02-19-2020, 06:41 PM
(This post was last modified: 03-27-2020, 08:44 PM by Von.
Edit Reason: New information
)
I have a 94 Suzuki Sidekick JLX 4x4 with a 1.6L 16v engine. The PO removed the catalytic converter for some reason and now is straight piped. I installed the Doug Thorley 4-2-1 header on the vehicle for it came with it when bought but was never installed. The header will not meet with the existing mid pipe and the flange is different. Before I cut and weld the proper flange to the mid pipe should I get a cat converter and install. I’ve heard the EGR needs the back pressure from the cat to function properly or it will throw a 51 code. Is this true for this model and if so should I put the cat back in? I have no emissions laws where I am from so this question is purely to make sure it is running properly.
Thank You
Edit: this thread started from a simple question regarding if I should re-install the catalytic converter that the PO removed prior to creating a custom exhaust setup to fit the Doug Thorley 4-2-1 headers. Prior to the header install I changed the water pump, timing belt, set the valve lash, replaced the spark plugs, all fluid, air filter, O2 sensor, and all popped or wrong amp fuses. After all this work I got the cat and installed. I went to fire it up and it would crank but not start. I was super worried for with all that work at once there could have been a number of things that could have gone wrong. I looked around the engine bay and found that the PO not only removed the cat but removed the EGR from the engine with all vacuum and wire still connected. I thought that this could be the reason why it did not start. I was re assured from kickfix that it would still start with the EGR in this state. I continued to look for issues and found that the IG Coil fuse under the dash was popping every time I tried to start the vehicle. I then disconnected the O2 sensor on a whim and the big Lexi fires right up (still with EGR disconnected). I’m now at the point where I’m trying to figure out the correlation between the O2 sensor and the IG Coil fuse.
Edit edit: I still don’t know why a bad O2 would cause the IG fuse to pop on startup but I replaced the O2 with a different one (Walker) and it fires right up. I have not lost another IG fuse to this point many miles later. Long story short, you need a functioning O2 sensor in this vehicle or you could pop an IG fuse. You should have a cat converter installed if you want to have enough back pressure to operate the EGR. Also make sure the pathways to the EGR are not clogged. As far as the Doug Thorley headers I’m not sure why they made them the way they are but they have a flange at the bottom pipe going towards the cat that has a conical gasket that looks to fit the flange for the down pipe I removed the only problem was that with the header the downpipe is basically removed entirely. The cat has a flat surface for the flange. These 2 flanges do not meet up and do not work together. The Doug Thorley header is not an exact fit bolt on header to the exhaust. What I did to fix this issue was cut the flange from the old down pipe and weld it to a new piece of pipe going to the cat. This way it fit like a conical gasket and socket flange. Also the rubberized gasket that came with the older kit melted so I got a new lead replacement Doug Thorley gasket that now come in the new kits from from trail tough my local shop. The lead has not yet melted or warped. I hope this helps someone in the future.
Thank You
Edit: this thread started from a simple question regarding if I should re-install the catalytic converter that the PO removed prior to creating a custom exhaust setup to fit the Doug Thorley 4-2-1 headers. Prior to the header install I changed the water pump, timing belt, set the valve lash, replaced the spark plugs, all fluid, air filter, O2 sensor, and all popped or wrong amp fuses. After all this work I got the cat and installed. I went to fire it up and it would crank but not start. I was super worried for with all that work at once there could have been a number of things that could have gone wrong. I looked around the engine bay and found that the PO not only removed the cat but removed the EGR from the engine with all vacuum and wire still connected. I thought that this could be the reason why it did not start. I was re assured from kickfix that it would still start with the EGR in this state. I continued to look for issues and found that the IG Coil fuse under the dash was popping every time I tried to start the vehicle. I then disconnected the O2 sensor on a whim and the big Lexi fires right up (still with EGR disconnected). I’m now at the point where I’m trying to figure out the correlation between the O2 sensor and the IG Coil fuse.
Edit edit: I still don’t know why a bad O2 would cause the IG fuse to pop on startup but I replaced the O2 with a different one (Walker) and it fires right up. I have not lost another IG fuse to this point many miles later. Long story short, you need a functioning O2 sensor in this vehicle or you could pop an IG fuse. You should have a cat converter installed if you want to have enough back pressure to operate the EGR. Also make sure the pathways to the EGR are not clogged. As far as the Doug Thorley headers I’m not sure why they made them the way they are but they have a flange at the bottom pipe going towards the cat that has a conical gasket that looks to fit the flange for the down pipe I removed the only problem was that with the header the downpipe is basically removed entirely. The cat has a flat surface for the flange. These 2 flanges do not meet up and do not work together. The Doug Thorley header is not an exact fit bolt on header to the exhaust. What I did to fix this issue was cut the flange from the old down pipe and weld it to a new piece of pipe going to the cat. This way it fit like a conical gasket and socket flange. Also the rubberized gasket that came with the older kit melted so I got a new lead replacement Doug Thorley gasket that now come in the new kits from from trail tough my local shop. The lead has not yet melted or warped. I hope this helps someone in the future.