while driving down the interstate the other day i realized my vtec kicks in at 5100-5200 from 3 to 5. I have always been told its 5800 all the way up. Is this normal?

Also, my 5th gear vtec kinda studders for a second when going in. Normal as well?

 

let me see if I get this straight...your Vtec kicks in at 5200 RPM from 3rd gear to 5th gear? Anyway that's about average, VTEC doesn't always kick in the exact same time every time, so don't be worried if it happens at 5800 RPM instead of 5200 or vise versa. Also there is usually a dip in fuel when vtec engages, you can see it on dyno slips a lot, better fuel management should help that though.

 

if you have a 4th gen you should be engauging at a constant rpm, if you have the car at close to WOT, do you have a 4th gen? .

check that you have enough oil, and have you noticed anything since this started happening?

vtec rpm can only be altered if the ThROTTLE position is less than what the ecu thinks is appropriate for vtec, otherwise it is a SET rpm that it engauges, period end of story.

most important thing, what gen prelude do you have

 

Wait a minute, Throttle position is a key factor to VTEC engagement. If your WOT(Wide Open Throttle) it should kick in ~5200 rpm. However, if your slowly accelerating, say at half throttle, it won't kick in until the noted ~5800. So unless your WOT, the VTEC engagement point will fluctuate by a few hundred rpm's.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by H22 VTEC &raquo;</TD></TR><TR><TD CLASS="quote">

Also, my 5th gear vtec kinda studders for a second when going in. Normal as well?</TD></TR></TABLE>

It's a common problem with 4th and 5th gen tranny's
i suggest using gm synchromesh tranny fluid to see if this
will cure your problem

 

yes at wot

1st- 5800
2nd- 5800
3rd- 5100
4th- 5100
5th- 5300ish

just tested

edit: prelittlelude, yes its a fourth gen

 

stock cross over point in the h22a1 is 4900, so on the tach it should appear as if your hitting vtec at around 5k or maybe 5100 depending on how far off your stock one is.

and if you did all these tests at wide open throttle, then there is definatly something wrong. in my car i always hit vtec at 4900 , every gear when at close to or WOT.

try checking this out, https://honda-tech.com/zerothread?id=830163

and has you car always done this? is your car an original vtec, or did you swap?

edit: BTW it is DEFINATLY not 5800, maybe your confusing it with when the IABs open on the GSR

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by prelittlelude &raquo;</TD></TR><TR><TD CLASS="quote"> and has you car always done this? is your car an original vtec, or did you swap?</TD></TR></TABLE>

yes it has always done it, its the original engine.....

edit: ah.....about the whole wot thing, when i first got my car i checked to see if any codes were stored and it did show the tps...could this be a problem?

 

then something is definatly not right.. you should get a buddy with a good video camera and good sound to record you doing some accelerations, and record you tach and the sound ,,

it should always be 4900 when the car is at WOT and properly warmed up,

my only other guess and this is a stab in the dark, is you might have some oil presure problems, and you dont develop enough oil presure until the higher rpms which then the ecu sees fit to alow vtec to engauge.

 

This is also happening to me sometimes. Ill be in 3rd gear about to go into VTEC and ill hear the VTEC get all super loud and such but I wont feel the power until a second later. Also is it a good idea to have a ground on the ECU to the chassis? I thought it already has grounds going to the pinouts.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 94vtecmn &raquo;</TD></TR><TR><TD CLASS="quote">Wait a minute, Throttle position is a key factor to VTEC engagement. If your WOT(Wide Open Throttle) it should kick in ~5200 rpm. However, if your slowly accelerating, say at half throttle, it won't kick in until the noted ~5800. So unless your WOT, the VTEC engagement point will fluctuate by a few hundred rpm's.</TD></TR></TABLE> no it kicks in at 5200 o not at all!!!!!

 

TPS is acting up...replace it and come back to us

 

i have a 93 vtec and my vtec kicks in at 5400 almost everytime, thats what the honda technician says it should kick in, if u do wide open throttle all the way through like stomping it, vtec should stay in vtec mode the whole way b/c it doesn't have enough time to shut off so ur in constant vtec...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by killalude03 &raquo;</TD></TR><TR><TD CLASS="quote">i have a 93 vtec and my vtec kicks in at 5400 almost everytime, thats what the honda technician says it should kick in, if u do wide open throttle all the way through like stomping it, vtec should stay in vtec mode the whole way b/c it doesn't have enough time to shut off so ur in constant vtec...</TD></TR></TABLE>

well unless i shift at 7500, mine falls out of 1st and 2nd.

