Hey all, at the moment im starting to put together what i plan to do with my engine/transmission but i have a few question to ask regarding my ecu. Its a standard turbo ecu but i will only be modifying the turbo, cam and possibly the plenum (later on). my question is will i need an aftermarket ecu to run the cam and plenum? i searched up the answer for the turbo, but cant find an answer for either the cam or plenum. thanks

if you want to upgrade the cam your more than likely goin to need a aftermarket ecu.

Not at all tdoyle88, AFM based (MAF) systems do not require any flow tuning because the AFM measures precisely the mass air flow the engine needs, so if you change cam, plenum, filter, exhaust, TBs etc etc All handled by flow. This is not the case with some aftermarket ECUs that rely on MAP instead, because MAP derives flow based on pressure drop, AFM doesnt This doesnt mean that you cant trim the ECU later on in respect of ignition timing and maybe make it slightly richer at the top end when the cam starts to do its job - but the latter part of that can do with a true rising rate regulator anyway Some original photos have not been recovered yet.

as niche said, however ive read about putting cams in on standard ecu, some can run stage 2 cams some cant. Although no stage 2 cam is the same so it may have been that difference in that 1 was huge and the other was mild.

I have a stage 3 cam on my standard ecu, just advanced the hell out of my timing.

Quote: Originally Posted by EN94GE I have a stage 3 cam on my standard ecu, just advanced the hell out of my timing. but stage 1 from company A can be the same as stage 3 from company B, which is what i was getting at.

Ahhh I see what ya mean.

thanks for your input niche, im not wanting to run a big cam probably a stage one or sumthin that gives me a bit more performance down low

You know all this "stage" stuff is bs...... Whats the point... "I have a stage 1 cam..." But whats stage 1... if its a stage 3 from another company.... Like "theVLguy" said.... It just depends on how big the cam you get is... whether you'll need an ecu or not.... But if you are going to buy a plenum and cam, why wouldn't you buy an ecu? for tuning purposes

Yeah agree all the stage stuff is marketing hype, we really really need a proper variable valve timing setup, would put a few cam grinders out of work but hey the performance would be best of both, great economy and great performance at any rev range we select from the dash. Trouble is, although there are many working designs for variable timing, its not implemented due to perceived high cost - but how much to people spend on cams and labour, far more than getting it right first time I would expect... <shrug>

To get the most outa any plenium/cam setup ur gunna need a aftermarket ecu.

Quote: Originally Posted by Niche Not at all tdoyle88, AFM based (MAF) systems do not require any flow tuning because the AFM measures precisely the mass air flow the engine needs, so if you change cam, plenum, filter, exhaust, TBs etc etc All handled by flow. This is not the case with some aftermarket ECUs that rely on MAP instead, because MAP derives flow based on pressure drop, AFM doesnt This doesnt mean that you cant trim the ECU later on in respect of ignition timing and maybe make it slightly richer at the top end when the cam starts to do its job - but the latter part of that can do with a true rising rate regulator anyway Hate to pull you up mate, but a MAF is sensitive to larger cams. That's the main reason for changing from MAF to Mafless tunes on LS1 engines or why large cammed GTR's or Skylines go to a MAP/tps tune. Or they recal the MAF numbers. Try put even an 818 in a VL and run a MAF. It runs like sh1t. A maf relies on air speed to change the resistance in the sensors in the air flow. Large cams pulse the air in the air intake due to overlap. this reduces airspeed across the sensor in the airflow meter, allowing the resistor to get hotter, this increases resistance and gives a lower voltage reading at the ecu. THis makes the ecu think it is flowing less air. There will be replies like "my mate runs an 1147 on a stock ecu." I don't care. A MAF only reads a voltage and then uses a look up table to know how much fuel to put in. Iwouldrecommend changing the ecu as soon as cam is changed Some original photos have not been recovered yet.

