetooth-Adapter(link) to access the ODB-Protocol with my android-smartphone. It is basically working. The app that I use ("Torque") can connect to the ECU, shows me different values ...
5
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2answers
190 views

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 ...
5
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3answers
31k views

What does it take to program a used ECU?

I own a Mazda MPV 2000 with a faulty ECU. The vehicle has an immobilizer. It will not start with the former ECU. It floods the engine with fuel. After extensive diagnostics on the vehicle and the ...
5
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1answer
4k 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 ...
5
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1answer
172 views

Relation of VIN of a car with emission norms of a country it is sold

A VIN of a car determines the country of manufacture. So if a car has a VIN of Canada (CARB emission standard) and is sold in India (BS-IV emission standard), will the car comply with BS-IV standards? ...
5
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1answer
686 views

How to calculate fuel consumption and CO2 emission on flex fuel cars using OBDII data?

Here is the thing: I'm trying to estimate the fuel consumption of cars using OBDII data. It's quite simple if we can treat each fuel and its stoichiometric air fuel ratio separately, but when it turns ...
5
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2answers
177 views

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 ...
5
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2answers
3k 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 ...
5
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1answer
105 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 ...
5
votes
1answer
613 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 ...
5
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0answers
635 views

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 ...
4
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2answers
11k 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 ...
4
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3answers
3k 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 ...
4
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3answers
152 views

ECM voltage, spark spike

When the car was idling in the garage this morning (hooked up to HP Tuners), I saw a spike on the "Spark" graph at the same time as the car stumbled. "Control Module Voltage" also went from > 14 down ...
4
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1answer
129 views

Why modern car networks are known as “unsafe”?

Engineers and tech people like Craig Smith (who made a great book about hacking cars) never stop warning about car security. Saying that modern cars ain't secure and can be hacked from the outside (...
4
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2answers
2k views

DLC Pinout for SVX ECU

Below is the pinout for a 92 Subaru SVX Engine Control Unit (ECU). Since the wiring harness is no longer collocated with original car, I have no idea as to what the pinout for the Data Link ...
4
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1answer
3k views

96 Impreza ECU Pinout

I'm still working on getting this EG33 into a 96 Impreza. I have received some wiring harness diagrams, but am unable to match them to the ECU which is in the car. I'm wondering if what I have are the ...
4
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1answer
4k 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 ...
4
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4answers
3k views

Is it possible for an oxygen sensor spacer to cause a car to stall?

VW CC 2010 2.0L CBFA I installed an O2 sensor spacer on my downstream O2 sensor and it seemed to be working for a day. One day later, after the car had cooled down it would rough idle and stall when i ...
4
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1answer
345 views

Won't pass emissions, Bad ECU?

So, Last year my 94 Acura Integra AT passed emissions by the skin of its teeth, this year it won't pass, I have noticed in past year and half that dropped from around 30mpg to about 15mpg. Some times ...
4
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1answer
3k views

Help tracking down a battery drain issue on a 2007 Vauxhall Corsa

I'm really hoping someone can help track down a battery drain issue with a 2007 Vauxhall Corsa. We've been back and forth to a Vauxhall garage with this car since we bought it and have had a hell of ...
4
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2answers
242 views

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 ...
4
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2answers
250 views

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 ...
4
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1answer
2k views

Fiat 500 Airbag Sensor

My Fiat 500, 2008, 1.2 Pop, 51Kw has had its front left side somewhat crushed. The body has been fixed for the most part, but the electrician/mechanic tells us he cannot turn on the vehicle in order ...