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Clevo120Y

I need ECU education

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Hey guys, I need a breakdown on how all the sensors work, there voltage ranges, the affect on fuel and timing maps ect ect.

Using an EB manual ECU as an example, can sensors be manipulated to "trick" the ecu and if so how and what does it do to engine performance, everyday drivability is of no concern.

Please explain it to me like I'm stupid hahaha.

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Heya Clevo =) , No such thing as a stupid question... =)

......was down your way on the weekend for the Moutain Bike Downhill race, mate from Italy came 44th out of 90 entrants.... not bad for a guy hasn't been on a bike for 6 months and smokes like a chimney..... lol . He had an awesome stack on the car jump though..... hehehe. Met his Idol, world champ Sam Hill, so he was stoked.

 

Ok, mate I gotta fly soon to get me brakes sorted......AGAIN, but this is basically it.

There is only a piggyback chip like a J3 that will allow you to manipulate changes to normal ECU functions, but will not actually let you change the ECU, it's like an interface that stores tunes/ adjustments.

Stock ECU parameters are fixed pretty much at factory. It's a learning ECU and will make adjustments on the fly to suit conditions/driving style.

 

Ok, so it works like this...... the engines timing, fuel injection and adjustments to ratios are all made from the ECU after it reads from the sensors, eg. The air pressure sensor in the manifold, the throttle position switch and the engine coolant sensor.......

On the exhaust side you have the O2 sensor, which feeds back info to the ECU on how rich/lean it is running so the ECU can adjust the fuel injector rate to the right mixture.

There is also other sensors, but thats a basic run down.

 

All sensors can be tricked if all they look at is resistance.

If you want I can give you the resistance ranges for any of the sensors, have them all in my workshop manuals, I just don't have time right at this second...

If you want to get RIGHT into it, there is a guy in Welshpool ....EFI Auto Parts..... this guy repairs ECU's, there is nothing he don't know about them.

If its for stock sedan speedway, pretty sure modified ECU is a no no, has to run stock unit.

XR6 ECU has a slightly different set up to the stock ECU and you can't tell them apart, except for the number on them.

 

I would see what the rules are on Piggyback ECU's..... because you still run the stock ECU..... just tell em its for ease of tuning..... hehehe

 

Jack.

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I'll tell you all I know:

 

Mass Air Flow (MAF): can be digital or analog. On the EFI 4.1 Fords I believe they were analog, using a carbon variable resistor attached to a spring-loaded flap (vane type). EA onwards did away with this and used MAP only.

 

Manifold Absolute Pressure (MAP): sensors on Fords are a funny output of both frequency and pulse width. Very hard to intercept and/or modify this digital signal. GM map sensors are much simpler with a 0-5v output. This is what MSD uses for their "boost retard" or what is basically the load map. Obviously this sensor on any engine without an airflow meter is at the heart of the fuel curve. Some intercept boxes modify this signal to alter mixture.

 

Throttle Position (TPS): tells the computer when to give some "accelerator pump" effect, when to employ "closed loop" operation (O2), and when idle and full-load occur. Not much gain in modifying this signal unless you want to change the closed-loop setting. Often a variable resistor with a simple analog (voltage) signal back to the computer. Some have a built-in switch to cut fuel on overrun.

 

Coolant temp (CTC): either resistance to earth or voltage back to ECU, provides enrichment when cold. Also changes spark map. Same goes for intake air temp sensor (IAT). Some intercept boxes use the IAT signal as a means of trimming the mixture.

 

Oxy sensor (O2 or lambda): used only in steady-state cruise and very light loads. Constantly adjusts mixture from slightly rich to slightly lean, which ensures your cat has enough oxygen going through to burn up any nasties left behind.

 

Crank angle sensor (apart from timing ignition and injection) doesn't directly affect mixture but does tell the computer whereabouts on the fuel and spark maps it should be looking. Obviously you can't modify this signal for mixture.

