Need some help: VTEC not engaging

Hey all..

So i installed my J's racing 70RS Ti single exhaust last night. I previously had a skunk2 dual exhaust 70mm on.

As soon as i installed it i took it out for a run. After letting the car warm up to appropriate 3 bar or whatever i tried hitting vtec and it wouldnt engage. It just bounces off like a rev limiter at 6k RPM and cuts the accel.

My theory is that the silencer that came with the exhaust was originally wrongly sized and for a 60mm js exhaust (the hole is TINY and smaller than the pics I looked up online for the 70mm silencer). Maybe there is too much backpressure from the silencer and the ecu is trying to protect the engine and not letting vtec engage?

I can't get the silencer out myself as its stuck in there - planning to go to an exhaust shop tomorrow but i was just wondering if anyone else has ever had this issue?

After looking up some online posts i did find someone with a similar problem (the resolution was they ordered the wrong sized silencer).

My oil levels are fine, car is warm (so its not those common problems).

So final questions:
1. has anyone had similar issues?
2. any recommendations? (I'm planning on resetting ECU as it could just be an AFR issue from going from a dual exhaust to single - this i kinda doubt though...)
3. If it is the excessive backpressure from the silencer, will this damage my engine by driving around with it on?

Thanks all!

The 02 sensors all good?
Back pressure shouldnt cause stop your VTEC from engagement. The J's exhaust with silence will still be less restricitve than a stock exhaust.
Give the ecu a reset. I reckon because the exhaust flows better, the sensors think your leaning out not letting you hit VTEC as a precaution.

Yeah 02 sensor is just on the cat yeah? We didnt touch or knock the cat out of whack to displace the sensor i dont think. I'll give it a quick check later anyway in case.

EDIT: Also, if it was an 02 sensor issue - it would throw a CEL correct?

Hmm yeah i was thinking that too.... well its not as if i was coming from a stock exhaust. I had a skunk2 70mm which should sort of flow similarly to the Js?

reset the ecu and tell us how you go

also check your vtec fluid while you've got the hood open

I will reset the ecu tonight after work and give an update.

and yeah i have checked oil level its all good

I have a pos exhaust that i put on my car to clear epa once. it is clogged up with crap, stock exhaust. it won't hit vtec because of the shit that's in it = too much backpressure or some crap. pretty sure that is your problem.

try something for me, floor it and try to hit vtec, see what revs it cuts at, then *slowly* try to hit vtec, see what revs it cuts at. should rev slightly further if you do it slowly. then again, mine is clogged differently to yours, not with a silencer, so this may not prove anything if it cuts at the same rpm each time.

so it turns out memory did not serve me correctly. the car should still hit vtec with the silencer. mine was correct silencer though so yeh

so yeh, get the silencer out is my advice. as for damaging your car, i've spoken to a few people about it as i had to put the clogged-up stock exhaust on for a couple of days when i was clearing epa. they reckon it won't damage the car at all, i am also of the opinion that it won't damage the car at all as it reved freely so long as i didn't try and hit vtec. but it's pointless as the car is worthless without the top third of it's rev range :P.

inb4 flux capacitor check.

actually blocked exhausts and cats force exhaust gasses past piston rings, taking the oil with it.

Quote:

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Originally Posted by pure_na

I have a pos exhaust that i put on my car to clear epa once. it is clogged up with crap, stock exhaust. it won't hit vtec because of the shit that's in it = too much backpressure or some crap. pretty sure that is your problem.

try something for me, floor it and try to hit vtec, see what revs it cuts at, then *slowly* try to hit vtec, see what revs it cuts at. should rev slightly further if you do it slowly. then again, mine is clogged differently to yours, not with a silencer, so this may not prove anything if it cuts at the same rpm each time.


i run a 70rs ti. if memory serves me correct, it will NOT hit vtec with the silencer installed.

so yeh, get the silencer out is my advice. as for damaging your car, i've spoken to a few people about it as i had to put the clogged-up stock exhaust on for a couple of days when i was clearing epa. they reckon it won't damage the car at all, i am also of the opinion that it won't damage the car at all as it reved freely so long as i didn't try and hit vtec. but it's pointless as the car is worthless without the top third of it's rev range :P.

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Hmm.. i read up on s2ki to see if anyone else ran a 70rs with the silencer they said there was no issue with preventing vtec engaging.

I did try to rev up to it slowly but it seems it cuts off at the same revs (6k rpm just before vtec).

Anyway thanks for the advice. I will be trying to take out the silencer once the exhaust is nice and hot hopefully the metal would have expanded enough to be able to yank it out this time.

