I just swapped 2k ITR cams for my stocker gsrs and have found that at 1/2 throttle in 3rd or 4th, right after VTEC engages, i get a sputter, like lack of fuel for maybe 400 rpms, then everything is cool again.. The car pulls hard before and after this and my plugs look fine.. Valve adjustment went fine, everything else is cool, ign. timing is normal, timing belt/cam gear teeth are cool (everything at tdc), everything checks out.. It's just that damn sputter.. I'm hoping it's not detonation, but that's impossible with this info..

I'm running open header, and at first thought it was only backpressure, but then after I caused it to happen again and again, i feel loss of power along with the sputtering sound.. tia

 

You're making this 'sputter' sound more serious than what a VAFC can do to help the power lag at 4400 rpm most of us suffer(ed) when swapping to these cams.

Is installing a VAFC and changing the crossover to 4800-5500 rpm the answer? I hope so. Good luck.

 

Yah, I was hoping this too.. (forgot to mention it).. It's not just a power drop though.. It's like fuel bog, but just can't be in this instance.. Again, the open header can make it out to be more than it is.. Any other sugg's?


[Modified by HKxBlur, 12:18 PM 10/24/2001]

 

boggin is usually from too much fuel. lower fuel press and or setting on the vafc, look at your plugs

 

double check you got the motor at TDC correctly.
you used the one single white line on the crank pulley right?

(not the yellow line in between two red lines... which is about an inch ahead of the TDC white line. using the yellow line would produce a ping/knock.)

~otherwise I am stumped.

 

I think you need to change your VTEC x-over point from stock (4400) to about 5200 rpm to get rid of the bog. This the hidden cost of installing different cams in a GSR: You have to spend $$$ to get a VTEC controller or reprogrammed ECU to set the correct VTEC x-over point.

 

YA GET A v-afc and you should be fine

 

yeah but, why are you at half throttle with vtec engaging? I never engage vtec without my foot on the floor, because if I am going to use it, I want to go fast.

I guess I'm just trying to figure out when the problem occurs for you. Are you saying that you are in vtec in 3rd or 4th gear (both really fast, so you are going either 80 to 120mph) and you are at half throttle? THe bogging ONLY happens in this instance?

What about at WOT (wide open throttle)? Do you have the same problem? Or with regular around the town driving, is there a slight bog at 4500rpm?

Just want to clarify.

Also, do any of you think this might be an OBDII related prob?

Thanks

 

v-afc...up the vtec point

 

I ran them on my GSR. I found the best X-over to be 5.1-5.3K. If you leave it at the stock 4.4, it feels like you hit the brakes (well, almost).

-C

 

V-AFC, V-AFC, V-AFC.

I'm surprised no one has said, "just get a turbo"

The fact that a V-AFC may be needed I am not denying, but I would like a little more clarification around the peculiarity of this problem. I don't want to re-iterate my last post, however, I am curious if this is truly the prob, or just odd driving.

Why doesn't owen_the_soyboy have any hesitating probs with his itr cams? Could it be because its a 1994? which brings me back to my last post again.

and just out of curiosity, 01gsr, how do you know its the v-afc if you don't even have one? (maybe your webpage isn't up to date - not flinging darts, just curious)

 

what I say is from experience. If you don't believe then dyno your GSR before and after Type-R cams without changing the vtec point. You will see the bog he is talking about (and starting at the rpm he mentioned).

 

Hey, i completely believe you, but "seeing" may be "believing," but not necessarily "feeling"

i think its odd to be hanging around in vtec range at hlf throttle. thats it.
i also wonder about this dip, because shops tell me that it doesn't exist until you "see" it on a dyno. What gives?

-confucius-ed

 

I just wanted to know what your doing at VTEC enguagement point at half throttle anyway. Dang bro, when do you shift. Are you the type of person that I scream at as they drive my at 7000 RPM "SHIFT, FOR CHRIST SAKE, SHIFT!"

 

Can we get someone knowledgeable to sort this all out?

 

open header?
holy crap!
try an exhaust and see if that helps. seriously.

open header would cause the loss in power, really will.

 

bwahahha he does do that !!!!

 

If it makes you happy I can "see" it on the dyno chart and "feel" it driving the car

 

Problem is solved.. The 'bogging' and sputter is due to the dip in performance from ~4600 to ~5200.. The ITR cams weren't designed to run at this RPM in VTEC as seen in dyno plots where it dips hard from ~4600-5300, and the solution was raising the vtec crossover to 5300.. I'll post up a link to the proof as soon as I make the page..

In my case, the problem is NOT applicable at wide-open, and I experienced the problems in 2nd getting on clover-leaf freeway entrances where u are going ~45 and are part throttle, and when driving late-night at ~95 in 5th.. Coming back from Immortal's house tonight, I just stayed out of VTEC when cruising ~90..

Again, the main reason I was concerned, and maybe others were not is because I am running open and any difference in output can be herd quite distinctly.. I'm assuming that this is normally overlooked with normal-type exhaust systems since it's not as apparent..

I just about died when I read that.. I'm still smiling.. lol


[Modified by HKxBlur, 1:41 PM 10/27/2001]

 

does the vfac remove the rev limiter???

 

no it doesnt