 

That's all I got :D

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Thanks fellas, yeah I can't use a piggy back or modify the ecu itself so changing the actual signal from the sensor was the only thing I can think of. The only one I can see if I'm understanding you guys is the coolant temp sensor, changing the output to say that the engine is colder than it is would allow more fuel to be added, what timing changes would this achieve? Does the engine normally back the timing off as the engine gets hotter?

Outback I saw the mountain bikes on the news mate, I was away from Thursday to Monday dropping off Chris's head and manifold and then onto Northam to sort some work shit out, this is the second time a forum member has come down when I've been out of town. Hope it was a good weekend for ya's and hopefully get to catch up next time your down :)

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Heya Clevo, I would maybe look at the O2 sensor (HEGO sensor).... if it's reading lean it will richen the mixture up....so maybe there is a good starting point. 

AU injectors......., they are 1 or 2 pound higher than the XG ones, with a wider spray pattern. Might be worth a look, look same as stock ones.

 

I think playing with the coolant temp sensor may be possible, will richen mixture if too cold , but you will need a seperate way to tell engine temp, and is a possibility the ECU may try to go into LIMP mode if the coolant temp is too low while you run it as normal or put excessive load on it.

 

Yeah was good weekend mate, besides the chick on Albany highway just as we got into town who opened her door right in front of the ute....didn't even look.

Luckily my cat like reflexes saved the day and one almost squashed scrubber.

Weather was crap, even colder and wetter than normal Albany weather, slept in the ute in freezing cold with me 50kg rotti as a hot water bottle... hehehe.

 

Cool , yeah love to catch up.

Also if ya up this way, always welcome to pop in and see me in Donnybrook. We have apples, a pub , even an Auto Pro store...... hehehe.

Nothing like the big smoke in Albany though..... they had Hungry Jacks....

 

Jack.

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The ecu tend to retard timing as the engine warms up. From memory XR6 have a higher release pressure on their fuel pressure therefore bumping up the rail pressure. Oxygen sensor is only a minor trimming device of fuel delivery the difference isn't really worth the effort. Best go is the coolant temp sensor, you will have to do something about the oxygen sensor though, it will unsuccessfully try to lean out the mixture causing it to log a fault code. Could you plug in an oxygen sensor that isn't screwed into the exhaust?

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For what u are trying to achieve i would look into tweaking the CLT sensor with a resistor as this is ur best result at affecting mixtures. It will only add like 3-4% across the board at the maximum (minimum temp reading) and if u go too far the ecu will go into LOS mode and then your stuffed. Take a reading with a multimeter at stone cold and fit a resistor inline and bypass the sensor so it reads cold all the time no matter what the CLT is seeing. Then you can bump the rail pressure a tad with a adjustable fuel reg if u are allowed to do that. The HEGO will only trim for light cruise/idle mixtures.. all other times it is disregarded. I would fit a innovate wideband sensor and controller and use the narrowband output wire for your ecu input amd ditch the old ford/bosch one. And then u can see what mixtures u are really getting and what changes do affect it. You will achieve a result but i wouldnt be expecting to much from it.

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Hey guys, I need a breakdown on how all the sensors work, there voltage ranges, the affect on fuel and timing maps ect ect.

Using an EB manual ECU as an example, can sensors be manipulated to "trick" the ecu and if so how and what does it do to engine performance, everyday drivability is of no concern.

Please explain it to me like I'm stupid hahaha.

 

Different level I know but I placed the coolant temp sensor from the head of my EST xflow in the washer bottle to keep timing up cos when it warmed it retarded the fuck out of it :)

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Thanks guys, I will look into coolant temp sensor and get some readings. I appreciate the help, my thinking is that if I can get a bit more fuel in and keep the timing in as well then I can run a bit more cam successfully with the stock ecu. Already changed to an XR6 fuel regulator and have a couple of ideas floating around my head :)

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8 minutes ago, jimeoin351 said:

I saw somewhere yesterday and I'm trying to find it again that you can run an AU VCT with a BA ecu. This would allow fuel trim and spark curve tuning. 

 

 

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