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Old 8th November 2010, 15:56   #16
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Originally Posted by rajivc666 View Post
I have to start by telling you that I have no experience modding cars, and have only basic knowledge of the working which got from reading on the internet, so my knowledge is something like a block diagram ,would like to clear some doubts anyway. Also is there a 6 to 12% improvement in max power produced.

I believe the oxygen sensor is insensitive outside the ideal a/f ratio so why is Indica using it at wot. Does it run 14.7 A/F at wot for fuel economy or it uses some other sensor to calculate a/f ratios.

In open loop WOT I believe the ecu uses inputs from MAF and IAT sensors mainly (lets ignore other inputs for keeping it simple) and no feed back from o2 sensor. Also some long term adjustments learned is stored in memory is applied as corrections (I am not sure about this whether they are applied in open loop). So assuming company has done a good job with stock air filter in calculating a/f ratios from these inputs at WOT, the increased airflow due to aftermarket filters will be picked up by the MAF and fed to the ecu resulting in increased fuel input and correct a/f ratio as with the stock filter. Also do a ctr-alt-del of the ecu to remove the earlier learned long term corrections. So where did I go wrong.

I am saying all this because I could feel some definite improvement in my car after 5000 rpm. If the ecu was not increasing fuel then it should have just leaned out at 5000 rpm and reduce power.
Haven't we all started off the same way ?

Here are my answers:

1. yes, we have seen 6 to 12% increase in max power

2. TATA seems to be very particular in minimising emissions, so running closed loop even under WOT ! Obviously, someone at TATA will be better placed to say why they do so. You are right, the narrow band sensor cannot be used outside the ideal (or stoichometric ratio of 14.7).

3. As I already mentioned in my other post, increased fuelling will yield higher power only up to a point. After that, power will begin to drop. Hence by the extra air, this extra rich mixture will be leaner then before, but can develop more power. This can happen even without a piggyback on some cars, depending on how rich they were running in the first place and how much extra airflow was introduced. If there was a piggyback, the AFR could have been more precisely adjusted for even better power, that's all !

You did not go wrong, you most likely got some extra power!

We have seen cars improving power just by changing the air filter to a K&N, while some cars hardly show any change.

Next time you drive past Coimbatore, you are welcome to drop by and do free dyno runs of your car with and without your intake system !

After all, to measure is to know !

I hope I have clarified your queries.
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Old 8th November 2010, 18:42   #17
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Originally Posted by sapl View Post
The first part:
The only way an engine measures AFR is using the lambda probe. It has no other means of measuring the AFR.
..........
..........
The most important features in a dyno are sensitivity and repeatability.
Except for the unusually high 9.5 AFR for the accord at open loop WOT rest of his argument sounds logical to me. But then I am no expert. CPH can you please elaborate.

Last edited by Amartya : 8th November 2010 at 22:23. Reason: Edited out the large quoted post. In cases where you just need a reference to a post, edit out most of the content. Thanks
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Old 8th November 2010, 23:05   #18
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Originally Posted by sapl View Post
The ecu will keep adjusting fuel so that the AFR oscillates around the 14.7 mark as long as it is in closed loop (which is typically in part throttle and lower rpms). If one observes the lambda signal with an oscilloscope while in a closed loop condition, this will be very clearly visible.
Hi,
What would be the period (in terms of time/ cycles) of this oscillation? Does it change? If so with what?

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Old 8th November 2010, 23:11   #19
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A number of other systems are capable of doing the same. And the Unichip will never beat a standalone system and in most cases (when ECUs can be re-mapped) the re-map is better when done professionally.
I'd concur with this. Even with plain logic, it seems highly unlikely that a piggy back system can result in performance gains greater than a remapped ECU. However, "when done professionally" is crucial, because a remap is harder to execute well, than setting up a piggy back system.

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This is misleading information. First of all, the Unichip can't do this in all applications and any standalone can do this much more precisely. Other than that a number of ECUs will recognize the alteration and revert back to standard setting or go into emergency mode.
Do share some details about ECUs reverting to factory/default settings when it detects an alteration. If possible, share "how" it detects an alteration.

