i have a 2000 si, and i suspected the cat was clogged, so i swapped it with a test pipe just to be sure before i spent money on a cat or o2 sensor. Well, with the test pipe in, I no longer have the check engine light, and the car runs 100 times better. Plus the cat was rattling pretty bad so I am pretty sure the cat was the problem. However, now that there are no codes and no CEL, it doesn't seem like vtec is working. before, when i hit 5500 it sounded crazy. super loud, very obvious vtec was on. now, there doesn't seem to be any sound change all the way to 8000. The car seems to pull all the way through, but it doesn't sound like vtec is engaging. Is it possible that the test pipe makes the vtec quieter? I didn't think so, but figured i'd ask if anyone else noticed a change after a test pipe. the other question is how can i tell if vtec is working? Is the only way to hook up a light and go drive it?

thanks in advance.

 

This doesn't sound right. There's a test pipe but no CEL for a secondary O2 sensor?

The test pipe would either have no effect on VTEC sound or make it louder. Not usually quieter. You should be able to hear VTEC on a B16A loud and freaking clear as long as you have an intake or a loud exhaust.

Is the CEL working? Does it initiate when you turn the car on?

 

yes, CEL is working. I agree, i thought the sound would be louder with a test pipe, which is why i am confused. I do have a SRI, so it used to super loud and obvious, now not at all.

When i had the exhaust off, i started the car just to see how it sounded with just the manifold, lol, and i got a code 65 and 67. 65 was secondary o2 sensor heater, 67 is low catalyst efficiency. both make sense as the secondary o2 sensor was disco'd when i ran the car with no exhaust. i've had 67 for a while; that and the poor performance was the reason i put the test pipe in. I re-installed the exhaust with the test pipe, disco'd the batt to clear the codes, then drove it. There is no CEL, but it doesn't sound any different at 6500rpm than it does at 4500rpm.

it's really weird, if vtec wasn't working, wouldn't i get a code for that? or would it depend on why it wasn't working? and yes, i do have oil in the car, i check it every fill up and i just got gas 80 miles ago.

thanks.

 

bump. any ideas? the car seems to run great, just way too quiet for vtec to be working. at least, way more quiet than it has ever been before.

 

ok a little update. just drove home from work and got a CEL. code 67, cat efficiency low, which makes sense since there is no cat. i know that code won't stop vtec from engaging, since i've had that code for months and vtec was fine. so i listened more carefully, and it does sound like something is happening, and it pulls strong all the way through 8k, so i think vtec is working but it's just super quiet now. is it possible that with the cat all clogged, it was creating more back pressure, which somehow caused the noise of the intake to be louder? I don't know, just thinking out loud here, but it sorta makes sense, i guess.

anyway, any thoughts?

 

If it revs to 8000 RPM and pulls consistently without a huge dropoff in the torque curve, then VTEC is working, no matter what it sounds like.

If VTEC wasn't engaging, you'd know it. The car would be a slug over 6500 RPM.

 

thanks, that's kinda my thought as well. appreciate the input.

 

B16As are slow, though. To the inexperienced, it may be hard to tell. I remember when my VSS went out...my car felt super wheezy at high RPMs. But if you hadn't been around the car for a while, you'd just figure it was another slow *** japanese econobox.

err...well...slowER *** japanese econobox. The Si is allready like the world's slowest car or something.

 

lol, hey man, my si is a race car, how dare you call it slow???? jk, yeah it's not a really fast car, but damn it was bad before. no joke, i was pulling away from a light and losing ground to a damn mail truck for pete's sake, it was really bad. running much better now, just need to get a new cat for it and i should be good.

thanks for the help guys, appreciate it.

 

I am also having this problem with my b17. It pulls all the way to 8k but vtec isnt poping like it should. The motor is all stock with an intake. I had a friend pulg his hondata s300 in to my car and it it keeps saying somthing about the ELD code. Could this make vtec not pop?

 

what is the ELD code?

listening more carefully, i can hear a change on mine, it is just super quiet now. i'm not too concerned, as i don't need it super loud, i just want some sort of confirmation it is working. However, I realized this morning that I can spin the tires all the way through to 8k with just a tiny bit of water on the road, and it pulls hard allt he way to 8k, so I think mine is working.

 

the ELD is the electronic load detector. It has nothing to do with VTEC...but without a ELD, the alternator won't charge the battery.