I have an imported 98 Civic Type R, Supercharged 11 psi, Hondata S100 tuned, RC 440 injectors, new correct for S/C spark plugs and wires.

I had it tuned back in March, then changed the header from a tri-y design to an RMF style narrow header. Got tired of the loud HKS exhaust that came with the car and swapped out for a Apexi style WS2 (only used the axle back portion).

When I changed out the axle back, I started hearing what I can only describe as a burble in the exhaust. It'll sound normal then every once in a while it'll have what almost sounds like bass from a sub. like brrrrrrrboombrrrrrrboomboombrrrrrrrrr. lol.

Then I found a problem with the head, the valve seals were going bad and compression in cylinder #4 was down about 20 psi from the others. I took the head in for servicing, replaced all gaskets, seals, resurfaced/cleaned. Replaced headgasket (cometic complete upper kit), gates timing belt/ water pump kit, honda front crank seal, replaced all drive belts including s/c belt with gates v-rib. Did all this with hopes that the weird exhaust sound would also go away.

Well we installed the head and all the other parts back on the car. Runs like a champ once warm, but exhaust sound is still there, and I've found other issues.

Now, along with the exhaust burbling, if the engine isnt warm and I got WOT and enter vtec( anytime i'm over 3k rpm and 5psi) it bogs down really bad (running extremely rich by the wideband A/F gauge). Once warm it doesnt bog at all. Also once warm, if I turn off the car and go to restart it is hard to start. It takes a few seconds of turning the key for it to start up.

I think I need to go back in for a retune since I'm sure the head is flowing better, and the swapping of the header and exhaust will make a difference. But is the tune most likely the cause of my problems? I didn't have a problem starting the car before the head was taken in for service. The guy that installed the head knows his stuff and I'm sure everything was done correctly (I was there helping out). I am going to check everything I can later today and double check all wiring connections and all.

Any ideas welcome, going to be calling my tuner in the morning to setup a time to check/correct the tuning map.

 

No CEL codes lit up...?

 

changing exhaust on an already tuned setup is going to give you problems every time, you have the evidence right in front of you, if your AFR have swung rich, and you have no CEL indicating a problem, that header and axle back exhaust setup has just cost you a ton of power, by reducing flow

 

No cel. And it doesn't feel like a loss of power but I won't know for sure until it's on the dyno. Going to get it up to the tuner this week as soon as he is available.

 

Headed to the tuner in the morning. Will report back!

 

why put a header on that will not be any gain but a loss in HP
s100 is going to struggle with getting a good tune
what plugs did you use?

I have the same car 99 ek9
My Setup:-
EK9 B16BRX all stock super low Ks
LHT modded inlet and s-tube +high flow cooler
Mild ported m62 + stripped rotors
LHT header 3" +3" catback +split into twin at tank then twin 3" to custom mufflers
LS crank pulley, Endyn stepper14%, 4" charger pulley
GRS inlet cam
CTR exhaust cam
68mm Throttle body
ORC 309 clutch
custom sealed CAI 4" from pickup to TB
Hondata s300 + virgin NEW P72

 

Car didn't come with a stock header, had the tri-y that hung really low and scrapped on everything.
Spark plugs are NGK BKR7E's. Have the regular JRSC that's been ported, with a Motorvations motorsports stepper pulley, jrsc upgraded pulley. Exhaust is 2.5 inch with no cat, header is also 2.5inch. The s100 tuned fine the first time, the guy tuning it is well known for tuning jrsc's and is personal friends with Oscar Jackson. Anyhow, sounds like you got a pimp *** setup, I'm jealous!

 

re plugs you will find a big diffrence with BKR7EIX @.28 gap

"sounds like you got a pimp *** setup, I'm jealous!"
thanks
about to retune in a couple of days
will be posting results in JRSC thread

 

Will definitely try those out! And look for your results. Have looked into the Lht stuff and it's on my todo list, just gotta save them Pennies lol.

 

Well he couldn't get to it today. Will be Friday booo..

 

Got it retuned today. It's a hell of a lot smoother now. The fuel map was all over the place due to the narrow header (4-1) and quieter exhaust setup restricting the flow more than the other tri-y and loud as bawls HKS windmaster. Lost 10 hp on the dyno compared to before but I'm still happy with it because its not any where near as loud and embrassing as before lol.

Numbers before were 248hp/160 tq with tri-y and HKS windmaster under the axle catback.

now 238hp/155 tq with Rmf style narrow 4-1 with HKS mid pipe then yonaka motorsports (apexi ws2 knock off) curved piece and over the axle quiet muffler.

the burble is still there but the tuner said it was possibly there before just couldnt hear it because of the loud exhaust, or because of the newly created restriction. Also learned why it was hard to start sometimes, bangs head on something hard. I pressure washed the head after install and apparently the spark plugs didnt seal so well. Had water down in the spark plug hole of cylinder #2. Cleared it out and it does fine now.

Next step will be to find a nice header that will flow better and have good clearance. Still going to keep a quieter exhaust but might have it customized to a 3 inch if it'll fit. until next time I'm happy and good to go. Will be headed to Import Alliance in Nashville tomorrow if anyone else is there look for me!

 

very nice results
3" + short header will gain some numbers back
any chance to see the dyno print out?
even if you pm it to me Id like to see it

myn went in for retune yesterday will be a couple of days

 

I didn't even get a print out this time. Was running way late because people kept coming by the shop. Was supposed to start at 10am, didnt get started until a little after 12pm. Left at like 1:30 pm and its an hour and a half drive away. Had to haul butt to get to my kids school to pick him up lol. I did take a picture of it, will have to get it off my phone though.

The graph was identical as the previous 248 hp run just lower throughout the rpm range because of more restriction. Kind of neat to see, also had the belt slipping at about 8500 rpms until we got it tighten up good.

 

The exhaust is backed up with the changes u made so u need less fuel and air going into the motor cuz u r.restricting it on the exhaust side

 

definitely, the header is the main issue, yeah it looks cool but its not very functional at least for a supercharger. Will be getting another later down the line. Exhaust will stay, but as I said, gonna look into a full 3 inch rather than 2.5 inch like i have.

 

A sticky somewhere on here says .44 gap is really good.

 

not in a supercharged engine

 

Finally found the problem that was causing the exhaust burble in case someone finds this thread and has the same problem. It was caused by the distributor. Apparently sometime the screw holding the rotor on came out and destroyed the inside pretty good. 3 out of 4 points on the head were bent, the rotor itself had broken plastic. Only discovered when the ICM wentout, I assume due to the fact the screw was sitting on it. Anyway, I replaced the whole distributor and now the engine runs great, exhaust note is back to normal. Although now the tune is running really really rich since the tuner had to adjust due to the bad distributor. So another retune is in the future.

Already replaced the header with a Skunk2 Megapower Alpha header and love it. Have a few other plans before i take it back to the tuner to at least get my monies worth lol.

 

any updates been a while