New Header Bad News, Need Advice Please
 

So the problem is:
I went down to pick up my 1990 n/a at the exhaust shop where the header was extensively modified to fit and installed. They had to bend the down pipe and lengthen the O2 sensor wire which the location is now right in front of the cat.
So I started it and let it run for a minute or two, to warm up a little. Then I was playing with the throttle a little to see how it sounds. That’s when it went wrong, it died. I restarted it and found it easy to start but now running very rich(lots of black smoke) and really rough .
So my thoughts are that the o2 sensor might have got fouled by the burning of the paint because I had repainted the whole header before it was installed. I will be going back down to the shop tomorrow since the car is stuck there. I’m just trying to get some advice since I want the shop to look at it before I start messing with it. I did not disconnect the o2 sensor since it was hard wired in. That was my first thought. So any help is much appreciated, Thanks.

Thats a strange one
 

I don't know much about the O2 sensor. Curious as to why you would think it could cause the car to die? Back Smoke usually means carbon being burned doesn't it? I have only seen that during fuel injection cleaning and such, Thanks, Scott

Because the o2 sensor ajusts the fuel/air mixture my measuring the oxygen in the exhaust, hence the name.

Ok
 

OK thats cool, but how can that lead to burning black smoke? Anyway Thanks for all your help I found my problem on the red Supra you have been helping me with the timing belt must have jumped. The belt is in real bad shape but not broken. Cracked and missing teeth. Timing marks are off by quite a bit! Has to be why it died. I will come back to this thread though and hope to learn more about the O2 sensor. I have never replaced one or had to. Thanks, Scott

you painted the inside of your exhaust? also the toyota o2 is wierd it could just be because of its placement it reads completely backward of a normal o2 i doubt it would cause this though my o2 is bad and i run 15.0 -15.7 afr at idle warm and 11.3-13.0 afr at wot 3rd gear on a 700-6500 rpm pull the shop might have just missed something or left something unplugged

I didn't paint the inside on purpose but i'm sure some paint made its way in there.

just overspray wouldnt be enough to foul your o2 its built to have carbon chunks thrown at it and its always coated with unburnt fuel and carbon

howd you like the sound before it died though?

it sounded good but cost way too much

do you know what all needed to be modified? besides the dp

make the stud holes bigger

make the o2 sensor fit right

bend the downpipe

get band clamps for connection between downpipe and header

grind the main flange to fit the head