Emissions question for fj62

[STAGE 2]

So I'm having an argument with my dad about emissions and tranny swaps. Specifically, putting an H55 5 speed into an FJ 62. As we live in California, smog testing is always an issue with vehicles so that is always a starting point for modifications.

So here's the deal. He seems to think that converting the 4 speed auto to the 5 speed manual may have an effect on emissions. I don't see how this could be possible (from my albeit limited knowledge of smog testing). Since nothing in the engine changes, the tailpipe output at any given RPM is going to be the same. The only difference is going to be in what gear the RPM is reached.

So assuming the 62 already has an engine that passes smog, swapping the auto for the H55 shouldn't make any difference correct?

 

[cruiseroutfit]

Should not make a negligible difference and depending on the type of testing equipment used and the tester, it could reduce it. For example here in Utah they used to do a motionless 1500 & 3000 rpm (could have those slightly off) test, again the vehicle was under no load. Now they do a load test with the vehicle on rollers, at I think 15mph and 35mph (would have to double check the actual numbers).

I've had some Cruisers that wouldn't pass but you could shift them down in to the next gear, let the torque of the inline 6 compensate for the lower RPM's and reduce the emissions. Slightly harder to do with the automatic which is less efficient overall. To boot most claim a mpg increase with a manual swap, while not an accurate test of overal emissions its often a sign of increase fuel efficiency in general.

As far as the systems are concerned, your correct, the manually controlled auto trans has no feedback from the motor or computer in regards to emissions that I would see having any impact.

 

[redthies]

I would have to agree. I don't see any way a 5spd could cause you to fail emissions. On a truck that old there is so little information going from tranny to engine and vice/versa. Something to be said for simplicity...

 

[BKCowGod]

Your only slight change will be with the new rolling road smog check, in which case your engine speed will be different for the 25mph portion of the test. Though I doubt it will be an issue. My jeep has an upgraded carb, free-flow cat, and changed gear ratios and it made it through just fine. You have quite a bit of leeway before you get close to failing.

EDIT: You don't mention where you are, so the rolling road may not matter to you. Yet. It is moving its way into the boonies slowly.

 

[ntsqd]

One way that a manual changes emissions is in the shifting. When an auto trans'd vehicle shifts the engine stays under partial load. Not so with a manual. There is a brief period that the engine is unloaded during a manual trans shift, and during that time the mixture goes rich. Not much and not for long, but it does happen and the EPA knows about it. A old Ford that I had used a funky valve on the side of the intake manifold that would create a huge vacuum leak just during the shifts, specifically to offset the rich tendency at those points.

In computer controlled vehicles that were offered either way the manual trans ECU can have a less aggressive timing curve. This is true for the 5.0L Ford Mustang engines. Most of the folks doing such a swap into an older car want to use the auto trans ECU for this reason, unless they plan on using a "Tweaker" in which case it doesn't matter which they use.

 

[STAGE 2]

EDIT: You don't mention where you are, so the rolling road may not matter to you. Yet. It is moving its way into the boonies slowly.

San Diego

 

[ChuckB]

If you want a direct and complete answer call these guys TLC. They are in the know :ylsmoke: HTH.