@FRASHD mmm, You are partly right and have offered examples that overlap the issue and this requires some clarification, the practical reality however is more complex and as often happens subject to varying propoganda from a little ignorance on the part of some tuners who get used to doing something without occasionally knowing why and then perpetuating a misunderstanding though it has a practical outcome... MAF doesnt need "speed" to measure mass air flow, the prinicple of operation means it can measure the actual mass of air flow regardless of speed and this has been reliably demonstrated on dynos, test benches, physics labs etc.. This is all assuming it is properly plumbed with consideration of all the issues that an engine operation does in exposing any sensor to non-linearities. The issue you bring up though, and close enough, is that a really wild cam does produce larger reverse flow pulses and the conventional MAF system (with cheaper AFMs') cannot distinghuish forward flow from reverse pulses. I'm not acquainted in detail with the LS1, but if the factory setup uses MAF and a change in cam requires a change to MAP then it demonstrates the AFM is getting far more reverse pulses than it can handle in comparison with the factory design. Most MAF systems use a cheaper AFM that can only measure flow in one direction at a time with only one output connection for overall flow regardless of direction. This is a consquence of a change to the factory design and yes MAP is practical to get around it, the other option is to plumb the AFM in front of an inlet resonator to absorb the reverse pulses - but because of the misunderstanding almost no-one does this or even knows how to do it properly but it is a cheaper option if you have a little space. Newer AFM's (not generally used on factory cars in Australia) have a thin film bidirectional element that is very discriminating and can tell extremely well the direction of flow and this has all sorts of advantages, such as the ability to asses inlet plenum resonances with a cam change, something that is otherwise quite hard to do. The other issue that causes confusion and often a total misunderstanding is the whys and wherefores of trimming the ECU tune for a wilder cam - if you do manage to have the conventional AFM and its not getting misled by too much reverse flow pulses. A wilder cam with more overlap acts a little like the engine has suddenly got EGR, and quite a large amount and this can drop power (or rather not give as much power as expected and the AFM gets blamed), to counteract this it is beneficial to trim the fuel maps at that part of the rev/load range where the EGR becomes substantial. However a lot of people, including tuners just arent aware of this particular detail and wrong conclude its an issue of the AFM when its a complication not related to it directly... In the case of a turbo during sustained load (not when a BOV operates) there are virtually no reverse pulses for a properly plumbed AFM which is located in front of the turbo - the turbo acts like a really effective one way valve for cam generated plenum pulses. But, if the AFM is plumbed after the IC *and* you have a wild cam then you face the problem again of the cheaper AFM not being able to discriminate reverse flow and the complication of the larger effective EGR from large overlap. The way around this is to move the AFM to front of turbo or to change to MAP. I know which option I would be using first for pure economics. So, for the most part I stand by my initial statement, but add the proviso that it is more true for AFM in front of turbo in factory location that the MAF system automatically compensates for inlet flow changes... Edit: Typos & EGR=Exhaust Gas Recirculation

farrrrrrrrrrrrrrrrrk, thats a good read ^^^ when i said i mgiht do plenum it meant i wanna keep my old one but have it bored a tiny bit and larger throttle body.. i dont want massive power figures, i jsut want a neat calais turbo and to keep it as stock looking as i can with a few minor necessary things good stuff niche

