4L60e to 700r4 swap

[1962 Panel]

Quick question for anyone who is familiar with how a 4L60e communicates with the motor in a 1993 c1500. I drove a 1993 c1500 with a 350 for a while that needed a transmission when I got it. I knew it had a 4L60e in it but I was unable to find a reasonably priced unit so I put a 700r4 in it that I got for a steal. The truck would sometimes idle rough and stall when put into gear but I always assumed it was a bad intake gasket because it did the same thing before the trans swap. Eventually I ended up selling the truck to a friend of mine and he replaced the gasket, and confirmed that it was leaking. Long story short after redoing the intake it runs even rougher apparently and stalls every time it is put into gear unless you two foot it to keep it going. My buddy insists that it is running like crap because the trans isn't communicating with the ecm. I don't think this can be possible because the truck idles rough even when its in park or neutral. I also don't see how lack of signal from the trans could cause it to stall when put into gear.

Can anyone weigh in on this issue because I'm trying to help him figure this out because I am the one who sold him the truck. Thanks in advance

[b454rat]

The don't it would a difference. The ECM thinks there's a tranny there, but not getting any feedback. So it would throw codes but don't see how it would affect the way the engine runs. Also isn't 93 the "4L60" andnot the 4L60E? Basically the same as the 700?

[Bigdav160]

No. Pickups were the first to get the 4L60e in '93. Cars stayed with the 4L60 until '94.

I don't think the mismatched transmission is causing the running issue. There is something else going on. Still, if it were me, I would go back with the 4L60e. The guts are the same as the 4L60.

[1962 Panel]

Thanks for the replys guys, pretty much backed up what I was thinking. It does always have about a half dozen trans codes stored all the time but only ever had one engine code "unable to find correct idle speed" or something to that effect which I always attributed to the vacuum leak since I replaced the IAC and it didn't help the problem. Technically the transmission I swapped in was a 4L60 being that it was from a 92 truck, but identical to a 700r4 other than the name GM gave it. And my friend is considering going back to the 4L60E anyway, because he is convinced that is the problem, but I suppose it would be better in the long run to have the electronic control back and be able to lock the torque converter properly and so on.
Thanks for the insight!

[bonnieclyde100]

Originally Posted by 1962 Panel

Thanks for the replys guys, pretty much backed up what I was thinking. It does always have about a half dozen trans codes stored all the time but only ever had one engine code "unable to find correct idle speed" or something to that effect which I always attributed to the vacuum leak since I replaced the IAC and it didn't help the problem. Technically the transmission I swapped in was a 4L60 being that it was from a 92 truck, but identical to a 700r4 other than the name GM gave it. And my friend is considering going back to the 4L60E anyway, because he is convinced that is the problem, but I suppose it would be better in the long run to have the electronic control back and be able to lock the torque converter properly and so on.
Thanks for the insight!

if it stalls worse after a gasket change you might want to check your map sensor . it might be choking the engine when in gear .