I recently put a hypertec chip in the car (3.1 auto) with the prom. Since then the car intermittenly has a rough idle and the check engine light comes on. The engine code is 35, which is NOT in my Haynes book. When the engine light comes on I noticed the it is after about 20 min of driving and has always come on while in drive but idling (rough or not). Usually it goes out shortly after while driving/accelerating. Everytime the car is turned off and restarted the light is out. Any ideas?

 

Try re-installing the old eprom and see if the problem goes away. If so, then the Hypertech eprom is hyper-crap.

 

I already tried that and the problem went away. I just wonder why its so random and why the engine code is one I cant find anywhere.

 

Sounds like the eprom was not properly programmed. I had a similar "weird thing" when I didn't quite erase my eprom on one of my old memcals quite long enough. It was erased long enough to look okay, but it didn't quite re-program properly. Could also be the eprom is "partially" erased. Bottom line, the eprom isn't working right and you need to get a new one. Now you know why we call them "Hypercrap".

 

Engine code 35 (DTC 35) is an idle error. The ECM/code can not control the idle speed within a certain range. If your stock chip isn't AZTY1407 (the BCC code) best bet is to get that burned on a chip and use it. It is the latest GM BCC for your vehicle.

RBob.

 

I have been driving the car with the chip just as before and believe it or not the problem seems to be going away. It has a weak idle and it triggers the engine light less frequently. I am going to wait and see if it goes away completely. I will post when its gone or when there is a problem. Thanks.

 

OK with me. . .

RBob.

 

Maybe the idle speed set inside the eprom is off (too high or too low...need to read it off the eprom to be sure). It is not stock after all.

Try adjusting the IAC on the TB down. Possibly the Commanded Idle Speed in th eprom is lower than your IAC will permit and it is giving the error because the IAC is adjusted such that the ECM cannot get to that low of idle speed as set in the Hypertech chip.