 

well to my understanding you have 3 stages of vtec right? well if this is true you will sometimes here it before you feel it. my vtec is set at 4300 then a grand later it hits its full potential at 5300 but this is with it tuned on vafc. stock it sounded like an eplosion when it hit and my wheels would chirp/spin sometimes so they set it back and made it take longer to engage because i was losing power when it hit all at once. this is with mods though. i honestly dont know everything about vtec i know how it works and everything but when it comes to its engagement it's kinda weird. my friends b16 n/a is set at 6k the oposite of mine for he raised his and i lowered mine when tuned.

 

IIRC the Prelude uses a dual-stage intake manifold much like the Integra GS-R's B18C1 engine. Don't confuse the sound of the secondary intake runners flipping open with the VTEC system switching cam lobes.

VTEC was designed to be seemless, hence there is minimal sound change when you move onto the other cam lobes.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by H22 VTEC &raquo;</TD></TR><TR><TD CLASS="quote">
when i first got my car i checked to see if any codes were stored and it did show the tps...could this be a problem? </TD></TR></TABLE>

BINGO, TPS thats the problem,

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by LookingForStang &raquo;</TD></TR><TR><TD CLASS="quote"> no it kicks in at 5200 o not at all!!!!!</TD></TR></TABLE>

its actually 4900 or not at all, and thats on a 4th gen

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by killalude03 &raquo;</TD></TR><TR><TD CLASS="quote">i have a 93 vtec and my vtec kicks in at 5400 almost everytime, thats what the honda technician says it should kick in, if u do wide open throttle all the way through like stomping it, vtec should stay in vtec mode the whole way b/c it doesn't have enough time to shut off so ur in constant vtec...</TD></TR></TABLE>

the honda technician is wrong and if i were you i would check my car, or you stock tach is WAY off, and once your in vtec its not until you fall below a ceritan rpm that the soliniod closes agian, and i think it might be 4800, not completely sure its been a while :*( .. but if you don't shift at redline in first its hard to stay in vtec because you fall below that rpm and the solinoid shuts

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jackedcrew &raquo;</TD></TR><TR><TD CLASS="quote">well to my understanding you have 3 stages of vtec right? well if this is true you will sometimes here it before you feel it. my vtec is set at 4300 then a grand later it hits its full potential at 5300 but this is with it tuned on vafc. stock it sounded like an eplosion when it hit and my wheels would chirp/spin sometimes so they set it back and made it take longer to engage because i was losing power when it hit all at once. this is with mods though. i honestly dont know everything about vtec i know how it works and everything but when it comes to its engagement it's kinda weird. my friends b16 n/a is set at 6k the oposite of mine for he raised his and i lowered mine when tuned. </TD></TR></TABLE>

for the sake of simplicity we are not going to get into i-vtec, the vtec on the h22s and b series is 1 stage, high and low cam , thats it. depending on a engines build and configuration certian changes in vtec engaugement and when the IABs open can help horsepower,

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TheGSRGuy &raquo;</TD></TR><TR><TD CLASS="quote">IIRC the Prelude uses a dual-stage intake manifold much like the Integra GS-R's B18C1 engine. Don't confuse the sound of the secondary intake runners flipping open with the VTEC system switching cam lobes.

VTEC was designed to be seemless, hence there is minimal sound change when you move onto the other cam lobes.</TD></TR></TABLE>

thats right, we have a dual stange intake manifold , they secondarys open at 4800 and vtec engauges at 4900 on a stock ecu.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by prelittlelude &raquo;</TD></TR><TR><TD CLASS="quote">
BINGO, TPS thats the problem,
</TD></TR></TABLE>

so even though its not throwing it now, its still bad?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by H22 VTEC &raquo;</TD></TR><TR><TD CLASS="quote">

so even though its not throwing it now, its still bad?</TD></TR></TABLE>

if you ever had a problem with it, then either its a sensor thats going bad is intermitant or has bad wiring. i think that is your problme