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Old 5th July 2010, 12:06   #1
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Default DIY : 2 rupee performance modification for the Skoda Octavia 1.9 TDI. Works too!

I ve just done a really cheap mod on my octy. we soldered a 2.2K ohm 1/4 W resistor on the number 7 pin wire of the injection fuel pump connector[ yellow blue/ green] and also a similar resistor on the number 1 pin wire of the MAP sensor both were properly insulated after that. The purpose was to intercept and alter the readings fed to the ECU of fuel and IAT and lower them substantially.Can be checked on VCDS. The resistors cost about a rupee each. I ve noticed a marked improvement in performance.
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Old 5th July 2010, 12:38   #2
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What? A 2 rupee performance mod?? Could you please elaborate a little more.
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Old 5th July 2010, 18:25   #3
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Yup, sounds too good to be true.Each 2.2K ohm resistor will cost you about a rupee, Plus the cost of soldering them to the respective wires. Insulate, and you r good to go.
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Old 5th July 2010, 18:47   #4
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Quote:
air870 : The purpose was to intercept and alter the readings fed to the ECU of fuel and IAT and lower them substantially.

I ve noticed a marked improvement in performance.
@Air870 : What & how did the readings change ?

What exactly is the difference in the performance ? How did you measure it ? And what ALL are the changes ?
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Old 5th July 2010, 21:31   #5
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This is sold in a fancy box and as a fancy thirdmarket addon; well known here as the Tri Phase module

What you've done is artifically lower the IATs, so the ECU will inject more fuel thinking that the air going in the cylinders is colder, and therefore denser. This makes the engine run a little richer.

Last edited by pranavt : 5th July 2010 at 21:35.
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Old 5th July 2010, 22:15   #6
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Infact this is what most of the Fancy boxes sold do.Also this is what is also now being done in the name of Remaps for all petrol engines.There is no remap.Its just a series of jobs done to fool the ECU.

This is just the first step in fooling the ECU.

In fancy Boxes and Remaps the ECU is fooled into thinking that the RPM is 500 lower than what is actual.and hence it over revs at the top end of the rev limit.And this they call a remap.
This is the reason that these so called remaps now a days are so generic in nature.
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Old 5th July 2010, 22:21   #7
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Quote:
Originally Posted by pranavt View Post
This is sold in a fancy box and as a fancy thirdmarket addon; well known here as the Tri Phase module

What you've done is artifically lower the IATs, so the ECU will inject more fuel thinking that the air going in the cylinders is colder, and therefore denser. This makes the engine run a little richer.
Yes, I guess what a resistor does is to lower the values of the input, which inturn makes the ECU "think" that the air/fuel is less and pump in more fuel, which improves performance a bit, but then, it will definitely lower efficiency.

IMO this same effect can be achieved by tuning the ECU to deliver more fuel.
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Old 5th July 2010, 22:26   #8
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Quote:
Originally Posted by navpreet318 View Post
Infact this is what most of the Fancy boxes sold do.Also this is what is also now being done in the name of Remaps for all petrol engines.There is no remap.Its just a series of jobs done to fool the ECU.

This is just the first step in fooling the ECU.

In fancy Boxes and Remaps the ECU is fooled into thinking that the RPM is 500 lower than what is actual.and hence it over revs at the top end of the rev limit.And this they call a remap.
This is the reason that these so called remaps now a days are so generic in nature.
If tuners are doing this in the name of remaps, then it is the tuners who are to blame. Remaps are when the fuelling and ignition maps/tables are changed by hand after doing datalogging. There is a lot more to remap, but these two are essential for it to be called a remap.

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Originally Posted by dhanushs View Post
Yes, I guess what a resistor does is to lower the values of the input, which inturn makes the ECU "think" that the air/fuel is less and pump in more fuel, which improves performance a bit, but then, it will definitely lower efficiency.

IMO this same effect can be achieved by tuning the ECU to deliver more fuel.
No, the resistor reduces the voltage across the IAT sensor wire (Almost all sensors are linear 0-5V), which in turn makes the ECU think that the air temperatures of the air going into the intake are lower. If the temperature of the air is lower, the density is higher (more air going into the cylinders). The ECU then compensates for this by looking up its IAT correction tables and injects marginally more fuel into the cylinder.
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Old 6th July 2010, 09:18   #9
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The resistance in parallel, will give the ECU lower values from the senors , cheating it and making it think that the air temp is lower, similarly it will tell the ECU the fuel pressure is lower than factory set and make it run at Higher pressure. It works like the tri phase does. But since it's a passive setup, if and when the actual reading from both alter to give different reading, like fuel pressure increase due to FPR failure , the system will never now the difference and it will be an expansive repair.
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Old 6th July 2010, 09:46   #10
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Todays systems are closed loop, i dont think any one can have significant gains unless a remapping is done the way pranavt mentioned, looks like another claim to fame. no offenses but its hard to believe. As per me the tri phase module is useless.

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Old 7th July 2010, 10:46   #11
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Air870, I think you got for 2 bucks what others pay 10 grand for

1. Pictures?

2. How about dyno'ing the car to gauge any increase in BHP, however marginal?

3. Do you have access to a G-tech to time the 0 - 100? If not, we can arrange for the same. Will be fun to time the improvement.

Last edited by GTO : 7th July 2010 at 10:48.
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Old 7th July 2010, 10:58   #12
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Quote:
Originally Posted by GTO View Post
Air870, I think you got for 2 bucks what others pay 10 grand for

1. Pictures?

2. How about dyno'ing the car to gauge any increase in BHP, however marginal?

3. Do you have access to a G-tech to time the 0 - 100? If not, we can arrange for the same. Will be fun to time the improvement.

I had similar queries in mind.

Also, what are the risks involved in a set-up like that?

Really no offense but this seems too good (and too inexpensive) to be true.

Hence, a detailed explanation plus some concrete data to gauge the effect in performance will be highly appreciated.

Lastly, Is a similar set-up likely to be as effective on a petrol engine? If that is the 'set-up' in question is effective at all.
I am not in a mood to experiment on my Baleno but it would not hurt to try on an old Alto we have.


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Old 7th July 2010, 12:54   #13
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The improvements would be a little more for Diesel cars. For petrol vehicles, they would range from none to marginal. Just dumping more fuel isn't going to radically improve performance. And a fun fact is that the engine makes more power when running leaner but it runs hotter as well. Law of diminishing returns applies, as usual.
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Old 7th July 2010, 16:24   #14
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Real remaps are proper intellectual property. Four dimensional maps involving fuel, ignition, cam phasing and valve timing is a serious amount of work.
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Old 7th July 2010, 16:33   #15
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I have read about this mod on the net long time back, but was always afraid to do. Now i know its efficeint.
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