Question: 200 4R - ECM and the lock up torque converter

[dougfather]

Question

I plan to use a 200 4R transmission with my 350SBC in my 84 Grand Prix. I am doing an engine swap (was a 231 V6 with 200C). I have looked at the wiring schematic and it appears that the torque converter lockup is done by the ECM.

1) Has anyone had difficulties getting the ECM to work on an engine swap?

2) Is there and after market module I could use to make the torque converter lock up without using the ECM?

As for emissions, I plan to keep the catalytic conv, smog pump, egr, etc. As for the ECM, I am debating. I am having a hard time finding a good V8 g-body in the junkyard with all the parts I need to keep the ECM

 

[pontiacgp]

the lock up is activated by a 12 volt switch and there are aftermarket switches

http://www.americanautowire.com/product ... sories.cfm

 

[rwd_pete]

I think some 2004r's are wired diferent than others. From my experience ones that come on carburated engines have a one wire to ground hookup. I had a 2004r from an 83 T type that was that way.

I installed a 700r4 from an 86 Caprice(carburated) in a 62 Pontiac. I wired it through a vacuum switch to unlock the convertor when it accelerated and I used a cruisecontrol brakelight switch to disengage it when I braked. It worked out fine.

Also the lowest factory gear that I have seen behind a 2004r is 2.78. Some of the V6's came with 2.41. I don't know if could handle the overdrive ratio.

Pete

 

[pontiacgp]

also the lowest factory gear that I have seen behind a 2004r is 2.78

I have a 305 with the 200 R4 and the factory gear is a 241

 

[rwd_pete]

Wow. In overdrive that puts you down around 1.6-1.7.

When I put the 700r4 in the Pontiac it had 3.08's, 27"tires and a 400sbc with a Crane 272 H cam. When it went into overdrive at low speeds it wasn't happy and droned pretty bad. I installed a toggle switch so that I could leave the lockup disengaged around town.
I guess with a stock cam you may be able to get away with it.

pete

 

[pontiacgp]

I'm running slightly taller tires and according to my GPS my speedo at 50 mph is off by 5 mph. If I'm in overdrive it'll kick in around there I don't slide it into overdrive till 65. I like the gears on the highway, I have the stock tach in the car and it's not accurate so I can't tell the exact revs but they're not high.

 

[ryanwitski]

I am clueless with transmission stuff and I had a problem with my ECM and carb. Instead of getting it fixed I bought a carb for an 87 olds and a distributer w/ vac. adv. I did not know my computer locked up my torque converter. does it matter on a 3 speed auto or am I confused? Where are the wires to put on a switch. Thanks learning more each day!

 

[rwd_pete]

If you are talking about THM350 3 speeds. some lockup and some don't as I understand. Early ones didn't. Probably after around 1980 they did.

If it's a lockup convertor now, there will be an electrical plug on the side of the transmission.

If the car originally had a lockup convertor, the wire(probably green) is usually run through a vacuum switch mounted on the top of the driver side inner fender. A hose goes to a vacuum source(carb). Then the wire goes down to the trans electrical plug. When you are cruising, vacuum is high, the switch closes, and the convertor locks. When you open the throttle, vacuum drops and the switch opens, convertor unlocks.

 

[ryanwitski]

oh okay I have an 84. I'll took for it, thanks!

 

[Chevyman85]

If you have an '84 then you most deffinatly have a lock-up converter. You can also feel it lock up at freeway speeds. Its a nice feature for gas mileage but it makes the transmission and converter weak.