The other day i was driving and vtec felt like it stopped working. The car just didn't seem to pull as hard as it did before. You could tell the most difference in the higher gears like 3rd and 4th. You could still here the Vtec crossover but it wasn't as noticeable. So today i pulled off the exhaust and ran the car open header. After doing this vtec seemed to work perfectly. The car pulled very hard and wasnt slugish at all. My question is why was vtec not working as well with the exhaust on.

The car is a 200 civic si , the motor is a poor mans type r, the exhaust system is a toda header with test pipe and a 5zigen cat back.

Any ansewers to this would help me alot , I cant drive around open header all the time.

 

What size pipping are you running? I would try to make sure that your exhaust system is cleaned inside and not clogged.

 

Thanks man ill pull the exhaust off again tommorow and check it out

 

Get back with your results, this is interesting.. When I run open header I cannot hear crossover what so ever.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by IDriveAHonda &raquo;</TD></TR><TR><TD CLASS="quote">Get back with your results, this is interesting.. When I run open header I cannot hear crossover what so ever. </TD></TR></TABLE>

Even tho you dont hear the crossover , does your car still kick into vtec?

 

And when i run open header the throttle response is like 10 times better. Its like driving a different car completely.

 

I think it's God trying to tell you to get some killer's.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Kendall &raquo;</TD></TR><TR><TD CLASS="quote">I think it's God trying to tell you to get some killer's.</TD></TR></TABLE>

Maybe so Kendall, I know we talked about it yesterday

 

did you try to save money on gas by switching the regular octane gas!!
PREMIUM is your answere

 

My motor did the same thing when I had clogged a cat. Pulled it off and it ran like a champ.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HATCHingMN &raquo;</TD></TR><TR><TD CLASS="quote">did you try to save money on gas by switching the regular octane gas!!
PREMIUM is your answere </TD></TR></TABLE>

Nope its not my gass , I do run premium I run 95 octane.

 

I checked the pipping today , It wasnt cloged everything looked just fine. Any other suggestions?

 

was the cat clear as well?


or do you have an exhaust leak of some kind?!??!

 

well im not running a cat , just a test pipe. I checked the test pipe aswell and it looked good aswell.

 

TJ isnt the 5Zigen 2 1/4? With your psychotic compression, and cams that is alot being pushed out through some small exhaust. VTEC engagement shouldnt matter though Im stumped

 

oil level up? you arent running into a low oil problem?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HybridHatch88 &raquo;</TD></TR><TR><TD CLASS="quote">TJ isnt the 5Zigen 2 1/4? With your psychotic compression, and cams that is alot being pushed out through some small exhaust. VTEC engagement shouldnt matter though Im stumped</TD></TR></TABLE>

Yeah your right the piping size is a little small for that setup, and i will be fixing that quite soon. But your right again the size should not efect the vtec engagement. I remember when the motor first went in i had to start the car up and run it for a couple days with the stock si exhaust and it had no problems with that exhaust on there.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boostedcivicsir &raquo;</TD></TR><TR><TD CLASS="quote">oil level up? you arent running into a low oil problem?</TD></TR></TABLE>

yeah the oil level is fine, oil pressure switch is good, sending unit is good and still not throwing any vtec codes.

 

i told ya TJ....gotta get the upgraded, sealed, teflon coated muffler bearings.....and some spray cleaner for the kanooten valve....damn thing gets me every time.....

 

anybody else?

 

its your exhaust. Plain and simple. My boy had same problem. Just get a 2 1/4 catback and watch what happens.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 95civicSirCoupe &raquo;</TD></TR><TR><TD CLASS="quote">its your exhaust. Plain and simple. My boy had same problem. Just get a 2 1/4 catback and watch what happens.</TD></TR></TABLE>

Ummm...he already has a 2 1/4 inch catback on the car.

I maintain though, I want to see this car with killers.

 

Also, have you considered swapping the head to a different car and seeing if the problem exists in the different car? You could install the head from the other car and check there as well. It's kind of crazy I know, but it will help us isolate whether it's an electrical problem or a mechanical problem.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by T.J. &raquo;</TD></TR><TR><TD CLASS="quote">

yeah the oil level is fine, oil pressure switch is good, sending unit is good and still not throwing any vtec codes.</TD></TR></TABLE>

try changing the oil....i remember once a friend could not hit vtec after going 6k miles on the same oil...when we drained it, it was pitch black.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Damon &raquo;</TD></TR><TR><TD CLASS="quote">try changing the oil....i remember once a friend could not hit vtec after going 6k miles on the same oil...when we drained it, it was pitch black.</TD></TR></TABLE>

It's a fresh engine with maybe 500 miles on it. Since it's been back running, T.J. has changed the oil at least twice and I've changed it once, hell I even dropped the oil pan out of the damn car after about 250 miles. We can safely say it's not a problem of fresh oil.