Quote: Originally Posted by Niche @FRASHD mmm, You are partly right and have offered examples that overlap the issue and this requires some clarification, the practical reality however is more complex and as often happens subject to varying propoganda from a little ignorance on the part of some tuners who get used to doing something without occasionally knowing why and then perpetuating a misunderstanding though it has a practical outcome... MAF doesnt need "speed" to measure mass air flow, the prinicple of operation means it can measure the actual mass of air flow regardless of speed and this has been reliably demonstrated on dynos, test benches, physics labs etc.. This is all assuming it is properly plumbed with consideration of all the issues that an engine operation does in exposing any sensor to non-linearities. The issue you bring up though, and close enough, is that a really wild cam does produce larger reverse flow pulses and the conventional MAF system (with cheaper AFMs') cannot distinghuish forward flow from reverse pulses. I'm not acquainted in detail with the LS1, but if the factory setup uses MAF and a change in cam requires a change to MAP then it demonstrates the AFM is getting far more reverse pulses than it can handle in comparison with the factory design. Most MAF systems use a cheaper AFM that can only measure flow in one direction at a time with only one output connection for overall flow regardless of direction. This is a consquence of a change to the factory design and yes MAP is practical to get around it, the other option is to plumb the AFM in front of an inlet resonator to absorb the reverse pulses - but because of the misunderstanding almost no-one does this or even knows how to do it properly but it is a cheaper option if you have a little space. Newer AFM's (not generally used on factory cars in Australia) have a thin film bidirectional element that is very discriminating and can tell extremely well the direction of flow and this has all sorts of advantages, such as the ability to asses inlet plenum resonances with a cam change, something that is otherwise quite hard to do. The other issue that causes confusion and often a total misunderstanding is the whys and wherefores of trimming the ECU tune for a wilder cam - if you do manage to have the conventional AFM and its not getting misled by too much reverse flow pulses. A wilder cam with more overlap acts a little like the engine has suddenly got EGR, and quite a large amount and this can drop power (or rather not give as much power as expected and the AFM gets blamed), to counteract this it is beneficial to trim the fuel maps at that part of the rev/load range where the EGR becomes substantial. However a lot of people, including tuners just arent aware of this particular detail and wrong conclude its an issue of the AFM when its a complication not related to it directly... In the case of a turbo during sustained load (not when a BOV operates) there are virtually no reverse pulses for a properly plumbed AFM which is located in front of the turbo - the turbo acts like a really effective one way valve for cam generated plenum pulses. But, if the AFM is plumbed after the IC *and* you have a wild cam then you face the problem again of the cheaper AFM not being able to discriminate reverse flow and the complication of the larger effective EGR from large overlap. The way around this is to move the AFM to front of turbo or to change to MAP. I know which option I would be using first for pure economics. So, for the most part I stand by my initial statement, but add the proviso that it is more true for AFM in front of turbo in factory location that the MAF system automatically compensates for inlet flow changes... Edit: Typos & EGR=Exhaust Gas Recirculation I'm not partly right, I am right. 1. We are talking about a VL airflow meter. They are dumb. 2. ECU gets voltage from airflow meter, puts in required fuel as per standard set, (correct) 3. Voltage measures at aiflow meter is only due to resistance between supplied voltage and signal voltage. 4. Change in resistance is caused only by air speed/flow across the resistor wire in airflow meter. RESULT: larger cam = change in ecu signal voltage or Hz (depending on ECU) = different (incorrect) amount of fuel delivered to engine. ANSWER: intercept and alter airflow meter readings to ECU (trim). PROBLEM: trimming airflow meter signal not only adjusts fuel delivery, it also adjusts timing. Not always in the way you want. Yes there are ways around it. Why bother. ECU's are that cheap these days. Plus your car wont look like Marty an Docs car out of Back to the future with sh1t hanging off it every where. CONCLUSION: NO, the airflowmeter left un-intercepted will run CORRECTLY with a large cam shaft. (don't have all day to right 7 page essay)

Niche was saying your partly right because of your statement #4 which says that Change in resistance is caused only by air speed/flow across the resistor wire in the airflow meter. Change in resistance has nothing to do with air speed in the afm, as niche has already said!!! It measures the exact quantity of air directly. For example, just say that you increase the diameter of the intake piping on a vl, including the afm. The same amount of air could be flowing through but it would be flowing at a slower speed, so if the AFM got its readings based on airspeed, it would be giving the wrong output in this case. Thats like a MAP sensor, you would have to re-tune the ecu because of the intake change. Niche is trying to tell you that the AFM measures the exact quantity of air going through it, regardles of speed, pressure etc....

Quote: Originally Posted by airbagsVL Niche was saying your partly right because of your statement #4 which says that Change in resistance is caused only by air speed/flow across the resistor wire in the airflow meter. Change in resistance has nothing to do with air speed in the afm, as niche has already said!!! It measures the exact quantity of air directly. For example, just say that you increase the diameter of the intake piping on a vl, including the afm. The same amount of air could be flowing through but it would be flowing at a slower speed, so if the AFM got its readings based on airspeed, it would be giving the wrong output in this case. Thats like a MAP sensor, you would have to re-tune the ecu because of the intake change. Niche is trying to tell you that the AFM measures the exact quantity of air going through it, regardles of speed, pressure etc.... Change of the resistance has everything to do with airspeed!!!!!!! The VL airflow meter is dumb, you can mount it before or after the turbo and it runs fine, regardless of air temps. Especially in a VL. faster air running across a heated wire changes it resistance. And your comment on changing the airflow meter size will change the speed is correct. Thats why when you change an airflow meter on a skyline to a larger one you recal the voltages. I know it measures the exact amount of air passing through the airflow meter. BUT THIS IS THE BIT YOU DON'T SEEM TO GET.. A LARGER CAM HAS MORE OVERLAP. THIS CAUSES PULSING ACROSS THE AIRFLOW METER. THEREFORE GIVING A LOWER VOLTAGE/ Hz AT THE ECU. YES IT MEASURES THE AIR THAT PASSES THROUGH THE AIRFLOW METER BUT THE FACTORY SETTINGS IN THE ECU FOR THE MEASURE AMOUNT OF AIR WILL NOT BE ENOUGH FOR THE ENGINE TO RUN CORRECTLY... PLEASE REFER BACK TO THE FIRST POST AND NICHES REPLY. THE FACTORY AIRFLOW METER ON THE VL WILL NOT SELF ADJUST FOR A LOW AIR OR PULSING IN THE INTAKE. SO THE FACTORY ECU WILL HAVE TO BE REMAPPED OR THE AIRFLOW METER SIGNAL INTERCEPTED. PLAIN AND SIMPLE. END OF STORY. BEEN THERE DONE THAT. DON'T BELIEVE ME FINE. GO PUT AN 818 IN A VL AND SEE WHAT HAPPENS.

