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

learn more… | top users | synonyms

2
votes
0answers
18 views

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
votes
2answers
60 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 ...
2
votes
2answers
34 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 ...
2
votes
2answers
37 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 ...
2
votes
2answers
59 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 ...
3
votes
3answers
104 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 ...
1
vote
0answers
17 views

'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 ...
1
vote
1answer
151 views

2001 Toyota 4Runner - ECU Drive Cycle Reset

After changing sensors that were bad on this 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 ...
1
vote
1answer
89 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 ...
4
votes
2answers
71 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 ...
3
votes
1answer
19 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 ...
6
votes
1answer
88 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 ...
0
votes
1answer
129 views

Do I need a new ECU after replacing the transmission?

I replaced the transmission in my 2002 Lexus RX 300 about one month ago. The mechanics reprogrammed my ECU immediately, and they advised me to replace my ECU with a new one, because with the old ECU I ...
1
vote
1answer
953 views

Mazda Lantis 323 1997: OBDI or OBDII?

I'm still trying to figure out if my 1997 Mazda Lantis 323 GLX 1.8L DHOC Manual is OBD 1 or 2. It's supposedly similar to the Protege of the same year and it says on autozone: In order to ...
3
votes
1answer
123 views

Mazda 323: Does the EMU / ECU learn?

I have a Manual 97 Mazda Lantis 323 1.8L DOHC 16 Valve BP and was wondering if the EMU / ECU on it learns? Could unplugging the battery to reset it help some of my problems with erratic idle? I found ...
1
vote
1answer
94 views

Scanning CANBUS [duplicate]

I am in search for a method of scanning the CAN on my car using a cheap ELM327 chip. I can query the ECU (made by Denso) without issue, however when I attempt to set the ELM327 scanner into ...
3
votes
1answer
279 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 ...
0
votes
0answers
176 views

Error Message from OBD-II (7F 01 11)

I have been extracting OBD-II DATA from UART board (ELM327) on my TOYOTA INNOVA. It responded correctly few weeks before and gave all supported sensor values. But now, for every response, ECU responds ...
5
votes
2answers
832 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 ...
2
votes
1answer
309 views

2005 Nissan Sentra - Pressing gas pedal has no effect - vent control valve

My car (2005 Nissan Sentra) had a problem for a while: gas spills out when pumping. I was lazy and did nothing about it. After a month or so, the car started to fail. At first it was only hiccups, but ...