1993 Honda Accord automatic idle jumps to 1200 rpm when put in gear
 

Step just got this car had bad transmission, sent off tcm and had new one made, replaced transmission and when we tested it the Rpm would go from 600 rpm to 1200 rpm when put in gear. Have replaced speed sensor,ICV and TCV no help. Does anyone have any ideas. I am leaning toward TCM sending wrong signal when put in gear. Any suggestion would be greatly appreciated. Thanks

Welcome to HAF.

I've moved this to General Tech. Questions like this do not go in the DIY Section, there is a sticky at the top stating this.

What is the rpm in Park once the engine is at normal op temp?

The idle is around 600 rpm when car is at normal operating temp. I am stumped just dont know what else to look at and the company that built the
tcm says that a certified mechanic has to say there is something wrong with
TCM before they will honor warranty.

Some things to check: AT throttle cable tension. It should begin to move the AT control arm at same time throttle plate begins to open.

If you have AC, does the cycling begin when AC load is added?

Problem sounds like system is trying to compensate for load addition, but over running. Suggest cleaning IACV valve intake screen, iacv valve movement (make sure it opens/closes easily w/ addition of 12V), clean iacv inlet/outlet passages, and clean both sides of throttle plate.

good luck

Have replaced IAC and TCV and it looks like At arm moves when throttle opened, step son had throttle body offf when we pulled engine out to change transmission as original one was bad. When I pulled the code gave and injector code and speed sensor code but we changed speed sensor and it still did same thing. Scracthing my head on this one for sure.

Idle speed is controlled by IACV and combined w/ low idle speed (600 rpm) suggest IACV is not working correctly. If it walks/talks/acts like a duck, it probably is a duck.

good luck

The a/c is inop so dont think that has anything to so with it,when car is in park or nuetral it idles just fine only when it is put in drive or reverse the idle jumps up to 1200 rpm. Stepson tells me sometime at traffic light it will act normal then it starts asting up again.