I do believe you, i understand all the cam stuff and how the afm can only measure oneway airflow and that back pulses will mess up the output, i wasnt saying anything about that, i know that you know what your talking about with all that. I was simply trying to make the point that the AFM does not use "airspeed" to calculate the amount of air, it knows the airflow regardless of the airspeed.

@FRASHD, Calm down old man I was talking VLT, turbo acts as a pretty effective one way valve, changing to a more agressive cam on a VLT which has more powerful reverse pulses wont be an issue, well unless you are unlucky and have moved the AFM to after the IC. Airspeed is only a factor for the AFM if the mass of air is *also* higher at the same time. You can have faster airspeed but less mass and the AFM will measure the mass correctly Here is something to consider FRASHD that might be helpful:- For a turbo engine with an IC, the air speed into turbo and out of IC are different, yet you can mount the AFM either infront of turbo or after IC and it will still measure the correct *mass* airflow on each occasion. It wouldnt be able to do that if its operation was solely based on airspeed, so please read up the detail from the manufacturers about how an AFM actually manages to be so effective. The AFM might be dumb, it is a very simple device afterall but doesnt output a resistance as you claim it outputs a voltage (which is log) based on two factors, one is the bridge element of the platignum hotwire, the other is a temperature correction, you will notice there is a thin film temp sensor in the air flow adjacent to the wires. Although the AFM is simple (as you say dumb) it operates on a well known principle in physics and is remarkably effective. I've already indicated how you can get past the issue of reverse pulses, what more needs to be said ? Some things seem intuitively correct but the devil is in the details, I'm supplying this yet you seem to want to only appreciate part of the issue Quote: Originally Posted by airbagsVL I was simply trying to make the point that the AFM does not use "airspeed" to calculate the amount of air, it knows the airflow regardless of the airspeed. This is true, the misleading thing for some people is the fact that airspeed is often correlated with mass flow rate - its not always the case, i think thats where FRASHD has missed the point. Its like the misunderstanding people have about humid air being more dense ie. Intuitively you would expect so but its opposite to that and I have seen so many people argue till they are blue in the face without thinking they need to look at the details, they feel challenged yet if they take just a little time to check it out and why then they would have a better understanding... Thats why we have these forums and why I enjoy the practice Well we all know the earth is flat - cant you see it FFS whats wrong with you Quote: Originally Posted by FRASHD PLEASE REFER BACK TO THE FIRST POST AND NICHES REPLY. See my last para in post #13 for clarification in context with your suggestion... Some original photos have not been recovered yet.

You still miss the point.. Mass of air is the same as Grams per second. How do you get X amount of grams through an airflow meter. Speed. Yes I am aware of the thin film temp sensor. The same amount of air that goes into the turbo goes through the intercooler. regardless of where the airflow meter is. Try move the airflow meter in a skyline r33 into the cooler piping. They dont run right. You still mis the point too. Yes the air passing through the meter is measured, but the progtammed delivery amount will not make the car run correctly. my question is will i need an aftermarket ecu to run the cam and plenum? Not at all tdoyle88, AFM based (MAF) systems do not require any flow tuning because the AFM measures precisely the mass air flow the engine needs, so if you change cam, plenum, filter, exhaust, TBs etc etc All handled by flow. THE FACTORY ECU WILL NOT RUN CORRECTLY LEFT UNTOUCHED. I have tuned enough of these things to stand by what I say. Personally I would not stuff around with the factory ECU or intercepting airflowmeter signals. My fingers are worn out from replying. bluJ3t you do what you want mate, and all the best what ever choice you make.