Engine Question

Hey i have a 2005 VFR800 VTEC and i just put Delkevic Headers and Exhausts on so i replaced the entire system. Just got the thing back from the shop cause i got it tuned and now im noticing that when the VTEC kicks in it lags for a second then HITS and every now and then it goes back to the normal kick of the VTEC nice and smooth. what do yall think? just normal since the tune changed it up or what?

 

What exactly do you mean when you say you got it "tuned" ?? Many times when you replace an entire exhaust system including the headers you are required to remap the fuel system to accommodate for the changes. Does your bike have a Power Commander on it? Was the bike Dyno tested?

Rollin

 

yes i have the PC3 on it and i took it to the shop to get it dyno'd

 

Did you do the O2 sensor eliminator and swith the airfilter? Might want to post the graph from the dyno chart so other Guru can chimp in to help.

 

Air filter is on the way and no i did not do the o2 eliminator. i will post the dynos later on when i find them again

 

The lag your getting is a computational quark. The ecu sees the pc3 dumping fuel into the system to maximize the vtec jump. But the ecu knows from its map that it should be running leaner so it cuts the fuel way back causing it to hesitate a bit then as the rpms come up for vtec everything goes back to normal so the ecu just carries on.
The short of it is, to fool the ecu with a pc system you really do need to do the o2 delete mod or the ecu will try to interfere with the pc3 adjustments. You will need a few resistors of at least 0.5watt power rating.

To bad the pc didnt do o2 intervention to get the ecu to do what we want. Would make a way better and more smoother system. But they dont.

 

So the PC3 came with the eliminators but since i replaced the stock headers with catless delkevic headers i didnt know what to do. Ill post the dyno runs later today when i get out of work and if i do the O2 Elims now do i just go back and put the bolts that came on the headers (where the O2 sensors go) back in and take the O2 sensors out and get it remapped?

 

You need to make the ecu think that its at stoic. There is a thread here on o2 eliminating. You must use the resistors to make the ecu think that the o2 sensors are still there. As for the o2 sensor plugs, once your all setup with the resistors just remove the o2 units and plug off the holes.

You will not need a remap unless your tuner was using a dynamic maping method. Best is to talk to him and see if it needs a tweek.

 

When you unplugged the 02 sensors, they are still connected to the bike. So presumably you have the plugs "somewhere" there. The resistors that Zen speaks of 330ohm resistors, available at Radio Shack or similar. Can't find the link on our site, but here's a link to our friends at the other VFR site.

http://www.vfrdiscussion.com/forum/index.php/topic/20350-make-your-own-o2-sensor-eliminators/

My 2000 is catless and I've been running this setup for years without a single hiccup.

 

So the plugs that i recieved when i got the catless headers do i put them back in or should i leave the now unhooked O2 sensor there? i already have the resistors that came with the PC3. Im trying to figure out if i leave the sensor itself in the system or if i should put the plugs back into it. And in you guys opinion should i go back to the shop and have them tweak the map on the PC3 or what.

Rollin_Again, Scubalong, Zen Biker, Pliskin y'all are extremely helpful and i can't thank y'all enough.

 

Take the sensors off and put them in a drawer. If your pc3 came with resistor plugs then use them, they are required. The sensors being connected is telling your ecu that it is very very very lean (not enough fuel).

 

So just to make sure i am getting this correct. Take the left fairing off and disconnect the both O2 sensor connection and place the resisters on and take out the both of the actual sensor from the Y-connecter where the headers connect together. Then put the plug back into the Y- connector in place of the actual O2 sensor?

 

I'm sure one of the experienced guys will respond but in the mean time i'd tell you that you've got it right. I'm anxious to see if this stops the symptoms.

 

Yes your right. This is the fix for pc issues as you are messing with fuel and timing metrics without being kind enough to let the ecu know about it until after. If your going to hog tie and blind fold the ecu, at least make sure it cant smell either.

 

hahahaha that is a hilarious comparison

 

When your taking control of a system, its best if its blind, deaf and dumb. Best option is to make it that way.

 

Wouldn't he have been seen an FI light error if he had a PC III but the O2 elims supplied by PC weren't installed? They ECU and PC would be fighting for control, and thus producing an error, wouldn't they? Oh well. Is it fixed now?

Also, what happened to the dyno results?