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All professional mapping is done with on chassis dynos/hub dynos with load cells as they are needed for the use with eddy currents for evaluation. This again is misleading information making out that everyone else is doing it on the cheap.
Correct.
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Originally Posted by CPH View Post
It is not. There is other systems available doing the same.
From what I know of piggy back systems, there's an inherent issue it; such a system manipulates the MAP sensor’s signal to the ECU telling it that it has more air being gulped down by the engine and it should increase the injector’s pulse width, or vice versa. This in turn changes the air to fuel ratio which directly effects engine timing.
Piggy-back units alter timing without implicitly. That is , a piggy-back unit cannot really control fuel and timing independently.

Last edited by Amartya : 8th November 2010 at 23:13.
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Old 8th November 2010, 23:44   #20
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Except for the unusually high 9.5 AFR for the accord at open loop WOT rest of his argument sounds logical to me. But then I am no expert. CPH can you please elaborate.
The lambda probe in the ECUIs is only of limited use for the ECU.

Let me digress a bit in order to make it clearer. ECUs like the Bosch EDC 16 and 17 (Diesel) have smoke limiter tables. They also have torque limiter tables. How does the ECU know where the torque limit is? Or how does it know when the engine starts smoking?

Well the answewr is clear> It does not know. So why do we have these maps/tables?

The answer to it n ot much mor difficult. The ECU needs these limiting factors as overriding tables that come into force when the request from the sensors go above certain limits.

These tables are created by the software designers and have been given values under extensive testing.

Open loop only comes into /ecus when extreme situations occur. There is no point to have closed loop under extreme acceleration.

The primary function of the lambda is preventing damage to engine and cat. The cat needs a rather lean mixture, which is around the stochiometric ratio. For short spaces of time it is okay to go to extremes. When the car is under full load and well above the normal cruising rpm the engine needs a very rich mixture, which is well above (in richness but the ratio number is lower) the stochiometric ratio. The changes are so quickly that even a wide band lambda can't compensate quicly enough anymore and in powerful cars the changes in AFR would send the ECU in Jo-jo mode.

In Super cars they usually also have a cat bypass pipe for the protection of the cat when not in cruising range.

Still, some sensors are being read by the /ecu during open loop. This is already necessary to compensate ignition timing and the knock sensor is also live. In many ECUs the post lambda is live even in open loop.

Try to disconnect a map or a AFR on many cars. They will not run properly, whether in closed loop or open loop. Turn a Bosch AFR the wrong way round in the pipe and it will run terribly in open loop.

There is a lot of experience packed into different tables, which are limiting or overriding tables.

There is a lot more to it, but I don't want to go too deep into the technicalities right here. I will do this over a nice meal in the restaurant when I meet up with you.
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Old 9th November 2010, 01:32   #21
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This is very good information. So even with a wide band lambda sensor the engine goes into open loop at extreme conditions like WOT and high rpm. So I guess the advantage of a WB Lambda sensor is wider AFRs like a leaner mixture for cruising in closed loop than just maintaining 14.7. Can you please confirm this.

Well it goes without saying that even in open loop the ecu is taking readings from other sensors except for I think the lambda sensor. If I am right the post lambda sensor is only for correct operation of the Catcon and does not play a dominant role in calculating the AFR even if its is being read in the open loop.

But as SAPL mentioned if the ecu is taking direct readings from the lambda sensor in closed loop the ECU will still maintain stoichiometric AFR despite the piggyback. what do you think.

Also can you tell me at what AFR a too rich flame-out will occur.
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Old 9th November 2010, 02:23   #22
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Originally Posted by rajivc666 View Post
This is very good information. So even with a wide band lambda sensor the engine goes into open loop at extreme conditions like WOT and high rpm. So I guess the advantage of a WB Lambda sensor is wider AFRs like a leaner mixture for cruising in closed loop than just maintaining 14.7. Can you please confirm this.

Well it goes without saying that even in open loop the ecu is taking readings from other sensors except for I think the lambda sensor. If I am right the post lambda sensor is only for correct operation of the Catcon and does not play a dominant role in calculating the AFR even if its is being read in the open loop.

But as SAPL mentioned if the ecu is taking direct readings from the lambda sensor in closed loop the ECU will still maintain stoichiometric AFR despite the piggyback. what do you think.

