i just put in a mugan chiped p 28 ecu into nmy buddys 99 si and the thing sounds like the vtec is going to pblow up. the motor has a jg edlebrock intake manifold, AEM CAI, dc 4-2-1 headers, aem fuel rail and fuel filter, aem regulater, venom injectors, vtec controller, msd sport compact box, blaster coil, nology wires, msd cap, greddy evo cat back and know a mugan computer.

when he is driving everything is fine up to around 5000 rpm, when the vtec kicks on the motor sounds like it is running an open header. does anyone know why it might be doing this. he is getting really frustrated and is ready to sell everything and put it back to stock.

good for me if he sells me his parts cheap, but i dont want another honda to go back to stock.

you guys have any ideas?

 

if the problem came about after you installed the p28 into the civic, put the stock ecu back in and see how it runs.

trial and error -- back track the things you installed until you have come to the part that is making that happen.

 

i did, that was the first thing we did but know the problem is still there. i am woried something broke.

the noise seriously sounds like gun fire going off under the hood. it is so loud.

 

and if it makes more power, whats the problem?
people mistake my vtec for a supercharger (but deeper)
the reason i say "my vtec screams like a virgin" because it does.
ill have to get a sound clip.

 

it isnt making any mre power though. it feels like it hits the rev limiter and then backs off. it has plenty of power up until that point

 

yyyeeaahhhhh!!!!!

 

My friends Si does the same type of thing

He has a JUN head a Hondata ECU and all the
usuall bolt ons. His car sounds like a type-R
when it hits Vtec. Your probably getting a lot
more fule due to the Mugen ECU.

 

yikes!

 

is this something to worry about

 

It messing with the timing, and your right, your not making more power, just more noise.

 

we figured out the problem. for some weird reason we noticed black around the header by the head. we pulled the header and the cat and the cat was cmpletly cloged. air must have had a hell of a time getting threw. we inded up just punching it out since it was broken anyways and know it runs like a champ. back presure is a pain in the ***!!!!!!