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The LX9 swap Grand Prix has been sitting for the past few months, waiting for completion of its tune. We paused for winter since the roads are all mucky.
The #1 priority for this car is to pass emissions in the spring. It bombed the test several times last year. The way the law works, is that when it is due for registration renewal it will be denied – so I do still have some time on the clock.
On its 2nd most recent test, the NOX was way too high, but CO and HC were within limits. On the latest test I had added an EGR valve and a new (aftermarket) 3 way cat converter. The NOX passed (but just) and the CO and HC exceeded the limits. It’s had more tuning since then, and has more to come before a re-test.
I have 3 things on my minds though. First, a ton of cars run more than one catalytic converter inline. I have cat converters just lying around. Would I only stand to gain from adding one? Yes, I know more restriction = less performance but this is a daily driver so I don’t care. So, that said would adding a second cat be beneficial at all? I’d move the primary cat as far forward as possible for quicker lightoff and the second one maybe 6 inches behind.
Second thought, I had to fabricate an EGR tube and it is much smaller diameter than an OEM EGR tube – I’d guess about 3/8” inside diameter. Is the flow adequate enough or would I benefit from using an OEM size tube? Would using a larger tube bring down the NOX emissions?
Third thought, air injection. The original motor had it and I tossed the pump since the 3400 manifolds I’m using don’t support air injection. I have an F body air pump that I could hook up to a catalytic converter with an air port. Would I benefit at all from that? I know they only run when the engine is cold, but I could wire it to run continuously just for the e-test if it has the potential to bring down any of the numbers.
The #1 priority for this car is to pass emissions in the spring. It bombed the test several times last year. The way the law works, is that when it is due for registration renewal it will be denied – so I do still have some time on the clock.
On its 2nd most recent test, the NOX was way too high, but CO and HC were within limits. On the latest test I had added an EGR valve and a new (aftermarket) 3 way cat converter. The NOX passed (but just) and the CO and HC exceeded the limits. It’s had more tuning since then, and has more to come before a re-test.
I have 3 things on my minds though. First, a ton of cars run more than one catalytic converter inline. I have cat converters just lying around. Would I only stand to gain from adding one? Yes, I know more restriction = less performance but this is a daily driver so I don’t care. So, that said would adding a second cat be beneficial at all? I’d move the primary cat as far forward as possible for quicker lightoff and the second one maybe 6 inches behind.
Second thought, I had to fabricate an EGR tube and it is much smaller diameter than an OEM EGR tube – I’d guess about 3/8” inside diameter. Is the flow adequate enough or would I benefit from using an OEM size tube? Would using a larger tube bring down the NOX emissions?
Third thought, air injection. The original motor had it and I tossed the pump since the 3400 manifolds I’m using don’t support air injection. I have an F body air pump that I could hook up to a catalytic converter with an air port. Would I benefit at all from that? I know they only run when the engine is cold, but I could wire it to run continuously just for the e-test if it has the potential to bring down any of the numbers.
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