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custom making downpipe ?

3K views 31 replies 14 participants last post by  dcr99vig 
#1 ·
i am currently custom making a 3 in down pipe and full exhaust for my 99 viggen. my ? is, is it ok to extend the o2 sensors wires to reach a new location? thanks
 
#2 ·
If you're talking about cutting them and soldering or something, you can do it, but if they are not done well, you may get improper voltage reading to the ecu which will affect air fuel ratio.
I would try to keep match the locations so you don't have to do this.
 
#6 ·
they would still be in the same locations. its just the rear o2 is about 6 inchs back further now. i was planning on soldering them then heatshrinking the wires. also i like fabrication work and have all the tools to cut and weld it. so i decided to give it a go and make my own. the front bends were a lil tricky but i got them to work.
 
#7 ·
The way I read it the wire length is important to keep the right resistance and when you buy a universal bosh unit, they make a big deal out of making the wire length exactly the same as the stock harness.

That tells me the wire length does effect ohm resistance and that is how the ecu interprets a/f and egt and everthing else and its very important to have that part of the system working properly. I would try to keep it in a spot where the stock wire harness will reach.

John
 
#11 ·
I have been told that since O2 sensors are sealed sensors, the only way for them to release air pressure as the air expands inside them is through the wires. Soldering them may affect that and cause some other issues. Im not sure what. I thought someone made extension harnesses. Or why not try and make your own harness? Get a few matching sealed connectors, crimp the connectors in and try that.
 
#13 · (Edited)
anyone else tried to make custom downpipe?

lous' custom makes and fits it for ~$400
GS sells it for 472+shipping+my time for fitting=a lot of money

There are bunch of $40 mandrel bent 3" dp's for hondas on ebay. i'm thinking about getting one or two and welding it into a straight one, w/out cat.

or getting this integra dp below, welding extra o2 sensor and hoping it will be long enough for my ss exhaust :)

advices?


vs
 
#25 ·
anyone else tried to make custom downpipe?
I've made several, just buy some bends, a flex section and a cat.

Like I said before, the aft-cat O2 sensor can be relocated to run down the back of the block and you won't have any issues with the wires reaching.

But, if you don't have a welder or someone who will weld it up for free then you really aren't going to save much versus buying one that is pre-made for a 9-3.
 
#28 ·
it wound up working out good rerouted the o2 and it was fine. making the pipe wasn't too difficult. used two u bends some straights and a cat. still had a few bends left after but i plan on running a full three inch so i will wind up using them. i still wish i had the money for the gs dp. oh well
 
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