And yeah I am still kinda of the cynical opinion that it MAY damage the car so I'm going to try get that bastard of a silencer out ASAP.

This makes me wonder however - why would a tuning company such as Js racing even offer a silencer for retail if it DOES damage the engine when installed? I'm sure there is a reason behind it.....

EDIT: there has also been suggestions that using a slide hammer works pretty well? This is probably going to be my last resort lol

The silencer wpuld expand if it is heated too wouldnt it?

Hopefully when theyre both heated up it'll be a bit easier to wiggle it out with some WD40....

i edited my post. i was wrong. car should hit vtec with silencer.

Quote:

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Originally Posted by pure_na

i edited my post. i was wrong. car should hit vtec with silencer.

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Thanks mate. Not sure if that is good or bad news for me haha. Im resetting ECU now will udpate post later.

Just reset ecu. Drove around to warm car up til 3 bars of temp and tried again. Same problem :(

How olds your oil ?

I have a feel its not related to the silencer

oxy sensor perhaps

do an ecu code scan and see if anything comes up

Oil is less than 1000k km old. Checked levels and colour its all good. This problem occurred straight after the install of the new exhaust. VTEC was fine on the way to my mates house where we installed it.

Haven't got the necessary tool/s for an ecu code scan :(

Check your ECU with a paperclip by shorting the SCS. No tools needed, just a paperclip.
Use this diagram: http://b16a2.kicks-ass.net/diy/pgmfi...-scs-s2000.jpg
Get to the green plug, you will see an adapter with only 2 wires coming into it, short that with your paperclip with your car off, then turn on ignition (but dont start) And watch the engine light.

Meanwhile, id check your oil pressure switch for loose connections, and take the vtec solenoid off and give it a clean. Check for clogs on the screen or leaks through the gasket.. I cant think of anything exhaust related that would mess with vtec..

did you unplug the VTEC Pressure Switch or VTEC Solenoid when you worked on the exhaust ?

did you smack the VTP or VTS with tools and damage them or the wiring ?

Quote:

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Originally Posted by ECU-MAN

did you unplug the VTEC Pressure Switch or VTEC Solenoid when you worked on the exhaust ?

did you smack the VTP or VTS with tools and damage them or the wiring ?

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Didn't go near the solenoid or pressure switch.

What's the VTP or VTS? We didn't go near anything past the cat. And the sensor on the cat was untouched.

VTP = VTEC Pressure Switch
VTS = VTEC Spool

doesn't hurt to check them and the ECU

all sorted guys. removed silencer and vtec is back. Must have been wrong sized silencer for sure.

thanks for all the help!!

car would sound amazing.. why did i buy a jazz for?? :(( lolll

Quote:

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Originally Posted by black8thgen

all sorted guys. removed silencer and vtec is back. Must have been wrong sized silencer for sure.

thanks for all the help!!

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yeah just need to reset ecu think my afr is a bit out of whack

but sounds AWESOMEEEE

ahahaa never too late to sell =P

Wow. A silencer caused all this?

My knowledge of the time and space continuum has went out the window.

yep, previous owner probably got sent or ordered the silencer for the 60rs or something (maybe even for the exhaust of another car such as the jazz or something). The hole for the 70rs PROPER silencer is a bit larger than a 50c piece. The hole in mine was about as big as a 10c piece, creating much much more back pressure than the engine is meant to take probably - hence NO VTEC.

S'all good now

Opinion of the 70RS ?

Can't give much of an opinion yet. Only drove it locally to park the car after picking it up and had to head into work. Will update tonight after i go for a longer drive including a bit of highway travelling.

But so far - awesome. Loud, but awesome.

demand a review!
glads its all good now man

After driving it a fair bit last night both highway and local driving here are some thoughts:

1. It's loud.
2. It sounds great - much nicer sound than the skunk 2 i previously had
3. You better hope you enjoy listening to music relatively loud or it could get annoying.
4. There is some drone at around 3-4k RPM as all users of the 70RS will say - but its bearable, less drone than skunk 2 and cruising at say 90-100km/hr is no where near as bad as skunk2 if you're in 6th.
5. Up top the exhaust sounds very nice though. But I've only got an injen CAI - would prob sound better with a header setup as well. And of course a test pipe will remove the drone but i doubt anyone wants to risk the penalties

Had a fellow s2k owner take me for a ride with the 70RS Ti w/ HFC and headers. It's pretty loud as you say, to the point where my ears were buzzing.

Not sure if it's bearable for me but the sound of this exhaust in VTEC sounds absolutely amazing.