Hey everyone i just had a quick question! I just resolved a problem i had with my cars vtec.. Ive never ran this car w/o my vtec controler on. I have always setup the h22 to enage at 5000. the ecu i have in my car i bought off ebay and it was jun chipped i believe like a 5700 or 5900 vtec engagement and what not. Well tonight after figuring out why i was getting a vtec oil pressure code. I took it out for a test drive.. w/o the vafc on! It just didnt seem to roar like it does at 5000 or pull anything like it.... Is this normal and indeed that you can have vtec engage to late? im hoping that there is not something else wrong.

 

never heard of vtec ingaging to late

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HAccord &raquo;</TD></TR><TR><TD CLASS="quote">Hey everyone i just had a quick question! I just resolved a problem i had with my cars vtec.. Ive never ran this car w/o my vtec controler on. I have always setup the h22 to enage at 5000. the ecu i have in my car i bought off ebay and it was jun chipped i believe like a 5700 or 5900 vtec engagement and what not. Well tonight after figuring out why i was getting a vtec oil pressure code. I took it out for a test drive.. w/o the vafc on! It just didnt seem to roar like it does at 5000 or pull anything like it.... Is this normal and indeed that you can have vtec engage to late? im hoping that there is not something else wrong. </TD></TR></TABLE>

Yes, it can be set too late, and you'll feel the dip in power.. Best thing to do is get on a dyno to find the best vtec engagement point. Try and make the line smooth, without a noticeable vtec engagement hump.

Mike

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by sledgehammer &raquo;</TD></TR><TR><TD CLASS="quote">Yes, it can be set too late, and you'll feel the dip in power.. Best thing to do is get on a dyno to find the best vtec engagement point. Try and make the line smooth, without a noticeable vtec engagement hump.e</TD></TR></TABLE>

sledgehammer knows what he's talking about. If it's set too late, you will feel a very noticable dip in power. Find a dyno and get it tuned.

 

Alright... all im going to do it put the vtec controller back on.. And set it back up to engage at 5 or so like factory.. Thats all i was curious to know! I just wanted to make sure.. becuase its set so late that its loosing a bunch of power and it doesnt rev up faster like it did before when vtec was engaging at 5. Does that make sense to you?

 

It makes perfect sense. When the motor is not in VTEC, it uses a short duration, low overlap cam profile that makes good low end power but really starts to drop off at around 5000. So between 5000 and the 5900 that the car was crossing over at, the engine made less power which in turn moved everything at a slower rate causing it to rev slower.

 

no like up untill 5500 or something it has great power but after that it breaks off a bit and when vtec enages at 5900 or so.. it just doesnt have the pull it used to!

 

when i had vtec engage at 5000 the tires would break loose and the vtec would roar and it pulled hard untill 8000.. now when vtec enages there is only a slight noise crossover and it has trouble trying to make it to 8000

 

Find a dyno and get it tuned. It's possible that it had some form of preset tuning that was somehow messed up when you removed it. Or if the car was owned before you with the controller, it's possible that the previous owner had it tuned.

And yes the power curve levels off between about 5000 and 5500 before it starts losing power, but the ideal VTEC engagement point is right at the beginning of that flat spot, in this case at the 5000 rpm mark.

 

ahh your thinking to hard! all i want to know is if you have vtec activate to late.. is it going to loose power on high end?

 

I have a jun chipped ecu also, and the program definately switches vtec too late. I know exactly what you are talking about. Also the jun program also seems to run too rich imo.

 

umm yeah it does! But i see it as its better to be runnin rich than lean! But ok.. im just going to toss the v-afc on and see what happens!