ls/200r4

[D-adams]

I'm needing some help please. I have a 1972 c10 that has had the 5.3 with the 200 r4 behind it for 6 years now working wonderfully. This spring I pulled the motor and done a cam swap and upgraded the stall converter. I sent the ecm out to get tuned and when I got it back it will stall out every now and then now. Mainly coming to a stop sign or backing up. When I hook my scanner up to it, it says its in 3rd gear when its in park. I also noticed since the ecm has been tuned that my speedo on the dash works but my electric speedo I run off my OBD2 does not. Could anyone tell me what tells the ecm what gear the tranny is in? The tuner believes the ecm is cant adjust the rpms for what gear it is in because it dont know. And iIm not sure why I all of the sudden dont have a working digital speedo.

[LS short box]

I would ask the same question over on LS1tech.com

[cj847]

I am definitely not a tuner but none of this makes sense to me.

1) A 200r4 can't tell the computer anything. I thought (don't know) that the tuners set the ecm to act like its connected to a manual transmission when using a non electronic automatic trans.

2) I thought (don't know) that the tuner has to input your rear gear ratio into the ecm so that it could calculate your speed off of the output shaft of your electronic transmission via the vehicle speed sensor (which you may have but may not be sending the correct signal - ecm programmable pulse). I am curious how you were getting an electronic speed signal before.

3) It seems your tuner would have only had to adjust fuel tables for your cam and wouldn't have changed anything else???

are you getting any CEL's?