tranny swap

[87blazerproject]

does anyone out there know if it is smog leagal in ca to swap a 700r4 with a sm465?
i have an 87 blazer that is my daily driver and all the parts for the conversion, i just dont know if it is legal

 

[toomany]

I know CA has some weird smog laws, but I think you can do this swap without a problem. The trans doesnt have much to do with emissions. But I'd wait for someone who lives in CA to pop in, just to be sure.

 

[Burbdood 74]

Assuming you have EFI since it's an 87, I *think* the ECM controls the lock-up on the tranny and without the input coming from the trans, it could throw your system into shock. If you can find an 87-95 TBI truck with a manual tranny, just grab the ECM from it and your parameters will stay the same.

Again, I'm not 100% certain more like 90%.

 

[Russell]

The ECM does control the torque converter solenoid, but it receives no electrical input from it, and doesn't look for any drop in RPM, increased engine manifold vacuum or anything similar to make sure it is working.

You will not have any trouble with the ECM setting any codes when you get rid of the 700r4, but I would reccomend making the switch to a manual trans PROM anyways. They have different timing characteristics & TPS positions based on if the engine detects if you are downshifting or not. Also, it ignores the park / neutral input since a manual trans truck doesn't have one, and idles the engine at 800 rpm instead of 650 - 750 rpm.

 

[dyeager535]

X2. Since you get smogged, it's *possible* the different timing/fueling parameters could lead to excessive emissions. It'd be easy enough to have someone burn a "manual trans" TBI chip, although that may cause just as much problems, IF GM used a different cam for each.

Isn't there someplace you can call in CA that can answer questions like this? IIRC there is, and you need to get your answers straight from the horses mouth, as they are the ones who ultimately say yes or no.

 

[Burbdood 74]

The ECM does control the torque converter solenoid, but it receives no electrical input from it, and doesn't look for any drop in RPM, increased engine manifold vacuum or anything similar to make sure it is working.

That makes sense. I'm still kind of a newb when it comes to computer controlled vehicles.

Not to hi-jack, but the P.O. swapped out the 700R4 in my 88 Suburban and put in a TH350. Should I be worried about my ECM?

 

[dyeager535]

The 300 or so RPM difference between lockup and non-lockup is probably well within the amount the ECM can compensate for the expected vs. actual load on the engine.

That'd be my take anyways. The difference in load between auto and manual is the torque converter. Although GM installed tens (probably hundreds) of different spec torque converters in the trucks, none but MAYBE diesel are so different from each other that the ECM can't easily compensate for the different characteristics.

Timing (and I'm sure base fuel, so remember, fueling isn't using O2 when the engine is cold) is quite a bit different between manual and automatic PROM's. Although timing is also "fluid" to a degree with EFI, if the engine starts to knock, EFI takes timing out, which would really hurt in an emissions test.

Probably overanalyzing this, but the ramifications to the system are quite large when making even minor changes, whether the ECM is able to compensate or not. Since this is going to be tested via emissions, you are going to want it running as optimally as possible.