Also can you tell me at what AFR a too rich flame-out will occur.
I don't think you are aware what you are asking here. LOL. This is going to be a long night for me.

To start with the stochiometric value is a purely theoretical value. To achieve a complete combustion once the fuel is ignited you need three components:

14.7 parts of air (weight)
1 part of petrol (weight)
and the right amount of time.

Time is our biggest problem in the engine. Different combustion chamber shapes will affect the flame front speed, which means that every engine reacts different. Therefore different times are needed to complete combustion and this in turn does affect the AFR.

This means we have to forget about the stochiometric value. At tickover the AFR in most normally aspirated cars is anything between 19:1 and 16:1.. The AFR will go down with increasing rpm. Most road going engines will drop to 13.5 and in some cases to under 13 for optimal power.

Again depending on the engine construction it depends on how low at what rpm range. With the PSA engines we usually have a fairly rich situation at mid range, which is unusual for other engines. Lean out and you loose power. Richen it up and you lose power too. In any case it always is a flat spot there. Many other engines behave very much different all with their own funny little stunts.

The post lambda sensor is not a primary sensor, but if it goes badly it can create some havoc. It cna lean out the engine when it signals to the engine extreme richness. Then you have in some ECU a fighting going on sending the AFR in to jo-jo mode.

To be honest what SAPL mentioned does not make sense here. However the ECU does not keep the stochiopmetric value rather than what it needs for each load factor and each rpm factor.

The flame out you see on some road cars or race cars is more likely cam related than overfueling. Obviously overfueling does help it. But every engine is being overfueld when running with standard ignition.

If the flame out would have its reason in overfueling alone, you would lose power as the fuel pushes out (volumetric) oxygen, which is missing from the combustion.
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Old 9th November 2010, 03:41   #23
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Originally Posted by CPH View Post
The flame out you see on some road cars or race cars is more likely cam related than overfueling. Obviously overfueling does help it. But every engine is being overfueld when running with standard ignition.
Mechanical and/or electronic timing, no? Isn't that the basic premise of anti-lag?
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Old 9th November 2010, 07:55   #24
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Hi,
What would be the period (in terms of time/ cycles) of this oscillation? Does it change? If so with what?

Regards
Sutripta
The waveform below is a typical narrowband sensor waveform (the blue trace). The frequency is about 1 Hz.

Name:  NBO2.JPG
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The frequency depends on how quickly the ecu reacts to the NBO2 signal, and how quickly the changes are detected by the O2 sensor - this will depend on the geometry and design of the engine.

On the various other points my response is:

Any system has to be tuned professionally, especially with powerful systems. And that statement has to hidden meaning whatsoever ! There are many accomplished tuners in the market and I respect every one of them.

The Unichip is capable of altering fueling and timing independently.

There is no way that a piggyback can replace a standalone ecu. When you want to extract the ultimate out of an engine, that's the way to go. But for street applications, piggybacks are the way to rapidly do some tuning.

The title of this thread is "how does Unichip increase performance" and I am sticking to that topic alone !
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Old 9th November 2010, 15:10   #25
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Mechanical and/or electronic timing, no? Isn't that the basic premise of anti-lag?
As this is getting into a topic, which is well over the discussion of piggybacks and will take alot of talking I answer this question when I meet you. So please remind me on this when we meet.

@ SAPL - You were digressing from the topic. And the other statement you came up with is that the Unichip is superiorr over any other system. Interstingly none of the European top tuner uses the Uni chip.

Also I do know that quite a few people binned the Uni chip because they did not get the claimed or promised results. After going to alternative ECU control solutions they got the results.

Any of my associates have decided in due course not to work on cars with a Uni chip before the owner removes it.
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Old 9th November 2010, 15:33   #26
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As this is getting into a topic, which is well over the discussion of piggybacks and will take alot of talking I answer this question when I meet you. So please remind me on this when we meet.

@ SAPL - You were digressing from the topic. And the other statement you came up with is that the Unichip is superiorr over any other system. Interstingly none of the European top tuner uses the Uni chip.

Also I do know that quite a few people binned the Uni chip because they did not get the claimed or promised results. After going to alternative ECU control solutions they got the results.

