Wideband exhaust location

what would be the best place for a wideband bung on a standard mk2 8v exhaust? Would the beginning of the mid section after the downpipe be too far out or does it to be on the downpipe?

 

I'm not 100%, but I'd have thought you want it on the single pipe at the end of the down pipe, ideally. If you have it on the split section, you're only measuring one half of the engine.

 

Good point, so there shouldn't be much difference if fitting it to the beginning of the mid pipe then as its only a couple of inch further down the exhaust, anyone else think thats not a good idea? The main reason I'm hoping the mid pipe wont be a problem is because it will be easier for me to remove from the car or maybe even get a straight through replacement and fit the bung before refitting onto the car.

 

If you read the manual of your wideband, it should tell you. I've read that turbo cars shouldn't have the sensor on the outlet of the turbo as heat can damage it. Around a metre away downstream is recommended.

 

I have yet to buy the sensor but it will be a bosch one. Also the car is not going turbo until well after Christmas. Hopefully the MS will be in and running before Christmas.

 

Can't see why not, but maybe more technical folks will chime in...

 

Toyotec sometimes uses a portable sensor for mapping that clamps to the tailpipe. While this is further away than if installed permanently in the vehicle / factory position, it is still effective as a tuning aid. Steady state wouldn't matter as you can assume the mixture is fairly constant & wide open throttle has high gas flow.

Beginning of the "mid pipe" will be fine.

 

i would say on the pipe that come from cylinder number one, as that cylinder will inevitable get more air than the others, so if its for mapping purposes map cylinder 1 to be safe, the other will be a tad richer but safe all the same

 

I don't know about the 'best' position along the exhaust system, but I would have thought you're okay once you've got past the bulkhead; i.e. go somewhere beteen bottom of bulkhead and gearstick area. For instance the G60 Syncro downpipe has the bung right at the bottom of it where it mates to the cat / cat bypass section.

Also of great importance is the orientation of the lambda sensor. Basically, ensure it is at least ten degrees above horizontal to ensure water doesn't collect into it. (That's based on information from my old Zeitronix kit.) In the G60 Syncro downpipe, the factory lambda sensor bung is right on top so the sensor is mounted vertically pointing down, which is probably the most ideal. However in practical situations it can be tricky finding an area where you have room for the lambda sensor. On my 16V G60 which has a stainless four-branch, I put the bung on that connecting piece that adapts the four-branch to the rest of the system. Ensuring that the back of the sensor was tilted up by at least ten degrees, I ended up making a square opening in the transmission tunnel heatshield to allow the back of the sensor room to poke into.

 

thanks for the info guys. Im glad the mid pipe is acceptable as I am being a lazy git and dont fancy removing the downpipe just yet.

 

Is it going to be mapped on a dyno?

 

I think it will be a combination of road and dyno. I have only just realised that a wideband controller is needed for MS where as before I thought the lambda wired up straight to MS, luckily I didnt waste money on buying a lambda sensor on its own.

 

Get yourself a gauge to go with it too. It helps if you are tuning yourself.

 

If you are going on the dyno it doesn't matter where you place it..

and yeah better to get a gauge as well

 

It depends what youre doing with it. The WB sensors work a long way down the exhaust, theyre fitted after the cat on a mk4. So if youre just using it for monitoring then its not too critical.

However if youre using the narrow-band output from the WB controller to correct fueling in closed-loop mode in the ECU then youd be better of getting closer to the engine IMO. It doesnt matter if its only working on 2 of the 4 cylinders, as long as theyre all matched and theres no faults.

Wont a mk 3 or 4 ex manifold with a boss fit on one of those? The mk3 Spi exhaust manifolds should fit and thay have a boss, probably not good for the power though

 

I am about to purchase my wideband kit. I was going for the Innovate LC-1 but I prefer the look of the Innovate MTX. The MTX has some sort of integrated controller and has outputs for megasquirt etc... Before I order can anyone advise me if this MTX kit is ok to go for or if I should stick with the LC-1

MTX below

 

I use the LC-1 on my track car, the MTX wasn't available when I fitted my megasquirt. If I was doing it now I'd probably go for the MTX. It looks pretty good and simpler to install than the LC-1.

My sensor is installed vertically just after the joint in my 4 branch. the wire routes through a hole in the transmission tunnel into the car, this is fine on my track car but might not be suitable for a road car:

 

Steve's solution above is EXACTLY the same as mine on my 16V G60. Even the four-branch looks like it could be the same as mine. I put it on that connecting piece as Steve as, and then I made a hole in the shield. The only difference was that mine is positioned at a more intermediate angle rather than fully vertical.

Also, like a complete knob end, I welded in the boss and afterwards realised that a ring piece that is loose on the tube needed to have been one side, not the other. So I had to cut the feckin' tube and re-weld it.

 

LC-1 has an external controller for the heater circuit and sensor to gauge signal.
MTX has this in the gauge, similar to a LM-1 or LM2.

 

I'm not familiar with the mtx. If you get the LC1 and the serial XD16 gauge you will have two analogue outputs to play with, one simulated narrow-band output for the ECU and the other for anything you want like; logging, different AFR, etc, etc. I have found two outputs valuable while experimenting. You can even have a system which automatically switches between race and cruise AFRs