I installed a 00 jdm integra type r into my 94 civic si this weekend and am having some vtec problems. It sounds like the vtec is kicking in @ 5k like it should but it doesn't pull any harder. I think that it might be the back pressure on my exhaust because where my old exhaust system mates to the integra exhaust (under the firewall) we had to put a temporary connection (two bolts with big washers) so it leaks a pretty good bit. Does this sound like it could be the problem? Also am i going to need to get a bigger radiator? I would like to avoid putting in the integra one because i would have to lose my ac condenser. I also do not have the knock sensor hooked up on my car, but the ecu isn't looking for it because the check engine light isn't coming on could this be why the Vtec isn't working???

 

VTEC is not affected by your exhaust not being hooked up...Mines is not hooked up and when I cross into VTEC around 4.5K RPM I hear difference and notice the RPMs climb up quicker...Do you have any CELs??

 

no there are no CELs

 

If you are certain that VTEC kicks in, the problem may lie deeper...Good Luck...

 

you will know if you are hitting vtec or not. its a very noticable difference. 5k? unless you have a vtec controller it shouldn't hit until like 5600 or so, depending on what ecu

ps depending on your ecu, the knock sensor might need to be connected. mine worked fine without knock sensor but i know others that did.

 

Knock sensor could be the problem, but you should definitely hear the crossover. Check your oil level as well.

What ECU are you using?

 

I am running a JDM OBD1 ECU that i got with the motor from hmotorsonline. The ECU is supposed to be chipped to remove the top speed limiter because i wanted the USDM one that goes 140 mph instead of the JDM one that only goes to 120 or so, and they were out of USDM ones.

 

check oil level...

 

Yesterday I hooked up the knock sensor but that didn't help. There is plenty of oil in the car as well. However, for ***** and giggles i disconnected the chipped ecu that came with my engine and plugged in my old civic ecu. It worked, the vtec kicked in and it hauled ***. I ran it up through 1st and 2nd, then turned around to try it again and nothing, it worked for 5 f*^king seconds and then nothing; what a tease. So now I am back to where i was, does anyone have a clue what is wrong. Another thing that i forgot to mention is that when i first got it running, and the vtec wasn't working, the exhaust note got real loud when the vtec should have kicked in (around 5k rpms). The guy who put the engine in my car, brian, said that it shouldn't be that loud, he said that it shouldn't get much louder. This sounds like it has something to do with the vtec not working because yesterday when it did work for 5 seconds it didn't get loud @5k like brian said should happen. If anyone knows what could be wrong please let me know. Now that i've gotten a taste i want it even worse now.

 

hook up a milti-meter to the vtec wire at the ecu, drive it and see if it reads 12V+ when it should be crossing over. you may have a sticky vtec solenoid.

Landon

 

what exactly is the chipped JDM ecu you have? a P08, P30??? (check the part number sticker on the side of the ecu body).

On a side note..
JDM OBD2 engines don't have a VTEC pressure switch on them. What did you or whoever installed your engine do about this?

 

The ecu is a p30