Any of my associates have decided in due course not to work on cars with a Uni chip before the owner removes it.
Hi CPH

I have nowhere stated Unichip is superior to any other system. I only stated that it is probably the most powerful piggyback ecu.

Working or a particular system is certainly a matter individual preference. looks like you have had issues with the Unichip.

All I can say is that we have got some excellent results with the Unichip Q and Q+. 2 of our competition cars (one running in the National Racing Championship and another in the National Rally Championship) are running on the Unichip and are performing well.

Would be nice to catch up with you any time you are in India.
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Old 9th November 2010, 16:57   #27
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I'm curious about the Unichip since you say that fuel and timing can be altered independently. How does it go about this? It's pretty obvious that it's tapping into more than just the MAP/MAF sensor, and that it's using one of the other sensors to adjust the values so as to make the ECU compensate and thus get the desired ign values.

What is the maximum range of adjustability of the fuelling and timing values? I assume the timing adjustment to be relative to the actual advance values in the stock tables and not the ability to adjust to an absolute value regardless of the stock tables, am I right?

Quote:
Originally Posted by CPH
As this is getting into a topic, which is well over the discussion of piggybacks and will take alot of talking I answer this question when I meet you. So please remind me on this when we meet.
Will do for sure.

Last edited by pranavt : 9th November 2010 at 16:59.
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Old 9th November 2010, 18:13   #28
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Let me get this straight.
From what I understand about ECUs in general, even with a piggyback ECU, everything related to fuel delivery and engine management is done by ECU.
All the piggyback ECU does is "lie to the ECU" to trick it to do something else as opposed to what ECU would naturally do.
A remap would mean rewriting the software inside ECU so the ECU itself does different things than what the mfr intended it to do?

Am I correct?
Or do Piggyback ECUs directly control the fuel pump/injectors etc.,
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Old 9th November 2010, 20:41   #29
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The waveform below is a typical narrowband sensor waveform (the blue trace). The frequency is about 1 Hz.

.....

The frequency depends on how quickly the ecu reacts to the NBO2 signal, and how quickly the changes are detected by the O2 sensor - this will depend on the geometry and design of the engine.
I take it that this 1 sec period is essentially independent of engine load/ speed? (Assuming that it remains in closed loop)
It would be interesting if one were to also fit a wideband, and output its value on the second beam. And other parameters, one by one.

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Originally Posted by pranavt View Post
I'm curious about the Unichip since you say that fuel and timing can be altered independently. How does it go about this? It's pretty obvious that it's tapping into more than just the MAP/MAF sensor, and that it's using one of the other sensors to adjust the values so as to make the ECU compensate and thus get the desired ign values.
Why don't we have an architecture where the piggyback sits between the engine/ environment and the stock ECU, monitoring all inputs in parallel with the stock ECU (except, I suppose lambda), and intercepting all outputs. Those which are not its concern are passed through as is. Those which are (esp. injector PW) are modified. (The delay introduced might be a problem, but given the speed difference between electronics and mechanics, surmountable). Will we not get more flexibility this way.

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Old 9th November 2010, 22:14   #30
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Originally Posted by pranavt View Post
I'm curious about the Unichip since you say that fuel and timing can be altered independently. How does it go about this? It's pretty obvious that it's tapping into more than just the MAP/MAF sensor, and that it's using one of the other sensors to adjust the values so as to make the ECU compensate and thus get the desired ign values.

What is the maximum range of adjustability of the fuelling and timing values? I assume the timing adjustment to be relative to the actual advance values in the stock tables and not the ability to adjust to an absolute value regardless of the stock tables, am I right?
.
The Unichip can intercept upto 7 signals simultaneously, including timing. Others could be TPS, fuel (MAP or MAF), boost, and so on.

Each of these signals can be mapped over a 24 x 13 matrix based on individual reference parameters.

We typically go up to 20 degrees of additional advance/retard over and above stock timing. You are right, the timing adjustment will be relative to the oem ecu's timing at that particular point. A piggyback cannot do absolute adjustment.

As far as fuelling goes, we can apply upto +/- 5 volts on the input for voltage. We can also appply corrections to frequency fuelling systems like the Cedia.

We can even simulate some signals based on some inputs. We can generate VTEC actuation, and many other such additional items such as nitrous, water or methanol injection and so on.
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