V6 Petrol - suspect boy racer go faster mod

[apole]

Hi,

When trying to find a place to install an inverter I discovered what looks to be a DIY cheapo boy racer add on:



Basically these are common on ebay etc, and it's a resistor that changes the signal from an engine sensor to make the engine run a bit richer. This could be a MAF reading, or maybe engine coolant temperature.

It has been installed with scotchlocks so I can't believe it's likely to be a mazda dealer fitment. I may well be wrong here but it's a fairly common thing used to "enhance" the performance of an engine.

Anyway, not impressed with the dodgy wiring, or the idea that I maybe using more fuel than needed, I felt brave and decided to try and remove it. Before I do this I decided to "bridge" it out of the circuit by using thickish wire around the resistor, then just in case I might need to back track I put in a switch. So when the switch is on, the least path of resistance will be down the temp black wire (so no resistor in circuit), when off it's back to as it was.

This is all temporary and no I hate scotchlocks but for the purpose of a test on wiring that will hopefully soon be coming out I used them for speed.



So over the next few days I'll run and see how it goes.

Hoping this isn't something I'll regret but I can't see that it should be there.

[waycar8]

hmmn, never heard of them, wonder if mines got one as it does seem to run a bit rich wil have to go have a nosy.

keep us posted

[bigdaddycain]

hmmn, never heard of them, wonder if mines got one as it does seem to run a bit rich wil have to go have a nosy.

keep us posted

I thought yours was diesel wayne?

[waycar8]

, yes it it , didnt have one anyway, maybe thats the reason

[g8dhe]

Can you identify the plugs and/or colour of wires it actually connects to ?

[apole]

Hi,

From memory it was a green wire with a red stripe that it was tapped into.

I've done some web research, all comments on these things are negative. Most popular thing it to tap into MAF/IAT sensor and alter it to make ECU think engine running cold so advances timing and enriches mixture.

It's in the garage monday so I'll ask the bongo specialist whilst I'm there.

Keep you posted.

[g8dhe]

There is an R/G (Red/Green) wire from the PCM that goes to a resistive sensor mounted at the Top N/S rear of the engine.
There is also a G/R (Green/Red) wire that goes up to the display console and into a module that has no symbol just a load of Japanese writing but it also has a link to a solenoid on the exhaust system - that sounds a bit like the cold start system ?
Make of that what you will!

[missfixit70]

Apole has a v6 if that makes a difference Geoff

[g8dhe]

AH yes V6 it does say that in the title doesn't it Been in front of the screen to much today
Right for a V6 there is a LG/R (Light Green/Red) which goes to a resistive sensor at the Front, Top, Nearside of the engine and is part of the Injection wiring loom.
and there is a G/R (Green/Red) which goes via the module in the console again to an inductive sensor on the drive shaft so I would guess a speed sensor, again part of the Injection wiring loom.

[cheffy34]

Im confused surely by making it run rich will not improve performance by chucking more fuel in won't make it go quicker with out the relevant air, spark etc, the unburnt fuel will just end up in your exhaust where's TGP he will know the answer


Roll on the pretender


Dar

[The Great Pretender]

As Apole said, it attempts to richen up the fuel. It's a crude tool to fool the ECU, it may alter the sensor from the air temp, water temp or preferably the lambda. The ECU will after reading all its inputs use the Oxygen sensor (if closed loop) to adjust fueling to 14.7/1, however for maximum power the air/fuel ratio needs to be 12.5/1.
Hope this helps.

[cheffy34]

MMMMMMMMMMM HAVN'T GOT A CLUE all i understand is go faster But interesting but won't it fail emmisions


Dar

[apole]

Hi,

Just did a quick measurement today, reading on that wire flicks between 16.9Mv and 1.8 volts about 2 per second, those are averages.

Suspect it's the reading from the MAF/IAT sensor as the O2 sensor is between 0.1 and 0.9v.

Anyway I'll monitor the MPG etc, seems to run a bit smoother but that isn't scientific.

I'll also try and trace the wires to find out where they are from.

Keep you posted.

BTW if you google the MAF resistor mod there is nothing posetive to be said about it, crude attempt to overfuel which doesn't really work.

Andy

[cheffy34]

Hi,

Just did a quick measurement today, reading on that wire flicks between 16.9Mv and 1.8 volts about 2 per second, those are averages.

Suspect it's the reading from the MAF/IAT sensor as the O2 sensor is between 0.1 and 0.9v.

Anyway I'll monitor the MPG etc, seems to run a bit smoother but that isn't scientific.

I'll also try and trace the wires to find out where they are from.

Keep you posted.

BTW if you google the MAF resistor mod there is nothing posetive to be said about it, crude attempt to overfuel which doesn't really work.

Andy

I wish i could find things like that apole beyond my diagnostic skills I still can't get my head around it. Is this what you were talking about in that other thread connected to the ecu I never did get around to looking must go back and have a look but i'm not affraid to say computer stuffs scares me I wouldn't have even noticed something didn't look original if you understand me unless it is obvious, could that be why you had idle issues or was that something else I'm off to google


Dar

[apole]

Hi Dar,

Basically the ECU uses signals from various sensors around the engine to adjust things like the timing and fueling to the engine. These sensors include coolant temp, O2 sensor, MAF, IAT (mass air flow / intake air temperature).

It is possible to confuse the engine into adding more fuel and or advancing the timing. This is a crude way of trying to get more performance, but in most cases it doesn't do anything except waste fuel.

On mine I noticed that one of the wires going to the ECU had a fuse holder grafted into it. Now theres no way that is likely to be standard, and when I opened the holder it had a resistor in there.

It will take some time for me to build up a picture as to if isolating this has changed my MPG, assuming of course that my mod has worked.

I'm pretty sure with all the research I've done that this is one of those cheap mods and that removing it will do no harm.

One example of write up about it here:

http://www.qcwo.com/technicaldomain/?p=64

http://reviews.ebay.co.uk/The-Truth-Abo ... 0004700921

Keep you posted.