i have a 96 jdm b18c and vtec kicks in at 5000 rpms on a stock ecu, but at around 4400 a radle starts and gets louder asit aproches 5000 but after that its all vtec. Has anyone ever had this problem?? it sounds as if the radle is coming from inside the motor i have no idea were to start to stry and fix it but it sounds shitty going into vtec i need some help if anyone hass ever had or knows how i could fix this

 

That sounds like detonation.

Quit being a cheap *** and use premium fuel...

 

the VTEC should cut in at 4400rpm on a stock ECU....are you throwing any codes?

 

that doesnt help. ive always used premium and it only started to do this a while after my swap, and its a jdm ecu, it doesnt sound like full vtec until 5000 rpms but from about 4 to 5000 its a radle and it changes as it gets closer to vtec can anyone help me out here, after 5000 its normal operation but the radle is anoying

 

that would be rattle..........not radle...............

 

do you have the stock b18 down pipe? if you do, it might be a RATTLE from the pipes inside the down pipe. this is quite common.

 

Get into your engine bay and make sure all pipes - and other loose **** - are tied down properly! Then maybe give your engine mounts a look. There should be 3 of them I think. Once when i was doing a swap with my friend we notice that this guy was driving around with his Gas filter untied to any bracket. It made a rattling noise and eventually broke his gas line...MEGA DANGEROUS.

 

i do have the stock b18 headers/downpipe, has this ever happened to anyone else?
i had no idea there was a second set of pipes in the down pipe, is there any way to fix besides spending money on new headers? its only right before the vtec engage and disengage point, its a huge anoyance and i wanna fix it but i have hardly no idea were to start i need some expertice......

 

i dont want to start anything with anyone and this will be my only post on this matter. had the same problem slack in the timing belt caused it. a domestic guy noticed it and told me to look at the belt and it was slacking up just as he said. i didnt really think that much about it at the time now my head is fucked. check the timing belt. if it isnt the belt causing problems than ok its something else. but make sure that belt is tight. mine would flap out and smack the cover. and it would have an awful metalic rattling sound. looked all over the car couldnt find anytning else rattle. put a wooden stick to valve cover and when the belt flapped the head rattled.

 

my civic did the same thing ended up being the upper knock sensor it would try to mess with the timing as it went under v-tech.