I just wanted to let the world know I have a 2001 honda accord 2.3l ex sedan automatic with a H22A4 auto trans swap. I was getting code p1705 and my car was going into a limp mode ( only 2nd and 3rd gear). Anyway I couldn't figure what the hell was going on. I took it to a specialist that worked on car electronics. They had it for a day and said they wanted to take my aftermarket alarm out. They did and it's running better than ever. No more limp mode or anything it's like driving a totally different car. I'm posting this to warn anybody if there thinking about putting a aftermarket alarm system in there car that it might make there car run like crap. Just to be clear I was getting a code p1705 and it was going into limp mode.

 

The alarm itself was most likely not the cause itself. A bad installation can wreak havoc on a cars electrical system. This also goes for aftermarket radio installations.
The alarm was probably tapped onto or piggybacked onto a power and/or ground circuit of the PCM wiring, which would bugger up the electrics.

A properly installed alarm would never affect the running of the car, unless the intended purpose of the alarm system was to interupt power to the fuel pump. injectors, or ignition system(s) to prevent theft.