i have a 95 eg hatch with a 94 lx motor sohc d16y6 before i droped the motor into my car i drove it first no problems then when i drooped it into my hatch the idle was going up and down i figured it might be my exauhst because its aftermarket it feels like its not getting enough air flow through cuz the piping on the car is 3 inch. i switched the map sensor to a newer 1 and it still did it. i figure if i get a stock exaust it will stop? i dunno help

 

3 in. is probably a little over kill on a stock n/a, lol. but anyways, check/clean your iacv, fitv, check coolant levels and vacuum hoses. If you need help on these, use the search button for how-to's and other threads of the same that will explain these.

 

will do ill write back if problem keeps occuring or if i tried everything that honda tech says then i failed

 

This might be overly obvious.. but have you checked your IACV and FITV?
When improperly fitted, or dirty, these can cause all sorts of havoc on both your idle.. and your warmup process.

also, a 94 lx motor is not a d16y7.. that's a 96-00 civic motor.

3 inch piping and exhaust is way overkill unless you're seriously boosting, even then, your low end power is gonna suck hard. I've never heard of exhaust causing idle problems..

 

well my bad on the d16y7 its a d16 z6 but i bot the shell from a guy that had an ls turbo on it and the iavc shouldnt i just go to a honda mechanic so they can spit the codes out for me? yea 3 inc is an over kill when i drive the car it doesnt give me any power untill 4000 rpm every gear...so i should 1. get the stock exauhst and 2. get the idle problem to the mechanic or its fixable to do so myself.. help

 

iacv and fitv are 95% likely to be your problem if you have a wildly fluctuating idle. I don't know if you kept the iacv and fitv from the other car though... but it could be that something is loose somewhere when you put your car back together.

do a search on here. there are plenty of threads relating to this. Hell, i recently posted in some of them.

Get the stock exhaust. Any junkyard civic will have it.
If you want to get a little power, i would say get the stock piping and put on a slightly bigger muffler.
Any low end torque loss ( from bigger exhausts ) sucks hard on these motors.

****, i put a K&N filter in my car and whoop.. there goes my power below 3krpm