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How does the car's ECU detect a misfire?

This comes directly from this web site: http://www.obdii.com/articles/Onboard_Diagnostics_Demystified.html What it says, is that early OBD-II systems could not detect misfires, but since then a few ...
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16 votes
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Sharp cornering is turning my Service light on for a second

It could be that you are cornering so hard that you're pushing the oil in the sump to one side, away from the pickup pipe. This temporarily means you're oil pump is sucking up air and you are ...
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15 votes

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

I think I have an answer But bear in mind that this is my assessment with the limited information at my disposal. I'll walk through my reasoning here. If someone finds a flaw in my logic then I'm ...
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12 votes

How does the car's ECU detect a misfire?

Engine misfire can also be detected by looking at the coil voltage just after the plug is fired. When the fuel/air mixture actually ignites there are lots of ions and radicals floating around. This ...
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8 votes
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ECM vs. PCM vs. ECU?

From my personal experience with this particular subject you have many variables that come into play. My shop specializes in computer systems on some of the newer vehicles (Mostly Japanese), but we do ...
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8 votes
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Is there a way to use a PC as an ECU for testing CANBUS Sniffer devices?

Sadly you are not going to be able to do what you want simply connecting CAN-H and CAN-L to a serial port. Here is a pointer to the physical interface layer for CANBUS. CANBUS Physical layer ISO ...
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8 votes
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Can a car operate without a catalytic converter?

Most vehicles which are OBD-II compliant (newer vehicles are a little different) use just the O2 sensors located before the cat to adjust the air/fuel ratios. The in-cat or after-cat O2 sensors are ...
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7 votes

How are fuel injectors controlled?

The injector has a plunger/pintle which is controlled by an electromagnet. The humming you heard is from that. The plunger/pintle has a spring which pushes back against the electromagnet so when the ...
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7 votes

Why don't thermostats have a sensor?

It might seem easy to integrate a sensor that detects the opening/closing of a mechanical thermostat's pintle (LVDT, for example) but here are some challenges which would need to be addressed: Cost ...
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7 votes
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How do I pull error codes from my Kawasaki motorcycle?

How do I pull error codes from my Kawasaki motorcycle? Here are the instructions to pull error codes from your 2001 or later Kawasaki street motorcycle. Step 1 Pull off your seat and near the battery ...
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7 votes
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Will disconnecting battery lead to remaps being reset?

No, it shouldn't. During a remap, there are tables which the ECU reads to know what/when/how fueling and other events should occur. This is in non-volatile memory. There are other parts of the ECU ...
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6 votes

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

There are 6 pins in the OBD-II connector which the manufacturers can use at their discretion. In modern vehicles there are usually 2 or more communication buses. Only one bus is for engine and ...
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6 votes

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

VTEC - Variable Timing and Lift Electronic Control VTEC requires the ability to understand the state of the environment and motor in order to change the valve timing. Various sensors from oxygen, ...
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6 votes
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How is barometric pressure related to emissions testing?

The federal test procedures for vehicle emission certification(FTP) is run on a dynamometer. It starts with the vehicle at an exact temperature and barometric pressure and humidity. It is run in a lab ...
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6 votes

Determining active gear from OBD2 for Ford Fiesta

You can determine the gear by comparing the engine RPM and the vehicle speed. Most cars that have a shift light though do not actually know what gear they are in, they use engine RPM, engine load and ...
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6 votes
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What is the cost/benefit for reprogramming an ECU for a non-enthusiast?

You can't necessarily re-program an ECU that is stock from factory. There are a few aftermarket ECUs that you can buy though. On that particular vehicle it won't make too much difference. You can ...
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6 votes
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Keep Alive Memory (KAM)

KAM remains powered when the ignition is off due to the fact it receives power from the battery. It is the same as RAM in the sense that it is a volatile form of memory and will lose its data if power ...
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6 votes
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Could a modern car be modded enough to work without ECUs?

Yes, it is possible Albeit with some trade-offs. A modern-day road car is an amalgamation of several sub-systems, and electronics usually have an important role to play in them. The nice thing is ...
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6 votes

How does the car's ECU detect a misfire?

Variations in current drawn by the "high-tension" (HT) coils can also identify misfires to the engine ECU. This is one reference that I found to back this up AutoTap: Analyzing Ignition Misfires (...
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6 votes
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Bike currently running rich due to aftermarket exhaust, will adding an aftermarket air filter without any ecu work fix it

If anything, your bike should be running lean Thoughts You put an aftermarket non-restrictive exhaust on your MV, that increases the flow of gasses which requires more fuel to compensate for the ...
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6 votes
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Tapping into the on-board computer

You cannot easily "tap" into any ECU/PCM. Depending on what year your vehicle is, it could be a simple set of analog gauges which you could tap into the signal line, but you'll need to do some ...
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5 votes

Do I need to reprogram ECU when adding custom Air filter

There is no need to reprogram the ECU This is for a couple of reasons: The engine barely feels a difference Contrary to what the name implies, a "free-flowing" intake impacts the pressure at the ...
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5 votes
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Do I need to reprogram ECU when adding custom Air filter

The exact answer to this is - It Depends... The reason for this is that your existing ECU, whether it be on a bike or in a car, has a range of inputs and a range out outputs, and a mapping between ...
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5 votes

A most intriguing cold-start misfire mystery

Root Cause: probably a couple of things Sadly, I feel that there isn't enough data here to uncover the smoking gun, but I have realized some things upon reflection that can indicate what is probably ...
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5 votes

ECU replacing procedures

I have replaced he old ECU ( SIRIUS 32N ) with another one ( SIRIUS 32 ) which is used before, the car has not started the first two tries but have started normally the third time, the immobilizer ...
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5 votes

Tapping into the on-board computer

If your car has a OBD2/ODBII port then it is achievable. I'd imaging the simplest way would be to use a ELM327 type cable or even a bluetooth adapter to provide the interface between the pi and the ...
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5 votes

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

Essentially you have put 10 milliliters of oil in your gastank I have done this before with more oil than that on accident into my truck. My solution was to fill the tank to the top and dilute it as ...
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5 votes

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

Here's how to decipher INPA lambdaintegrator Short-term fuel trim. Both banks have a short-term correction of 28%. This should settle down to 0% fairly quickly, so the fact that it stays red ...
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5 votes
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Cannot Access ABS-control-unit with ODB2-adapter

To my knowledge, access to the ABS module will not be possible through a generic OBDII adapter. The most commonly available option for VW's of this era is a VAG-COM cable with RossTech software on a ...
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